WO2016013001A2

WO2016013001A2 - An "on-demand" self-degrading polymer composition and method thereof

Info

Publication number: WO2016013001A2
Application number: PCT/IL2015/050737
Authority: WO
Inventors: Ariel Givant; Shai GARTY
Original assignee: Tama Plastic Industry; Pillar Investments & Development Ltd
Priority date: 2014-07-22
Filing date: 2015-07-16
Publication date: 2016-01-28
Also published as: WO2016013001A3

Abstract

An "on-demand" self-degrading polymer composition is disclosed comprising a polymer into which a substance is incorporated, the substance being unreactive when dry and forming or releasing an active substance upon exposure to water, the active substance acting to degrade the polymer. In preferred embodiments of the invention, the substance is a mixture of an inorganic superoxide and an inorganic peroxide. In particularly preferred embodiments of the invention, the substance is encapsulated by a material such as a hydrophilic polymer. Methods of manufacture of the composition and of producing a self-degrading polymer composition are disclose.

Description

AN "ON-DEMAND" SELF -DEGRADING POLYMER COMPOSITION AND METHOD

THEREOF

FIELD OF THE INVENTION

[1] This invention relates generally to means and methods for degrading polymers. Specifically, it relates to self-degrading polymer compositions in which a substance is incorporated into a polymer, the substance being unreactive when dry but, upon contact with water, forms or releases a reactive substance that can degrade the polymer.

BACKGROUND OF THE INVENTION

[2] Synthetic polymers are ubiquitous in modem life. Disposal of synthetic polymers and of objects made therefrom is considered to be an issue of major environmental concern, especially since many of the most widely used types of synthetic polymer materials are not biodegradable and have lifetimes of decades or even centuries.

[3] While in some cases, naturally biodegradable polymers can be used, there are still numerous advantages to the use of polymers such as polyalkenes, polyamides, polyurethanes, polyacryales and methacrylates, among many others. The environmental and economic benefits of a system that can degrade such polymers would thus be enormous.

[4] An ideal system would not just degrade polymers into simpler components, but would be a self- degrading system in which all of the components necessary for degradation of the polymer are present in the composition, without any need to add other substances that require special manufacture or purchase when the polymer product is no longer of use. Furthermore, an ideal system would be an "on-demand" system, that is, one in which the start of the degradation process is at least potentially under the control of the consumer. Such a system has not yet been disclosed in the art.

[5] Thus, a system that can perform "on-demand" degradation, particularly oxidative degradation, of polymeric substances that normally degrade on very long time scales (if at all) thus remains a long-felt but unmet need.

SUMMARY OF THE INVENTION

[6] The invention disclosed herein is designed to fulfill this need. An "on-demand" self- degrading composition is disclosed in which a substance that is inert while dry but forms or releases an active substance on contact with water is incorporated into a polymer. The resulting composition is thus stable as long as it is kept dry, but when the substance incorporated into the polymer is exposed to water, the active substance is formed and/or released and reacts with the polymer, thereby degrading it.

[7] It is therefore an object of the present invention to disclose an "on-demand" self- degrading composition, wherein said composition comprises a first polymer and a substance in contact with said first polymer, said substance characterized as being unreactive with said first polymer when dry and as forming and/or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

[8] It is a further object of this invention to disclose the "on-demand" self-degrading composition as defined above, consisting of a first polymer; and a substance in contact with said first polymer, said substance characterized as being unreactive with said first polymer when dry and as forming and/or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

[9] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said contact is direct.

[10] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said contact is indirect.

[11] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said first polymer is a polyalkene. In some embodiments of the invention, said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene. In some preferred embodiments of the invention, said first polymer is high-density polyethylene (HDPE).

[12] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said substance undergoes, upon contact with water, a chemical reaction that yields said reactive substance as a reaction product.

[13] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said reactive substance comprises an oxidizing agent of strength sufficient to at least partially oxidize said first polymer. In some embodiments of the invention, said reactive substance is selected from the group consisting of inorganic superoxide salts, inorganic peroxide salts, chromates, permanganates, mixtures thereof, and combinations thereof. [14] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said substance comprises encapsulated particles, said encapsulated particles comprising said active substance and an encapsulation comprising a protecting / activating agent, and further wherein said encapsulation at least partially decomposes upon contact with water, thereby releasing said reactive substance. In some embodiments of the invention, said active substance is in the form of nanoparticles.

[15] In some embodiments of the invention, said substance comprises other encapsulating geometries, such as fibrous ones, continuous, or non-continuous. In other embodiments of the invention, said reactive substance is mixed with another substance, to generate a construct of any geometry, such as spherical or fibrous, of nanometric, micrometric or even larger dimensions.

[16] In some embodiments of the invention, said encapsulation physically decomposes upon contact with water. In some embodiments of the invention, upon contact with water, said protecting / activating agent undergoes a chemical decomposition reaction, thereby decomposing said encapsulation. In some embodiments of the invention, said substance comprises particles of an oxidizing agent encapsulated by a protecting / activating agent. In some embodiments of the invention, said reactive substance comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some preferred embodiments of the invention, said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide. In some especially preferred embodiments of the invention, said oxidizing agent comprises an approximately 1 :1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some embodiments of the invention, said oxidizing agent is selected from the group consisting of permanganate and dichromate.

[17] In some embodiments of the invention, said encapsulated particles have been compounded into said first polymer. In some embodiments of the invention, said encapsulated particles have been incorporated into said first polymer in the form of a particle- polymer composite material comprising said encapsulated particles compounded into a second polymer. In some preferred embodiments of the invention, said second polymer is selected from the group consisting of polyethylene-poly(ethylene-co -vinyl alcohol) (PE- EVOH) block copolymer; and PE-EVOH with PE grafted with maleic anyhdride. In some preferred embodiments of the invention, said composition comprises about 10% w/w of said particle-polymer composite material. [18] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said substance comprises a material for enhancing penetration of water into said first polymer. In some embodiments of the invention, said material for enhancing penetration of water into said first polymer is selected from the group consisting of hygroscopic materials; materials that increase the porosity of said first polymer; hydrophilic polymers; and materials having a chain-like molecular structure having at least one hydrophilic head and at least one hydrophobic tail.

[19] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said substance comprises a material for enhancing penetration of water into said first polymer. In some embodiments of the invention, said material for enhancing penetration of water into said first polymer is selected from the group consisting of hydrophilic materials that enhance water permeability to said encapsulated particles; hygroscopic materials; materials that increase the porosity of said first polymer; hydrophilic polymers; and materials having a chain-like molecular structure having at least one hydrophilic head and at least one hydrophobic tail. In some embodiments of the invention, said material for enhancing penetration of water into said first polymer performs also as the material encapsulating or being mixed with the reactive substance which, upon contact with water, releases the reactive substance able to at least partially degrade said first polymer.

[20] In some embodiments of the invention, said protecting / activating agent comprises molecules characterized by a hydrophilic end comprising at least one hydrophilic functional group and a hydrophobic end comprising at least one hydrophobic functional group, thereby producing encapsulated particles comprising an exterior surface and an interior volume. In some embodiments of the invention, molecules of said protecting / activating agent are oriented such that said hydrophilic end of said molecules is oriented substantially toward said interior volume and said hydrophobic end of said molecules is oriented substantially toward and/or lies substantially on, said exterior surface. In some preferred embodiments of the invention, said hydrophilic end comprises at least one cationic functional group selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations. In some preferred embodiments of the invention, said hydrophobic end comprises at least one first functional group that can react with at least one second functional group on said hydrophobic end of a molecule of said protecting / activating agent to form at least one covalent bond between atoms of said first functional group and said second functional group. In some embodiments of the invention, both said first functional group and said second functional group each comprise at least one reactive double bond.

[21] In some embodiments of the invention, said protecting / activating agent is selected from the group consisting of methyl(undecan-l l-ol)imidazolium halide, triethyl(undecan-l l- ol)ammonium halide, dioctadecyl di(undecan-l l-ol)ammonium halide, methyl(undecan-l l- methacrylate)imidazolium halide, triethyl(undecan-l l-methacrylate)ammonium halide, and dioctadecyl di(undecan-l l-methaciylate)ammonium halide.

[22] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said composition does not comprise hydrogen peroxide.

[23] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said composition does not comprise any organic peroxides.

[24] It is a further object of this invention to disclose the composition as defined in any of the above, wherein said first polymer is not biodegradable.

[25] It is a further object of this invention to disclose a method for producing an "on-demand" self-degrading composition, wherein said method comprises obtaining a first polymer; and incorporating within said first polymer a substance characterized as being unreactive with said first polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

[26] It is a further object of this invention to disclose such a method, wherein said method consists of obtaining a first polymer and incorporating within said first polymer a substance characterized as being unreactive with said first polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

[27] It is a further object of this invention to disclose such a method for producing an "on- demand" self-degrading composition as defined in any of the above, wherein said substance comprises a material for enhancing penetration of water into said first polymer. In some embodiments of the method, said material for enhancing penetration of water into said first polymer is selected from the group consisting of hygroscopic materials; materials that increase the porosity of said first polymer; hydrophilic polymers; and materials having a chain-like molecular structure having at least one hydrophilic head and at least one hydrophobic tail. [28] It is a further object of this invention to disclose such a method for producing an "on- demand" self-degrading composition as defined in any of the above, wherein said step of incorporating comprises: encapsulating in a protecting / activating agent particles of at least one active substance that is capable of at least partially degrading a first polymer, thereby forming encapsulated particles; and incoiporating said encapsulated particles into said first polymer. In some embodiments of the method, said step of encapsulating particles of at least one active substance comprises encapsulating nanoparticles of said at least one active substance. In some embodiments of the method, said step of incoiporating said encapsulated particles into said first polymer comprises compounding said encapsulated particles into said first polymer. In some embodiments of the method, it further comprises compounding said encapsulated particles into a second polymer, thereby producing a particle-polymer composite material, wherein said step of incorporating said encapsulated particles into said first polymer comprises compounding said particle-polymer composite material into said first polymer. In some embodiments of the method, said step of incorporating comprises compounding said encapsulated particles with a material for enhancing penetration of water into said first polymer, said step of compounding performed prior to said step of incorporating said encapsulated particles into said first polymer. In some preferred embodiments of the invention, said material for enhancing penetration of water into said first polymer is selected from the group consisting of hydrophilic materials that enhance water permeability to said encapsulated particles; hygroscopic materials; materials that increase the porosity of said first polymer; hydrophilic polymers; and materials having a chain-like molecular structure having at least one hydrophilic head and at least one hydrophobic tail. In some embodiments of the method, said hydrophilic head comprises at least one cationic functional group selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations. In some embodiments of the method, said hydrophobic end comprises at least one first functional group that can react with at least one second functional group on said hydrophobic end of a molecule of said protecting / activating agent to form at least one covalent bond between atoms of said first functional group and said second functional group. In some embodiments of the method, both said first functional group and said second functional group each comprise at least one reactive double bond.

[29] In some embodiments of the method, it consists of encapsulating particles of an oxidizing agent in a protecting / activating agent, thereby forming encapsulated particles; compounding said encapsulated particles into a second polymer, thereby producing a particle- polymer composite material; and incorporating said encapsulated particles into said first polymer by compounding said particle-polymer composite material into said first polymer.

[30] It is a further object of this invention to disclose such a method for producing an "on- demand" self- degrading composition as defined in any of the above, wherein said first polymer is a polyalkene. In some embodiments of the method, said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene. In some preferred embodiments of the method, said first polymer is a polyalkene. In some embodiments of the invention, said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene.In some particularly preferred embodiments of the invention, said first polymer is high-density polyethylene (HDPE),

[31] It is a further object of this invention to disclose such a method for producing an "on- demand" self- degrading composition as defined in any of the above, wherein said active substance is an oxidizing agent. In some embodiments of the invention, said oxidizing agent comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some preferred embodiments of the invention, said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide. In some preferred embodiments of the invention, said oxidizing agent comprises an approximately 1 : 1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some embodiments of the invention, said oxidizing agent is selected from the group consisting of permanganate and dichromate. In some embodiments of the invention, said hydrophilic end comprises at least one cationic functional group selected from the group consisting of quaternary anmionium cations, quaternary imidazolium cations, and quaternary phosphonium cations. In some embodiments of the invention, said hydrophobic end comprises at least one first functional group that can react with at least one second functional group on said hydrophobic end of a molecule of said protecting / activating agent to form at least one covalent bond between atoms of said first functional group and said second functional group. In some embodiments of the invention, both said first functional group and said second functional group each comprise at least one reactive double bond.

[32] It is a further objection of this invention to disclose such a method comprising a step of encapsulating as defined in any of the above, wherein said protecting / activating agent is selected from the group consisting of methyl(undecan-l l-ol)imidazolium halide, triethyl(undecan-l l-ol)ammonium halide, dioctadecyl di(undecan-l l-ol) ammonium halide, methyl(undecan- 11 -methacrylate)imidazolium halide, triethyl(undecan- 11 - methacrylate)ammonium halide, and dioctadecyl di(undecan-l l-methacrylate)ammonium halide.

[33] It is a further objection of this invention to disclose such a method comprising a step of encapsulating as defined in any of the above, wherein said step of encapsulating comprises:

[34] preparing a mixture, solution, emulsion, dispersion or suspension comprising:

[35] said particles of said oxidizing agent;

[36] said protecting / activating agent;

[37] in cases in which said protecting / activating agent comprises a polymerizable functional group, at least one substance selected from the group consisting of polymerization initiators and polymerization accelerators; and,

[38] a molar excess of a hydrophobic liquid;

[39] encapsulating said particles of said oxidizing agent within said protecting / activating agent, thereby forming wet encapsulated particles;

[40] in cases in which said protecting / activating agent comprises a polymerizable functional group, reacting said polymerizable functional groups of molecules comprising individual encapsulated particles; and,

[41] drying said mixture, solution, emulsion, or suspension, thereby producing said encapsulated particles.

[42] In some embodiments of the method, said step of incorporating comprises mixing said encapsulated particles and said first polymer. In some embodiments of the method, said step of incorporating comprises incorporating about 10% w/w encapsulated particles relative to the weight of the final product. In some embodiments of the method, said step of compounding comprises preparing a dry mixture of said encapsulated particles in a second polymer; and heating said dry mixture to a temperature selected from the group consisting of its melting point, its softening point, and its processing temperature. In some preferred embodiments of the method, said dry mixture comprises between 0.1% and 20% w/w encapsulated particles. In some especially preferred embodiments of the method, said dry mixture comprises about 10% w/w encapsulated particles. [43] It is a further objection of this invention to disclose a method as defined in any of the above, wherein said method does not comprise any step comprising adding hydrogen peroxide.

[44] It is a further objection of this invention to disclose a method as defined in any of the above, wherein said method does not comprise any step comprising adding an organic peroxide.

[45] It is a further objection of this invention to disclose a method as defined in any of the above, wherein said first polymer is not biodegradable.

[46] It is a further object of this invention to disclose an encapsulated particle, wherein said encapsulated particle comprises a dry inorganic oxidizing agent coated with a protecting / activating agent. In some embodiments of the invention, said encapsulated particle consists of a dry inorganic oxidizing agent coated with a protecting / activating agent. In some embodiments of the invention, said protecting / activating agent comprises molecules characterized by a hydrophilic end comprising at least one hydrophilic functional group and a hydrophobic end comprising at least one hydrophobic functional group, thereby producing encapsulated particles comprising an exterior surface and an interior volume. In some embodiments of the invention, said hydrophilic end comprises a cation selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations. In some embodiments of the invention, said at least one hydrophobic substituent comprises at least one polymerizable functional group. In some preferred embodiments of the invention, said polymerizable functional group is a methacrylate. In some embodiments of the invention, said protecting / activating agent is selected from the group consisting of methyI(undecan-l l-ol)imidazolium halide, triethyl(undecan-l l-ol)ammonium halide, dioctadecyl di(undecan-l l-ol)ammonium halide, methyl(undecan- 11 -methacrylate)imidazolium halide, triethyl(undecan- 11 - methacrylate)ammonium halide, and dioctadecyl di(undecan-l l-methacrylate)ammonium halide. In some embodiments of the invention, said molecules of said protecting / activating agent are oriented such that said hydrophilic end of said molecules is oriented substantially toward said interior volume and said hydrophobic end of said molecules is oriented substantially toward and/or lies substantially on, said exterior surface.

[47] In some embodiments of the invention, said encapsulated particles have been compounded with a material for enhancing penetration of water into a polymer. In some preferred embodiments of the invention, said material for enhancing penetration of water into a polymer is selected from the group consisting of hydrophilic materials that enhance water permeability to said encapsulated particles; materials that increase the porosity of said first polymer; and hydrophilic polymers.

[48] In some preferred embodiments of the encapsulated particles, said oxidizing agent comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some embodiments of the invention, said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide. In some preferred embodiments of the invention, said oxidizing agent comprises an approximately 1:1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt. In some embodiments of the invention, said oxidizing agent is selected from the group consisting of permanganate and dichromate.

[49] It is a further object of the present invention to disclose the use of an encapsulated particle as defined in any of the above in the preparation of an "on-demand" self-degrading composition.

[50] It is a further object of the present invention to disclose a method for degrading a polymer, wherein said method comprises incorporating a substance into said polymer, said substance characterized as being unreactive with said polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said polymer; exposing said substance to water, thereby forming said reactive substance; and reacting said reactive substance with said polymer, thereby degrading it.

[51] It is a further object of the present invention to disclose such a method for degrading a polymer, consisting of incorporating a substance into said polymer, said substance characterized as being unreactive with said polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said polymer; exposing said substance to water, thereby forming said reactive substance; and reacting said reactive substance with said polymer, thereby degrading it.

[52] It is a further object of the invention to disclose a method for degrading a polymer as defined in any of the above, wherein said step of incorporating comprises incorporating particles comprising said active substance encapsulated by a protecting / activating agent.

[53] It is a further object of the invention to disclose a method for degrading a polymer as defined in any of the above, wherem said active substance comprises an oxidizing agent. In some embodiments of the invention, said oxidizing agent comprises an oxidizing agent selected from the group consisting of inorganic superoxide salts, inorganic peroxide salts, chromates, permanganates, mixtures thereof, and combinations thereof,

[54] It is a further object of the invention to disclose a method for degrading a polymer as defined in any of the above, wherein said step of obtaining a composition comprises obtaining a composition made according to the method for making an "on-demand" self- degrading composition as defined in any of the above.

[55] It is a further object of the invention to disclose a self-degrading polymer sheet for covering ground on which plants are growing or are to be grown, comprising a sheet comprising the composition as defined in any of the above or made according to the method as defined in any of the above.

[56] It is a further object of the invention to disclose a self-degrading packaging material for packaging agricultural products, comprising the composition as defined in any of the above or made according to the method as defined in any of the above.

[57] It is a further object of the invention to disclose an article of manufacture comprising the composition as defined in any of the above or made according to the method as defined in any of the above.

[58] It is a further object of the invention to disclose a composition as defined in any of the above, wherein said substance comprises at least two components that have been combined to form a construct. In some embodiments of the invention, the construct is characterized by a geometry selected from the group consisting of spherical and fibrous, In some embodiments of the invention, the construct is characterized by a median size selected from the group consisting of nanometric, micrometric, and larger than micrometric.

[59] It is a further object of the invention to disclose a composition wherein said substance comprises encapsulated particles as defined in any of the above, wherein said substance is characterized by an encapsulating geometry selected from the group consisting of fibrous, continuous, and non-continuous.

[60] It is a further object of the invention to disclose a composition wherein said substance comprises encapsulated particles as defined in any of the above, wherein said substance is characterized by a median size selected from the group consisting of nanometric, micrometric, and larger than micrometric. [61] It is a further object of the invention to disclose a composition comprising wherein said substance comprises encapsulated particles and a material for enhancing penetration of water into said first polymer as defined in any of the above, wherein said protecting / activating agent comprises said material for enhancing penetration of water into said first polymer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[62] In the following description, various aspects of the invention will be described. For the purposes of explanation, specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent to one skilled in the art that there are other embodiments of the invention that differ in details without affecting the essential nature thereof. Therefore the invention is not limited by that which is illustrated in the figure and described in the specification, but only as indicated in the accompanying claims, with the proper scope determined only by the broadest interpretation of said claims.

[63] As used herein, the term "degradation" refers to the decomposition of a complex substance into simpler parts. As a non-limiting example, decomposing a polymer with an average chain length L into units with smaller chain lengths (monomers, oligomers, or polymers with an average chain length L' < L) would be considered "degradation" within the meaning of the term as it is used herein.

[64] The invention herein disclosed provides composition and method for performing "on- demand" degradation of polymers, especially polymers such as polyalkenes that are not normally easily degradable by other methods. Non-limiting examples of polyalkenes that are within the scope of the invention include polyethylene (any type of polyethylene is contemplated by the inventors as being within the scope of the invention), polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene. It is emphasized that the material and system disclosed herein is not limited to use with polyalkenes; it can be used with any type of polymer including polymers that are normally considered to be degradable by other means as well as with polymers that are not normally considered to be degradable by other means but that can in fact degrade via reaction with an appropriate reactive substance such as an oxidizing agent.

[65] Thus, the "on-demand" degrading composition comprises at least a polymer and a substance in contact with the polymer, the substance being unreactive when dry, but which, upon exposure to or contact with water, forms (e.g. by chemical reaction) or releases (e.g. by decomposition of a protective coating) a reactive substance. It is this reactive substance that degrades the polymer.

[66] In some embodiments of the invention, the active substance is an oxidizing agent. In more preferred embodiments of the invention, the oxidizing agent is a mixture of potassium superoxide and sodium peroxide, preferably in an approximately 1 :1 molar ratio. Upon contact with water, this mixture undergoes the following chemical reaction:

leading to oxidative degradation of the polymer. Unlike many peroxide/superoxide systems known in the art, the oxidizing agent is dry; no addition of ¾<¾ (or, for that matter, organic peroxide) is necessary at any point in the production of the composition. In other embodiments of the invention, any appropriate oxidizing agent may be used. Non-limiting examples of other oxidizing agents that can be used include inorganic salts containing peroxide, superoxide, permanganate, or dichromate.

[67] In preferred embodiments of the invention, the "on-demand" degrading composition comprises a polymer into which particles of an oxidizing agent encapsulated by a protecting / activating agent are incorporated. Upon activation by contact with water, the particles release the oxidizing agent, which then degrades the polymer. While the encapsulated particles can cover a broad range of sizes, in preferred embodiments of the invention, nanoparticles are used. The small size of the particles ensures a high surface / volume ratio and hence a more rapid reaction with the activating agent.

[68] In some embodiments of the invention, the protecting / activating agent is a substance characterized by a hydrophilic end and at least one hydrophobic substituent bound to the hydrophilic end. Non-limiting examples of substance used in typical embodiments, the hydrophilic end is a quaternary ammonium, imidazole, or phosphonium ion, and the hydrophobic substituent generally comprises an aliphatic chain. In preferred embodiments, the protecting / activating agent is selected from the group consisting of methyl(undecan-i 1- ol)imidazolium halides, triethyl(undecan-l l-ol)ammonium halides, dioctadecyl di(undecan- l l-ol)ammonium halides, methyl(undecan-l l-methacrylate)imidazolium halides, triethyl(undecan-l 1-methacrylate) ammonium halides, and dioctadecyl di(undecan-l 1- methacrylate)ammonium halides. In more preferred embodiments, bromides are used. The protecting / activating agent may comprise any molecule that has the desired chemical properties. Surfactants, phase-transfer catalysts, and ionic liquids are non-limiting examples of useful protecting / activating agents.

[69] In preferred embodiments of the invention, the protecting / activating agent is oriented such that the hydrophilic end is in the interior of the particle (i.e. closest to the oxidizing agent), while the hydrophobic end is exposed to the environment. The protecting / activating agent thus acts both to shield the oxidizing agent from the environment, as well as to draw the water to the hydrophilic particle center (i.e. where the oxidizing agent is located) when contact with water is made. In the most preferred embodiments of the invention, the protecting / activating agent comprises a hydrophobic substituent that incorporates at or near its terminal end (i.e. the end furthest from the hydrophilic portion of the molecule) at least one polymerizable functional group. The encapsulated particles are formed, as described in detail below, such that the polymerizable functional groups of the molecules encapsulating a single particle of oxidizing agent have reacted to form a polymerized protecting / activating coating around the particle of oxidizing agent.

[70] In the most preferred embodiments of the invention, the encapsulated particles are compounded with a hydrophilic polymer. Since the environment in the interior of the polyalkene is hydrophobic, reaction with water will generally be slow. Compounding of the encapsulated particles with a hydrophilic polymer will thus speed the rate at which water is drawn into the hydrophilic center of the particle. Non-limiting examples of hydrophilic polymers with which the encapsulated particles may be compounded include PE- poly(ethylene-co-vinyl alcohol) (EVOH) block copolymer; and PE-EVOH with PE grafted with maleic anyhdride.

[71] In other embodiments of the invention, the protecting / activating agent is a hydrophilic or hygroscopic material that attracts or absorbs water, thereby wetting the oxidizing agent and activating it.

[72] Articles of manufacture made from the "on-demand" self- degrading composition herein disclosed, or made from materials produced by the methods herein disclosed, are considered by the inventors to be within the scope of the invention. Non-limiting examples include products for agricultural use such as polymer sheets used to cover the ground on which plants are being grown in order to prevent growth of weeds. Sheets made of the composition of the present invention would thus be stable while in use, but as soon as the plants of interest are harvested, the sheets would be rinsed with water and thereby degraded. Similarly, packaging materials for agricultural goods are envisioned by the inventors as being within the scope of the invention. These examples merely scratch the surface of the possible uses to which the compositions and methods of the invention herein disclosed can be put.

EXAMPLES

[73] The following examples are provided to illustrate principles of the manufacture and use of the invention as disclosed herein, and to describe certain embodiments of the invention in order to aid one of ordinary skill in the art to make and use the invention herein disclosed. The examples are illustrative only and are not to be construed as limiting the scope of the invention in any way.

EXAMPLE 1

[74] Methyl(undecan-l l-ol)imidazolium bromide (MI-Cl l-OH) was prepared according to the following procedure.

[75] lOg of 11-bromo-l-undecanol (MW 251.20 g/mol, 0.04 mol) was placed in a 250ml round-bottom flask equipped with a condenser, a magnetic stirrer and CaCl₂ tube. 2.94g of methylimidazole (MW 82.10 g/mol, 0.36 mol) was added to the flask.

[76] The flask was placed in an oil bath of 100°C with stirring at 700 rpm for at least 4 days.

[77] The brown viscous liquid was cooled to 40°C (usually followed by an increase of viscosity or solidification) and 100 ml of dichloromethane was then added. After about 10 minutes, a brown solution was formed and transferred to a 250ml separatory funnel. lOOml of petroleum ether 40-60° was added to the funnel and the two phases were mixed vigorously. The phases were then allowed to and the lower brown phase was transferred to another 250ml separatory funnel. The extraction procedure with petroleum ether was performed once more. Ethyl acetate (100 ml) was then added to the funnel containing the brown dichloromethane solution of methyl(undecan-l l-ol)imidazolium bromide and the two phases were mixed vigorously. After separation of the phases, the lower brown phase was transferred to another 250ml separatory funnel, and the procedure of extraction with ethyl acetate was then performed a second time.

[78] The lower brown solution of methyl(undecan-l l-ol)imidazolium bromide in dichloromethane was separated and the solvent removed in vacuum at 40°C.

EXAMPLE 2

[79] Triethyl(undecan-l l-ol)ammonium bromide (TUAB) was prepared according to the following procedure. [80] 10 g of 11-bromo-l-undecanol (0.04mol) was placed in a 250 ml round-bottom flask equipped with a condenser, a magnetic stirrer and CaCl₂ tube. 5 ml of triethylamine (MW 101.19 g/mol, d=0.7255 g/ml, 0.036 mol) was added to the flask.

[81] The flask was placed in an oil bath at 100°C with stirring at 700 rpm for at least 4 days.

[82] The resulting brown viscous liquid was cooled to 40°C (usually followed by increase of viscosity or solidification) and 100 ml dichloromethane was then added. After around 10 minutes a brown solution formed and was transferred to a 250 ml separatoiy funnel. 100 ml of petroleum ether 40-60° was added to the funnel and the two phases were mixed vigorously. After separation of the phases, the lower brown phase was transferred to another 250 ml separatory funnel. The procedure of extraction with petroleum ether was then performed once more. 100 ml of ethyl acetate was then added to the funnel containing the brown solution of triethyl(undecan-l l-ol)ammonium bromide in CH2CI2 and the two phases were mixed vigorously. After separation of the phases, the lower brown phase was transferred to another 250 ml separatory funnel, and the procedure of extraction with ethyl acetate was then performed a second time.

[83] The lower brown solution of triethyl(undecan-l l-ol)ammonium bromide in dichloromethane was separated and the solvents were distilled in vacuum at 40°C.

EXAMPLE 3

[84] Dioctadecyl di(undacan-l l-ol)ammonium bromide (2(18:11)) was prepared according to the following procedure.

[85] 3.2 g of 11-bromo-l-undecanol (0.013 mol) was placed in a 100 ml round-bottom flask equipped with a condenser, a magnetic stirrer and CaCl₂ tube. 3 g of dioctadecyl amine (MW 521.99 g/mol, 0.006 mol) were added to the flask.

[86] The flask was placed in an oil bath at 100°C with stirring at 700rpm for at least 4 days.

[87] The resulting brown viscous liquid was cooled to 40°C (usually followed by increase of viscosity or solidification), and 35 ml of dichloromethane was then added. After around 10 minutes a brown solution formed and was transferred into a 100 ml separatoiy funnel. 35 ml of petroleum ether 40-60° was added to the funnel and the two phases were mixed vigorously. After separation of the phases, lower brown phase was transferred to another 100 ml separatory funnel, and the procedure of extraction with petroleum ether was performed once more. 35 ml of ethyl acetate was then added to the funnel containing the brown dichloromentane solution of dioctadecyl di(undecan-l l-ol)ammonium bromide, and the two phases were mixed vigorously. After separation of the phases, the lower brown phase was transferred to another 100 ml separatory funnel, and the procedure of extraction with ethyl acetate was then performed a second time.

[88] The lower brown solution of dioctadecyl di(undecan-l l-ol)ammonium bromide in dichloromethane was then separated and the solvent removed in vacuum at 40°C.

EXAMPLE 4

[89] Methacrylation of methyl(undecan-l l-ol)imidazolium bromide was performed according to the following procedure. 11.7 g of 11-bromo-l-undecanol (0.35 mol) was placed in a 250 ml round-bottom flask equipped with a magnetic stirrer to which 50 ml of dichloromethane was then added. After around 10 minutes a brown solution formed.

[90] The flask was placed in a water-ice bath with stirring at 700 rpm, and equipped with a 250 ml dropping funnel. The dropping funnel was fed with 40 ml dichloromethane and 25 ml methacryloyl chloride (MW 104.53 g/mol, d=1.07 g/ml, 0.26 mol). The system was flushed with nitrogen gas, and the content of the dropping funnel was then added dropwise to the round-bottom flask. In some cases, smoke was observed during the addition of the methacryloyl chloride to the methyl(undecan-l l-ol)imidazolium bromide solution; in such cases, the dripping was stopped for 2 minutes. After all of the methacryloyl chloride solution was added to the round-bottom flask the dropping funnel was removed and the round-bottom flask was flushed with nitrogen gas and sealed. The vessel was allowed to warm slowly to room temperature while stirring was continued at 700 rpm for at least 3 days.

[91] At that point the flask was opened and 90 ml of toluene and 7 ml of triethylamine were added. The flask was heated to boiling of the dichloromethane and immediately filtered in vacuum. The filtrate was boiled and filtered again, with addition of 2 ml of triethylamine prior to the additional boiling and filtering. This procedure of boiling and filtering was repeated until no additional residue was formed (7-15 times).

[92] The filtrate was precipitated in 400 ml of petroleum ether 50-60°, filtered under vacuum and kept in a disiccator under vacuum.

EXAMPLE 5

[93] Methyl(undcane-l l-methacrylate)imidazolium bromide was prepared according to the following procedure. [94] 10 g (0.04 mol) 11-bromo-l-undecanol was placed in a 250ml round-bottom flask equipped with a condenser, a magnetic stirrer and CaCl₂ tube. 2.94g of methylimidazole (0.036 mol) was added to the flask.

[95] The flask was placed in an oil bath at 100°C with stirring at 700rpm for at least 4 days.

[96] The brown viscous liquid was cooled to 40°C (usually followed by increase of viscosity or solidification) before 50ml of dichloromethane was added. After around 10 minutes a brown solution formed.

[97] The flask was placed in a water-ice bath and equipped with a 250 ml dropping funnel and magnetic stirring at 700 rpm. The dropping funnel was fed with 40 ml dichloromethane and 25 ml of methacryloyl chloride (0.26 mol). The system was purged with nitrogen before the content of the dripping flask was added to the round-bottom flask dropwise. In case smoke was observed during the addition of the methacryloyl chloride to the methyl(undecan- l l-ol)imidazolium bromide solution the dripping was ceased for 2 minutes. When all the methacryloyl chloride solution was added to the round-bottom flask the dropping funnel was removed, the round-bottom flask was flowed with nitrogen gas and sealed. The vessel was allowed to cool slowly to room temperature while stirring was continued at 700 rpm for at least 3 days.

[98] At this point, the flask was opened and 90 ml of toluene and 7 ml of triethylamine were added. The flask was heated to boiling of the dichloromethane and immediately filtered at vacuum. The filtrate was boiled and filtered again, and then 2 ml of triethylamine was added prior to additional boiling and filtering. This procedure of boiling and filtering was repeated until no additional residue was formed (7-15 times).

[99] The filtrate was precipitated in 400 ml of petroleum ether 50-60°, filtered under vacuum and kept in a disiccator under vacuum.

EXAMPLE 6

[100] Methacrylation of triethyl(undecan-l l-ol)ammonium bromide was performed according to the following procedure,

[101] 12.3 g (0.035 mol) of 1 1-bromo-l-undecanol was placed in a 250 ml round-bottom flask equipped with a magnetic stirrer. 50 ml of dichloromethane was added. After about 10 minutes a brown solution formed. [102] The flask was placed in a water-ice bath and equipped with a 250 ml dropping funnel and magnetic stirring at 700 rpm. The dropping funnel was fed with 40 ml dichloromethane and 25 ml of methacryloyl chloride (0.26 mol). The system was purged with nitrogen before the content of the dripping flask was added dropwise to the round-bottom flask. In some cases, smoke was observed during the addition of the methacryloyl chloride to the triethyl(undecan-l l-ol)ammonium bromide solution; in these cases, the dripping was stopped for 2 minutes. When all the methacryloyl chloride solution was added to the round-bottom flask the dropping funnel was removed, the round-bottom flask was purged with nitrogen gas and sealed. The vessel was allowed to warm slowly to room temperature while stirring was continued at 700 rpm for at least 3 days.

[103] At that point the flask was opened and 90 ml of toluene and 7 ml of triethylamine were added. The flask was heated to boiling of the dichloromethane and immediately filtered under vacuum. The filtrate was boiled and filtered again, and then 2 ml of triethylamine was added prior to additional boiling and filtering. This procedure of boiling and filtering was rehearsed until no additional residue was formed (7-15 times).

[104] The filtrate was precipitated in 400 ml of petroleum ether 50-60°, filtered under vacuum and kept in a disiccator under vacuum.

EXAMPLE 7

[105] Triethyl(undecan-1 1 -methacrylate)ammonium bromide was prepared according to the following procedure.

[106] 10 g (0.04 mol) 11-bromo-l-undecanol was placed in a 250 mi round-bottom flask equipped with a condenser, a magnetic stirrer and CaCl₂ tube. 5 ml (0.036 mol) triethylamine was then added to the flask.

[107] The flask was then placed in an oil bath at 100 °C with stirring at 700 rpm for at least 4 days.

[108] The brown viscous liquid was cooled to 40 °C (usually followed by increase of viscosity) and 50ml of dichloromethane was then added. After around 10 minutes a brown solution was accepted.

[109] The flask was placed in a water-ice bath and equipped with a 250 ml dropping funnel and magnetic stirring at 700 rpm. The dropping funnel was fed with 40 ml dichloromethane and 25 ml methacryloyi chloride (0.26mol). The system was purged with nitrogen before the content of the dripping flask was added dropwise to the round-bottom flask. In some cases, smoke was observed during the addition of the methacryloyi chloride to the triethyl(undecan-

I l-ol)ammonium bromide solution; in these cases, the dripping was stopped for a 2 minutes. When all the methacryloyi chloride solution was added to the round-bottom flask the dropping funnel was removed, the round-bottom flask was purged with nitrogen gas and sealed. The vessel was allowed to heat slowly to room temperature while stirring was continued at 700 rpm for at least 3 days.

[110] At this point, the flask was opened and 90 ml of toluene and 7 ml of triethylamine were added. The flask was heated to boiling of the dichloromethane and immediately filtered at vacuum. The filtrate was boiled and filtered again, and 2 ml of triethylamine was added prior to additional boiling and filtering. This procedure of boiling and filtering was repeated until no additional residue was formed (7-15 times).

[111] The filtrate was precipitated in 400 ml of petroleum ether 50-60°, filtered under vacuum and kept in a disiccator under vacuum.

EXAMPLE 8

[112] Dioctadecyl di(undecan-l l-methacryiate)ammonium bromide was performed by methacrylation of dioctadecyl, di(undecan-l l-ol)ammonium bromide according to the following procedure.

[113] 5.6 g dioctdecyl di(undecan-l l-ol)ammonium bromide (MW 942 g/mol, 0.006 mol) was placed in a 100 ml round-bottom flask equipped with a magnetic stirrer. 30 ml of dichloromethane was added. After around 10 minutes a brown solution formed.

[114] The flask was placed in a water-ice bath and equipped with a 250 ml dropping funnel and magnetic stilting at 700 rpm. The dropping funnel was fed with 15 ml dichloromethane and 7.5 ml (0.08 mol) methacryloyi chloride. The system was purged with nitrogen before the content of the dripping flask was added to the round-bottom flask dropwise. In some cases, smoke was observed during the addition of the methacryloyi chloride to the triethyl(undecan-

I I -ol)ammonium bromide solution; in these cases, the dripping was stopped for 2 minutes. When all the methacryloyi chloride solution was added to the round-bottom flask, the dropping funnel was removed, the round-bottom flask was purged with nitrogen gas and sealed. The vessel was allowed to warm slowly to room temperature while stirring was continued at 700 rpm for at least 3 days. [115] At this point, the flask was opened and 30 ml of toluene and 2 ml of triethylamine were added. The flask was heated to boiling of the dichloromethane and immediately filtered at vacuum. The filtrate was boiled and filtered again, and then 0.5 ml of triethylamine was added prior to additional boiling and filtering. This procedure of boiling and filtering was rehearsed until no additional residue was formed (7-15 times).

[116] The filtrate was precipitated in 400 ml of petroleum ether 50-60°, filtered under vacuum and kept in a disiccator under vacuum.

EXAMPLE 9

[117] Degradation of HDPE by SPO in solution was performed according to the following procedure.

[118] 3 g HDPE was placed in a 500 ml round-bottom flask equipped with a condenser and a magnetic stirrer. 225 ml xylenes was added to the flask and heated to 140 °C (reflux) in an oil bath while stirring at 700 rpm. After 10-30 minutes the HDPE was completely dissolved.

[119] A saturated solution of K0₂ and Na₂0₂ in DMSO was prepared by placing 0.4g of potassium dioxide (71.1 g/mol, 0.0056 mol) and 0.4g of crushed sodium peroxide (77.98 g/mol, 0.005 lmol) in a glass vessel, adding 20 ml extra dry DMSO, and stirring until no more salt dissolved. In a separate vessel, 2 g quaternary ammonium surfactant containing at least one hydroxyl chemical functional group, e.g. methyl(undecan-l l-ol)imidazolium bromide, triethyl(undecan- 11 -ol)ammonium bromide, dioctadecyl, di(undecan- 11 -ol)ammonium bromide was dissolved in 5 ml 1,4-dioxane and the surfactant solution was then added to the glass vessel.

[120] The liquid content of the glass vessel was added dropwise to the round-bottom flask containing the HDPE solution. Afterwards the heating of the oil bath was turned off, and the round-bottom flask was allowed to cool spontaneously to room temperature and left to mix for 1 week.

[121] At this point, the content of the round-bottom flask was precipitated in 300 ml of petroleum ether 40-60° and the solids were filtered in vacuum.

EXAMPLE 10

[122] The following procedure was used to degrade an increased amount of HDPE by SPO in solution. [123] 3 g HDPE was placed in a 500 ml round-bottom flask equipped with a condenser and a magnetic stirrer. 225 ml xylenes was added to the flask and heated to 140 C (reflux) in an oil bath while stimng at 700 rpm. After 10-30 minutes the HDPE was completely dissolved.

[124] A saturated solution of K0₂ and Na₂0₂ in DMSO was prepared by placing 2.4 g K0₂ and (0.034mol) and 2.4 g crushed Na₂0₂ (0.03 lmol) in a glass vessel. 100 ml of extra dry DMSO was added to the vessel and stirred until no more salt dissolved. In a separate vessel, 2 g quaternary ammonium surfactant containing at least one hydroxy! chemical functional group, e.g. methyl(undecan-l l-ol)imidazolium bromide, triethyl(undecan-l l-ol)ammonium bromide, dioctadecyl, di(undecan-l l-oi)ammonium bromide was dissolved in 40 ml of 1,4- dioxane and the resulting solution added to the K0₂/Na₂0₂ solution.

[125] The liquid content of the glass vessel was added dropwise to the round-bottom flask containing the HDPE solution. The oil bath was then set to 40°C and left to mix for 1 week.

[126] At that point the content of the round-bottom flask was precipitated in 300ml of petroleum ether 40-60° and the solids were filtered in vacuum.

EXAMPLE 11

[127] The following example provides a procedure for degradation of HDPE with permanganate in solution,

[128] 2 g of HDPE was placed in a 500 ml round-bottom flask equipped with a condenser and a magnetic stirrer. 120 ml xylenes was added to the flask and heated to 140 °C (reflux) in an oil bath with stimng at 700 rpm. After 10-30 minutes the HDPE was completely dissolved.

[129] A saturated solution of KMn0₄ in DMSO was prepared by placing 0.8 g of potassium permanganate (MW 158 g/mol, 0.005 mol) in a glass vessel, adding 20 ml extra dry DMSO, and the mixture stirred until no more KMn0₄ dissolved. In a separate container, 2.2 g of BMIM (l-butyl-3-methyl imidazolium chloride, MW 174.67 g/mol, 0.013 mol) was dissolved in 10 ml of 1,4-dioxane and added to the glass vessel.

[130] The liquid content of the glass vessel was added dropwise to the round-bottom flask containing the HDPE solution and left to mix for 1 week.

[131] At that point the content of the round-bottom flask was precipitated in 300 ml of petroleum ether 40-60° and the solids were filtered in vacuum. EXAMPLE 12

[132] The following example provides a procedure for the degradation of HDPE by dichromate in solution.

[133] 2 g of HDPE was placed in a 500 ml round-bottom flask equipped with a condenser and a magnetic stirrer. 120 ml xylenes was added to the flask and heated to 140 °C (reflux) in an oil bath with stilling at 700 ipm. After 10-30 minutes the HDPE was completely dissolved.

[134] A saturated solution of K₂Cr₂0₇ was prepared by placing 0.8 g of potassium dichromate (MW 294.2 g/mol, 0.0027 mol) in a glass vessel, adding 20ml of extra dry DMSO, and stirring until no more K₂Cr₂0₇ dissolved. 2.2 g of BMIM (0.013 mol) was dissolved in 10 ml of 1,4-dioxane and added to the glass vessel.

[135] The liquid content of the glass vessel was added dropwise to the round-bottom flask containing the HDPE solution and left to mix for 1 week.

[136] At that point the content of the round-bottom flask was precipitated in 300ml of petroleum ether 40-60° and the solids were filtered in vacuum.

EXAMPLE 13

[137] Polymer-coated SPO nano-packages were prepared according to the following procedure.

[138] A saturated solution of K0₂ and Na₂0₂ in DMSO was prepared by placing 1 g of potassium dioxide (0.014 mol) and 1 g of crushed sodium peroxide (0.013mol) in a glass vessel, adding 15 ml of extra dry DMSO, and stirring until no further salt was dissolved. In a separate container, 7.4 g of quaternary ammonium surfactant containing at least one methacrylate chemical functional group, e.g. methyl(undecan-l l-methacrylate)imidazolium bromide, triethyl(undecan-l l-methacrylate)ammonium bromide, dioctadecyl, di(undecan-l l- methacrylate)arnmonium bromide) was dissolved in a mixture of 10 ml extra dry dimethylsulfoxide and 10 ml 1,4-dioxane and the surfactant solution added to K0₂/Na₂0₂ solution. 1 g of benzoyl peroxide (BPO) was then added to the glass vessel and dissolved.

[139] The liquid content of the glass vessel was added dropwise to a 250 ml round-bottom flask containing 50 ml of xylenes and freshly dissolved BPO at 100 °C. The SPO solution was added with stirring at 700 rpm. Afterwards the slurry was left 30-60 min to mix at 100 °C, then cooled to 4 °C and centrifuged at 2000 ipm for 8 minutes. The upper liquid was rinsed and the solid residue was dried in a desiccator under vacuum. EXAMPLE 14

[140] Polymer-coated SPO in HDPE was prepared according to the following procedure.

[141] A slurry of polymer-coated SPO (e.g. coated with methyl(imdecan-l l- methacrylate)imidazoIium bromide, triethyl(imdecan-l l-methacrylate) ammonium bromide, dioctadecyl di(undecan-l l-methacrylate)ammonium bromide) in dioxane was prepared (0.01 g-0.3g polymer- coated SPO in 20 ml dioxane). The slurry was added to a solution of 1 g HDPE in 100 ml xylene at 140°C, then precipitated in 200 ml of petroleum ether 40°C-60°C.

EXAMPLE 15

[142] A second procedure for preparing polymer-coated SPO in HDPE was performed as follows.

[143] 40 g of HDPE were mixed with up to 2g of polymer-coated SPO (e.g. coated with methyl(undecan-l 1 -methacrylate)imidazolium bromide, triethyl(undecan-l 1- methacryiate)ammonium bromide, dioctadecyl di(undecan-l l-methacrykte)ammonium bromide). The mixture was flowed through a microcompounder at 260°C.

EXAMPLE 16

[144] An HDPE blend with a hydrophilic polymer solvent cast was prepared according to the following procedure.

[145] 1 - 1.5 g of Polyvinyl alcohol (PVA) co-ethylene (27% ethylene) was dissolved in 30ml-35ml of DMSO and 10 - 15 mol 1,4-dioxane. In a separate vessel, 3.5 - 4 g HDPE 4080 was dissolved in 200 ml of xylene at 140°C. The two solutions were combined and then precipitated in 600 ml of petroleum ether 40°C-60°C.

EXAMPLE 17

[146] A polymer-coated SPO in HDPE blend with a hydrophilic polymer solvent cast was prepared according to the following procedure.

[147] A solution of polyvinyl alcohol (PVA) co-ethylene (27% ethylene) in a DMSO / 1,4- dioxane mixture was prepared (0.75 g - 2.5 g PVA co-ethylene, 30 ml DMSO, 10 ml 1.4- dioxane). In a separate container, HDPE 4080 (5 g-6.5 g) was dissolved in 200 ml xylene at 140 °C, and 0.375 g of polymer- coated SPO (e.g. coated with methyl(undecan-l l- methacrylate)imidazolium bromide, triethyl(undecan-l 1 -methacrylate)ammonium bromide, dioctadecyl di(undecan-l l-methacrylate)ammonium bromide) was added. The two solutions were combined and then precipitated in 600 ml of petroleum ether 40°C-60°C.

Claims

CLAIMS We claim:

1. An "on-demand" self-degrading composition, wherein said composition comprises:

a first polymer; and,

a substance in contact with said first polymer, said substance characterized as being unreactive with said first polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

2. The "on-demand" self-degrading composition according to claim 1, consisting of:

a first polymer; and,

3. The composition according to either one of claims 1 or 2, wherein said contact is direct.

4. The composition according to either one of claims 1 or 2, wherein said contact is indirect.

5. The composition according to either one of claims 1 or 2, wherein said first polymer is a polyalkene.

6. The composition according to claim 5, wherein said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene,

7. The composition according to claim 6, wherein said first polymer is high-density polyethylene (HDPE).

8. The composition according to either one of claims 1 or 2, wherein said substance undergoes, upon contact with water, a chemical reaction that yields said reactive substance as a reaction product.

9. The composition according to either one of claims 1 or 2, wherein said reactive substance comprises an oxidizing agent of strength sufficient to at least partially oxidize said first polymer.

10. The composition according to claim 9, wherein said reactive substance is selected from the group consisting of inorganic superoxide salts, inorganic peroxide salts, chromates, permanganates, mixtures thereof, and combinations thereof.

11. The composition according to either one of claims 1 or 2, wherein said substance comprises encapsulated particles, said encapsulated particles comprising said active substance and an encapsulation comprising a protecting / activating agent, and further wherein said encapsulation at least partially decomposes upon contact with water, thereby releasing said reactive substance.

12. The composition according to claim 11, wherein said active substance is in the form of nanoparticles.

13. The composition according to claim 11, wherein said encapsulation physically decomposes upon contact with water.

14. The composition according to claim 11, wherein, upon contact with water, said protecting / activating agent undergoes a chemical decomposition reaction, thereby decomposing said encapsulation.

15. The composition according to claim 11, wherein said substance comprises particles of an oxidizing agent encapsulated by a protecting / activating agent.

16. The composition according to claim 15, wherein said reactive substance comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt.

17. The composition according to claim 16, wherein said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide.

18. The composition according to claim 16, wherein said oxidizing agent comprises an approximately 1 : 1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt.

19. The composition according to claim 11, wherein said oxidizing agent is selected from the group consisting of permanganate and dichromate,

20. The composition according to claim 11, wherein said encapsulated particles have been compounded into said first polymer.

21. The composition according to claim 11, wherein said encapsulated particles have been incorporated into said first polymer in the form of a particle -polymer composite material comprising said encapsulated particles compounded into a second polymer.

22. The composition according to claim 21, wherein said second polymer is selected from the group consisting of polyethylene-poly(ethylene-co -vinyl alcohol) (PE-EVOH) block copolymer; and PE-EVOH with PE grafted with maleic anyhdride.

23. The composition according to claim 22, wherein said composition comprises about 10% w/w of said particle-polymer composite material.

24. The composition according to either one of claims 1 or 2, wherein said substance comprises a material for enhancing penetration of water into said first polymer.

25. The composition according to claim 24, wherein said material for enhancing penetration of water into said first polymer is selected from the group consisting of:

hygroscopic materials;

materials that increase the porosity of said first polymer;

hydrophilic polymers; and,

materials having a chain-like molecular structure having at least one hydrophilic head and at least one hydrophobic tail.

26. The composition according to claim 11, wherein said substance comprises a material for enhancing penetration of water into said first polymer.

27. The composition according to claim 26, wherein said material for enhancing penetration of water into said first polymer is selected from the group consisting of:

hydrophilic materials that enhance water permeability to said encapsulated particles; hygroscopic materials;

materials that increase the porosity of said first polymer;

hydrophilic polymers; and,

28. The composition according to claim 11, wherein said protecting / activating agent comprises molecules characterized by a hydrophilic end comprising at least one hydrophilic functional group and a hydrophobic end comprising at least one hydrophobic functional group, thereby producing encapsulated particles comprising an exterior surface and an interior volume.

29. The composition according to claim 28, wherein molecules of said protecting / activating agent are oriented such that said hydrophilic end of said molecules is oriented substantially toward said interior volume and said hydrophobic end of said molecules is oriented substantially toward and/or lies substantially on, said exterior surface.

30. The composition according to claim 28, wherein said hydrophilic end comprises at least one cationic functional group selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations.

31. The composition according to claim 28, wherein said hydrophobic end comprises at least one first functional group that can react with at least one second functional group on said hydrophobic end of a molecule of said protecting / activating agent to form at least one covalent bond between atoms of said first functional group and said second functional group.

32. The composition according to claim 31, wherein both said first functional group and said second functional group each comprise at least one reactive double bond.

33. The composition according to claim 11, wherein said protecting / activating agent is selected from the group consisting of methyl (undecan-1 l-ol)imidazolium halide, triethyl(undecan-l 1- oI)ammonium halide, dioctadecyl di(undecan-l l-ol)ammomum halide, methyl(undecan~l l- methacrylate)imidazolium halide, triethyl(undecan-l l-methacrylate)ammonium halide, and dioctadecyl di(undecan- 11 -methacrylate)ammonium halide.

34. The composition according to either one of claims 1 or 2, wherein said composition does not comprise hydrogen peroxide.

35. The composition according to either one of claims 1 or 2, wherein said composition does not comprise any organic peroxides.

36. The composition according to either one of claims 1 or 2, wherein said first polymer is not biodegradable.

37. A method for producing an "on-demand" self-degrading composition, wherein said method comprises:

obtaining a first polymer; and,

incorporating within said first polymer a substance characterized as being unreactive with said first polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said first polymer.

38. The method according to claim 37, wherein said method consists of:

obtaining a first polymer; and,

39. The method according to either one of claims 37 or 38, wherein said substance comprises a material for enhancing penetration of water into said first polymer.

40. The method according to claim 39, wherein said material for enhancing penetration of water into said first polymer is selected from the group consisting of:

hygroscopic materials;

materials that increase the porosity of said first polymer;

hydrophilic polymers; and,

41. The method according to either one of claims 37 or 38, wherein said step of incorporating comprises:

encapsulating in a protecting / activating agent particles of at least one active substance that is capable of at least partially degrading a first polymer, thereby forming encapsulated particles; and,

incorporating said encapsulated particles into said first polymer.

42. The method according to claim 41, wherein said step of encapsulating particles of at least one active substance comprises encapsulating nanoparticles of said at least one active substance.

43. The method according to claim 41, wherein said step of incorporating said encapsulated particles into said first polymer comprises compounding said encapsulated particles into said first polymer.

44. The method according to claim 41, comprising compounding said encapsulated particles into a second polymer, thereby producing a particle-polymer composite material, wherein said step of incorporating said encapsulated particles into said first polymer comprises compounding said particle-polymer composite material into said first polymer.

45. The method according to claim 41, wherein said step of incorporating comprises compounding said encapsulated particles with a material for enhancing penetration of water into said first polymer, said step of compounding performed prior to said step of incorporating said encapsulated particles into said first polymer.

46. The method according to claim 45, wherein said material for enhancing penetration of water into said first polymer is selected from the group consisting of:

materials that increase the porosity of said first polymer;

hydrophilic polymers; and,

47. The method according to claim 41, wherein said method consists of:

encapsulating particles of an oxidizing agent in a protecting / activating agent, thereby forming encapsulated particles;

compounding said encapsulated particles into a second polymer, thereby producing a particle-polymer composite material; and,

incorporating said encapsulated particles into said first polymer by compounding said particle-polymer composite material into said first polymer.

48. The method according to any one of claims 37 or 38, wherein said first polymer is a polyalkene.

49. The method according to claim 48, wherein said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene.

50. The method according to claim 49, wherein said first polymer is high-density polyethylene (HDPE).

51. The method according to claim 41, wherein said first polymer is a polyalkene.

52. The method according to claim 51, wherein said first polymer is selected from the group consisting of polyethylene, polypropylene, copolymers comprising polyethylene, and copolymers comprising polypropylene.

53. The method according to claim 52, wherein said first polymer is high-density polyethylene (HDPE).

54. The method according to either one of claims 37 or 38, wherein said active substance is an oxidizing agent.

55. The method according to claim 54, wherein said oxidizing agent comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt.

56. The method according to claim 55, wherein said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide.

57. The method according to claim 55, wherein said oxidizing agent comprises an approximately 1 : 1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt.

58. The method according to claim 54, wherein said oxidizing agent is selected from the group consisting of permanganate and dichromate.

59. The method according to claim 41, wherein said active substance is an oxidizing agent.

60. The method according to claim 59, wherein said oxidizing agent comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt.

61. The method according to claim 60, wherein said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide.

62. The method according to claim 60, wherein said oxidizing agent comprises an approximately 1 :1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt.

63. The method according to claim 59, wherein said oxidizing agent is selected from the group consisting of permanganate and dichromate.

64. The method according to claim 41, wherein said step of encapsulating comprises encapsulating said particles in a protecting / activating agent comprising molecules characterized by a hydrophilic end comprising at least one hydrophilic functional group and a hydrophobic end comprising at least one hydrophobic functional group, thereby producing encapsulated particles comprising an exterior surface and an interior volume.

65. The method according to claim 64, wherein said step of encapsulating comprises encapsulating said particles in said protecting / activating agent such that said hydrophilic end of said molecules is oriented substantially toward said interior volume and said hydrophobic end of said molecules is oriented substantially toward and/or lies substantially on, said exterior surface.

66. The method according to claim 64, wherein said hydrophilic end comprises at least one cationic functional group selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations.

67. The method according to claim 64, wherein said hydrophobic end comprises at least one first functional group that can react with at least one second functional group on said hydrophobic end of a molecule of said protecting / activating agent to form at least one covalent bond between atoms of said first functional group and said second functional group.

68. The method according to claim 64, wherein both said first functional group and said second functional group each comprise at least one reactive double bond.

69. The method according to claim 41, wherein said protecting / activating agent is selected from the group consisting of methyl(undecan-l l-ol)imidazolium halide, triethyl(undecan-l l- ol)ammonium halide, dioctadecyl di(undecan-l l-ol)ammonium halide, methyl(undecan-l l- methacrylate)imidazolium halide, triethyl(undecan-l l-methacrylate)ammonium halide, and dioctadecyl di(undecan-l l-methacrylate)ammonium halide.

70. The method according to claim 41, wherein said step of encapsulating comprises:

preparing a mixture, solution, emulsion, dispersion or suspension comprising: said particles of said oxidizing agent;

said protecting / activating agent;

in cases in which said protecting / activating agent comprises a polymerizable functional group, at least one substance selected from the group consisting of polymerization initiators and polymerization accelerators; and,

a molar excess of a hydrophobic liquid;

encapsulating said particles of said oxidizing agent within said protecting / activating agent, thereby forming wet encapsulated particles;

in cases in which said protecting / activating agent comprises a polymerizable functional group, reacting said polymerizable functional groups of molecules comprising individual encapsulated particles; and,

drying said mixture, solution, emulsion, or suspension, thereby producing said encapsulated particles.

71. The method according to claim 70, wherein said step of incorporating comprises mixing said encapsulated particles and said first polymer.

72. The method according to claim 70, wherein said step of incorporating comprises incorporating about 10% w/w encapsulated particles relative to the weight of the final product.

73. The method according to claim 70, wherein said step of compounding comprises:

preparing a diy mixture of said encapsulated particles in a second polymer; and, heating said dry mixture to a temperature selected from the group consisting of its melting point, its softening point, and its processing temperature.

74. The method according to claim 73, wherein said dry mixture comprises between 0.1% and 20% w/w encapsulated particles.

75. The method according to claim 73, wherein said dry mixture comprises about 10%» w/w encapsulated particles.

76. The method according to either one of claims 37 or 38, wherein said method does not comprise any step comprising adding hydrogen peroxide.

77. The method according to either one of claims 37 or 38, wherein said method does not comprise any step comprising adding an organic peroxide.

78. The method according to either one of claims 37 or 38, wherein said first polymer is not biodegradable.

79. An encapsulated particle, wherein said encapsulated particle comprises a dry inorganic oxidizing agent coated with a protecting / activating agent.

80. The encapsulated particle according to claim 79, wherein said encapsulated paiticle consists of a dry inorganic oxidizing agent coated with a protecting / activating agent.

81. The encapsulated particle according to either one of claims 79 or 80, wherein said protecting / activating agent comprises molecules characterized by a hydrophilic end comprising at least one hydrophilic functional group and a hydrophobic end comprising at least one hydrophobic functional group, thereby producing encapsulated particles comprising an exterior surface and an interior volume.

82. The encapsulated particle according to claim 81, wherein said hydrophilic end comprises a cation selected from the group consisting of quaternary ammonium cations, quaternary imidazolium cations, and quaternary phosphonium cations.

83. The encapsulated particle according to claim 81, wherein said at least one hydrophobic substituent comprises at least one polymerizable functional group,

84. The encapsulated particle according to claim 83, wherein said polymerizable functional group is a methacrylate.

85. The encapsulated particle according to either one of claims 79 or 80, wherein said protecting / activating agent is selected from the group consisting of methyl(undecan-l l-ol)imidazolium halide, triethyl(undecan-l l-ol)ammonium halide, dioctadecyl di(undecan-l l-ol)ammonium halide, methyl(undecan- 11 -methacrylate)imidazolium halide, triethyl(undecan- 11 - methacrylate)ammonium halide, and dioctadecyl di(undecan-l l-methacrylate)ammonium halide.

86. The encapsulated particle according to claim 81, wherein said molecules of said protecting / activating agent are oriented such that said hydrophilic end of said molecules is oriented substantially toward said interior volume and said hydrophobic end of said molecules is oriented substantially toward and/or lies substantially on, said exterior surface.

87. The encapsulated particle according to either one of claims 79 or 80, wherein said encapsulated particles have been compounded with a material for enhancing penetration of water into a polymer.

88. The encapsulated particle according to claim 87, wherein said material for enhancing penetration of water into a polymer is selected from the group consisting of:

hydrophilic materials that enhance water permeability to said encapsulated particles; materials that increase the porosity of said first polymer; and,

hydrophilic polymers.

89. The encapsulated particle according to either one of claims 79 or 80, wherein said oxidizing agent comprises a mixture of an inorganic superoxide salt and an inorganic peroxide salt.

90. The encapsulated particle according to claim 89 wherein said inorganic superoxide salt is potassium superoxide and said inorganic peroxide salt is sodium peroxide.

91. The encapsulated particle according to claim 90, wherein said oxidizing agent comprises an approximately 1 :1 molar mixture of an inorganic superoxide salt and an inorganic peroxide salt.

92. The encapsulated particle according to either one of claims 79 or 80, wherein said oxidizing agent is selected from the group consisting of permanganate and dichromate.

93. The use of an encapsulated particle according to either one of claims 79 or 80 in the preparation of an "on-demand" self-degrading composition.

94. A method for degrading a polymer, wherein said method comprises:

incorporating a substance into said polymer, said substance characterized as being unreactive with said polymer when dry and as forming or releasing, upon contact with water, a reactive substance that is capable of at least partially degrading said polymer;

exposing said substance to water, thereby forming said reactive substance; and, reacting said reactive substance with said polymer, thereby degrading it.

95. The method according to claim 94, wherein said method consists of:

96. The method according to either one of claims 94 or 95, wherein said step of incorporating comprises incorporating particles comprising said active substance encapsulated by a protecting / activating agent.

97. The method according to either one of claims 94 or 95, wherein said active substance comprises an oxidizing agent.

98. The method according to claim 97, wherein said oxidizing agent comprises an oxidizmg agent selected from the group consisting of inorganic superoxide salts, inorganic peroxide salts, chromates, permanganates, mixtures thereof, and combinations thereof.

99. The method according to either one of claims 94 or 95, wherein said step of obtaining a composition comprises obtaining a composition made according to the method of either one of claims 37 or 38.

100. A self- degrading polymer sheet for covering ground on which plants are growing or are to be grown, comprising a sheet comprising the composition according to either one of claims 1 or 2.

101. A self- degrading polymer sheet for covering ground on which plants are growing or are to be grown, comprising a sheet comprising the composition according to claim 11.

102. A self-degrading polymer sheet for covering ground on which plants are growing or are to be grown, comprising a sheet comprising a composition made according to the method according to either one of claims 37 or 38.

103. A self-degrading polymer sheet for covering ground on which plants are growing or are to be grown, comprising a sheet comprising a composition made according to the method according to claim 41.

104. A self- degrading packaging material for packaging agricultural products, comprising the composition according to either one of claims 1 or 2.

105. A self-degrading packaging material for packaging agricultural products, comprising the composition according to claim 11.

106. A self-degrading packaging material for packaging agricultural products, comprising a composition made according to the method of either one of claims 37 or 38.

107. A self-degrading packaging material for packaging agricultural products, comprising a composition made according to the method of claim 41.

108. An article of manufacture comprising the composition according to either one of claims 1 or 2.

109. An article of manufacture comprising the composition according to claim 11.

110. An article of manufacture comprising a composition made according to the method of either one of claims 37 or 38.

111. An article of manufacture comprising a composition made according to the method of claim 41.

112. The composition according to either one of claims 1 or 2, wherein said substance comprises at least two components that have been combined to form a construct.

113. The composition according to claim 112, wherein said construct is characterized by a geometry selected from the group consisting of spherical and fibrous.

114. The composition according to claim 112, wherein said construct is characterized by a median size selected from the group consisting of nanometric, micrometric, and larger than micrometric.

115. The composition according to claim 11, wherein said substance is characterized by an encapsulating geometry selected from the group consisting of fibrous, continuous, and non- continuous.

116. The composition according to claim 11, wherein said substance is characterized by a median size selected from the group consisting of nanometric, micrometric, and larger than micrometric.

117. The composition according to claim 26, wherein said substance is characterized by an encapsulating geometry selected from the group consisting of fibrous, continuous, and non- continuous.

118. The composition according to claim 26, wherein said substance is characterized by a median size selected from the group consisting of nanometric, micrometric, and larger than micrometric.

119. The composition according to claim 26, wherein said protecting / activating agent comprises said material for enhancing penetration of water into said first polymer.