EP1608689A1 - Elimination de groupes terminaux thiocarbonyle de polymeres - Google Patents

Elimination de groupes terminaux thiocarbonyle de polymeres

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Publication number
EP1608689A1
EP1608689A1 EP04758719A EP04758719A EP1608689A1 EP 1608689 A1 EP1608689 A1 EP 1608689A1 EP 04758719 A EP04758719 A EP 04758719A EP 04758719 A EP04758719 A EP 04758719A EP 1608689 A1 EP1608689 A1 EP 1608689A1
Authority
EP
European Patent Office
Prior art keywords
polymer
group
optionally substituted
groups
monomer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04758719A
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German (de)
English (en)
Inventor
Dominique Charmot
Han-Ting Chang
Wenyue Wang
Marcello Piotti
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Symyx Technologies Inc
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Symyx Technologies Inc
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Filing date
Publication date
Priority claimed from US10/407,405 external-priority patent/US7012119B2/en
Priority claimed from US10/609,255 external-priority patent/US6919409B2/en
Application filed by Symyx Technologies Inc filed Critical Symyx Technologies Inc
Publication of EP1608689A1 publication Critical patent/EP1608689A1/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
    • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/30—Introducing nitrogen atoms or nitrogen-containing groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2438/00—Living radical polymerisation
    • C08F2438/03—Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX]
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2810/00—Chemical modification of a polymer
    • C08F2810/40—Chemical modification of a polymer taking place solely at one end or both ends of the polymer backbone, i.e. not in the side or lateral chains

Definitions

  • This invention provides methods for removing moieties from the ends of polymers. More specifically, the invention provides methods for cleaving tl ⁇ ocarbonylthio or thiophosphorylthio moieties from the ends of polymers made by a reversible addition fragmentation transfer polymerization, wherein the chain transfer agents used for polymerization contain the moiety that is ultimately cleaved from the polymer.
  • RAFT Reversible Addition Fragmentation Transfer
  • Olefin Addition-fragmentation agents are known as conventional chain transfer agents. Some of notable examples are allylic sulfide and ethyleneoxy derivatives. These compounds act as conventional chain transfer agents and allow control over molecular weight and bring functional groups to the polymer termini. However, because the transfer reaction is very slow when compared with dithiocompounds used in RAFT polymerizations, these addition-fragmentation agents do not provide material with the attributes of living polymerization, i.e. low molecular weight distribution and block architectures.
  • the polymers may contain one or more functional groups, such as dithioester, dithiocarbonate, dithiocarbazate, or dithiocarbamate, which absorb in the visible light and can be yellow in color.
  • the appearance potentially limits the polymer's potential applications to such areas as electronics, which may require a clear color.
  • the dithiocompound might be unstable under the conditions of use, or might degrade upon aging, and generate some unwanted effects such as odor, discoloration, etc.
  • WO 02/090397 discusses a method of radical reduction of dithiocarbonyl or dithiophosphoryl groups using a free radical initiator and a compound bearing a labile hydrogen atom.
  • the method disclosed essentially removes the unwanted group from the polymer chain end and replaces it with a hydrogen atom. It does not disclose or teach any other methods for removing unwanted groups from the end of a polymer chain, or replacing those moieties with anything other than hydrogen.
  • the use of a hydrogen labile compound may be undesirable in some circumstances, such as when those compounds are mercaptans, notoriously odoriferous, or alcohols, which maybe non-solvents of the polymers.
  • the invention provides a method for removing unwanted groups from a chain end of a polymer and replacing them with a more desirable group.
  • the invention provides a method of free radical polymerization.
  • the method includes forming a mixture of one or more monomers, at least one free radical source and a chain transfer agent, wherein the chain transfer agent includes a thiocarbonylthio group, and subjecting the mixture to polymerization conditions.
  • the resulting polymer, which has one or more thiocarbonylthio end groups is then contacted with a free radical source under cleavage reaction conditions.
  • the free radical source is activated to generate radicals, and at least 50% of the thio end groups of the polymer are replaced with a group of interest other than hydrogen.
  • a monomer with little to no homopolymerizability for example, a monomer having a propagation rate constant (k p ) less than 2000, is contacted with the polymer and the free radical source under cleavage reaction conditions.
  • the free radical source is activated to generate radicals, and at least 50% of the thio end groups of the polymer are replaced with a group of interest other than hydrogen.
  • an addition chain transfer agent is contacted with the polymer and the free radical source under cleavage reaction conditions.
  • the free radical source is activated to generate radicals, and at least 50% of the thio end groups of the polymer are replaced with a group of interest other than hydrogen.
  • the invention provides methods for end-functionalizing polymers produced by a RAFT process while eliminating unwanted moieties, such as sulfur moieties at one or more tennini.
  • the method includes exposing the polymer to an external radical source and activating the free radical source, optionally in the presence of an addition chain transfer agent or a monomer with little to no homopolymerizability.
  • the activated external free radicals cleave the unwanted moiety from the polymer and the polymer is capped with a more desirable moiety.
  • Another aspect of the invention provides a method of free radical polymerization which includes (1) forming a mixture of one or more acrylate monomers, at least one free radical source and a control agent, the control agent comprises a thiocarbonylthio group;
  • the method comprises contacting a polymer produced by a
  • RAFT process and having at least one chain end linked to a thio moiety, with a free radical initiator, in the presence of a monomer with little or no homopolymerizability, activating the free radical initiator to generate radicals that combine with the monomer, resulting in cleaving the thio moiety off the polymer chain end, and replacing the cleaved thio moiety with a group of interest, e.g., the monomer-initiator or initiator radical.
  • a group of interest e.g., the monomer-initiator or initiator radical.
  • This invention describes compounds and chain transfer agents useful for the control of free radical polymerization reactions, and compounds useful for removing portions of the chain transfer agents from the ends of the resulting polymers, hi general, a free radical polymerization is carried out with these chain transfer agents by creating a mixture of at least one polymerizable monomer, the chain transfer agent and optionally at least one source of free radicals, e.g., an initiator.
  • the source of free radicals is optional because some monomers may self-initiate upon heating. After or upon forming the polymerization mixture, the mixture is subjected to polymerization conditions.
  • Polymerization conditions are those conditions that cause the at least one monomer to form at least one polymer, as discussed herein, such as temperature, pressure, atmosphere, ratios of starting components used in the polymerization mixture, reaction time or external stimuli of the polymerization mixture.
  • cleavage of some or all of the thio portions of the chain transfer agents from the resulting polymers is carried out with the cleavage materials by creating a mixture of the polymer and the cleavage materials. After or upon forming the cleavage mixture, the mixture is subjected to cleavage conditions.
  • Cleavage conditions are those conditions that cause some or all of the dithio moieties of the chain transfer agents to be cleaved from the ends of the polymer, as discussed herein, such as temperature, pressure, atmosphere, ratios of components used in the cleavage mixture, reaction time or external stimuli of the cleavage mixture.
  • the remaimng polymer radical can be capped in one of several ways.
  • R group will generally have the structure that is recognized in the art as corresponding to R groups having that name.
  • R groups having that name.
  • representative R groups as enumerated above are defined herein. These definitions are intended to supplement and illustrate, not preclude, the definitions known to those of skill in the art.
  • R groups or the like can be identical or different (e.g., R 2 and R 3 in the structure of formula (1) may all be substituted alkyl groups, or R 2 may be hydrido and R 3 may be methyl, etc.).
  • alkyl refers to a branched or unbranched saturated hydrocarbon group typically although not necessarily containing 1 to about 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, ⁇ -butyl, isobutyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like.
  • alkyl groups herein contain 1 to about 12 carbon atoms.
  • the term “lower alkyl” intends an alkyl group of one to six carbon atoms, preferably one to four carbon atoms.
  • “Substituted alkyl” refers to alkyl substituted with one or more substituent groups, and the terms "heteroatom-containing alkyl” and
  • heteroalkyl refers to alkyl in which at least one carbon atom is replaced with a heteroatom.
  • alkenyl refers to a branched or unbranched hydrocarbon group typically although not necessarily containing 2 to about 24 carbon atoms and at least one double bond, such as ethenyl, r ⁇ -propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, and the like.
  • alkenyl groups herein contain 2 to about 12 carbon atoms.
  • the term "lower alkenyl” intends an alkenyl group of two to six carbon atoms, preferably two to four carbon atoms.
  • Substituted alkenyl refers to alkenyl substituted with one or more substituent groups
  • heteroatom-containing alkenyl and “heteroalkenyl” refer to alkenyl in which at least one carbon atom is replaced with a heteroatom.
  • alkoxy intends an alkyl group bound through a single, terminal ether linkage; that is, an "alkoxy” group may be represented as -O-alkyl where alkyl is as defined above.
  • a “lower alkoxy” group intends an alkoxy group containing one to six, more preferably one to four, carbon atoms.
  • aryloxy is used in a similar fashion, with aryl as defined below.
  • alkyl thio intends an alkyl group bound through a single, terminal thioether linkage; that is, an "alkyl thio" group may be represented as -S-alkyl where alkyl is as defined above.
  • a "lower alkyl thio” group intends an alkyl thio group containing one to six, more preferably one to four, carbon atoms.
  • aryl refers to an aromatic substituent containing a single aromatic ring or multiple aromatic rings that are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety.
  • the common linking group may also be a carbonyl as in benzophenone, an oxygen atom as in diphenylether, or a nitrogen atom as in diphenylamine.
  • Preferred aryl groups contain one aromatic ring or two fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, benzophenone, and the like.
  • aryl substituents have 1 to about 200 carbon atoms, typically 1 to about 50 carbon atoms, and preferably 1 to about 20 carbon atoms.
  • “Substituted aryl” refers to an aryl moiety substituted with one or more substituent groups, (e.g., tolyl, mesityl and perfluorophenyl) and the terms “heteroatom- containing aryl” and “heteroaryl” refer to aryl in which at least one carbon atom is replaced with a heteroatom.
  • aralkyl refers to an alkyl group with an aryl substituent
  • aralkylene refers to an alkylene group with an aryl substituent
  • alkaryl refers to an aryl group that has an alkyl substituent
  • alkarylene refers to an arylene group with an alkyl substituent.
  • haloalkyl refers to an alkyl, alkenyl or alkynyl group, respectively, in which at least one of the hydrogen atoms in the group has been replaced with a halogen atom.
  • heteroatom-containing refers to a molecule or molecular fragment in which one or more carbon atoms is replaced with an atom other than carbon, e.g., nitrogen, oxygen, sulfur, phosphorus or silicon.
  • heteroalkyl refers to an alkyl substituent that is heteroatom-containing
  • heterocyclic refers to a cyclic substituent that is heteroatom-containing
  • heteroaryl refers to an aryl substituent that is heteroatom-containing
  • the phrase “heteroatom-containing alkyl, alkenyl and alkynyl” is to be interpreted as “heteroatom-containing alkyl, heteroatom-containing alkenyl and heteroatom-containing alkynyl.”
  • Hydrocarbyl refers to univalent hydrocarbyl radicals containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including branched or unbranched, saturated or unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like.
  • lower hydrocarbyl intends a hydrocarbyl group of one to six carbon atoms, preferably one to four carbon atoms.
  • Substituted hydrocarbyl refers to hydrocarbyl substituted with one or more substituent groups
  • heteroatom-containing hydrocarbyl and “heterohydrocarbyl” refer to hydrocarbyl in which at least one carbon atom is replaced with a heteroatom.
  • substituted as in “substituted hydrocarbyl,” “substituted aryl,” “substituted alkyl,” “substituted alkenyl” and the like, as alluded to in some of the aforementioned definitions, is meant that in the hydrocarbyl, hydrocarbylene, alkyl, alkenyl or other moiety, at least one hydrogen atom bound to a carbon atom is replaced with one or more substituents that are groups such as hydroxyl, alkoxy, thio, phosphino, amino, halo, silyl, and the like.
  • substituted When the term "substituted" appears prior to a list of possible substituted groups, it is intended that the tenn apply to every member of that group. That is, the phrase “substituted alkyl, alkenyl and alkynyl” is to be interpreted as “substituted alkyl, substituted alkenyl and substituted alkynyl.” Similarly, “optionally substituted alkyl, alkenyl and alkynyl” is to be interpreted as “optionally substituted alkyl, optionally substituted alkenyl and optionally substituted alkynyl.”
  • sil refers to the -SiZ Z 2 Z 3 radical, where each of Z 1 , Z 2 , and Z 3 is independently selected from the group consisting of hydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl, aralkyl, alkaryl, heterocyclic, alkoxy, aryloxy and amino. ,
  • phosphino refers to the group -_?Z l 7?, where each of Z 1 and Z 2 is independently selected from the group consisting of hydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl, aralkyl, alkaryl, heterocyclic and amino.
  • amino is used herein to refer to the group -NZ ⁇ 2 , where each of Z 1 and Z 2 is independently selected from the group consisting of hydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl, aralkyl, alkaryl and heterocyclic.
  • thio is used herein to refer to the group -SZ 1 , where Z 1 is selected from the group consisting of hydrido and optionally substituted alkyl, alkenyl, alkynyl, aryl, aralkyl, alkaryl and heterocyclic.
  • Polymerization of the monomers can be conducted according to conventional methods such as bulk polymerization or in a solvent, or in emulsion by batch or semi- continuous or continuous polymerization.
  • the polymer can be obtained by dissolving requisite monomers in an organic solvent, then conducting a polymerization reaction in the presence of a polymerization initiator, such as an azo compound.
  • a polymerization initiator such as an azo compound.
  • Use of a chain transfer agent (CTA) during the polymerization process can be advantageous.
  • Organic solvents suitable for polymerization reactions of the invention include, for example, ketones, ethers, polar aprotic solvents, esters, aromatic solvents and aliphatic hydrocarbons, both linear and cyclic.
  • ketones include methyl ethyl ketone (2-butanone) (MEK), acetone and the like.
  • exemplary ethers include alkoxyalkyl ethers, such as methoxy methyl ether or ethyl ether, tetrahydrofuran, 1,4 dioxane and the like.
  • Polar aprotic solvents include dimethyl formamide, dimethyl sulfoxide and the like.
  • Suitable esters include alkyl acetates, such as ethyl acetate, methyl acetate and the like.
  • Aromatic solvents include alkylaryl solvents, such as toluene, xylene and the like and halogenated aromatics such as chlorobenzene and the like.
  • Hydrocarbon type solvents include, for example, hexane, cyclohexane and the like.
  • the polymerization reaction is conducted in a manner such that the concentration of monomers is about 5 to 95% in the solvent by weight.
  • the reactions are run between about 5% and about 95% percentage solids, preferably between about 20% and about 80% percent solids, and in particular, [0041]
  • the polymerization conditions that may be used include temperatures for polymerization typically in the range of from about 20°C to about 110°C, more preferably in the range of from about 50°C to about 90°C and even more preferably in the range of from about 60°C to about 80°C.
  • the atmosphere may be controlled, with an inert atmosphere being prefened, such as nitrogen or argon.
  • the molecular weight of the polymer is controlled via adjusting the ratio of monomer to chain transfer agent.
  • the molar ratio of monomer to chain transfer agent is in the range of from about 5:1 to about 5000:1, more preferably in the range of from about 10:1 to about 2000:1, and most preferably from 10:1 to about 1500:1.
  • a free radical source is provided in the polymerization mixture, which can stem from spontaneous free radical generation upon heating or preferably from a free radical initiator.
  • the initiator is added to the polymerization mixture at a concentration high enough to achieve an acceptable polymerization rate (e.g., commercially significant conversion in a certain period of time, such as listed below).
  • an acceptable polymerization rate e.g., commercially significant conversion in a certain period of time, such as listed below.
  • the molar ratio of free radical initiator to chain transfer agent for polymerization are typically in the range of from about 2:1 to about 0.02:1.
  • free-radical source refers broadly to any and all compounds or mixtures of compounds that can lead to the formation of radical species under appropriate working conditions (thermal activation, i ⁇ adiation, interaction with a reductant, etc.).
  • Polymerization conditions also include the time for reaction, which may be from about 0.5 hours to about 72 hours, specifically in the range of from about 1 hour to about 24 hours, more specifically in the range of from about 2 hours to about 12 hours.
  • time for reaction can include feed times. Conversion of monomer to polymer is at least about 50%, more specifically at least about 75% and more specifically at least about 85%.
  • the polymerization process generally proceeds in a "living" type manner.
  • a living character manifests itself by the ability to prepare block copolymers: hence, a polymer chain is first grown with monomer A, and then, when monomer A is depleted, monomer B is added to extend the first block of polymer A with a second block of polymer B.
  • Block copolymer formation through a living process can be demonstrated using analytical techniques such as polymer fractionation with selective solvent (of polymer A, polymer B, respectively), gradient elution chromatography and/or 2-dimensional chromatography.
  • Block copolymers tend to microphase-separate and organize in a variety of morphologies that can be probed by physical techniques such as X-ray diffraction, dynamic mechanical testing, and the like. Homopolymers and random copolymers resulting from copolymerization of different monomers either in a batch, semi-continuous or continuous mode are also within the scope of this invention.
  • the polymers of the invention can, in the general case, be linear or non-linear, and can be homopolymers, copolymers or higher ordered polymers.
  • Non-linear polymers of the invention can have a number of architectures, including for example star-polymers, branched polymers, graft polymers, semi-cross-linked polymers, and combinations thereof, among others. These various polymer architectures can be achieved with a high degree of control by the polymer preparation methods discussed herein.
  • Initiators may be optional.
  • initiators useful in the polymerization mixture and the inventive process are known in the art, and can be a commercially available free-radical initiator.
  • initiators having a short half-life at the polymerization temperature are utilized.
  • Such initiators are utilized because the speed of the initiation process can affect the polydispersity index of the resulting polymer. That is, the kinetics of controlled, living polymerization are such that less polydisperse polymer samples are prepared if initiation of all chains occurs at substantially the same time.
  • suitable free radical initiators include any thermal, redox or photo initiators, including, for example, alkyl peroxides, substituted alkyl peroxides, aryl peroxides, substituted aryl peroxides, acyl peroxides, alkyl hydroperoxides, substituted alkyl hydroperoxides, aryl hydroperoxides, substituted aryl hydroperoxides, heteroalkyl peroxides, substituted heteroalkyl peroxides, heteroalkyl hydroperoxides, substituted heteroalkyl hydroperoxides, heteroaryl peroxides, substituted heteroaryl peroxides, heteroaryl hydroperoxides, substituted heteroaryl hydroperoxides, alkyl peresters, substituted alkyl peresters, aryl peresters, substituted aryl peresters, peracids, percarbonates, alkyl peroxalates, alkylperoxidicarbonates, alkyl ketone peroxid
  • Specific initiators include cuinene hydroperoxide (CHP), t-butyl hydroperoxide (TBHP), t-butyl perbenzoate (TBPB), sodium carbonateperoxide, benzoyl peroxide (BPO), lauroyl peroxide (LPO), methylethylketone peroxide 45%, potasium persulfate, ammonium persulfate, 2,2-azobis(2,4-dimethyl-valeronitrile) (VAZO ® -65), l,l-azobis(cyclo- hexanecarbonitrile) ( VAZO ® -40) , 2,2-azobis(N,N'-dimethyleneisobutyramidine) dihydrochloride (VAZO ® -044), 2,2-azobis(2-amidino-propane) dihydrochloride
  • Fe(2 )/peroxide are also useful. Initiation may also be by heat or UV light, as is known in the art, depending on the embodiment being practiced (e.g., UV light may be used for the modified initiator or RAFT or MAD IX techniques discussed herein).
  • monomers that may be polymerized using the methods of this invention include at least one monomer from the group of styrene, substituted styrene, alkyl acrylate, substituted alkyl acrylate, alkyl methacrylate, substituted alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, butylacrylate, , methacrylamide, N-alkylacrylamide, N- alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, isoprene, butadiene, ethylene, vinyl acetate and combinations thereof.
  • Specific monomers or comonomers that may be used in this invention include butylacrylate, 6-[5-hydroxynorbornane-2-carboxylic acid lactone] acrylate, 2-[2-ethyladamantyl] acrylate, l-[3-hydiOxyadamantyl] acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, ⁇ - methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl
  • CTAs Chain transfer agents
  • CTAs useful in the present invention have the general formula (I):
  • R 1 is generally any group that is sufficiently labile to be expelled as its free radical form
  • Z can be found in WO98/01478, W099/35177, W099/31144, and W098/58974.
  • Z is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and combinations thereof. More specifically, Z may be selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted acyl, optionally substituted, aroyl, optionally substituted alkoxy, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted alkylsulfonyl, optionally substituted alkylsulfinyl, optionally substituted alkylphosphonyl, optionally substituted arylsulfinyl, and optionally substituted arylphosphonyl, amino and alkoxy.
  • the chain transfer agents described in this invention can have a phosphorous atom in place of the carbon atom and be characterized by the general formula: wherein R 1 is as described above, and Z 1 and Z 2 are each independently selected from the group defined for -_t.
  • the chain transfer agents may contain at least one N 1 - N 2 bond covalently bonded to a thiocarbonyl group.
  • the following moiety may be present in the chain transfer agents of this invention:
  • a sulfur atom is attached to the thiocarbonyl group, leading to a dithiocarbonyl moiety.
  • the substituents of N 2 (other than N ) form a heterocycle that includes N .
  • suitable CTAs useful in the present invention include those identified in US Patent No. 6,380,335, 6,395,850, 6,518,364, 6,569,969, 6,518,448 and 6,482,909, the contents of which are incorporated by reference. More specifically, CTAs of particular interest in combination with the monomers utilized throughout the specification can be characterized by the general formula (I"):
  • D is S, Te or Se.
  • D is sulfur.
  • R 1 is generally any group that can be easily expelled under its free radical form (R 1 *) upon an addition-fragmentation reaction, as depicted below in Scheme 1 (showing D as S):
  • P* is a free radical, typically a macro-radical, such as polymer chain.
  • R 1 is selected from the group consisting of hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom- containing hydrocarbyl, and combinations thereof. Even more specifically, R 1 is selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted alkoxy, optionally substituted heterocyclyl, optionally substituted alkylthio, optionally substituted amino and optionally substituted polymer chains.
  • R 1 is selected from the group consisting of-CH 2 Ph, -CH(CH 3 )C0 2 CH 2 CH 3 , -CH(CO 2 CH 2 CH 3 ) 2 , -C(CH 3 ) 2 CN, - CH(Ph)CN, -C(CH 3 ) 2 C0 2 R (alkyl, aryl, etc.) and -C(CH 3 ) 2 Ph.
  • R 2 and R 3 of the CTA are each independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and combinations thereof.
  • R 2 and R 3 can be each independently selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted acyl, optionally substituted, aroyl, optionally substituted alkoxy, optionally substituted heteroaryl, optionally substituted heterocyclyl, optionally substituted alkylsulfonyl, optionally substituted alkylsulfinyl, optionally substituted alkylphosphonyl, optionally substituted arylsulfinyl, and optionally substituted arylphosphonyl.
  • R 2 and/or R 3 are listed in the above definitions, and in addition include perfluorenated aromatic rings, such as perfmorophenyl. Also optionally, R 2 and R 3 can together form a double bond alkenyl moiety off the nitrogen atom, and in that case R 2 and R 3 are together optionally substituted alkenyl moieties.
  • R 4 of the CTA is selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and combinations thereof; and optionally, R 4 combines with R 2 and/or R 3 to form a ring structure, with said ring having from 3 to 50 non-hydrogen atoms.
  • R is selected from the group consisting of hydrogen, optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted acyl, optionally substituted aryl, amino, thio, optionally substituted aryloxy and optionally substituted alkoxy.
  • R 4 groups include methyl and phenyl.
  • R combines with either R or R to form a substituted or unsubstituted pyrazole moiety.
  • exemplary CTAs include:
  • the CTAs are synthesized, generally, by methods known to those of skill in the art as described, for example in U.S. Patent No. 6,380,335.
  • polymers formed with the chain transfer agents described herein are believed to be grown via a degenerative transfer mechanism.
  • monomers might appear between the R 1 — S bond, and any of the above formulas can be rewritten in a polymeric form.
  • the polymers may be characterized by the general formula (II):
  • M is a monomer or mixture of monomers or at least 2 blocks of different monomer (any from the above lists) and f is the degree of polymerization, and D, R 1 , and Z are as defined above.
  • the polymers may be characterized by the general fonnula (IF):
  • block copolymer refers to a polymer comprising at least two segments of differing composition; having any one of a number of different architectures, where the monomers are not incorporated into the polymer architecture in a solely statistical or uncontrolled manner. Although there may be three, four or more monomers in a single block-type polymer architecture, it will still be refened to herein as a block copolymer.
  • the block copolymer will have an A-B architecture (with “A” and "B” representing the monomers).
  • Other architectures included within the definition of block copolymer include A-B-A, A-B-A-B, A-B-C, A-
  • Block copolymers can be prepared a number of ways, including sequential addition of monomers or using multi-functional chain transfer agents described in US Patent No. 6,380,335. Of course with multi-functional chain transfer agents, the chain transfer agent may form a linking group between one or more blocks of the copolymers.
  • the polymers of this invention include block copolymers having one or more blocks of random copolymer together with one or more blocks of single monomers.
  • a polymer architecture of A-R, A-R-B, A-B-R, A-R-B-R-C, etc. is included herein, where R is a random block of monomers A and B or of monomers B and C.
  • the random block can vary in composition or size with respect to the overall block copolymer.
  • the random block R will account for between 5 and 80 % by weight of the mass of the block copolymer. In other embodiments, the random block R will account for more or less of the mass of the block copolymer, depending on the application.
  • the random block may have a compositional gradient of one monomer to the other (e.g., A:B) that varies across the random block in an algorithmic fashion, with such algorithm being either linear having a desired slope, exponential having a desired exponent (such as a number from 0.1-5) or logarithmic.
  • the random block may be subject to the same kinetic effects, such as composition drift, that would be present in any other radical copolymerization and its composition, and size may be affected by such kinetics, such as Markov kinetics. Any of the monomers listed elsewhere in this specification may be used in the block copolymers of these embodiments .
  • a "block" within the scope of the block copolymer embodiments of this invention typically comprises about 10 or more monomer units of a single type (with the random blocks being defined by composition and/or weight percent, as described above). In some embodiments, the number of monomer units within a single block is about 15 or more, about 20 or more or about 50 or more.
  • block copolymers of this invention include blocks where a block is defined as two or more monomer units that are not represented elsewhere in the copolymer. This definition is intended to encompass adding small amounts of a second monomer at one or both ends of a substantially homopolymeric polymer. In this alternative embodiment, the same copolymer architectures discussed above apply.
  • a telechelic polymer is a block copolymer with in the definitions of this invention.
  • the groups present at one or both ends of a telechelic polymer may be those known to those of skill in the art, including, for example, hydroxide, aldehyde, carboxylic acid or carboxylate, halogen, amine and the like, which have the ability to associate or form bonds with another molecule.
  • block copolymer embodiments of the invention are intended to encompass telechelic polymers containing bifunctional groups, such as allyl-tenninated or vinyl-terminated telechelics, sometimes refened to as macromonomers or macromers because of their ability to participate in polymerization reactions through the terminal group.
  • the polymer may be a block copolymer having the architecture F-A-B-F, where F represents functional groups that may be the same or different within a single F-A-B-F structure (which, therefore, may encompass F-A-B-F').
  • F represents functional groups that may be the same or different within a single F-A-B-F structure (which, therefore, may encompass F-A-B-F').
  • Other polymer architectures within the scope of this invention include A-R-B-F and F-A- R-B-F.
  • Other architectures will be apparent to those of skill in the art upon review of this specification - indeed, without wishing to be bound by any particular theory - it is the living nature of the emulsions of this invention that provide the ability to even make these polymers.
  • block copolymers are assembled by the sequential addition of different monomers or monomer mixtures to living polymerization reactions.
  • a pre-assembled functionalized block such as a telechelic oligomer or polymer
  • a living free radical polymerization mixture yields a block copolymer.
  • the growth of each block occurs to high conversion.
  • Conversions can be determined by size exclusion chromatography (SEC) via integration of polymer to monomer peak. For UV detection, the polymer response factor must be determined for each polymer/monomer polymerization mixture. Conversions can also be determined by use of NMR or Raman spectroscopy. Typical conversions can be 50% to
  • polymers can be prepared by grafting processes, preparation of telechelic polymers, preparation of macromonomers, etc.
  • at least one polymer segment is derived from a living or controlled process of the invention, while other segments can be derived from any polymerization process, including, for example, controlled or uncontrolled radical polymerization, condensation polymerization, Ziegler-Natta and related processes, Ring-Opening
  • Metathesis Polymerization ionic polymerization, surface modification or grafting, or other addition or step-growth processes.
  • Multi-arm or star polymers can be generated using initiators capable of initiating multiple free radical polymerizations under the controlled conditions of the invention.
  • Such initiators include, for example polyfunctional chain transfer agents, discussed in US
  • the growth of each arm is controlled by the same living kinetics described for linear polymers, making it possible to assemble star polymers whose arms include individual homopolymers as well as di, tri or higher order coplyhiers or block copolymers.
  • multi-arm polymers are formed by growing end-functionalized oligomers or polymers followed by the addition of a cross- linking monomer such as ethylene glycol diacrylate, divinyl benzene, methylene bisacrylamide, trimetylol propane triacrylate, etc.
  • the small hydrodynamic volume of star polymers produced according to these methods provides properties such as low viscosity, high Mw, and high functionality useful in applications such as rheology control, thermosets, and separation media.
  • the inclusion of branched or multiple ethylenically unsaturated monomers enables the preparation of graft polymers, again exhibiting the living kinetics characteristic of this invention.
  • a block copolymer according to this invention is determined by methods known to those of skill in the art, including nuclear magnetic resonance (NMR), measured increase of molecular weight upon addition of a second monomer to chain-extend a living polymerization of a first monomer, microphase separation (e.g., long range order, microscopy and/or birefringence measurements), mechanical property measurements, (e.g., elasticity of hard/soft block copolymers), thermal analysis and chromatography (e.g., absence of homopolymer).
  • NMR nuclear magnetic resonance
  • microphase separation e.g., long range order, microscopy and/or birefringence measurements
  • mechanical property measurements e.g., elasticity of hard/soft block copolymers
  • thermal analysis and chromatography e.g., absence of homopolymer
  • the resulting polymers described above will have one or more termini having a thio group, specifically a tl ⁇ ocarbonylthio group. Depending on the application intended for the polymer, the thio group may be undesirable. Thus, this invention provides a method for removing and/or replacing the group. [0072] After the polymerization (e.g., completed or terminated) some or all of the residual thio-moiety (e.g., a thiocarbonylthio moiety) of the CTA can be cleaved from the polymer by chemical or thermal ways in order to reduce the sulfur content of the polymer and prevent possible problems associated with presence of the chain transfer agents chain ends, such as odor or discoloration.
  • some or all of the residual thio-moiety e.g., a thiocarbonylthio moiety
  • the resulting polymer contains a control agent moiety (a portion of the control agent, such as the dithio carbonyl portion) at a terminal end, whether the end is at the end of a backbone, a star arm, a comb end, a branch end, or a graft.
  • a control agent moiety a portion of the control agent, such as the dithio carbonyl portion
  • a free radical chain transfer reaction is believed to decouple a residue, such as the dithio control agent moiety, from the polymer end by addition of an external radical source, and optionally an addition fragmentation agent, or a monomer with little or no homopolymerizability, and then cap the polymer chain end with the external radical source and/or a portion of the addition fragmentation agent or monomer with little or no homopolymerizability.
  • k p (L/mol/sec.)of the monomer is less than 2000, specifically less than 1000, more specifically less than 500, and more specifically less than 300.
  • the external radical source is a common radical initiator, such as any initiator listed above.
  • the free-radical source implemented in the procedure according to the invention is utilized under cleavage reaction conditions that allow for the production of free radicals, which, in one embodiment, is accomplished via thennal activation, i.e., by raising the temperature of the reaction medium, usually to a temperature in the range of about room temperature (approximately 20°C) to about 200°C, and specifically from about 40°C to about 180°C, and more specifically from about 50°C to about 120°C.
  • free radicals are produced via light activation.
  • free radical sources activatable by UV light such as benzoin ethers, and benzophenone.
  • High energy radiations such as Gamma rays and electron beams are also known to produce radicals.
  • free radicals are produces via redox reaction of the free radical source with a reductant.
  • reductants include chemicals such as sodium folmaldehyde sulfoxalate, sodium bisulfite, iron sulfate, dimethyl analine, etc.
  • the free-radical source utilized may be introduced into the reaction medium in one single increment. However, it may also be introduced gradually, either by portions or continuously.
  • the cleavage reaction conditions that may be used include conditions such as temperature, pressure, atmosphere, reaction times and ratios of reaction components. Temperatures useful are those in the range of from about room temperature (approximately 20°C) to about 200°C, and specifically from about 40°C to about 180°C, and more specifically from about 50°C to about 120°C. hi some embodiments, the atmosphere may be controlled, with an inert atmosphere being prefened, such as nitrogen or argon. In other embodiments, ambient atmosphere is used.
  • the cleavage reaction conditions also include open or closed atmospheres and pressures at ambient conditions.
  • the cleavage reaction is canied out in a closed atmosphere, and the temperature is above room temperature, the pressure could rise as a result of any heated solvents.
  • light control is also desired.
  • the reaction may be canied out in visible light, or under UV light.
  • additional reagents may be added which will undergo a redox reaction with the radical source.
  • the quantity of the free-radical source depends on its effectiveness, on the manner in which the source is introduced, and in the desired end product.
  • the free- radical source that is utilized may be introduced in a quantity such that the amount of free radicals that can be released by the source is between about 1% and about 800% (molar), specifically between about 50% and about 400% (molar), and more specifically between about 100% and about 300% (molar), and more specifically between about 200% and about 300% in relation to the total molar amount of the groups in the polymers for which cleavage is desired.
  • complete removal of the thio groups or as near as complete as possible is desired and in those embodiments, an excess of free radical source is introduced.
  • the excess free radical source is intended to account for the side reactions that are well known in free radical processes as shown below (for example in Scheme 6), as well as the possible free radical loss caused by the cage effect.
  • the free radical source efficiency factor defined as the ratio of active radicals to total radicals generated upon free radical source decomposition, can be used to adjust the concentration of initiator (I 2 ).
  • Typical initiators that can be used as a free radical source are selected among alkyl peroxides, substituted alkyl peroxides, aryl peroxides, substituted aryl peroxides, acyl peroxides, alkyl hydroperoxides, substituted alkyl hydroperoxides, aryl hydroperoxides, substituted aryl hydroperoxides, heteroalkyl peroxides, substituted heteroalkyl peroxides, heteroalkyl hydroperoxides, substituted heteroalkyl hydroperoxides, heteroaryl peroxides, substituted heteroaryl peroxides, heteroaryl hydroperoxides, substituted heteroaryl hydroperoxides, alkyl peresters, substituted alkyl peresters, aryl peresters, substituted aryl peresters, alkyl peracids, substituted alkyl peracids, aryl peracids, substituted aryl peracids, dialkyl peroxid
  • Specific initiators include lauroyl and benzoylperoxide (BPO), Dimethyl 2,2'-azobis(isobutyrate), and AIBN.
  • Some prefened azo compounds include l,r-Azobis(cyclohexane-l-carbonitrile), 2,2'-Azobis(4- methoxy-2,4-dimethyl valeronitrile), Dimethyl 2,2'-azobis(2-methylpropionate), 1- [(cyano-l-methylethyl)azo] formamide, 2,2'-Azobis(N-cyclohexyl-2- methylpropionamide), 2,2'-Azobis(2,4-dimethyl valeronitrile), 2,2'-Azobis(2- methylbutyronitrile), 2,2'-Azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'- Azobis(N-butyl-2-methylpropionamide), 2,2'-Azobis[2-(5
  • Other initiators are activatable by high energy such as gamma rays and electron beams.
  • the half-life time can be adjusted by setting the reaction temperature to the required range. The latter is determined by the temperature dependence of the initiator decomposition rate, available through the supplier information package or in the literature (e.g. "The Chemistry of Free Radical Polymerization, G.Moad, D.H. Salomon, Eds. Pergamon Pub. 1995).
  • the rate of decomposition, hence the radical production, is also adjustable by the addition of reducing agents, in particular when the initiator has an oxidizing character, such as peroxides: for instance metabisulfite, ascorbic acid, sulfite-formaldehyde adduct, amines, and low oxidation state metals, etc., can be used together with peroxides type initiators to accelerate the radical flux.
  • reducing agents such as peroxides: for instance metabisulfite, ascorbic acid, sulfite-formaldehyde adduct, amines, and low oxidation state metals, etc.
  • Cleavage reaction conditions also include the time for reaction, which may be from about 0.5 hours to about 72 hours, preferably in the range of from about 1 hour to about 24 hours, more preferably in the range of from about 2 hours to about 12 hours.
  • Cleavage of thio group from the polymer is at least about 50%, more specifically at least about 75% and more specifically at least about 85%, and even more specifically at least about 95%.
  • at least about 50%, at least about 75%, at least about 85%, or at least about 95% of the thio groups located at the end(s) of the polymer are replaced with groups other than hydrogen.
  • the cleavage reaction mixture may use a reaction media that is typically a solvent.
  • Cleavage reaction conditions also include sti ⁇ ing or refluxing the reaction media.
  • Scheme 4 represents the radical coupling of the polymer radical generated in scheme 3 and the free radical generated in scheme 2, which produces the resulting capped polymer P-I.
  • Scheme 5 represents a transfer reaction between the polymer radical generated in scheme 3 and the free radical initiator that produces the cleaved polymer as well a new free radical source.
  • Scheme 6 represents a coupling reaction between two polymer radicals.
  • schemes 4 and 5 are the desired reactions.
  • Scheme 6 is a side reaction that contributes in increasing molecular weight and broadening molecular weight distribution of the bulk polymer sample. It has been found that the described cleavage reaction conditions lead to quantitative cleavage of the dithiocompounds with little to no change in molecular weight characteristics (Mw and polydispersity index).
  • the polymer is treated with free radical source, such as an initator, under cleavage reaction conditions so that the reactions 5 and 6 are favored.
  • These conditions include introducing the radical source in a quantity such that the amount of free radicals that can be released by the source is between about 200% and about 500% (molar), specifically between about 200% and about 300% (molar) in relation to the total molar amount of the groups in the polymers for which cleavage is desired.
  • the resulting polymer has a new group at its terminus, which may make the polymer more desirable for specific applications.
  • the polymer above may be more desirable for applications that cannot allow the presence of sulfur in the amounts present in the polymer before modification, such as home and personal care products where odor may present a problem.
  • Addition-fragmentation agents are typically represented by the general formula:
  • R 5 and R 6 are each independently selected from the group consisting of hydrogen or alkyl, specifically hydrogen, X is OR 7 or CH 2 X'(R 7 ) n where R 7 is an optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, or optionally substituted saturated, unsaturated or aromatic, aromatic carbocyclic or heterocyclic ring; X' is carbon or an element selected from Groups IV, V, VI or VII of the Periodic Table or a group consisting of an element selected from Groups IV, V, or VI to which is attached one or more oxygen atoms; and n is a number from 0 to 3, such that the valency of the group X' is satisfied and, when n is greater than 1, the groups represented by R 7 may be identical or different; and
  • Y is equivalent to R 1 described above. More specifically, Y is selected from the group consisting of optionally substituted alkyl, optionally substituted aryl, optionally substituted alkenyl, optionally substituted alkoxy, optionally substituted heterocyclyl, optionally substituted alkylthio, optionally substituted amino and optionally substituted polymer chains, and more specifically, Y is selected from the group consisting of -CH 2 Ph, -CH(CH 3 )C0 2 CH 2 CH 3 , -CH(CO 2 CH 2 CH 3 ) 2 , -C(CH 3 ) 2 CN, -CH(Ph)CN and -C(CH 3 ) 2 Ph.
  • the polymer is treated with free radical source, such as an initiator, under cleavage reaction conditions such that the schemes 4 and 5 described above are favored.
  • the initiator residue i.e. P-I
  • the conditions are chosen so that schemes 7 and/or 8 are favored.
  • the radical source is used to sustain a free radical chain reaction that converts the polymer chain dithio moiety into the required functional polymer free of the dithio end group. Once the reaction is taking place, it is believed that a steady state concentration of polymer radical P» is fonned which is then trapped by the addition-fragmentation agent, that then undergoes fragmentation, yielding the polymer on one end and the expelled radical Y* on the other end.
  • cleavage reaction conditions include, in addition to those reaction conditions discussed above, a molar ratio of addition-fragmentation agent to ditliio end groups from about 1.0:1 to about 10:1, and more specifically from about 1.5:1 to about 5:1, and a mole ratio of free radical initiator to dithio end groups from about 0.01:1 to about 5:1, and more specifically from about 0.2:1 to about 2:1.
  • Addition-fragmentation transfer agents are generally known.
  • a monomer with a low propagation rate is utilized with the free radical generator in the cleavage reaction.
  • the free radical generator in the cleavage reaction.
  • Scheme 9 represents the creation of a radical resulting form the addition of the monomer with little or no homopolymerizability and the radical generated by the free radical initiator; and Scheme 10 represents the addition-fragmentation of I[J] n * on the dithio-terminated polymer generating a polymer radical P «.
  • Monomers contemplated for use within this invention include maleimide, N- substituted maleimides, (including but not limited to, N-phenylmaleimide, N- methylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-propylmaleimide, N-(4- ethylphenyl)maleimide, N-(4-acetylphenyl) maleimide, N-(para-tolyl)- maleimide, N- cyclohexyl maleimide N-dodecyl maleimide, N-tert-butyl maleimide, N-isopropyl maleimide, N-(2-hydroxyethyl) maleimide, and N-(3 -hydroxypropyl) maleimide) maleic anhydride,
  • Cleavage reaction conditions include, in addition to those reaction conditions discussed above, a molar ratio of monomer with little or no homopolymerizability to dithio end groups between about 0.5:1 and 10:1, and more specifically between about 1.0:1 and 5:l, and more specifically from about 1.5:1 to 3:1, and a mole ratio of free radical initiator to dithio end groups of between about 0.01:1 to 8:1, more specifically between about 0.2:1 to 5:1, and more specifically between about 1:1 to 4:1.
  • Scheme 4 represents the radical coupling of the polymer radical generated in Scheme 3 or 10 and the free radical generated in Scheme 2, which produces the resulting capped polymer P-I
  • Scheme 6 represents the coupling reaction between two polymer radicals generated in Schemes 3 and/or 10.
  • Scheme 11 represents the radical coupling of the polymer radical generated in Scheme 3 or 10 and the free radical generated in Scheme 9, which produces the resulting capped polymer P- [J] .
  • Scheme 12 represents the addition of the polymer radical with a monomer unit J, resulting in a new radical P-J* which is believed to react according to Schemes 12.1- 12.4.
  • Scheme 12.1 represents the radical coupling of the polymer radical generated in Scheme 12 and the free radical generated in Scheme 2, which produces the resulting capped polymer PJI.
  • Scheme 12.2 represents the radical coupling of the polymer radical generated in Scheme 12 and the free radical generated in Scheme 9, which produces the resulting capped polymer P[J] n + ⁇ I •
  • Scheme 12.3 represents a coupling reaction between two polymer radicals generated in Scheme 12.
  • Scheme 12.4 represents a coupling reaction between the polymer radical generated in Scheme 12 and a polymer radical generated in Scheme 3 or 10.
  • Scheme 12.5 represents the further addition of monomer J to the radical generated in Scheme 12, resulting in a new radical PJJ*, which can go on to further react as described above.
  • Schemes 4,11, 12.1 and 12.2 are the desired reactions.
  • Schemes 12.3, 12.4 and 6 are side reactions that contribute to increasing molecular weight and broadening molecular weight distribution of the bulk polymer sample. It has been found that the described cleavage reaction conditions lead to quantitative cleavage of the dithiocompounds with little to no change in molecular weight characteristics (Mw and polydispersity index).
  • the polymer is treated with a free radical source, such as an initiator, and a monomer with little or no homopolymerizability, under cleavage reaction conditions so that the reactions 12.3, 12.4 and 6 are favored.
  • a free radical source such as an initiator
  • a monomer with little or no homopolymerizability under cleavage reaction conditions so that the reactions 12.3, 12.4 and 6 are favored.
  • These conditions include introducing the radical source and the monomer with little or no homopolymerizability in a quantity such that the amount of free radicals containing one or more units of the monomer is between about 100% and about 800% (molar), and specifically between about 200% and about 500% (molar) in relation to the total molar amount of the groups in the polymers for which cleavage is desired.
  • the resulting polymer has a new group at its tenninus, which may make the polymer more desirable for specific applications.
  • the polymer above may be more desirable for applications that cannot allow the presence of sulfur in the amounts present in the polymer before modification, such as home and personal care products where odor may present a problem, or electronics, where color may present a problem.
  • the following examples illustrate the principles and advantages of the invention.
  • N,N- dimethylformamide containing 0.1 % of frifluoroacetic acid was used as an eluent for the rapid GPC system whereas THF for the conventional system and polystyrene-based columns. All of the molecular weight results obtained are relative to linear polystyrene standards.
  • NMR was canied out using a Bruker spectrometer (300 MHz) with CDC1 3 (chloroform-d) as solvent. Elemental analysis was performed by a characterization laboratory using methods well known to those of skill in the art. Removal of control agent residue: EXAMPLE 1
  • the GPC data indicates very little deviation in molecular weight before and after the treatment, which indicates there was negligible chain-chain coupling. Because the dithio compound is a strong UV absorbing moiety, it is easy to track it with GPC. When the dithio compound is cleaved off of the polymer chain, the UV signal on the polymer decreases down to almost baseline. The UV data indicates that less than 1% of the chain transfer moiety remained on the polymer.
  • MAIB Solution 0.636 g 2,2'-dimethylazobis (methylpropionate) (MAIB) + 15 mL MEK
  • reaction flask was then removed from the glove box and the mixture was degassed by three freeze-pump-thaw cycles, followed by backfilling of the system with high purity nitrogen or argon (and left under a bubbler of inert gas).

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Abstract

La présente invention concerne un procédé permettant d'éliminer des groupes indésirables d'une extrémité de chaîne d'un polymère et de les remplacer par un groupe plus recherché. Dans une variante, cette invention concerne un procédé de polymérisation radicalaire. Ce procédé consiste à former un mélange composé d'un ou plusieurs monomères, d'au moins une source de radicaux libres et d'un agent de migration de chaîne, ledit agent de migration de chaîne comprenant un groupe thiocarbonylthio, puis à soumettre ce mélange à des conditions de polymérisation. Le polymère obtenu, qui comporte un ou plusieurs groupes terminaux thiocarbonylthio, est ensuite mis au contact d'une source de radicaux libres et éventuellement d'un agent de fragmentation d'addition ou d'un monomère présentant peu ou pas d'aptitude à l'homopolymérisation dans des conditions de réaction de clivage. La source de radicaux libres est activée afin qu'elle génère des radicaux et au moins 50 % des groupes d'extrémité thio du polymère sont remplacés par un groupe d'intérêt autre que l'hydrogène.
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US609255 1996-02-29
US10/407,405 US7012119B2 (en) 2000-09-28 2003-04-03 Cleaving and replacing thio control agent moieties from polymers made by living-type free radical polymerization
US407405 2003-04-03
US10/609,255 US6919409B2 (en) 2003-06-26 2003-06-26 Removal of the thiocarbonylthio or thiophosphorylthio end group of polymers and further functionalization thereof
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