WO2015138164A1

WO2015138164A1 - Process for preparing surface functionalized polymeric and polymeric/silica hybrid hollow nanospheres

Info

Publication number: WO2015138164A1
Application number: PCT/US2015/017916
Authority: WO
Inventors: Hau-Nan LEE; Stephanie A. BERNARD; Jelena LASIO; Andrew Jay Duncan
Original assignee: E I Du Pont De Nemours And Company
Priority date: 2014-03-11
Filing date: 2015-02-27
Publication date: 2015-09-17

Abstract

The disclosure provides a process for preparing a surface functionalized polymeric or polymeric/silica hybrid hollow nanospheres comprising: providing a mixture comprising water, at least one non-reactive solvent, at least one acrylic or styrenic monomer; at least one functionalized acrylic or styrenic monomer; an initiator; at least one surfactant; and, optionally, a polymerizable silane if the polymeric/silica hybrid hollow particles are desired; and shearing the components of the mixture with high shear energy at an energy density of at least 10^6 J/m^3 to form a mini-emulsion; and heating to at least about 50°C, more typically about 50°C to about 90°C; and still more typically about 60°C to about 80°C to form, in one step, a surface functionalized polymeric or polymeric/silica hybrid hollow nanosphere.

Description

TITLE

PROCESS FOR PREPARING SURFACE FUNCTIONALIZED POLYMERIC AND POLYMERIC/SILICA HYBRID HOLLOW

NANOSPHERES

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to a process for making surface functionalized polymeric or polymeric/silica hybrid hollow nanospheres, more particularly to a preparation process for making surface

functionalized polymeric or polymeric/silica hybrid hollow nanospheres utilizing a one-step mini-emulsion preparation process and their use in coating compositions. Description of the Related Art

Nanospheres are submicroscopic colloidal systems composed of a solid or liquid core surrounded by a thin polymer or inorganic shell. This solid or liquid core is removed to form hollow nanospheres. Such core- shell systems may be prepared from micro or miniemulsions via polymerization reaction at the interface of the droplets, the so-called interfacial polymerization reaction. Interfacial polymerization occurs at the interface of two immiscible phases, for example, oil and water, and a thin shell is formed. In the formation of the shell, the monomers are in either oil or water phase to participate in the reaction. Typically, for the preparation of core-shell nanocapsules via interfacial polymerization, a microemulsion or miniemulsion is first prepared, either water in oil or oil in water, wherein in the former nanocapsules with an aqueous core suspended in oil are formed and in the latter nanocapsules with an oily core suspended in water are formed. Existing processes for the preparation of surface functionalized polymeric or polymeric/silica hybrid hollow particles either require a multi-step polymerization or grafting process, or use a sacrificial polymer or inorganic hard template.

A need exists for a surface functionalized polymeric or

polymeric/silica hybrid hollow nanosphere via an interfacial miniemulsion polymerization reaction. It is also needed that the process can be prepared through a one step process and provide superior performance for opacity enhancement in architectural and industrial coatings.

SUMMARY OF THE DISCLOSURE

The disclosure provides a process for the synthesis of surface functionalized polymeric or polymeric/silica hybrid hollow nanospheres.

The surface properties of the particles are tuned through copolymerization with a variety of functionalized acrylic or styrenic monomer.

In a first aspect, the disclosure provides a process for preparing a surface functionalized polymeric and polymeric/silica hybrid hollow nanospheres comprising:

a) providing a mixture comprising water, at least one non-reactive solvent, at least one acrylic or styrenic monomer; at least one functionalized acrylic or styrenic monomer; an initiator; at least one surfactant; and, optionally, a polymerizable silane if the

polymeric/silica hybrid hollow particles are desired

b) shearing the components of the mixture from (a) with high shear energy at an energy density of at least 10^Λ6 J/m^A3 to form a mini- emulsion; and

c) heating to at least about 50°C, more typically about 50°C to about 90°C; and still more typically about 60°C to about 80°C to form, in one step, a surface functionalized polymeric or polymeric/silica hybrid hollow nanosphere.

By non- reactive solvent we mean that the solvent does not substantially react, more typically does not react, with any of the other components added to the reaction.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is the structure of the resulting particles from Example 1 that was analyzed using transmission electron microscopy.

Figure 2 is the structure of the resulting particles from Example 2 that was analyzed using transmission electron microscopy. Figure 3 is the structure of the resulting particles from Example 3 that was analyzed using transmission electron microscopy.

Figure 4 is the structure of the resulting particles from Example 4 that was analyzed using transmission electron microscopy.

DETAILED DESCRIPTION OF THE DISCLOSURE

The disclosure relates to a process for preparing a surface

functionalized polymeric or polymeric/silica hybrid hollow nanospheres. These surface-functionalized polymeric and polymeric/silica hybrid hollow nanospheres are useful as hiding or opacifying agents in coating and molding compositions. They are also useful as drug delivery systems in the pharmaceutical and medical industries; in food, personal care and cosmetics; and agriculture.

The disclosure describes the process for surface functionalized polymeric and polymeric/silica hybrid hollow nanospheres with tunable functional group on the hollow particles' surface. The surface properties of the particles are tuned through copolymerization with a variety of functionalized acrylic or styrenic monomer.

These nanospheres have a particle size of about 5 nm to about 400 nm, more typically about 50 nm to about 300 nm, and still more typically about 50 nm to about 250 nm. The solids concentration of these nanospheres dispersion is at least about 5% solids, more typically about 5 wt% to about 30 wt%, still more typically about 5 wt% to about 20 wt%.

The surface functionalized polymeric and polymeric/silica hybrid hollow nanospheres are prepared by a process comprising:

(a) providing a mixture comprising water, at least one non- reactive solvent, at least one acrylic or styrenic monomer; at least one functionalized acrylic or styrenic monomer; an initiator; at least one surfactant; and, optionally, a polymerizable silane if the polymeric/silica hybrid hollow particles are desired

(b) shearing the components of the mixture from (a) with high shear energy at an energy density of at least 10^Λ6 J/m^A3 to form a mini-emulsion; and (c) heating to at least about 50°C, more typically about 50°C to about 90°C; and still more typically about 60°C to about 80°C to form, in one step, a surface functionalized polymeric or polymeric/silica hybrid hollow nanosphere.

The non-reactive solvent may be an alkane, a hydrocarbon oil, aromatic hydrocarbon or halogenated hydrocarbon liquid, more typically alkane or hydrocarbon oil.

The at least one acrylic or styrenic monomer may be methyl methacrylate, methyl acrylate, n-butyl methacrylate, t-butyl methacrylate, t- butyl acrylate, ethyl glycol dimechacrylate, styrene or divinylbenzene; more typically methyl methacrylate or styrene. The monomer is present in the amount of about 5 wt % to about 30 wt %, more typically about 5 wt% to about 20 wt%, based on the total weight of all components.

The at least one functionalized acrylic or styrenic monomer may be a monomer having one of the following formulas:

X-OC(O)CR=CH₂,

wherein R = H or Chb, and X and Y are the functional groups that can be introduced onto the hollow particle surface. A large spectrum of functionalities can be used, for example boronic acid, sulfonic acid, silyl phosphonates, phosphonic acids, amines, alcohols, epoxides, carboxylic acids, thiols, thioethers, carbamates, isocyanates, quarternary ammonium ions. Some suitable functionalized acrylic or styrenic monomers are glycidyl methacrylate, phosphoric acid 2-hydroxyethyl methacrylate ester, 4-vinylbenzenephosphonic acid, 4-vinylbenzeneboronic acid, 4- vinylbenzene sulfonic acid and salts or esters. Depending on the hydrophobicity of the functionalized acrylic or styrenic monomer, the functional groups can be located in the either inner or outer surface of the hollow spheres. The functionalized acrylic or styrenic monomer is present in the amount of about 0.1 wt % to about 20 wt %, more typically about 1 wt% to about 12 wt%, still more typically about 2 wt% to about 8 wt% based on the total weight of all monomers.

Some suitable initiators include azo compounds such as 2,2'- azobisisobutyronitrile (AIBN) or 2,2'-azobis(2-methylpropionamide) dihydrochloride (AIBA); metal persulfate such as potassium persulfate (KPS) or sodium persulfate; more typically AIBN or KPS. The initiator is present in the amount of about 0.05 wt % to about 0.5 wt %, more typically about 0.1 wt% to about 0.3 wt%, based on the total weight of all components.

Some suitable surfactants include cetyltrimethylammonium bromide (CTAB), lauryltrimethylammonium bromide, dodecyltrimethylammonium bromide, octyltrimethylammonium bromide, sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), dioctylsulfosuccinate , nonionic surfactants such as alkylphenol polyoxyethylene,

polyoxyethylene glycol alkyl ethers, polyoxypropylene glycol alkyl ethers, octylphenol ethoxylates, or poloxamers, more typically SDS, SDBS or CTAB. Some useful commercially available surfactants series include Triton X® manufactured by The Dow Chemical Company, Brij®

manufactured by Croda International PLC, or Pluoronic® manufactured by BASF. The surfactant concentration is about 0.001 wt % to about 5 wt %, more typically about 0.1 wt% to about 2 wt%, based on the total weight of all components.

Optionally, a polymerizable silane may be needed if the

polymeric/silica hybrid hollow particles are desired. Some suitable polymerizable silanes are allyltriethoxysilane, allyltrimethoxysilane, diethoxy(methyl)vinylsilane, dimethoxymethylvinylsilane,

triethoxyvinylsilane, trimethoxy(7-octen-1 -yl)silane, 3-(trimethoxysilyl)- propyl acrylate, 3-(trimethoxysilyl)propyl methacrylate, or

vinyltrimethoxysilane, more typically 3-(trimethoxysilyl)propyl acrylate or 3-(trimethoxysilyl)propyl methacrylate. The monomers to non-reactive solvent ratio is about 0.1 to about 6, more typically about 0.5 to about 3, still more typically about 0.5 to about 2; oil to water or water to oil ratio is about 0.01 to 0.55, more typically 0.05 to 0.25; and surfactant concentration is about 0.001 wt % to about 5 wt %, more typically 0.1 wt% to about 2 wt%, based on the total weight of all components. The water phase comprises water and surfactant and the oil phase comprises at least one non-reactive solvent, at least one acrylic or styrenic monomer; at least one functional ized acrylic or styrenic monomer and the optional polymerizable silane. Depending on the initiator used, the initiator may be considered to be in either the water phase or oil phase. It is important because the combination of monomers to non- reactive solvent ratio, oil to water ratio and surfactant level determine the particle size, hollow or non-hollow particle structure, and the shell thickness.

The mixture in step (a) may be prepared in any glass container or stainless steel reaction vessel .

The mixture of the above components is then sheared at an energy density of at least 10^Λ6 J/m^A3, more typically about 10^Λ7 J/m^A3 to about 5*10^Λ8 J/m^A3, to form a mini-emulsion. Some useful means for shearing include an ultrasonic disruptor, high speed blender, high pressure homogenizer, high shear disperser, membrane homogenizer or colloid mill, more typically an ultrasonic disruptor, high speed blender, or a high pressure homogenizer. Typically shearing occurs for a period of about 5 to about 120 minutes depending on amount of emulsion needed to be prepared and desired emulsion size range, more typically about 30 minutes to about 60 minutes. Typically, shearing is accomplished at room temperature. Optionally, a defoamer may be needed to avoid foaming during emulsifying. Some suitable defoamers include BASF Foamaster®, Dow Corning® 71 and 74 Antifoams.

The mini-emulsion formed in step (b) is then heated to at least about 50°C, more typically about 50°C to about 90°C; and still more typically about 60°C to about 80°C to form, in one step, a surface functionalized polymeric or polymeric/silica hybrid hollow nanosphere. Heating may be accomplished using hot plate, heating mantle or any other heating method.

Applications:

The surface functional ized polymeric or polymeric/silica hybrid hollow nanospheres are useful as hiding or opacifying agents in coating and molding compositions. They are also useful as drug delivery systems in the pharmaceutical and medical industries; in food, personal care and cosmetics; and agriculture. EXAMPLES

Glossary:

AIBN 2,2'-azobisisobutyronitrile

CTAB cetyltrimethylammonium bromide Example 1 :

An oily mixture which contained 5.0 g of hexadecane, 36.8 g of octane, 28.8 g of methyl methacrylate, 3.6 g of ethylene glycol

dimethacrylate, 3.6 g of styrene, 1 .8 g of 4-vinylbenzene boronic acid and 0.798 g of AIBN was first prepared, and added to a water solution which contains 420.0 g of water, 0.9 g of CTAB and 0.5 g of defoamer

(Foamaster® 1 1 1 , BASF). Miniemulsification was achieved by shearing the mixture for 30 minutes with a high speed blender at 9500 rpm. After forming a stable miniemulsion, the polymerization was started by heating to 70 °C for at least 16 hours. The structure of the resulting particles was analyzed using transmission electron microscopy and shown in Figure 1 . The average particle size of the resulting hollow particles determined by dynamic light scattering is 146.5 nm with a polydispersity of 0.168.

Example 2: An oily mixture which contained 5.0 g of hexadecane, 36.8 g of octane, 28.8 g of methyl methacrylate, 3.6 g of ethylene glycol

dimethacrylate, 3.6 g of styrene, 0.9 g of 4-vinylbenzene boronic acid and 0.798 g of AIBN was first prepared, and added to a water solution which contains 420.0 g of water, 0.9 g of CTAB and 0.5 g of defoamer

(Foamaster® 1 1 1 , BASF). Miniemulsification was achieved by shearing the mixture for 30 minutes with a high speed blender at 9500 rpm. After forming a stable miniemulsion, the polymerization was started by heating to 70 °C for at least 16 hours. The structure of the resulting particles was analyzed using transmission electron microscopy and shown in Figure 2. The average particle size of the resulting hollow particles determined by dynamic light scattering is 72.4 nm with a polydispersity of 0.141 .

Example 3:

dimethacrylate, 3.6 g of styrene, 0.9 g of phosphoric acid 2-hydroxyethyl methacrylate ester and 0.798 g of AIBN was first prepared, and added to a water solution which contains 420.0 g of water, 0.9 g of CTAB and 0.5 g of defoamer (Foamaster® 1 1 1 , BASF). Miniemulsification was achieved by shearing the mixture for 30 minutes with a high speed blender at 9500 rpm. After forming a stable miniemulsion, the polymerization was started by heating to 70 °C for at least 16 hours. The structure of the resulting particles was analyzed using transmission electron microscopy and shown in Figure 3.

Example 4: An oily mixture which contained 6.0 g of hexadecane, 5.4 g of methyl methacrylate, 0.6 g of ethylene glycol dimethacrylate, 0.6 g of phosphoric acid 2-hydroxyethyl methacrylate ester and 0.133 g of AIBN was first prepared, and added to a water solution which contains 60.0 g of water and 0.05 g of sodium dodecylbenzene sulfonate. Miniemulsification was achieved by ultrasonicating the mixture for 60 s with a Branson sonifier W150 at 100% amplitude and then stopping for 30 s; and repeating this cycle 10 times. To avoid polymerization due to heating, the mixture was cooled in an ice-bath during homogenization. After forming a stable miniennulsion, the polymerization was started by heating to 70 °C for at least 16 hours. The structure of the resulting particles was analyzed using transmission electron microscopy and shown in Figure 4. The average particle size of the resulting hollow particles determined by dynamic light scattering is 229 nm with a polydispersity of 0.162.

Claims

CLAIMS What is claimed is:

1 . A process for preparing a surface functionalized polymeric or polymeric/silica hybrid hollow nanospheres comprising:

(a) providing a mixture comprising water, at least one non- reactive solvent, at least one acrylic or styrenic monomer; at least one functionalized acrylic or styrenic monomer; an initiator; at least one surfactant; ;

(b) shearing the components of the mixture from (a) with high shear energy at an energy density of at least 10^Λ6 J/m^A3 to form a mini-emulsion; and

(c) heating to at least about 50°C to form, in one step, a surface functionalized polymeric or polymeric/silica hybrid hollow nanosphere.

2. The process of claim 1 wherein the mixture in step (a) further comprises a polymerizable silane.

3. The process of claim 1 wherein heating is to about 50°C to about 90°C.

4. The process of claim 1 wherein heating is to about 60°C to about 80°C.

5. The process of claim 1 wherein the non-reactive solvent is an alkane, a hydrocarbon oil, aromatic hydrocarbon or halogenated hydrocarbon liquid.

6. The process of claim 5 wherein the non-reactive solvent is alkane or hydrocarbon oil.

7. The process of claim 1 wherein the at least one acrylic or styrenic monomer is methyl methacrylate, methyl acrylate, n-butyl methacrylate, t-butyl methacrylate, t-butyl acrylate, ethyl glycol dimechacrylate, styrene or divinylbenzene.

8. The process of claim 7 wherein the at least one acrylic or styrenic monomer is methyl methacrylate or styrene.

9. The process of claim 1 wherein the functional ized acrylic or styrenic monomer may be a monomer having one of the following formulas:

X-OC(O)CR=CH₂,

wherein R = H or Chb, and X and Y are boronic acid, sulfonic acid, silyl phosphonates, phosphonic acids, amines, alcohols, epoxides, carboxylic acids, thiols, thioethers, carbamates, isocyanates, or quarternary ammonium ions.

10. The process of claim 1 wherein the functionalized acrylic or styrenic monomer is glycidyl methacrylate, phosphoric acid 2-hydroxyethyl methacrylate ester, 4-vinylbenzenephosphonic acid, 4-vinylbenzene- boronic acid, 4-vinylbenzene sulfonic acid, salts thereof or esters thereof.

1 1 . The process of claim 1 wherein the initiator is an azo

compound; or a metal persulfate.

12. The process of claim 10 wherein the azo compound is 2,2'- azobisisobutyronitrile (AIBN) or 2,2'-azobis(2-methylpropionamide) dihydrochloride (AIBA).

13. The process of claim 10 wherein the metal persulfate is potassium persulfate (KPS) or sodium persulfate.

14. The process of claim 1 1 wherein the initiator is AIBN or KPS.

15. The process of claim 1 wherein the surfactant is

cetyltrimethylammonium bromide (CTAB), lauryltrimethylammonium bromide, dodecyltrimethylammonium bromide, octyltrimethylammonium bromide, sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), dioctylsulfosuccinate, nonionic surfactant, octylphenol ethoxylate, or poloxamer.

16. The process of claim 15 wherein the surfactant is SDS, SDBS or CTAB.

17. The process of claim 1 wherein the polymerizable silanes is allyltriethoxysilane, allyltrimethoxysilane, diethoxy(methyl)vinylsilane, dimethoxymethylvinylsilane, triethoxyvinylsilane, trimethoxy(7-octen-1 - yl)silane, 3-(trimethoxysilyl)propyl acrylate, 3-(trimethoxysilyl)propyl methacrylate, or vinyltrimethoxysilane.

18. The process of claim 17 wherein the polymerizable silanes is 3- (trimethoxysilyl)propyl acrylate or 3-(trimethoxysilyl)propyl methacrylate.

19. The process of claim 1 wherein the mixture of the above components is then sheared at an energy density of about 10^Λ7 J/m^A3 to about 5^*10^Λ8 J/m^A3 form a mini-emulsion.

20. The process of claim 1 wherein the shearing means is an ultrasonic disruptor, high speed blender, high pressure homogenizer, high shear disperser, membrane homogenizer or colloid mill.