SE1830166A1 - Polymer particles - Google Patents

Abstract

A polymer particle prepared from a nucleated composition comprising a monomer of formula (I) and a process for preparation of said polymer particle are provided:(I)wherein;(a) X and Y is independently -O-CH-CH-, -O-CH-CH(CH)-, or-O-CH(CH)-CH-;(b) Z is -O-C(O)-CH=CH, -O-C(O)-C(CH)=CH, -NH-C(O)-CH=CH,-NH-C(O)-C(CH)=CH,-O-CH=CH, -O-CH-CH=CH, -CH=CH,-CH-CH=CH, -O-C(O)-CH-CH-SH, -NH-C(O)-CH-CH-SH, or SH; (c) W is -(CH)-(XY)-Z, a hydrogen, a functional group, an alkyl group, or a functionalized alkyl group; and(d) each of a, b, c, d, e, f, g, h, i, j, k, 1, m, n, o, and p is independently a number in the range 0-100.

Description

POLYMER PARTICLES TECHNICAL FIELD This invention pertains in general to the field of synthetic polymer particles, their forrnulation, and their preparation.

BACKGROUND OF THE INVENTION A polymer is a macromolecule built up of many small building blocks, also referred to asmonomers. The polymers are often divided into synthetic ones and natural ones. The synthetic polymersare manmade. The natural polymers are the polymers found in nature but can also be synthesized and/ormodified in laboratories and industries. The composition of a polymer is deterrnined by the monomersused for its preparation. The monomers will bring certain Characteristics to the polymer. For example,a functional monomer will provide the polymer with functional groups and a cross-linking monomerwill provide a cross-linked polymer network. After polymerization, the polymer may be processedfurther by a range of post-polymerization procedures in order to prepare it for its final application. Forexample, functionalization will provide new functional groups, coupling with molecules of various sizesand types will provide new characteristics and properties, further cross-linking or attachment to surfaceswill increase the stability, and derivatization with biocompatible compounds will increase thebiocompatibility of the polymer.

Polymers can be prepared in different size and shape. Polymer particles are particularlyinteresting since they are used in a wide range of applications in many sectors in the society [Gokmenand Prez, Progress in Polymer Science 37 (2012) 365-405]. In laboratory and chemical industrysettings, polymer particles are used as stationary phases in various small and large-scale separations andpurifications (e. g., in liquid chromatography and solid-phase extraction), as supports (solid phases) insolid-phase synthesis, as supports for immobilization of macromolecules and cells, as catalysts, etc.Emerging applications in medicine include their use as carriers in drug delivery and tissue engineering,as immunologic adjuvants in vaccines, and as recognition elements in assay and sensor applications. Inthe environmental and energy fields, polymer particles are useful as sorption media for purification ofwater, for hydrogen storage, and for carbon capture/sequestration. Another application area is in printingand additive manufacturing for the production of 2D- and 3D-structures and objects. Polymer particlesare also used in a wide range of consumer products such as cosmetics, detergents, and toothpaste. Hence,there is a large need of polymer particles as well as efficient and sustainable methods for their preparation.

Polymer particles of various sizes and shapes can be prepared by a range of methods, forexample, by mechanical disintegration of monolithic polymers, by dispersion polymerization, byprecipitation polymerization, by suspension polymerization, or by emulsion polymerization.Mechanical disintegration of monolithic polymers into particles is a tedious procedure and typicallyprovides irregularly shaped particles; fractionation is required to provide the desired size range, oftenresulting in low yields. While both dispersion polymerization and precipitation polymerization involveprecipitation of the polymer during the polymerization, the former method typically provides micro-sized particles while precipitation polymerization provides particles in the sub-micron size range. Inboth methods, the particles precipitate as they polymerize from a homogenous highly diluted solutionof monomers dissolved in an organic solvent. In dispersion polymerization, a colloidal stabilizer ispresent in the solution. Key to both dispersion polymerization and precipitation polymerization is thatthe solvent should be a good solvent for the monomers but a poor solvent for the polymer particles topromote precipitation during the polymerization. In suspension polymerization, water-insolublemonomers are suspended in a continuous water phase by vigorous mixing. Stabilizers, for example,polymers or detergents, are used to stabilize and prevent coalescence of the droplets formed during theagitation. Addition of a water-immiscible porogenic solvent to the suspended phase influences on thesize and porosity of the particles. Polymerization is typically carried out by free-radical polymerizationusing an initiator dissolved in the suspended phase. Mixing is continued throughout the fullpolymerization time period. A wide range of particle sizes, from sub-micrometer to several millimetersin diameter, can be produced by suspension polymerization. In emulsion polymerization, water-insoluble monomers and surfactants are dispersed in a continuous water phase by vigorous stirring,resulting in the formation of monomer-containing small micelles and larger droplets of monomers.Polymerization of the monomers in the micelles, using a water-soluble initiator, provides polymerparticles, which continuously grow by diffusion of monomers from the larger monomer droplets to themicelles until the monomers are depleted in the droplets. Typical sizes of the resulting particles arearound 100 nm. In mini-emulsion polymerization, a co-stabilizer is used in addition to the surfactantand high-sheer mixing by, for example, ultrasound is applied. Polymerization using a water-solubleinitiator provides polymer particles in the size range 50-500 nm. In micro-emulsion polymerization, ahigh concentration of surfactant is used to produce a therrnodynamically stable micro-emulsion ofmonomer-filled micelles, which are polymerized after addition of a water-soluble initiator. The typicalparticles size of the resulting particles is in the range 10-50 nm.

Overall, current methods for producing polymer particles are rather complex, labor-intensive,and non-sustainable; improved methods are clearly needed. The present invention addresses these needsby providing environmentally friendly, low energy-consuming, and sustainable methods for the production of polymer particles.

SUMMARY OF THE INVENTION The invention provides synthetic polymer particles suitable for a range of applications. In oneembodiment, the polymer particle is comprised of a polymerized cross-linking monomer of the following forrnula (I) and is prepared from a nucleated composition comprising said monomer: (1)<ßflgifl-<>d-~z\fv--C---<<>H2>. ---<>h ----2,----<><,Yk>. ----2Wherein; (a) X and Y is independently -O-CH2-CH2-, -O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Z is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CH2, ~O-CH=CH2, -O-CHz-CH=CH2, -CH=CHz,-CHz-CH=CH2, -O-C(O)-CH2-CH2-SH, -NH-C(O)-CH2-CHz~SH, or SH; (c) W is -(CH2)m-(XnY0)p-Z, a hydrogen, a functional group, an alkyl group, or a functionalizedalkyl group; and (d) each of a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, and p is independently a number in the range0-100.

In another embodiment the polymer particle is further comprised of additional co-polymerizedmonomer(s).In another embodiment the invention provides a process for preparing said polymer particlecomprising the steps:(a) dissolving the monomer(s) in a Water-miscible solvent, forrning a solution comprising saidmonomer(s);(b) interfacing said solution With a Water phase to forrn a mixture in Which spontaneous andinstantaneous forrnation of nucleated droplets comprising said monomer(s) takes place; and (c) polymerizing said monomer(s).

The novel process of the invention is based on a concept that is different than conventional andprior-art methods for the production of polymer particles. The invention provides, spontaneously andinstantaneously, droplets of monomers through a simple, environmentally friendly, and energy-efficientprocedure. The droplets nucleate When a preferred proportion of a solution, comprising monomersdissolved in a Water-miscible solvent, is interfaced With a Water phase. Only a brief initial mixing isrequired to interface the tWo liquids for the forrnation of the droplets; no extended mechanical agitation is required and no surfactants, stabilizers, or dispersants are needed. A non-toxic harrnless solvent such as ethanol can be used as the water-miscible solvent, making the procedure environmentally friendlyby obviating the use of harrnful solvents. The droplets are easily transforrned into solid particles bypolymerization. The polymer particles of the invention may be used directly for the intended applicationor may be further processed before their final use. The particles are useful in all applications wherepolymer particles are needed. The particles of the invention are particularly suitable for use as supportsin solid-phase synthesis, as drug carriers in targeted drug delivery and sustained drug release, as contrast agents or markers in medical imaging, and as sorbents in separations and purifications.

BRIEF DESCRIPTION OF THE DRAWINGS Figure l. (a) Right triangle phase diagram of the temary system PETRA-ethanol-water beforepolymerization. The region providing nucleated droplets, appropriate for polymerization to particles, islocated below the dotted line. (b) Right triangle phase diagram after polymerization.

Figure 2. Influence of interfacing method on the particle size distribution of poly(PETRA).Interfacing was carried out by (a) manual shaking (20 inversions); (b) stirring using an overhead stirrerequipped with a radial flow impeller (700 rpm, 3 min); (c) homogenization using a homogenizerequipped with a dispersing element (8 000 rpm, l min); and (d) homogenization using an ultrasonichomogenizer equipped with an ultrasonic probe (6 >< 10 s, 20 W). DLS analysis (intensity based, n=30)was carried out on particles dissolved in water.

Figure 3. Influence of polymerization conditions on the particle size distribution ofpoly(PETRA). Polymerization was carried out by subjecting the samples to (a) heat (60 °C for 6 h); or(b) UV light (350 nm for 2 h). DLS analysis (intensity based, n=l0) was carried out on particlesdissolved in water.

Figure 4. Derivatization of the polymer particle with (a) linkers to provide a solid-phasesynthesis support; (b) drugs to provide a drug-carrier suitable for sustained and/or controlled drugrelease; (c) aff1nity ligands to provide a ligand-particle conjugate; (d) imaging probes to provide aparticle-based contrast agent; and (e) PEG chains to increase the biocompatibility of the polymerparticle. The figure is schematic and although only one conjugated molecule is drawn in each example,it should be understood that a multitude of molecules can be conjugated to each particle.

Figure 5. Schematic drawing showing cross-sections of polymer particle-based drug carriersprepared by (a) conjugating the drug to the particle; (b) adsorbing the drug to the surface of the particle;and (c) entrapping the drug in the polymer network.

DETAILED DESCRIPTION Several embodiments of the present invention are described in more detail below, with referenceto the accompanying drawings in order for those skilled in the art to be able to carry out the invention.The invention may, however, be embodied in many different forrns and should not be construed as limited to the embodiments set forth herein. Furthermore, the terrninology used in the detaileddescription of the particular embodiments is not intended to be limiting of the invention.

The invention provides in one embodiment polymer particles of well-defined compositions andsize distributions. The size distribution is adjusted by adjusting the parameters of the preparationprocess. Typically, the polymer particles are in the size range l-5000 nm. More typically, the polymer particles are in the size range 5-1500 nm. Most typically, the polymer particles are in the size range 10-1000 nm. The polymer particles are suitable for a range of applications, either applied directly asprovided by the invention°s preparation process or after further post-polymerization processing.

The polymer particles of the invention are composed of polymer networks, forrned bypolymerization of monomers, used as polymer building blocks. The group of monomers used in the invention can be divided into cross-linking monomers and non-cross-linking monomers. In oneembodiment of the invention, the polymer particles are comprised of a polymerized cross-linkingmonomer of the following forrnula (1): (1)<<>H2>a --<>fi --~ 2W WC“*““(CH2)@ ”Wwíxfight ”W Zr--<>t ---- 220 wherein; (a) X and Y is independently -O-CH2-CH2-, -O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-;(b) Z is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CH2, ~O-CH=CHz, -O-CHz-CH=CHz, -CH=CHz,-CHz-CH=CH2, -O-C(O)-CH2-CH2-SH, -NH-C(O)-CHz-CHz~SH, or SH;25 (c) W is -(CH2)m-(XnY0)p-Z, a hydrogen, a functional group, an alkyl group, or a functionalizedalkyl group; and(d) each of a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, and p is independently a number in the range0-100.

Examples of other cross-linking monomers that can be applied as a polymer building block in30 the invention include, but are not limited to, divinylbenzene [H2C=CH-C6H4-CH=CH2], glyceroldiglycidyl ether [C9H16O5], glycerol dimethacrylate [H2C=C(CH3)CO2CH2CH[OR(H)]CH2OH(R); R = H or COC(CH3)=CH2], divinyl sulfone [(H2C=CH)2SO2], Vinyl acrylate [HzC=CH-C(O)-O-CH=CH2], Vinyl rnethacrylate [H2C=C(CH3)-C(O)-O-CH=CH2], ethylene glycol diacrylate[H2C=CH-C(O)-O-CHz-CHz-O-C(O)-CH=CH2], ethylene glycol dimethacrylate [H2C=C(CHs)-C(O)-O-CH2-CH2-O-C(O)-C(CH3)=CH2], di(ethylene glycol) dirnethacrylate [[H2C=C(CH3)-C(O)-O-CH2CHz]2O], di(ethylene glycol) diacrylate [[H2C=CH-C(O)-O-CH2-CHz]20], IA-butanediol[H2C=CH-C(O)-O-(CHz)4-O-C(O)-CH=CHz), lA-butanediol[H2C=C(CH3)-C(O)-O-(CH2)4~O-C(O)-C(CH3)=CH2), glycerol propoxylate triglycidylglycoßdiacrylate [H2C=CH-C(O)-(O(CH2)3)3~O-C(O)-CH=CHz], Érflpropyleneglycoßdirnethacrylate [H2C=C(CH3)-C(O)-(O(CH2)3)3-O-C(O)-C(CH3)=CH2], p01y(ethy1ene glycol-400)-diacry1ate [H2C=CH-C(O)-(OCH2CH2)9-O-C(O)-CH=CH2], p01y(ethy1ene g1yco1-400)-dirneth-[H2C=C(CH3)-C(O)-(OCH2CHz)9~O-C(O)-C(CH3)=CH2] , N,N ” -methylenediacrylamide[H2C=CH-C(O)-NH-CH2-NH-C(O)-CH=CH2], N,N”-methylenedimethacrylamide [H2C=C(CH3)-C(O)-NH-CH2-NH-C(O)- C(CH3)=CH2], N,N”-phenylenediacrylamide [H2C=CH-C(O)-NH-C6H4-NH-C(O)- CH=CH2], N,N”-phenylenedimethacrylamide [H2C=C(CHg)-C(O)-NH-C6H4-NH-C(O)-C(CH3)=CH2], 3,5-bis(acry10y1amid0)benzoic acid [H2C=CH-C(O)-NH-C6H3(COzH)-NH-C(O)-CH=CH2], 3,5-bis(rnethacryloylarnido)benzoic acid [H2C=C(CHs)~C(O)-NH-C6H3(CO2H)-NH-C(O)-C(CH3)=CH2], N,O-bisacryloyl-L-phenylalaninol [H2C=CH-C(O)-NH-CH(CH2-C6Hs)~CH2-O-C(O)-CH=CH2], N,O-bisrnethacryloyl-L-phenylalanino1 [H2C=C(CH3)-C(O)-NH-CH(CH2-C6H5)-CH2-O-C(O)-C(CH3)=CH2], Vinyl acrylate [H2C=CH-C(O)-O-CH=CH2], Vinyl rnethacrylate[H2C=C(CH3)-C(O)-O-CH=CH2], diallyl succinate [(CH2CO2CHzCH=CH2)2], trimethylolpropanetrivinyl ether [(H2C=CH-O-CH2)3C(C2H5)], 2,4,6-tria11y1oxy-1,3,5-triazine [C12H15N3O3], 1,3,5-triallyl-l ,3 ,5 -triazine-2,4,6(1H,3H,5H)-tri0ne, tris[2-(acry10y10xy)ethy1] -isocyanuratq diürirnethylol-propane) tetraacrylate [((H2C=CH-C(O)-O-CH2)2C(C2H5)-CH2)2O],tetramethacrylate [((H2C=C(CHg)-C(O)-O-CH2)2C(C2Hs)-CH2)2O], pentaerythritol tetraacrylate[C(CH2-O-C(O)-CH=CH2)4], pentaerythritol tetramethacrylate [C(CH2-O-C(O)-C(CH3)=CH2)4],(PETRA) [HO-CHz-C(CH2-O-C(O)-CH=CHz)3], pentaerythritoltrimethacrylate [HO-CH2-C(CH2-O-C(O)-C(CH3)=CH2)3], trimethylolpropane triacrylate [CHg-CH2-C(CH2-O-C(O)-CH=CH2)3], trimethylolpropane trimethacrylate (TRIM) [CH3-CH2-C(CH2-O-C(O)-C(CH3)=CH2)3], trimethylolpropane benzoate diacrylate [(H2C=CH-C(O)-O-CH2)2C(C2H5)-CH2-O-C(O)-C6H5], dirnethacrylate [(H2C=C(CH3)-C(O)-O-CH2)2C(C2H5)-CH2-O-C(O)-C6H5], trimethylolpropane allyl ether [H2C=CH-CH2-O-CH2-C(CzHs)(CH2OH)z, diallyl [CzHsC(CH2OCH2CH=CHz)2CH2OH],trimethylolpropane ethoxylate (lEO/OH) rnethyl ether diacrylate [H2C=CH-C(O)-O-CHz-CHz-O-CH2)2C(C2H5)-CH2-O-CH2-CH2-O-CH3], pentaerythritol ethoxylate (3/4 EO/OH) tetraacrylate[C[CH;(OCH2CH2)I1O-C(O)-CH=CH2]4, pentaerythritol ethoxylate (3/4 EO/OH) tetramethacrylate diacrylate dirnethacrylate ether,tri(propy1ene acrylate diürirnethylolpropane) pentaerythritol triacrylate benzoate trimethylolpropane trimethylolpropane ether [C[CHg(OCH;CH2)nO-C(O)-C(CH3)=CH2]4, pentaerythritol propoxylate (5/4 PO/OH) tetraacrylate[C[CHg[OCH2CH(CH3)]I1O-CH=CH2]4, pentaerythritol propoxylate (5/4 PO/OH) tetramethacrylate[C[CHg[OCHgCH(CH3)]nO-C(CH3)=CH2]4, pentaerythritol ethoxylate (15/4 EO/OH) tetraacrylate[C[CH;(OCH2CH2)nO-C(O)-CH=CH2]4, pentaerythritol ethoxylate (15/4 EO/OH) tetramethacrylate[C[CHg(OCH;CH2)nO-C(O)-C(CH3)=CH2]4, trimethylolpropane ethoxylate (lEO/OH) rnethyl etherdimethacrylate [H2C=C(CHg)-C(O)-O-CH2-CH2-O-CH2)2C(C2H5)-CH2-O-CH2-CH2-O-CH3],trimethylolpropane ethoxylate (1/3 EO/OH) triacrylate [(H2C=CH-C(O)-O-(CHz-CHz-O)nCHz)sC-C2H5], trimethylolpropane ethoxylate (1/3 EO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(CH2-CH2-O)nCH2)3C-C2H5], trimethylolpropane ethoxylate (7/3 EO/OH) triacrylate [(H2C=CH-C(O)-O-(CH2-CH2-O)11CH2)3C-C2Hs], (7/3 EO/OH) trimethacrylate[(H2C=C(CH3)-C(O)-O-(CH2-CH2-O)11CH2)3C-C2H5], trimethylolpropane ethoxylate (14/3 EO/OH)triacrylate [(H2C=CH-C(O)-O-(CH2-CH2-O)HCH2)3C-CzHs], trimethylolpropane ethoxylate (14/3EO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(CH2-CH2-O)11CH2)3C-C2H5], trimethylolpropanepropoxylate (1/PO/OH) triacrylate [(H2C=CH-C(O)-O-(C3H6O)n-CH2)3C-CzHs], trimethylolpropanepropoxylate (1/PO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(C3H6O)n-CH2)3C-C2H5],trimethylolpropane propoxylate (2PO/OH) triacrylate [(H2C=CH-C(O)-O-(C3H6O)n-CH2)3C-C2H5],trimethylolpropane propoxylate (2PO/OH) trimethacrylate [(H2C=C(CH3)-C(O)-O-(C3H6O)n-CH2)3C-C2H5], glycerol propoxylate (lPO/OH) triacrylate [[H2C=CH-C(O)-O-[CH(CH3)-CH2-O]1CH2] [H2C=CH-C(O)-O-[CH(CH3)~CHz-O]m] [H2C=CH-C(O)-O-[CH(CHs)~CHz-O]nCHz] [- CH], glycerol ethoxylate-co-propoxylate triacrylate [CHFCH-C(O)-O-(C3H6O)X-(CH2CH2O)y-CH[CHz-(OCH2CH2)y-(OC3H6)X-O-C(O)-CH=CH2]z], [CH3-(CH2)7~CH=CH-(CH2)7-C(O)-O-CH(CH2-O-C(O)-(CH2)7-CH=CH-(CH2)7-CH3)2], trimethylolpropane triglycidyl ether[C15H26O6], 2,2-bis[4-(2-hydroxy-3-methacryloyloxypr0p0xy)pheny1]-propane, ethoxylated bisphenol- trimethylolpropane ethoxylate triolein A dirnethacrylate, pentaerythritol tetrakis(3-mercaptopropionate) [(HS-CHz-CHz-C(O)-O-CHz)4C],[(HS-CH2-CHz-C(O)-O-CHz)3C-CzHs], 2-hydr0xyrnethy1-2-rnethy1-1ß-propanediol tris-(3-mercaptopropionate) [(HS-CH2-CH2-C(O)-O-CHz)3C-CH3], 2,2-bis(su1fany1rnethy1)-1ß-propanedithiol [(HS-CH2)4C], di-3-rnercaptopropionate, p01y(ethy1ene glycol) dithiol [HS-CHg-CHg-(O-CHg-CHfln-SH], 1,3,4-thiadiazole-LS-dithiol, [C2H2N2S3], toluene-SA-dithiol [CH3C6H3(SH)2], benzene-IA-dithiol,benzene-IJ-dithiol, LS-benzenedithiol [C6H4(SH)2], biphenyl-4,4'-dithiol [HS-C6H4-C6H4-SH], p-terpheny1-4,4”-dithi01 [HS-C6H4-C6H4-C6H4-SHL hexa(ethylene glycol) dithiol [HS-(CHg-CHQ-O)5-CH2-CH2-SH], tetra(ethy1ene glycol) dithiol [HS-(CHg-CHg-Oß-CHg-CHg-SH], 2,2'-(ethylenedioxy)diethanethiol [HS-CHz-CHz-O-CHz-CHæO-CHz-CHrSH], lA-benzenedirnethane-thiol [C6H4(CH2SH)2], Lló-hexadecanedithiol [HS-(CH2)16-SH], dithiothreitol [HS-CH2-CH(OH)-CH(OH)-CH2-SH], 2-rnercaptoethyl ether [O(CH2CH2SH)2], LS-propanedithiol [HS-(CH2)3-SH], trimethylolprop ane tris(3 -mercaptopropionate) glycol 1,4-butanedithiol [HS-(CH2)4-SH], 1,5-pentanedithiol [HS-(CH2)s~SH], l,6-hexane dithiol [HS-(CH2)6-SH], 4arrn-PEG-SH [C(CHg-O-(CHgCHgOfiCHgCHgSH)4], Sarrn-PEG-SH, and analogs andderivatives of these.

Exaniples of non-crosslinking n1onon1ers that can be used in the inVention include, but are notlin1ited to, acid-containing n1onon1ers such as acrylic acid, niethacrylic acid (MAA),trifluoroniethacrylic acid, itaconic acid, Vinylacetic acid, 4-Vinylbenzoic acid (4-VBA), 4-Vinylphenylboronic acid, Vinylsulfonic acid, and Vinylphosphonic acid; ester-containing n1onon1erssuch as Vinyl acetate, Vinyl propionate, Vinyl pivalate, allyl acetate, n1ethyl acrylate, niethylniethacrylate, ethyl acrylate, ethyl niethacrylate, propyl acrylate, propyl niethacrylate, butyl acrylate,butyl niethacrylate, pentyl acrylate, pentyl niethacrylate, cyclohexyl acrylate, cyclohexyl niethacrylate,benzyl acrylate, benzyl niethacrylate, isobornyl acrylate, isobornyl niethacrylate, hydroxybutyl acrylate,hydroxybutyl niethacrylate, Vinyl decanoate, Vinyl 4-tert-butylbenzoate, glycidyl acrylate, and glycidylniethacrylate; an1ide-containing n1onon1ers such as acrylaniide, n1ethacrylan1ide, and N-Vinylacetaniide; an1ino-containing n1onon1ers such as allyl an1ine, 2-an1inoethyl niethacrylate, 2-(diethylaniino)ethyl niethacrylate, (Vinylbenzyl)trin1ethylan1n1oniun1 chloride, and 4-an1inostyrene;heteroaroniatic n1onon1ers such as l-Vinyliniidazole, 4-Vinylpyridine, 2-Vinylpyridine, l-Vinyl-2-pyrrolidinone, N-Vinylcaprolactani, and N-Vinylphtaliniide; hydroxyl-containing n1onon1ers such as 4-hydroxystyrene, alpha-Vinylbenzyl alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl niethacrylate(HEMA), S-hydroxypropyl acrylate, S-hydroxypropyl niethacrylate, 4-hydroxypropyl acrylate, 4-5-hydroxypentyl acrylate, 5-hydroxypentyl niethacrylate, 2,3- hydroxypropyl niethacrylate, dihydroxypropyl acrylate, 2,3-dihydroxypropyl niethacrylate, N-hydroxyniethylacrylaniide, N-hydroxyniethylniethacrylaniide, allyl alcohol, hydroxyethyl Vinyl ether, and allyl-2-hydroxy-2-phenylether; Vinyl acid halides such as acryloyl chloride, niethacryloyl chloride; halide-containing n1onon1erssuch as Vinyl broniide and Vinyl chloride; thiol-containing n1onon1ers such as 2-propene-l-thiol; silane-containing n1onon1ers such as Vinyltriniethylsilane, Vinyltriniethoxysilane, and S-glycidoxypropyl-triniethoxysilane; aroniatic n1onon1ers such as styrene, 2-Vinyl anthracene, 9-Vinyl anthracene, l-Vinylnaphtalene, 2-Vinylnaphtalene, l-Vinylphenanthrene, 9-Vinylphenanthrene, 4-Vinylbiphenyl, 4-Vinyl-o-terphenyl, 4-Vinylpyrene, 5-Vinylpyrene, 2-Vinyltetracene; and analogs and derivatives of these.

In another en1bodin1ent, the inVention provides a process for preparing said polynier particlesconiprising the steps: (a) dissolving the n1onon1er(s) in a Water-niiscible solVent, forrning a solution coniprising said n1onon1er(s);(b) interfacing said solution and a Water phase to forrn a niixture in Which spontaneous and instantaneous forrnation of nucleated droplets coniprising said n1onon1er(s) takes place; and (c) polynierizing said n1onon1er(s).

The process of the invention is particularly adVantageous since it is energy-efficient andenvironmentally friendly. The first step of the process is the preparation of a solution comprising themonomer(s) dissolved in a Water-miscible solVent. The resulting solution is hereafter referred to as thesolution. Examples of suitable solVents for the preparation of the solution include, but are not limitedto, Water-miscible alcohols, acetonitrile, N,N-dimethylforrnamide (also named DMF), dimethylsulfoxide (also named DMSO), acetone, acetic acid, acetaldehyde, hexamethylphosphoric triamide(also named HMPT), dimethoxyethane (also named glyme, monoglyme, dimethyl glycol, ethyleneglycol dimethyl ether, dimethyl cellosolVe, and DME), 1,4-dioxane, N-methyl-2-pyrrolidone (alsonamed NMP), pyridine, tetrahydrofuran (also named THF), or combinations thereof Examples ofalcohols include, but are not limited to, methanol, ethanol, 1,2-ethanediol (also named ethylene glycol),l-propanol, 2-propanol, 1,2-propanediol (also named propylene glycol), l,3-propanediol, l-butanol, 2-butanol, 1,2-butanediol, l,3-butanediol, 1,4-butanediol, l-pentanol, 2-pentanol, 3-pentanol, 1,2-pentanediol, l,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,4-pentanediol, 1,5-pentanediol,glycerol (also named glycerine), erythritol (also named butane-l,2,3,4-tetrol), pentaerythritol (alsonamed 2,2-bis(hydroxymethyl)propane-l,3-diol), furfuryl alcohol, diethylene glycol (also namedDEG), triethylene glycol (also named triglycol, TEG, and TREG), tetraethylene glycol, andpentaethylene glycol.

The next step of the process comprises interfacing the solution With Water by simply adding thesolution to Water or by, in addition, including a brief mixing/blending procedure, thereby forrning amixture of monomer(s), Water-miscible solvent, and Water. In some cases, the momentum of the solutionbeing added to the Water phase is enough to cause sufficient turbulence to mix/blend the two liquids.Upon mixing/blending, the Water-miscible solVent partitions into the Water phase and nucleation(droplet formation) of the monomer(s) occurs. Key to successful nucleation is to provide preferredfractions of the three (or more) components in the mixture. The preferred fractions are estimated froman experimentally deterrnined phase diagram. As an example, a temary phase diagram of pentaerythritoltriacrylate (PETRA), ethanol, and Water has been acquired and is provided in the format of a righttriangle phase diagram in Figure la. Within the nucleation region, located beloW the dotted line inFigure la, nucleation occurs spontaneously and instantaneously When the components areinterfaced/mixed. In the most preferred embodiments, the composition is comprised of at the most about20 mass percent (i.e., at the most about 0.2 mass fractions) of a Water miscible solVent and at the mostabout 1 mass percent (i.e., at the most about 0.01 mass fractions) of monomer(s). Only an interfacingor initial brief mixing/blending is required; no continued mixing or agitation is required. The dropletsremain stable in the mixture during time periods that are suff1ciently long to allow for a polymerizationof the monomer(s) to form solid polymer particles. The size of the droplets is indicated in Figure la.

Mixtures of compositions located outside of the nucleation region form either (i) a single phase or (ii) unstable, aggregated droplets. Upon polymerization, mixtures from the single-phase region mayundergo precipitation polymerization and mixtures from the unstable region may form aggregatedpolymer particles of large size distributions and/or monolithic gels. Hence, polymer particles of narrowsize distribution are formed only from mixtures located in the nucleation region. Figure lb shoWs theresulting particle sizes of the polymer particles formed after subj ecting the temary mixtures of PETRA,ethanol, and Water in Figure la to polymerization conditions.

As mentioned above, no extensive mixing or agitation is needed for nucleation to take placeWhen the composition of the components is located Within the nucleation region of the phase diagram.The methods for interfacing the solution and the Water phase include, but are not limited to, batch-Wisemethods and flow system methods. The batch-Wise methods include, but are not limited to, mixing byturbulent addition, mixing by manual inversion, mixing by automated inversion, mixing by manualshaking, mixing by automated shaking, mixing using a vortexer, mixing by ultrasonic treatment, mixingusing a magnetic stirrer, mixing using an overhead stirrer, mixing using a blender, mixing using adisperser device, and mixing using a homogenizer. The flow system methods include, but are not limitedto, mixing using a static mixer, mixing using a microfluidic mixer, mixing using a micromixer,continuous-flow capillary mixing, microfluidic mixing using Y junctions, microfluidic mixing using Tjunctions, and mixing using various three- or four-Way intersections or connectors. Mixing devicesproduced by microfabrication or 3D-printing are useful. Industrial scale mixing devices include, but arenot limited to, impellers, turbines, anchors, helical ribbons, high-shear dispersers, ribbon blenders,paddle mixers, double cone blenders, static mixers, liquid Whistles, dispersion mixers, mixing paddles,and continuous-flow mixers.

Figure 2 shoWs that there is no significant influence of the interfacing method on the resultingparticle size distribution of poly(PETRA) particles.

Although no extended mixing/agitation is needed for the formation of the droplets When thecomposition is located in the nucleation region of the phase diagram, more extensive mixing proceduresas Well as prolonged mixing periods may be applied in some cases for the purpose of affecting the finalparticle size. Although no stabilizer is needed for the formation of droplets When the composition islocated in the nucleation region of the phase diagram, one or more stabilizers may be added for thepurpose of affecting the mean particle size, the polydispersity, and the particle size distribution of theresulting polymerized particles or for the purpose of extending the time period that the droplets arestable in the mixture. The term stabilizers are here used to denote suspension stabilizers, suspendingagents, suspension agents, emulsif1ers, emulsion agents, emulsifying agents, dispersants, dispersingagents, and other agents used for similar purpose as the ones listed. The terms are used interchangeablyherein. Stabilizers may be minimally Water-soluble inorganic salts such as, but not limited to, those selected from the group consisting of tribasic calcium phosphate, calcium carbonate, calcium sulfate, barium sulfate, barium phosphate, magnesium carbonate, and mixtures thereof Water soluble organicstabilizers, such as, but not limited to, those selected from the group consisting of polyyinyl alcohol,poly-N-vinylpyrrolidone, polyacrylic acid, polyacrylamide, and hydroxyalkyl cellulose, can also beused. Surfactants can also be used, including anionic surfactants, cationic surfactants, or nonionicsurfactants. Anionic surfactants include, but are not limited to, the group consisting of alcohol sulfates,alkyl aryl sulfonates, ethoxylated alkyl phenol sulfates, ethoxylated alkyl phenol sulfonates, andmixtures thereof. More specific examples of anionic surfactants include, but are not limited to, sodiumlauryl sulfate, ammonium laureate, and sodium dioctyl sulfosuccinate. Cationic surfactants include, butare not limited to, the group consisting of quatemary ammonium salts. Nonionic surfactants useful inthe present inVention include, but are not limited to, the group consisting of ethoxylated alkyl phenols,ethoxylated fatty acids, and ethoxylated fatty alcohols and mixtures thereof. A combination of morethan one stabilizer can also be useful in the inVention.

In the third step of the process, the polymers are formed by assembling the monomers througha polymerization reaction, including, but not limited to, a free-radical polymerization, a thiol-enepolymerization, an anionic polymerization, a cationic polymerization, a redox-initiated polymerization,a chain-growth polymerization, a step-growth polymerization, a condensation polymerization, a livingpolymerization, a reVersible-deactivation radical polymerization, and a reVersible addition-fragmentation chain transfer (RAFT) polymerization. Free-radical initiators useful in the presentinVention include those norrnally suitable for free-radical initiation. These species include, but are notlimited to, azo compounds, organic peroxides, benzoine ethers, benzyl ketals, alpha-dialkoxyacetophenones, alpha-hydroxy alkylphenones, alpha-amino alkylphenones, acyl phosphine oxides,benzophenones, and thio-xanthones. Examples of azo compounds include low molecular Weight azoinitiators and macro azo initiators. Low molecular Weight azo initiators include, but are not limited to,2,2 ° -azobis(2-methylbutyronitrile), 2,2 ° -azobis(2-methylpropionitrile), l , l ° -azobis(cyclohexanecarbo-nitrile), phenyl-azo-triphenylmethane, and 4,4”-azobis(4-cyanovaleric acid). Commercial products ofthis type include, but are not limited to, VAZO 52, VAZO 64, VAZO 67, and VAZO 88 initiators fromDuPont. Macro azo initiators include, but are not limited to, compounds comprisingpolydimethylsiloxane units, such as the VPS series from Wako, and compounds comprisingpolyethyleneglycol units, such as the VPE series from Wako. Examples of peroxides include, but arenot limited to, tert-butyl peroxide, cumyl peroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide,tert-butyl hydroxyperoxide, and tert-butyl perbenzoate. The rate of the decomposition of peroxides maybe increased by the addition of tertiary amines, such as, but not limited to, N,N-dimethylaniline. Anionicinitiators useful in the present inVention include those norrnally suitable for anionic initiation. Examplesof anionic initiators include, but are not limited to, metal alkyls such as n-butyllithium. Cationic initiators useful in the present inVention include those norrnally suitable for cationic initiation. Examples of cationic initiators include, but are not limited to, sulfuric acid, tin(IV)chloride, boron trifluoride, andiodine. Redox-initiated polymerizations use a redox pair for initiation, exemplified by, but not limitedto, organic peroxides and tertiary amines, such as the benzoyl peroxide and N,N-dimethyl-p-toluidineredox pair. The polymerization may be manipulated by the addition of quenchers or inhibitors. In thecase of thiol-ene polymerizations, examples of quenchers include, but are not limited to, 3-mercaptopropionic acid and other thiols. Initiators, quenchers, and/or inhibitors are added either to thesolution or to the Water phase.

To promote the polymerization, the building blocks can be exposed to a source of energy, suchas, but not limited to, ultraviolet (UV) radiation, gamma radiation, and/or a heat source providing anelevated temperature for a time period suff1ciently long to promote the polymerization. Preferably, thereaction is carried out at a temperature of about -30-100 °C, more preferably at a temperature of 10-90 °C, and most preferably at a temperature of 30-70 °C. For polymerizations promoted by UV light,radiation in a Wavelength of about 200-400 nm is preferred. Combinations of elevated temperaturesand UV light can also be applied. Figure 3 shows the resulting particle size distributions When thepolymerizations Were carried out at an elevated temperature and under the influence of UV light,respectively.

In one embodiment, the invention provides directly (i.e., after the polymerization step) apolymer particle suitable for the final application. In another embodiment the polymer particle obtainedafter the polymerization step is subj ected to post-polymerization processing, including, but not limitedto, derivatization, conjugation, decoration, modification, or functionalization to fumish it for the finalapplication. A range of different final applications exists, some of Which are shown in Figure 4.

The invention provides in one embodiment a polymer particle suitable to be applied as a support(solid phase) in solid-phase synthesis of molecules (Figure 4a). Examples of molecules to besynthesized by solid-phase synthesis using the polymer particle of the invention as a solid phase include,but are not limited to, peptides, proteins, oligonucleotides, peptide nucleic acids, carbohydrates, smallorganic molecules, and molecule libraries. For applications as a solid phase support, the polymerparticle should preferentially be provided With a functional group that can serve as a starting point forthe solid-phase synthesis couplings. In one embodiment, one of the monomers used as a polymerbuilding block provides such a functional group. This functional group may be used directly as thestarting point for the solid-phase synthesis. In another embodiment, the polymer particle is derivatizedto provide a different functional group. Examples of functional groups suitable to be used as the startingpoint for the synthesis include, but are not limited to, amino groups, hydroxyl groups, and carboxylgroups. In another embodiment, a linker, a handle, or an intemal reference molecule, such as an intemalreference amino acid, is coupled to the functional group to provide a starting point for the solid-phase synthesis. A linker or handle facilitates subsequent cleavage of the synthesized assembly from the polymer particle by providing a bond that is easy to chemically cleave. Examples of linkers and handlesinclude, but are not limited to, the PAL linker, the HMPA linker, the HMFA linker, the PAM linker,the XAL linker, and the BAL linker. An internal reference molecule facilitates quantification of thecleavage yield.

In one embodiment, the invention provides a polymer particle for drug delivery applications byeither covalently conjugating a drug to the particle, adsorbing non-covalently a drug to the particlesurface, or entrapping a drug in the particle°s polymer network (Figure 4b and Figure 5). The drug iseither a biological drug or a conventional small molecule drug.

In one embodiment, the polymer particle is provided With a functional group suitable for clickchemistry, such as, but not limited to, the Huisgen l,3-dipolar cycloaddition, the Staudinger reaction,the thiol-ene reaction, and the Diels-Alder reaction. By a click reaction, the polymer particle is thereaftereasily derivatized With a preferred molecule or used for in-situ labeling of cells and tissue.

In one embodiment of the invention, the polymer particle is derivatized With a ligand. The ligandis selected from a group of ligands including, but not limited to, nucleic acids, nucleotides, amino acids,peptides, peptide mimetics, proteins, antibodies, mini-bodies, enzymes, cell-penetrating ligands,carbohydrates, small organic molecules, boronic acids, dyes, cofactors, cell adhesion molecules, metalcomplexes, biotin, avidin, and streptavidin. The ligand-particle conjugate is useful for targeting tobiomarkers, cells, tissue, and other biological molecules and structures. The ligand-particle conjugateis useful also in biological screenings, molecular recognition studies, and tissue engineeringapplications. When the ligand is an aff1nity ligand, the conjugate is useful in aff1nity capture,separations, and purifications.

In one embodiment of the invention, the polymer particle is conjugated to, or derivatized With,a molecule that can be imaged by an imaging modality selected from the group of imaging modalitiesincluding, but not limited to, fluorescent imaging, x-ray, computed tomography (CT), magneticresonance imaging (MRI), positron emission tomography (PET), single-photon emission computedtomography (SPECT), electron microscopy, optoacoustic imaging, and magnetic imaging. The polymerparticle containing the conjugated imaging probe (can also be called a reporter molecule), functions asa contrast agent or imaging agent during in vitro and in vivo imaging (Figure 4d).

In one embodiment, a biocompatible particle is provided through further polymerizationreactions to provide star, brush, or comb polymers on the surface of the particle. In one particularembodiment, PEG chains are conjugated to the particle to increase the biocompatibility of the particle(Figure 4e). In one embodiment, the polymer particle is comprised of a PEG-containing monomer. Inanother embodiment, the polymer particle is derivatized With a natural polymer including, but not limited to, chitosan, chitin, alginate, gelatin, starch, carrageenan, dextran, and cyclodextrins.

In one embodiment, the invention provides a polymer particle suitable for 2D- and 3D-printingapplications.

Combinations of any of the embodiments are possible. For example, in one embodiment, apolymer particle is derivatized With a drug, an imaging probe, and an aff1nity ligand to provide a particlecapable of targeted theranostics (i.e., combined therapy and diagnosis). The applications of the polymer particles of the invention are not limited to the embodiments listed here.

EXAMPLES Example 1 Identification of Compositions Providing Nacleated Droplets and Polymerized Particles Firstly, a temary PETRA-ethanol-Water phase diagram Was constructed for identification of thenucleation region. Water and ethanol Were purged With nitrogen gas prior to use. Temary mixtures (10mL) of PETRA, ethanol, and Water Were prepared by interfacing volumes (1-50 vol%) of a solution ofPETRA (2.5 mM-150 mM) in ethanol With volumes (5 0-99 vol%) of Water. The ethanolic solution Wasadded to the Water phase and the tWo liquids Were manually interfaced by inverting (shaking) the sampleapproximately 20 times. The resulting mixtures Were inspected and subj ected to dynamic light scattering(DLS) analysis using a Nanotrac Ultra Particle Size Analyzer from Mictrotrac (Montgomeryville, PA,USA) to determine the size distribution of the droplets. The mean droplet size Was calculated based onintensity using the Rayleigh-Debye theory (n = 10). The mass fractions of ethanol and PETRA,respectively, in each of the temary mixtures Were calculated. The calculated data Were combined Withthe DLS data and plotted in a phase diagram (Figure la). Secondly, mixtures for polymerization testingin small scale Were prepared following the same procedure, except that the Water phases Were preheatedto 60 °C and the ethanolic solutions included AIBN (40 mM) used as a free-radical initiator.Polymerizations Were carried out for 6 h in a Water bath set at 60 °C and the samples Were cooled toroom temperature before characterization. The resulting mixtures Were inspected and analyzed by DLS.

The data Were plotted in a phase diagram (Figure lb).

Example 2Synthesis of Poly(PE T RA ) Particles;Demonstration of the Applicabilitj/ of Dzflerent interfacing MethodsA solution containing PETRA (0.04 M) and AIBN (008 M) in ethanol Was prepared. Theethanol used had previously been purged With nitrogen gas for 10 min. The solution (1 volume part)Was then added to preheated (60 °C) Water that had previously been purged With nitrogen gas for 1 h(39 volume parts). The solution and the Water phase Were interfaced by applying either (i) manual shaking (20 inversions); (ii) an IKA Labortechnik Eurostar digital overhead stirrer (IKA-Werke Gmbh & Co., Staufen, Germany) equipped With a Heidolph TR 20 radial flow impeller Operating at 700 rpmfor 3 min; (iii) a model D125 basic dispersing device equipped With an S25N-25F dispersing element(IKA-Werke Gmbh & Co., Staufen, Germany) operating at 8000 rpm for 1 min; or (iv) a BandelinSonoplus ultrasonic homogenizer equipped With a VS70T titanium alloy probe (Bandelin Gmbh, Berlin,Germany) operating at 20 W for 6 x 10 s. The total Volume of each mixture Was 500 mL.Therrnolytically initiated polymerizations Were carried out in a 60 °C Water bath for 6 h. Thepolymerized mixtures Were centrifuged (9 500 rpm, 2 h). The supematants Were discarded and theparticles Were retained. The particles Were incubated repeatedly first With ethanol, then With Water, andfinally again With ethanol. After each incubation, the samples Were centrifuged (9 500 rpm, 2 h) anddecanted. The absorbance of the supematants Was measured at 210 nm. Extractions Were repeated untilthe absorbance of the supematants Was < 0.05 absorbance units. Finally, the particles Were dried invacuo oVemight. The dried particles Were dissolved in Water for DLS analysis (Table 1, Figures 2a-d).The mean particle size Was calculated based on intensity using the Rayleigh-Debye theory. Thepolydispersity index Was calculated as dv/dN, Where dv and dN are the mean particle sizes based on Volume and numbers, respectively, calculated using the Lorenz-Mie theory.

Table 1. Influence of Interfacing Method on Size and Polydispersity of Po1y(PETRA) Particles (DLS , n=3 0) Interfacing Method Mean Paiticle Size i SD (nm) Mean Polydispersity Index i SDManual shaking (20 inversions) 262 i 21 1.27 i 0.11Overhead stirrer (700 rpm, 3 min) 248 i 25 1.36 i 0.18Disperser/homogenizer (8 000 rpm, 1 min) 258 i 16 1.29 i 0.16Ultrasonic homogenizer (6 X 10 s, 20 W) 258 i 18 1.33 i 0.14Example 3 Synthesis of Poly(PE T RA ) Particles;Demonstration of the Applicabilitj/ of Dzflerent F :fee-Radical Generation Methods A solution Was prepared by dissolving PETRA (0.04 M) and AIBN (0.04 M) in ethanol that hadpreviously been purged With nitrogen gas for 10 min. The solution (1 volume part) Was then added toWater that had previously been purged With nitrogen gas for 1 h (9 Volume parts). Preheated (60 °C)Water Was used for therrnolytically initiated polymerizations and Water of room temperature Was usedfor photolytically initiated polymerizations. The solution and the Water phase Were interfaced byinverting the sample manually (shaking) approximately 20 times. The total Volume of the mixture Was250 mL. Therrnolytically initiated polymerizations Were carried out in a 60 °C Water bath for 6 h.Photolytically initiated polymerizations Were carried out under a DYMAX UV (350 nm) curing floodlamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixtures Were centrifuged (9 500 rpm,2 h) and the supematants Were discarded. The particles Were incubated repeatedly first With ethanol, then With Water, and finally again With ethanol. After each incubation, the samples Were centrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematants Was measured at 210 nm. ExtractionsWere repeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, the particlesWere dried in vacuo ovemight. The dried particles Were dissolved in Water for DLS analysis (Table 2, Figures 3a,b).

Table 2. Influence of Polymerization Conditions on Size and Polydispersity of Paiticles (DLS, n=10) Polymerization Conditions Mean Paiticle Size i SD (nm) Mean Polydispersity Index i SD 60 °C (Water bath), 6 h 415 i 32 1.23 i 0.16350 nm (UV flood lamp), 2 h 427 i 40 1.23 i 0.18Example 4 Synthesis of P0ly(PE T RA-co-Allylamine) Particles A solution Was prepared by dissolving PETRA (0.04 M), allylamine (0. 155 M) and AIBN (0.04M) in ethanol that had previously been purged With nitrogen gas for 10 min. The solution (1 volumepart) Was added to Water that had previously been purged With nitrogen gas for 1 h (9 volume parts).The solution and the Water phase Were interfaced by manual shaking (20 inversions). The total volumeof the mixture Was 250 mL. A photolytically initiated polymerization Was carried out under a DYMAXUV (350 nm) curing flood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixtureWas centrifuged (9 500 rpm, 2 h) and the supematant Was discarded. The particles Were incubatedrepeatedly first With ethanol, then With Water, and finally again With ethanol. After each incubation, thesamples Were centrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematant Wasmeasured at 210 nm. Extractions Were repeated until the absorbance of the supematant Was < 0.05absorbance units. Finally, the particles Were dried in vacuo ovemight. The particles tested positively inKaiser°s qualitative ninhydrin test, indicating the presence of free amino groups.

Example 4 demonstrates that the invention provides particles With free amino groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 5Synthesis of P0ly(PE T RA-co-MAA ) ParticlesA solution Was prepared by dissolving PETRA (0.04 M), methacrylic acid (MAA; 0.32 M), andAIBN (0.04 M) in ethanol that had previously been purged With nitrogen gas for 10 min. The solutionWas then added to Water that had previously been purged With nitrogen gas for 1 h. The solution and theWater phase Were interfaced by manual shaking (20 inversions). The total volume of the mixture Was250 mL. A photolytically initiated polymerization Was carried out under a DYMAX UV (350 nm)curing flood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixture Was centrifuged(9 500 rpm, 2 h) and the supematant Was discarded. The particles Were incubated repeatedly first With ethanol, then With Water, and finally again With ethanol. After each incubation, the samples Werecentrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematant Was measured at 210 nm.Extractions Were repeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, the particles Were dried in vacuo ovemight.

Example 6Synthesis of P0ly(PE T RA-c0-4- VBA) Particles A solution Was prepared by dissolving PETRA (0.04 M), 4-vinylbenzoic acid (4-VBA; 0.04 M)and AIBN (0.04 M) in ethanol that had previously been purged With nitrogen gas for 10 min. Thesolution Was then added to Water that had previously been purged With nitrogen gas for 1 h. The solutionand the Water phase Were interfaced by manual shaking (20 inversions). The total volume of the mixtureWas 250 mL. A photolytically initiated polymerization Was carried out under a DYMAX UV (350 nm)curing flood lamp model PC-2000 (Torrington, CT) for 2 h. The polymerized mixture Was centrifuged(9 500 rpm, 2 h) and the supematant Was discarded. The particles Were incubated repeatedly first Withethanol, then With Water, and finally again With ethanol. After each incubation, the sample Wascentrifuged (9 500 rpm, 2 h) and decanted. The absorbance of the supematant Was measured at 210 nm.Extractions Were repeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally,the particles Were dried in vacuo ovemight.

Examples 5 and 6 demonstrate that the invention provides particles With free carboxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 7Synthesis of P0ly( T RIM-co-HEMA ) Particles A solution Was prepared by dissolving trimethylolpropane trimethacrylate (TRIM; 0.04 M), 2-hydroxyethyl methacrylate (0.04 M), and AIBN (0.04 M) in ethanol that had previously been purgedWith nitrogen gas for 10 min. The solution Was then added to Water that had previously been purgedWith nitrogen gas for 1 h. The solution and the Water phase Were interfaced by manual shaking (20inversions). The total volume of the mixture Was 100 mL. A photolytically initiated polymerization Wascarried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT) for 2 h.The polymerized mixture Was centrifuged (9 500 rpm, 2 h) and the supematant Was discarded. Theparticles Were incubated repeatedly first With ethanol, then With Water, and finally again With ethanol.After each incubation, the sample Was centrifuged (9 500 rpm, 2 h) and decanted. The absorbance ofthe supematant Was measured at 210 nm. Extractions Were repeated until the absorbance of the supematant Was < 0.05 absorbance units. Finally, the particles Were dried in vacuo ovemight.

Example 7 demonstrates that the invention provides particles With free hydroxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 8Synthesis of P0ly(PE T RA ) Partícles in Presence of a SurfactantA solution Was prepared by dissolving PETRA (0.04 M) and AIBN (008 M) in ethanol that hadpreviously been purged With nitrogen gas. One volume part of the solution Was then added to 39 volumeparts of pre-heated (60 °C) and nitrogen-purged Water containing 005% Pluronic F68. The solution andthe Water phase Were interfaced by manual shaking (20 inversions). The total volume of the mixtureWas 500 mL. A therrnolytically initiated polymerization Was carried out in a 60 °C Water bath for 5 h.The polymerized mixture Was centrifuged (9 500 rpm, 2 h). The polymerized reaction mixture Wasanalyzed by DLS, shoWing a particle size of 159 i 9 nm.Example 8 demonstrates that, although stabilizers are not needed for the formation of theparticles, the size of the particles can be engineered by the addition of a stabilizing agent such as a surfactant.

Example 9Post-Polymerízatíon Derívatízatíon of P0ly(PE T RA ) Partícles with the PAL Línker Poly(PETRA) particles Were prepared as described in Example 3. Fmoc-Gly-OH (0595 g, 2mmol) Was dissolved in DMF (l mL) and added to the dried poly(PETRA) particles (200 mg). N,N°-diisopropylcarbodiimide (DIPCDI; 0.252 g, 2 mmol) in DMF (l mL) and 4-dimethylaminopyridine(DMAP; 25 mg, 0.2 mmol) in DMF (l mL) Were added. The sample Was placed on a rotating shakerfor 2 days. The particles Were centrifuged and repetitively suspended in DMF (5 times). DeprotectionWas carried out by treatment With piperidine-DMF (2 x l0 min). The particles Were again Washed WithDMF. Qualitative ninhydrin test (Kaiser test) Was positive. The PAL linker Was coupled by addingFmoc-PAL-OH (099 g, 2 mmol) in DMF (3 mL), DIPCDI (0252 g, 2 mmol) in DMF (l mL) and l-hydroxybenzotriazole (HOBt; 0.306 g, 2 mmol) in DMF (3 mL). The sample Was placed on a rotatingshaker for 2 days. The particles Were centrifuged (9 500 rpm, l h) and Washed repeatedly With DMFand finally With methanol.

Example 9 demonstrates that the carboxyl-containing poly(PETRA) particles can be derivatizedafter polymerization to provide amino groups suitable for further derivatizations/couplings. Theparticles of Example 9, functionalized With a cleavable linker, are suitable as a solid-phase synthesis support.

Example 10 Post-Polymerízatíon Derívatízatíon of P0ly(PE T RA-co-Allylamíne) Partícles with FIT C Poly(PETRA-co-allylamine) particles Were prepared as described in Example 4. FITC(fluorescein isothiocyanate; 5 mg) Was dissolved in ethanol (5 mL) and added to dried po1y(PETRA-co-allylamine) particles (100 mg). The sample Was placed on a rotating shaker for 2 days. The particlesWere centrifuged (9 500 rpm, l h) and Washed repeatedly With ethanol until the supematant Was colorless.

Example llPost-Polymerízatíon Derívatízatíon of P0ly(PE T RA-co-Allylamíne) Partícleswith a Radíopaque Derívatíve N-succinimidyl 2,3,5-triiodobenzoate Was synthesized in 85% yield by reacting N-hydroxysuccinimide (1.266 g, ll mmol), 2,3,5-triiodobenzoic acid (l.998 g, 10 mmol), and l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (2,l08 g, ll mmol) in methylene chloride (200 mL). After100 h, the solution Was extracted With Water (3 times) and saturated aqueous NaCl (3 times). The organicphase Was dried over MgSO4, evaporated, and dried in Vacuum. Poly(PETRA-co-allylamine) particlesWere prepared as described in Example 4. The particles Were mixed With N-succinimidyl 2,3,5-triiodobenzoate in DMF. The particles Were centrifuged (9 500 rpm, 1 h) and Washed repeatedly WithDMF and finally methanol.

Examples 10 and ll demonstrates that the particles of the inVention can be deriVatized Withfluorescent and radiopaque deriVatiVes, making the particles suitable as imaging probes and contrast agents.

Example 12 Post-Polymerízatíon Derívatízatíon of P0ly(PE T RA-co-Allylamíne) Partícles with PE G Poly(PETRA-co-allylamine) particles Were prepared as described in Example 4. The particles(10 mg) Were dissolved in Water (1 mL). Polyethylene glycol N-succinimidyl propionate (10 mg) Weredissolved in Water (0.25 mL) and added to the particles. The sample Was placed on a rotating shaker for1 day. The particles Were centrifuged (9 500 rpm, 1 h) and Washed repeatedly With methanol.

Example 12 demonstrates that the particles of the inVention can be deriVatized With PEG, providing particles suitable for biomedical and medical applications.

Example l3Synthesis of Poly( T rimethylolløropane E thoxylate T riacrylate) ParticlesThree different solutions, each containing a branched PEG-containing cross-linker (0.02 M;Table 3) and AIBN (0.04 M), Were prepared by dissolving the respective cross-linker in ethanol. Eachsolution (l volume part) Was then added to Water (19 volume parts; previously purged With nitrogen gasfor l h) and interfacing Was carried out by inverting the samples manually (shaking) approximately 20times. The total volume of each mixture Was 1000 mL. Therrnolytically initiated polymerizations Werecarried out in a 60 °C Water bath for 6 h. The polymerized reaction mixtures Were analysed by DLS, shoWing mean particle size and polydispersity index as indicated in Table 3.

Table 3. Composition, Size, and Polydispersity of Po1y(Trimethy1o1propane Ethoxylate Triacrylate) Particles (DLS, n=20) cmssLínker Mea: gåfëiïgeøSize Mean Polyíisspšrsity IndexTrimethylolpropane Ethoxylate (1 EO/OH) Triacrylate 274 i 17 1.35 i 0.14Trimethylolpropane Ethoxylate (7/ 3 EO/OH) Triacrylate 162 i 4 1.18 i 0.05Trimethylolpropane Ethoxylate (14/3 EO/OH) Triacrylate 165 i 3 1.17 i 0.06 Example l4Synthesis of Poly( T rimethylolløropane E thoxylate T riacrylate) Particles;Demonstration of the Applicabilitj/ of Various Interfacing MethodsSolutions Were prepared by dissolving trimethylolpropane ethoxylate (7/3 EO/OH) triacrylate(0.0l M) and AIBN (0.02 M) in ethanol. Each solution (l volume part) Was then added to Water(9 volume parts; previously purged With nitrogen gas for l h). The solutions and the Water phases Wereinterfaced by applying either (i) manual shaking (20 inversions); (ii) an IKA Labortechnik Eurostardigital overhead stirrer (IKA-Werke Gmbh & Co., Staufen, Germany) equipped With a Heidolph TR 20radial flow impeller operating at 1000 rpm for 30 s; (iii) a model Dl25 basic dispersing device equippedWith an S25N-25F dispersing element (IKA-Werke Gmbh & Co., Staufen, Germany) operating at 8000rpm for 30 s. The total volume of each mixture Was 100 mL. Photolytically initiated polymerizationsWere carried out under a DYMAX UV (350 nm) curing flood lamp model PC-2000 (Torrington, CT)for 2 h. The polymerized reaction mixtures Were analysed by DLS (n=20), shoWing mean particle size and polydispersity index as indicated in Table 4.

Table 4. Influence of Interfacing Method on Size and Polydispersity of Poly(Trimethylolpropane Ethoxylate Triacrylate)Particles Interfacing Method Mean Particle Size i SD (nm) Mean Polydispersity Index i SDManual shaking (20 inversions) 170 i 4 1.22 i 0.11Overhead stirrer (1000 rpm, 30 s) 177 i 8 1.29 i 0.12Disperser/homogenizer (8 000 rpm, 30 s) 188 i 5 1.20 i 0.09 Example 15Synthesis of P0ly( T rímethylolløropane E thoxylate T ríacrylate-co-HEMA ) Partícles A solution Was prepared by dissolving trimethylolpropane ethoxylate (7/3 EO/OH) triacrylate(0.018 M), 2-hydroxyethyl methacrylate (0.018 M), and AIBN (0.018 M) in ethanol. The solution(1 Volume part) Was then added to Water (9 Volume parts; previously preheated to 60 °C and purgedWith nitrogen gas for 1 h). The solution and the Water phase Were interfaced by inverting the samplemanually (shaking) approximately 20 times. The total volume of the mixture Was 250 mL. Atherrnolytically initiated polymerization Was carried out in a 60 °C Water bath for 6 h. The polymerizedreaction mixture Was analysed by DLS (intensity mode; n=l0), shoWing a mean particle size of 366 i17 nm.

Example 15 demonstrates that the invention provides particles With free hydroxyl groups, Which are suitable to serve as starting points for couplings/derivatizations.

Example 16Synthesis of P0ly(PE T RA-co-PE GMAA ) A solution Was prepared by dissolving PETRA (004 M), poly(ethylene glycol) methacrylate(PEGMAA; 0.08 M), and AIBN (008 M) in ethanol that had previously been purged With nitrogen gas.The solution (1 volume part) Was then added to Water (39 volume parts; previously preheated to 60 °Cand purged With nitrogen gas for 1 h). The solution and the Water phase Were interfaced by invertingthe sample manually (shaking) approximately 20 times. The total volume of the mixture Was 500 mL.A therrnolytically initiated polymerization Was carried out in a 60 °C Water bath for 6 h. Thepolymerized mixture Was centrifuged (9 500 rpm, 2 h) and the supematant Was discarded. The particlesWere incubated repeatedly first With ethanol, then With Water, and finally again With ethanol. After eachincubation, the sample Was centrifuged (9 500 rpm, 2 h) and decanted. The absorbance of thesupematant Was measured at 210 nm. Extractions Were repeated until the absorbance of the supematantWas < 0.05 absorbance units. Finally, the particles Were dried in vacuo ovemight. The dried particlesWere dissolved in Water for DLS analysis (intensity mode; n=l0), shoWing a mean particle size of 250i 15 nm.

Examples 13-16 demonstrate that the method of the invention can be applied to the preparationof PEG-containing particles. These particles are biocompatibility and suitable for biomedical and medical applications.

Example 17Synthesis of Polymer Particles by T hi0l-Ene Polymerization of PE TMP and TA TA TOA solution Was prepared by dissolving pentaerythritol tetrakis(3 -mercaptopropionate) (PETMP;20 mM), l,3,5-triallyl-l,3,5-triazine-2,4,6(lH,3H,5H)-trione (TATATO; 26 mM), and AIBN (8 mM)in ethanol. One Volume part of the solution Was added to 39 Volume parts of 60 °C pre-heated Water.The solution and the Water phase Were interfaced by manual shaking (20 inversions). PolymerizationWas carried out at 60 °C for 2 h. The polymerized reaction mixture Was analyzed by DLS, shoWing a mean particle size of 490 i 35 nm.

Example l8Synthesis of Polymer Particles by T hi0l-Ene Polymerization of PE TMP and PETRAA solution Was prepared by dissolving pentaerythritol tetrakis(3 -mercaptopropionate) (PETMP;20 mM), PETRA (26 mM), and AIBN (8 mM) in ethanol. One Volume part of the solution Was addedto 39 Volume parts of 60 °C pre-heated Water. The solution and the Water phase Were interfaced bymanual shaking (20 inversions). Polymerization Was carried out at 60 °C for 2 h. The polymerized reaction mixture Was analyzed by DLS, shoWing a mean particle size of 348 i 48 nm.

Example l9Synthesis of Polymer Particles by T hi0l-Ene Polymerization ofPE T MP and PETRA under the Influence of a QuencherA solution Was prepared by dissolving pentaerythritol tetrakis(3 -mercaptopropionate) (PETMP;20 mM), PETRA (26 mM), and AIBN (8 mM) in ethanol. One Volume part of the solution Was addedto 39 Volume parts of 60 °C pre-heated Water. The solution and the Water phase Were interfaced bymanual shaking (20 inversions). Polymerization Was carried out at 60 °C during a total time of 2 h. After50 min, 3-mercaptopropionic acid Was added to a final concentration of 2 mM in the mixture. The polymerized reaction mixture Was analyzed by DLS, showing a mean particle size of 280 i 17 nm.

Example 20Synthesis of Polymer Particles by T hi0l-Ene Polymerization ofPE T MP, PETRA, and benzyl methacrylateA solution Was prepared by dissolving pentaerythritol tetrakis(3 -mercaptopropionate) (PETMP;1.25 mM), PETRA (2.5 mM), benzyl methacrylate (5 mM), and AIBN (5 mM) in ethanol. One Volumepart of the solution Was added to 1.5 Volume parts of Water of room temperature. The solution and the Water phase Were interfaced by manual shaking (20 inversions). The total Volume Was 500 mL.

Polyrnerization Was carried out at 60 °C for 2 h. The polyrnerized reaction rnixture Was analyzed byDLS, showing a mean particle size of 430 i 14 nrn.

Exarnples 17-20 dernonstrate the preparation of particles by thiol-ene polyrnerization.

Claims (14)

1. A polymer particle prepared from a nucleated composition comprising a monomer of the following forrnula (1):Wherein; (a) X and Y is independently -O-CH2-CH2-, -O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-; (b) Z is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CH2, ~O-CH=CH2, -O-CHz-CH=CH2, -CH=CHz,-CHz-CH=CH2, -O-C(O)-CH2-CH2-SH, -NH-C(O)-CH2-CHz~SH, or SH; (c) W is -(CH2)m-(XnY0)p-Z, a hydrogen, a functional group, an alkyl group, or a functionalizedalkyl group; and (d) each of a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, and p is independently a number in the range0-
2. 2. The polymer particle of claim l Wherein the nucleated composition further comprises a monomer.
3. 3. The polymer particle of claim 2 Wherein said monomer contains a functional group selected fromthe group consisting of the amino group, the hydroxyl group, the carbonyl group, the aldehyde group,the haloforrnyl group, the carboxyl group, the carboxylate group, the ester group, the carbonate estergroup, the amide group, the imine group, the imide group, the azide group, the azo group, thehydrocarbyl group, the aromate group, the halo group, the cyanate group, the nitrate group, the nitrilegroup, the nitrite group, the nitro group, the nitroso group, the pyridyl group, the oxime group, thethiol group, the sulf1de group, the disulfide group, the sulfinyl group, the sulfonyl group, the sulfinogroup, the sulfo group, the thiocyanate group, the thioketone group, the thio ester group, thephosphino group, the phosphono group, the phosphate group, the borono group, the boronate group,the borino group, and the borinate group.
4. 4. The polymer particle of any of the previous claims Wherein the nucleated composition is formed byinterfacing a Water phase and a solution comprising said monomer(s) dissolved in a Water-miscible solvent.
5. 5. The polynier particle of any of the previous clainis Wherein the particle has a size of about 10 to1000 nni.
6. 6. A process for preparing a polynier particle, coniprising the steps:(a) providing a n1onon1er of the following forrnula (1): Wherein: (i) X and Y is independently -O-CHz-CHr, -O-CHz-CH(CH3)-, or-O-CH(CH3)~CHz- (ii) Z is -O-C(O)-CH=CH2, -O-C(O)-C(CH3)=CH2, -NH-C(O)-CH=CHz,-NH-C(O)-C(CH3)=CH2, ~O-CH=CHz, -O-CHz-CH=CHz, -CH=CHz,-CHz-CH=CHz, -O-C(O)-CHz-CHz-SH, -NH-C(O)-CH2-CHz~SH, or SH; (iii) W is -(CH2)m-(XnY0)p-Z, a hydrogen, a functional group, an alkyl group, or afunctionalized alkyl group; and (iv) each of a, b, c, d, e, f, g, h, i, j, k, l, ni, n, o, and p is independently a number inthe range 0-100; (b) dissolving said n1onon1er in a Water-niiscible solvent, forrning a solution coniprising then1onon1er; (c) interfacing said solution and a Water phase to forrn a niixture in Which spontaneous andinstantaneous forrnation of nucleated droplets coniprising said n1onon1er takes place; and (d) polynierizing said n1onon1er by a polynierization reaction.
7. 7. The process of claini 6 Wherein said solution further coniprises a n1onon1er.
8. 8. The process of claini 7 Wherein said n1onon1er contains a functional group selected fron1 the groupconsisting of the aniino group, the hydroxyl group, the carbonyl group, the aldehyde group, thehaloforrnyl group, the carboxyl group, the carboxylate group, the ester group, the carbonate ester group,the an1ide group, the in1ine group, the iniide group, the azide group, the azo group, the hydrocarbylgroup, the aron1ate group, the halo group, the cyanate group, the nitrate group, the nitrile group, thenitrite group, the nitro group, the nitroso group, the pyridyl group, the oxinie group, the thiol group, thesulfide group, the disulfide group, the sulfinyl group, the sulfonyl group, the sulfino group, the sulfo group, the thiocyanate group, the thioketone group, the thio ester group, the phosphino group, thephosphono group, the phosphate group, the borono group, the boronate group, the borino group, and the borinate group.
9. 9. The process of claini 6 Wherein said Water-niiscible solVent is selected from a group of solventsconsisting of niethanol, ethanol, 1,2-ethanediol, l-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol, l-butanol, 2-butanol, 1,2-butanediol, l,3-butanediol, 1,4-butanediol, l-pentanol, 2-pentanol, 3-pentanol, 1,2-pentanediol, l,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,4-pentanediol, 1,5-pentanediol, glycerol, erythritol, pentaerythritol, furfuryl alcohol, diethylene glycol,triethylene glycol, tetraethylene glycol, pentaethylene glycol, acetonitrile, N,N-din1ethylforrnan1ide,din1ethyl sulfoxide, acetone, acetic acid, acetaldehyde, hexaniethylphosphoric trian1ide,diniethoxyethane, l,4-dioxane, N-n1ethyl-2-pyrrolidone, pyridine, tetrahydrofuran, or con1binations thereof.
10. 10. The process of claini 6 Wherein said interfacing step is augniented by a niixing procedure selected from the group of niixing procedures known to those skilled in the art of niixing.
11. ll. The process of clain1 6 Wherein said polynierization reaction is a free-radical polynierization.
12. 12. The process of clain1 6 Wherein said polynierization reaction is a thiol-ene polynierization.
13. 13. The process of any of clain1s 6-l2 Wherein said niixture is coniprised of at the n1ost about 20 n1ass percent of the Water n1iscible solVent and at the n1ost about l n1ass percent of the n1onon1er.
14. l4. The process of any of clain1s 6-l2 Wherein the prepared polyn1er particle has a size of about 10 to 1000 nni.