Synthesis of amphiphilic block copolymers and polymer nanofibers produced therefrom

Abstract

The present disclosure relates to the field of synthesis of block copolymers and polymeric nanofibers having a core-shell morphology produced therefrom. The present disclosure relates to the field of synthesis of block copolymers, where one block is more hydrophobic than the other block and is of different composition. The present disclosure also relates to the use of these polymeric nanofibers in various applications, such as for reinforcing polymer matrices and for coating applications.

Description

[Technical field]

[0001] Related Applications This application claims priority from Australian Provisional Patent Application No. 2021903943, filed December 6, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of synthesis of block copolymers and polymeric nanofibers having a core-shell morphology produced therefrom. The present invention also relates to the use of these polymeric nanofibers in various applications, such as for reinforcing polymer matrices and for coating applications. However, it will be understood that the present invention is not limited to these particular fields of use. [Background technology]

[0003] The following discussion of the prior art is provided to place the present invention in an appropriate technical context and to provide a more complete understanding of the advantages of the present invention. However, it should be understood that any discussion of the prior art throughout this specification should not be construed as an explicit or implicit admission that such prior art is widely known or forms part of the common general knowledge in the art.

[0004] Polymerization-induced self-assembly (PISA) has recently attracted great interest for the synthesis of amphiphilic block copolymer nanoparticles with complex morphology at high solids contents (up to 50%). PISA can in principle be carried out using any reversible deactivation radical polymerization (RDRP) technique, but reversible addition fragmentation chain transfer (RAFT)-mediated PISA is by far the most commonly used method. It is also worth noting that PISA can be carried out using addition fragmentation chain transfer (AFCT) polymerization, i.e., a "non-living" polymerization technique. RAFT PISA can be practiced as both a dispersion polymerization and an aqueous emulsion polymerization.

[0005] In RAFT-mediated PISA, a solvophobic macro-RAFT agent is chain-extended with a solvophobic core-forming monomer(s). As polymerization proceeds, the increasing insolubility of the core-forming blocks drives in situ self-assembly resulting in block copolymer nanoparticles. Morphology is determined by several factors, but can be largely rationalized based on the relative molecular weights of the solvophobic blocks (i.e., the "corona" or shell-forming blocks) and the solvophobic blocks (the core-forming blocks). Morphology typically varies from spheres, fibers, and vesicles with increasing length of the solvophobic blocks.

[0006] Polymeric materials are ubiquitous in today's society. The use of various so-called fillers (additives) to tailor and improve the performance of polymeric materials is a common strategy and often a requirement. However, traditionally used fillers, e.g., carbon black and glass fibers, are associated with significant drawbacks, such as high density of the final reinforced polymeric material, the requirement of a relatively high weight fraction of the filler, and / or lack of transparency. In addition, traditional fillers tend to offer only limited material improvements in terms of high breaking strain and extensibility. Furthermore, current fillers are typically difficult to disperse in the polymer matrix and surface modification is typically required, adding cost to the process.

[0007] Prior art has demonstrated high T g Use of core forming blocks, and The paper teaches the formation of nanofibers prepared by PISA in aqueous emulsion polymerization and RAFT. Conventional wisdom holds that a "hard" core is necessary to form the nanofiber and also to provide mechanical properties as a filler. In particular, PISA uses styrene (T g ≒100℃), methyl methacrylate (MMA) (T g ≒105°C), and 2-hydroxypropyl methacrylate (HPMA) (T g ≒72℃) gIn other studies, only low-order spherical morphology was observed at low T in aqueous emulsion RAFT PISA. g These resulted from the use of core-forming blocks. These were the statistical copolymerization of MMA and n-butyl acrylate (nBA), nBA(T g ≒-54℃) and benzyl methacrylate (BzMA) (T g ≈54 °C) and copolymers formed by copolymerization of nBA and MMA with a poly(ethylene oxide) macro RAFT agent. In addition to these studies, there have been reports of copolymers of poly(acrylic acid)-b-poly(nBA) diblock copolymer nanoparticles, poly(glycerol monomethacrylate)-poly(BzMA) diblock copolymers, poly(2-(diethylamino)ethyl methacrylate)-poly(methacrylic acid-stat-BzMA), and poly(acrylic acid)-b-poly(nBA)-co-poly(styrene) triblock copolymer nanoparticles. However, in all of the previous studies, only spherical nanoparticles were obtained.

[0008] It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative. Summary of the Invention

[0009] Disclosed herein is the synthesis of self-assembled nanofibers formed via the RAFT-PISA process. In particular, in one aspect of the invention, amphiphilic block copolymers are disclosed, in which the core is a copolymer having a Tg of about 75° C. (or less). In another aspect of the invention, amphiphilic block copolymers are disclosed, in which the core is a homopolymer and has a Tg of about 16° C. (or less). In another aspect of the invention, nanofibers are disclosed, in which the core is a copolymer or homopolymer having a Tg of up to 16° C. Additionally, in a further aspect of the invention, block copolymers are disclosed, in which the core and shell are prepared from hydrophobic copolymers or homopolymers.

[0010] The present invention is a significant advance over the prior art. The copolymers of the present invention disclosed herein can efficiently self-assemble to form high concentrations of stable nanofibers that can be used in a variety of applications. The present invention provides one or more of the following advantages: composites comprising the nanofibers of the present invention that are tougher and / or have higher impact resistance; lower density composites comprising the nanofibers of the present invention; higher stiffness and relatively light weight (weight loss as low as about 10-20%, which is a significant reduction; in some embodiments, the weight loss is 5-40%); nanofiber reinforced composites that exhibit higher elongation to break; nanofiber reinforced composites that are substantially transparent by matching the refractive index of the nanofibers of the present invention disclosed herein to the polymer matrix in which they are dispersed; and / or improved control of the rheological properties (thixotropy) of emulsions through the use of the nanofibers of the present invention. In addition, as discussed above, current fillers for composites can be difficult to disperse in polymer matrices and surface modification is typically required, adding cost to the process. However, the nanofibers of the invention do not require surface modification because the outer surface or shell is solvent-philic and can be wetted by polar polymers, solvents, or other matrices, allowing them to be dispersed relatively easily in polymer matrices. Additionally, it is possible to prepare surface coatings and films that are substantially or entirely formed from the nanofibers of the invention.

[0011] According to a first aspect, the present invention provides polymer nanofibers having a core-shell morphology. , the shell is hydrophilic and the core is a) a hydrophobic copolymer, or b) a hydrophobic homopolymer having a Tg of less than 16°C.

[0012] According to a second aspect, the present invention provides a method for producing ... liquid crystal display comprising the steps of: A block [A] containing a hydrophilic homopolymer or copolymer; a) a hydrophobic copolymer having a Tg of less than about 75° C., or b) a block [B] comprising a hydrophobic homopolymer having a Tg of less than about 16° C.; and optionally a crosslinker.

[0013] In preferred embodiments of the first and second aspects of the invention, the hydrophobic homopolymer has a Tg in the range of about -70° C. to a maximum of or about 16° C. In preferred embodiments of the first and second aspects of the invention, the hydrophobic copolymer has a Tg in the range of about -70° C. to about 75° C.

[0014] According to a third aspect, the present invention provides a method for producing an amphiphilic block copolymer of the second aspect, the method comprising: a) reacting at least one hydrophilic monomer using RDRP to form a hydrophilic block [A]; b) adding a hydrophobic block [B] comprising at least one hydrophobic monomer to the hydrophilic block [A] using RDRP; c) optionally adding a cross-linking agent in step b).

[0015] According to a fourth aspect, the present invention provides nanofibers when self-assembled from amphiphilic block copolymers produced by the method of the third aspect.

[0016] According to a fifth aspect, the present invention provides the use of nanofibers of the first or fourth aspect for at least partially producing a film or coating.

[0017] According to a sixth aspect, the present invention provides a method of forming a film or coating of the fifth aspect, the method comprising: Dispersing the nanofibers of the first or fourth aspect in a solvent to form a dispersion; applying the dispersion to a surface; and c. allowing or causing the solvent to substantially or completely evaporate, thereby forming the film.

[0018] According to a seventh aspect, the present invention provides a method for producing a composition comprising the steps of: A matrix or binder; There is provided the use of the nanofibers of the first or fourth aspect to prepare a composite material comprising: the nanofibers of the first or fourth aspect dispersed throughout a matrix or binder.

[0019] According to an eighth aspect, the present invention provides nanofibres of the first or fourth aspect for modifying or improving the mechanical properties of a matrix or binder.

[0020] According to a ninth aspect, the present invention provides a method for producing a composite material, the method comprising: Providing a polymer dispersion; Dispersing the nanofibers of the first or fourth aspect in the polymer dispersion to form a mixture. A dispersing step; and drying the mixture to form a composite material.

[0021] According to a tenth aspect, the present invention provides a method for producing a composite material comprising a polymer and a nanofiber of the first or fourth aspect by melt extrusion, the method comprising: heating the polymer and the nanofibers to a temperature above the melting temperature of the polymer; mixing a polymer with nanofibers; and extruding the mixture to form a composite material.

[0022] According to an eleventh aspect, the present invention provides the use of polymeric nanofibers as viscosity or rheology modifiers, wherein the polymeric nanofibers comprise a core-shell morphology, the shell being hydrophilic and the core comprising a hydrophobic homopolymer or copolymer.

[0023] According to a twelfth aspect, the present invention provides the use of a polymeric nanofiber according to the first or fourth aspect as a viscosity or rheology modifier.

[0024] According to a thirteenth aspect, the present invention provides a method for producing a block copolymer, the method comprising: a) reacting at least one hydrophobic monomer using RDRP to form a substantially hydrophobic block [A], the block [A] being substantially soluble in a 20 / 80% by volume water / ethanol mixture; b) adding a hydrophobic block [B] comprising at least one hydrophobic monomer to hydrophobic block [A] using RDRP in the presence of at least one polar solvent, where block [B] is more hydrophobic than block [A] and is of a different composition than block [A]; c) optionally adding a cross-linking agent in step b).

[0025] The block copolymers produced according to the thirteenth embodiment may self-assemble into nanofibers having a core-shell morphology.

[0026] In a preferred embodiment of the thirteenth aspect, the block [A] is substantially insoluble in water.

[0027] The nanofibers of the present invention are formed from polymers. The monomer units can be of a single type (homopolymers) or of different types (copolymers). The physical behavior of a polymer is determined by several characteristics, including the total molecular weight, the composition of the polymer (e.g., the relative concentrations of different monomers), the chemical identity of each monomer unit and its interaction with the solvent, and the architecture of the polymer (e.g., whether it is single-chain or branched).

[0028] In one aspect, the present invention provides a polymerizable compound comprising blocks [A] and [B], Block [A] is a hydrophilic homopolymer or copolymer, Block [B] is a hydrophobic homopolymer having a Tg of less than or about 16°C, or a hydrophobic copolymer having a Tg of the hydrophobic block of less than about 75°C, The process comprises obtaining blocks [A] and [B] by RDRP, preferably via RAFT of ethylenically unsaturated monomers, A process for preparing amphiphilic block copolymers, optionally including a crosslinking agent, is provided.

[0029] In another aspect, the present invention provides a compound comprising blocks [A] and [B], Block [A] is a hydrophobic homopolymer or copolymer, Block [B] is a hydrophobic homopolymer or copolymer, The process comprises obtaining blocks [A] and [B] by RDRP, preferably via RAFT of ethylenically unsaturated monomers, A process for preparing a block copolymer, optionally including a crosslinking agent, is provided.

[0030] It will be appreciated that the block copolymers of the present invention self-assemble into nanofibers.

[0031] According to a fourteenth aspect, the present invention provides a block copolymer comprising a hydrophobic block [A], wherein block [A] is substantially soluble in a 20 / 80% by volume water / ethanol mixture, a hydrophobic block [B], wherein block [B] is more hydrophobic than block [A] and comprises at least one hydrophobic monomer of a different composition than block [A], and optionally a crosslinker.

[0032] According to a fifteenth aspect, the present invention provides polymeric nanofibers having a core-shell morphology, wherein the shell is hydrophobic, the shell comprises a polymer that is substantially soluble in a 20 / 80% by volume water / ethanol mixture, and the core is hydrophobic, the core comprises a polymer that is more hydrophobic than and of a different composition than the polymer of the shell.

[0033] Use of the block copolymer of the fourteenth aspect or the polymer nanofiber of the fifteenth aspect to at least partially produce a film or a coating.

[0034] Use of the block copolymer of the fourteenth aspect or the polymeric nanofibers of the fifteenth aspect to prepare a composite material comprising a matrix or binder and, dispersed throughout the matrix or binder, the block copolymer of the fourteenth aspect or the polymeric nanofibers of the fifteenth aspect.

[0035] Use of the block copolymer of the fourteenth aspect or the polymer nanofibers of the fifteenth aspect for modifying or improving the mechanical properties of a matrix or binder.

[0036] Use of the block copolymer of the fourteenth aspect or the polymer nanofiber of the fifteenth aspect as a viscosity or rheology modifier.

[0037] RAFT Polymerization RAFT polymerization is one of the most robust and versatile methods for providing living character to radical polymerization. By appropriate selection of chain transfer agent (RAFT agent) for monomer and reaction conditions, it is applicable to the majority of monomers subject to radical polymerization. The process can be used for the synthesis of well-defined homo-, gradient, diblock, triblock and star polymers, as well as more complex architectures including microgels and polymer brushes.

[0038] For example, when preparing a block copolymer in the presence of a chain transfer agent (RAFT agent), the terminal of the growing block is provided with a specific functional group that controls the growth of the block by RDRP. The functional group at the terminal of the block is of such a nature that the growth of the block in the second and / or third stage of the polymerization process can be reactivated, for example by other ethylenically unsaturated monomers providing a covalent bond between the first and second blocks [A] and [B], and by any further optional blocks.

[0039] Further details on the chemistry of the synthesis of block copolymers by the RAFT process can be found in the following publications, each of which is incorporated herein by reference in its entirety: Polymer, 2008, volume 49, 1079-1131; Chemical Society Reviews, 2014, volume 43, 496-505; Macromolecules, 1998, volume 31, 55 59-5562; and Polymer, 2013, volume 54, 2011-20 19.

[0040] In one non-limiting embodiment, block copolymers according to the disclosed and / or claimed inventive concepts are obtained by RAFT polymerization.

[0041] Radical Initiators The radical initiator is selected to have an appropriate half-life at the polymerization temperature sufficient to initiate polymerization.

[0042] Non-limiting examples of radical initiators suitable for the present invention include one or more of the following compounds: 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-cyanobutane), dimethyl 2,2'-azobis(isobutyrate), 4,4'-azobis(4-cyanovalerate), 4,4'-azobis-(4-cyanopentanoic acid), 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 1,1'-azobis(cyclohexanecarbonitrile), 2-(t-butyl)azobis(cyclohexanecarbonitrile), 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-cyanobutane), 2,2'-azobis(isobutyrate ... azo)-2-cyanopropane, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis{2-methyl -N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(isobutylamide) dihydrate, 2,2'-azobis(2,2,4-trimethylpentane), 2,2'-azobis(2-methylpropane), t-butylperoxyacetate Peroxynitrite, t-butyl peroxybenzoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutyrate, t-amyl peroxypivalate, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, dicumyl peroxide, dibenzoyl peroxide, dilauroyl peroxide, potassium peroxydisulfate, ammonium peroxydisulfate, di-t-butyl hyponitrite, dicumyl hyponitrite, etc. Other suitable initiating systems are described in the literature, for example in Moad and Solomon "The Initiating System of the Invention", Vol. 1, No. 1, pp. 111-115, 1997, 1998. See, "Chemistry of Free Radical Polymerization", Pergamon, London, 1995, pp 53-95.

[0043] In one embodiment, the radical initiator is 4,4'-azobis-(4-cyanopentanoic acid).

[0044] Chain Transfer Agents The chain transfer agent is generally selected taking into consideration the type of monomer to be polymerized. Suitable chain transfer agents for use in the present invention include chain transfer agents for nitroxide-mediated radical polymerization (NMP), atom transfer radical polymerization (ATRP), and RDRP, including RAFT. Other chain transfer agents will be known to those skilled in the art.

[0045] Examples of chain transfer agents suitable for the present invention are (I) [ka] wherein Z is a group that enhances the reactivity of the C=S moiety; R is a homoloytic leaving group capable of initiating radical polymerization.

[0046] In one embodiment of the invention, R is selected from the group consisting of secondary cyanoalkyl, such as cyanomethyl, 1-cyanoethyl, 2-cyanopropan-2-yl, primary and secondary alkoxycarbonylalkyl, such as ethoxycarbonylmethyl, 1-ethoxycarbonylethyl, and primary and secondary carboxyalkyl, tertiary cyanoalkyl, such as 2-cyanobutan-2-yl, 1-cyanocyclohexyl, 2-cyano-4-methylpentan-2-yl, 2-cyano-4-methoxy-4-methylpentan-2-yl, 2-cyano-4-carboxybutan-2-yl, 2-cyano-5-hydroxypentan-2-yl, secondary cyano(aryl)alkyl, such as cyano(phenyl)methyl, tertiary alkoxycarbonylalkyl, such as 2-alkoxycarbonylprop ... 1-cyanocyclohexyl, 2-cyano-4-methylpentan-2-yl, 1-cyanocyclohexyl, 2-cyano-4-methoxy-4-methylpentan-2-yl, 2-cyano-4-carboxybutan-2-yl, 2-cyano-5-hydroxypentan- -(butylamino)-2-methyl-1-oxopropan-2-yl, tertiary carboxyalkyl, secondary aryl(alkoxycarbonyl)alkyl, such as phenyl(ethoxycarbonyl)methyl, and other tertiary radicals, such as 1-(cyclohexylamino)-2-methyl-1-oxopropan-2-yl, 1-(2-hydroxyethylamino)-2-methyl-1-oxopropan-2-yl, 1-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylamino)-2-methyl-1-oxopropan-2-yl, 2-(4,5-dihydro-1H-imidazol-2-yl)propan-2-yl, and 2-(1-(2-hydroxyethyl)-4,5-dihydro-1H-imidazol-2-yl)propan-2-yl; Z is aryl, C 1~30 Alkyl, -SC alkyl, -O-aryl, -N(C 1~6 Alkyl)2, -N(aryl)(C 1~6 alkyl), -heteroaryl, -heterocyclyl, -OC 1~30 is selected from the group consisting of alkyl, heterocyclyl, and phosphate; 1~30 Alkyl, -heteroaryl, and -heterocyclyl are each C 1~30 Alkyl, =O, -CN, aryl, and -COOC 1~6It may be optionally substituted 1 to 4 times with substituents independently selected from the group consisting of alkyl.

[0047] In other embodiments of the present invention, the chain transfer agent is (II), (III), or (IV). [ka] [ka] [ka] wherein R, Z1, Z2, and Z3 are as defined in formula (I).

[0048] In one embodiment, the chain transfer agent is a RAFT agent.

[0049] In non-limiting embodiments, the chain transfer agent can be one or more compounds selected from the group consisting of dithiobenzoates, dithioesters, thioether-thiones, trithiocarbonates, dithiocarbamates, xanthates, and mixtures thereof.

[0050] In one embodiment, the RAFT agent is a macro-RAFT agent.

[0051] As used herein, the terms "macroRAFT" or "macroRAFT agent" refer to a RAFT agent that includes one or more monomers.

[0052] In certain embodiments, a macroRAFT agent is prepared by a process that includes polymerizing one or more unsaturated monomers under the control of a RAFT agent to form the macroRAFT agent.

[0053] In one embodiment, a macroRAFT agent is of the general formula (block[A])-RAFT, where block [A] is a hydrophilic polymer or copolymer as defined herein and RAFT is a RAFT agent as described herein. In other words, a macroRAFT agent consists of a RAFT agent attached to a hydrophilic block of the invention.

[0054] In one embodiment, the macroRAFT agent is P(AA-stat-PEGA)-DDMAT.

[0055] In another embodiment, the macroRAFT agent is P(AA-stat-PEGA)-TTC.

[0056] monomer Suitable polymers for the present invention include those prepared by any polymerization process. If desired, the monomers should also be capable of polymerizing with other monomers (e.g., copolymers). The factors that determine the copolymerizability of various monomers are well documented in the art. See, for example, Polymer Handbook 4th Edition (Brandup, J. and Immergut. EH, Grulke, EA, John Wiley & Sons Ltd., Hoboken, 1999) for information on the factors that determine the copolymerizability of various monomers. See Greenlee, RZ.

[0057] Suitable monomers that may be used according to the present invention are represented by formula (V): [ka] wherein U and W are -CO2H, -CO2R 1 , -COR 1 , -CSR 1 , -CSOR 1 , -COSR 1 , -CONH2, -CONHR 1 , -CONR 12. independently selected from hydrogen, halogen, and optionally substituted C1-C4 alkyl, or U and W together form a lactone, anhydride, or imide ring, which itself may be optionally substituted, and the optional substituents are hydroxy, -CO2H, -CO2R 1 , -COR 1 , -CSR 1 , -CSOR 1 , -COSR 1 , -CN, -CONH2, -CONHR 1 , -CONR 1 2, -OR 1 , -SR 1 , -O2CR 1 , -SCOR 1 , and OCSR 1 are independently selected from V is hydrogen; R 1 , -CO2H, -CO2R 1 , -COR 1 , -CSR 1 , -CSOR 1 , C.O.S.R. 1 , -CONH2, -CONHR 1 , -CONR 1 2, -OR 1 , -SR 1 , -O2CR 1 , -SCOR 1 , and -OCSR 1 is selected from Each R 1 are independently selected from optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted heteroarylalkyl, optionally substituted alkylaryl, optionally substituted alkylheteroaryl, and optionally substituted polymer chains.

[0058] R 1Examples of optional substituents for include those selected from alkyleneoxydyl (epoxy), hydroxy, alkoxy, acyl, alkylcarbonyl, carboxy, sulfonic acid, isocyanato, cyano, silyl, halo, amino (including salts and derivatives thereof).

[0059] Examples of polymer chains include those selected from polyalkylene oxides, polyarylene ethers, and polyalkylene ethers.

[0060] Non-limiting examples of monomers include maleic anhydride, N-alkylmaleimides, N-arylmaleimides, dialkylfumarates and cyclopolymerizable monomers, acrylate and methacrylate esters, acrylic and methacrylic acid, styrene, acrylamide, methacrylamide, and methacrylonitrile, mixtures of these monomers, methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, alpha-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers, e.g., n-butyl acrylate), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, Functional methacrylates, acrylates selected from glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, triethylene glycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate, triethylene glycol acrylate, methacrylamide, N-methylacrylamide, N,N-Dimethylacrylamide, N-tert-Butyl Methacrylamide, Nn-Butyl Methacrylamide, N-Methylol Methacrylamide, N-Ethylol Methacrylamide, N-tert-Butyl Acrylamide, Nn-Butyl Acrylamide, N-Methylol Acrylamide, N-Ethylol Acrylamide, Vinyl Benzoic Acid (all isomers), Diethylaminostyrene (all isomers), Alpha-Methyl Vinyl Benzoic Acid (all isomers), Diethylamino-alpha-Methyl Styrene (all isomers), p-Vinyl Benzene Sulfonic Acid, p-Vinyl Benzene Sulfonic Acid Sodium Salt, Trimethoxysilylpropyl Methacrylate, Triethoxysilylpropyl Methacrylate, Tributoxysilylpropyl Methacrylate, Dimethoxymethylsilylpropyl Methacrylate, Diethoxymethylsilylpropyl Methacrylate, Dibutoxymethylsilylpropyl Methacrylate, Diisopropoxymethylsilylpropyl Methacrylate, Di ... Examples of the silylpropyl acrylate include vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl chloride, vinyl fluoride, vinyl bromide, maleic anhydride, N-phenylmaleimide, N-butylmaleimide, N-vinylpyrrolidone, N-vinylcarbazole, butadiene, ethylene, and chloroprene.

[0061] Non-limiting examples of acrylate monomers include methyl acrylate, methyl alpha-bromoacrylate, methyl 2-(bromomethyl)acrylate, methyl 2-(chloromethyl)acrylate, methyl 2-(trifluoromethyl)acrylate, ethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-phenoxyethyl acrylate, alkoxylated phenol acrylate, alkoxylated tetrahydrofurfuryl acrylate, dicyclopentadienyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, ethoxylated hydroxyethyl acrylate, ethoxylated nonylphenol acrylate, methoxypolyethylene glycol acrylate, polypropylene glycol acrylate, triethylene glycol ethyl ether acrylate, ethyl 2-(bromomethyl)acrylate, ethyl cis-(beta-cyano)acrylate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, diacetone acrylate, mono-2-acryloyloxyalkyl succinate, mono-2-acryloyloxyethyl succinate, mono-2-acryloyloxyalkyl phthalate, mono-2-acryloyloxyethyl phthalate, ethylene glycol dicyclopentenyl ether acrylate, ethylene glycol methyl ether acrylate, ethylene glycol phenyl ether acrylate, ethyl 2-ethyl acrylate, 2-ethylhexyl acrylate, ethyl 2-propyl acrylate, 4-acetoxyphenethyl acrylate, [2-(acryloyloxy)ethyl]trimethylammonium chloride, 2-(4- Benzoyl-3-hydroxyphenoxy)ethyl acrylate, benzyl 2-propyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, tert-butyl 2-bromoacrylate, 4-tert-butylcyclohexyl acrylate, 2-carboxyethyl acrylate, 2-chloroethyl acrylate, di(ethylene glycol) ethyl ether acrylate, di(ethylene glycol) 2-ethylhexyl Sil ether acrylate, cyclohexyl acrylate, n-pentyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, hydroxypropyl acrylate, benzyl acrylate, phenethyl acrylate, isobornyl acrylate, isooctyl acrylate, tert-octyl acrylate, n-decyl acrylate, isodecyl acrylate, undecyl acrylate, 10- Undecenyl acrylate, dodecyl acrylate, lauryl acrylate, myristyl acrylate, stearyl acrylate, palmityl acrylate, octadecyl acrylate, n-eicosyl acrylate, isonorbornyl acrylate, pentabromobenzyl acrylate, pentabromophenyl acrylate, pentafluorophenyl acrylate, poly(ethylene glycol) methyl ether acrylate, poly(propylene glycol) acrylate, tetrahydrofurfuryl acrylate, 3,5,5-trimethylhexyl Acrylate, acetonyl acrylate, 2-carboxyethyl acrylate, carboxymethyl acrylate, oxazolidinyl ethyl acrylate, methoxyethoxyethyl acrylate, cyclohexyloxymethyl acrylate, methoxymethoxyethyl acrylate, benzyloxymethyl acrylate, 2-butoxyethyl acrylate, 2-ethoxyethoxymethyl acrylate, 2-ethoxyethyl acrylate, allyloxymethyl acrylate, 2,3-dibromopropyl acrylate, 4-bromophenyl acrylate, 1,3-dichloro-2-propyl acrylate, 2-bromoethyl acrylate, 2-iodoethyl acrylate, chloromethyl acrylate, 2-isocyanatoethyl acrylate, 2-acetoacetoxyethyl acrylate, dialkylaminoalkyl acrylates, such as 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 3-(dimethylamino)propyl acrylate, 3-(diethylamino)propyl acrylate, etc.; quaternary ammonium salts of dialkylaminoalkyl acrylates, such as acryloyloxyethyl trimethyl ammonium chloride, acryloyloxypropyl trimethyl ammonium chloride, acryloyloxypropyl lauryl dimethyl ammonium chloride, acryloyloxyethyl ethyl dimethyl ammonium ethyl sulfate, acryloyloxyethyl trimethyl ammonium sulfate phosphate, and acryloyloxyethyl trimethylammonium methosulfate, phosphorus-containing acrylates such as diethyl [(acryloyloxy)methyl] phosphonate, diethyl [(acryloyloxy)ethyl] phosphonate, diethyl (acryloyloxy)methyl phosphate, and diethyl (acryloyloxy)ethyl phosphate, sulfur-containing acrylates such as 4-thiocyanatobutyl acrylate, thiocyanatomethyl acrylate, 2-methylthioethyl acrylate, 2-methylsulfonylethyl acrylate, 2-ethylthioethyl acrylate, 2-ethylsulfonylethyl acrylate, 2-propylthioethyl acrylate, 4-methylthiobutyl acrylate, 2,3-bis(methylthio)propyl acrylate, 2,3-bis(methylsulfonyl)propyl acrylate, 2,3-bis(ethylthio)propyl acrylate, 2,3-bis(butylsulfonyl)propyl acrylate, and 2-methylthio-3-ethylthiopropyl acrylate; silicon-containing acrylates such as 2-(trimethylsilyloxy)ethyl acrylate, trimethylsilylmethyl acrylate, diphenylmethylsilylmethyl acrylate, ethyl 2-(trimethylsilylmethyl)acrylate, 3-[tris(trimethylsiloxy)silyl]propyl acrylate, and 3-(trimethoxysilyl)propyl acrylate; methyl methacrylate, methacrylate, methyl alpha-bromomethacrylate, methyl 2-(bromomethyl)methacrylate, methyl 2-(chloromethyl)methacrylate, methyl 2-(trifluoromethyl)methacrylate, ethyl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-phenoxyethyl methacrylate, alkoxylated phenol methacrylates, alkoxylated tetrahydrofurfuryl methacrylate, dicyclopentadienyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, ethoxylated hydroxyethyl methacrylate, acrylate, ethoxylated nonylphenol methacrylate, methoxypolyethylene glycol methacrylate, polypropylene glycol methacrylate, triethylene glycol ethyl ether methacrylate, ethyl 2-(bromomethyl)methacrylate, ethyl cis-(beta-cyano)methacrylate, 2-ethylhexyl 2-cyano-3,3-diphenyl methacrylate, diacetone methacrylate, mono-2-methacryloyloxyethyl succinate, mono-2-methacryloyloxyalkyl succinate ... oxyethyl phthalate, mono-2-methacryloyloxyalkyl phthalate, ethylene glycol dicyclopentenyl ether methacrylate, ethylene glycol methyl ether methacrylate, ethylene glycol phenyl ether methacrylate, ethyl 2-ethyl methacrylate, 2-ethylhexyl methacrylate, ethyl 2-propyl methacrylate, 4-acetoxyphenethyl methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, 2-(4-benzoyl 1-3-hydroxyphenoxy)ethyl methacrylate, benzyl 2-propyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, tert-butyl 2-bromo methacrylate, 4-tert-butylcyclohexyl methacrylate, 2-carboxyethyl methacrylate, 2-chloroethyl methacrylate, di(ethylene glycol) ethyl ether methacrylate, di(ethylene glycol) 2-ethylhexyl ether methacrylate,Cyclohexyl methacrylate, dialkylamino alkylene methacrylates such as 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 3-(dimethylamino)propyl methacrylate, and 3-(diethylamino)propyl methacrylate, quaternary ammonium salts of dialkylamino alkylene methacrylates such as methacryloyloxyethyl trimethyl ammonium chloride, methacryloyloxypropyl trimethyl ammonium chloride, methacryloyloxypropyl lauryl dimethyl ammonium chloride, methacryloyloxyethyl ethyl dimethyl ammonium ethyl sulfate, methacryloyloxyethyl trimethyl ammonium sulfate, and methacryloyloxyethyl trimethyl ammonium methosulfate, n-pentyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, hydroxypropyl methacrylate, benzyl methacrylate, phenoxypropyl methacrylate, methyl ... ethyl methacrylate, isobornyl methacrylate, isooctyl methacrylate, tert-octyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, undecyl methacrylate, 10-undecenyl methacrylate, dodecyl methacrylate, lauryl methacrylate, myristyl methacrylate, stearyl methacrylate, palmityl methacrylate, octadecyl methacrylate, n-eicosyl methacrylate, iso-norbornyl methacrylate, pentabromobenzyl methacrylate, pentabromophenyl methacrylate acrylate, pentafluorophenyl methacrylate, poly(ethylene glycol) methyl ether methacrylate, poly(propylene glycol) methacrylate, tetrahydrofurfuryl methacrylate, ethyl 2-(trimethylsilylmethyl) methacrylate, 3,5,5-trimethylhexyl methacrylate, acetonyl methacrylate, 2-carboxyethyl methacrylate, carboxymethyl methacrylate, oxazolidinyl ethyl methacrylate, methoxyethoxyethyl methacrylate, cyclohexyloxymethyl methacrylate,Methoxyme, methacrylate, benzyloxymethyl methacrylate, 2-butoxyethyl methacrylate, 2-ethoxyethoxymethyl methacrylate, 2-ethoxyethyl methacrylate, allyloxymethyl methacrylate, 2,3-dibromopropyl methacrylate, 4-bromophenyl methacrylate, 1,3-dichloro-2-propyl methacrylate, 2-bromoethyl methacrylate, 2-iodoethyl methacrylate, chloromethyl methacrylate, 2-isocyanatoethyl methacrylate, 2-acetoacetoxyethyl methacrylate, phosphorus-containing methacrylates such as diethyl[(acryloyloxy)methyl]phosphonate, diethyl[(acryloyloxy)ethyl]phosphonate, diethyl(acryloyloxy)methyl phosphate, and diethyl(acryloyloxy)ethyl phosphate, sulfur-containing methacrylates such as 4-thiocyanatobutyl methacrylate, acrylates, thiocyanatomethyl methacrylate, 2-methylthioethyl methacrylate, 2-methylsulfonylethyl methacrylate, 2-ethylthioethyl methacrylate, 2-ethylsulfonylethyl methacrylate, 2-propylthioethyl methacrylate, 4-methylthiobutyl methacrylate, 2,3-bis(methylthio)propyl methacrylate, 2,3-bis(methylsulfonyl)propyl methacrylate, 2,3-bis(ethylthio)propyl methacrylate, 2,3-bis(butylsulfonyl)propyl methacrylate, and 2-methylthio-3-ethylthiopropyl methacrylate; silicon-containing methacrylates, such as 2-(trimethylsilyloxy)ethyl methacrylate, trimethylsilylmethyl methacrylate, diphenylmethylsilylmethyl methacrylate, ethyl 2-(trimethylsilylmethyl)methacrylate, 3-[tris(trimethylsiloxy)silyl]propyl methacrylate, 3-(trimethoxysilyl)propyl methacrylate, and combinations thereof.

[0062] A more extensive list of exemplary methacrylate monomers, acrylate monomers, methacrylamide monomers, acrylamide monomers, styrenic monomers, diene monomers, vinyl monomers, monomers with reactive functional groups, and crosslinking monomers suitable for use as the radically polymerizable monomers herein are set forth in Moad et al., “Living Radical Polymerization by the RAFT Process—a Third Update,” Australian Journal of Chemistry 65:985-1076 (2012), which is incorporated herein by reference in its entirety.

[0063] Block Copolymers In a first embodiment, the present invention provides a compound comprising blocks [A] and [B], Block [A] is a hydrophilic homopolymer or copolymer, Block [B] is a hydrophobic homopolymer having a Tg of less than 16° C. or a hydrophobic copolymer having a Tg of the hydrophobic block of less than about 75° C., A process for preparing amphiphilic block copolymers is provided, the process comprising obtaining blocks [A] and [B] by RDRP, preferably via RAFT polymerization of ethylenically unsaturated monomers.

[0064] In this first embodiment, block [A] is a hydrophilic polymer or copolymer formed by polymerization of one or more monomers as described herein.

[0065] In one example of the first embodiment, block [A] is prepared from one or more of poly(ethylene glycol) methyl ether acrylate (PEGA), poly(ethylene glycol) methyl ether methacrylate (PEGMA), and acrylic acid.

[0066] In this first embodiment, block [B] is a hydrophobic polymer or copolymer formed by polymerization of one or more monomers as described herein.

[0067] In one example of the first embodiment, the block [B] is prepared from one or more of n-butyl acrylate (nBA), tert-butyl acrylate (tBA), and styrene.

[0068] In a second embodiment, the present invention relates to a process for preparing a block copolymer comprising blocks [A] and [B], comprising: Block [A] is a hydrophobic homopolymer or copolymer, Block [B] is a hydrophobic homopolymer or copolymer, The process comprises obtaining blocks [A] and [B] by RDRP, preferably via RAFT polymerization of ethylenically unsaturated monomers.

[0069] In one example of the second embodiment, the block [A] is prepared from poly(methyl methacrylate) (PMMA).

[0070] In one example of the second embodiment, the block [B] is prepared from one or more of benzyl methacrylate, ethylhexyl methacrylate, and methyl methacrylate, preferably PMMA70-b-PBzMA40 or PMMA70-bP(EHMA90-stat-MMA10).

[0071] Glass transition temperature As will be understood by those skilled in the art, the glass transition temperature (Tg) of a polymer is defined as the temperature at which both the long range segmental motion of the polymer chain and the coiling and uncoiling of the chain segments are "frozen" and the polymer behaves like a "solid glass" or has crystalline properties. Below its Tg, the polymer does not flow or exhibit rubber elasticity, but above its Tg, the polymer does. In other words, a polymer at a temperature below its Tg is harder and less elastic than the same polymer at a temperature above its Tg. The Tg of a polymer can be determined by any standard method known in the art, for example, using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA).

[0072] In an embodiment, block [B] comprises a hydrophobic copolymer selected to have a Tg of the hydrophobic block less than about 75°C, preferably in the range of -70°C to 75°C.

[0073] In another embodiment, block [B] comprises a hydrophobic homopolymer selected to have a Tg of less than 16°C, preferably in the range of -70°C to 16°C.

[0074] Reaction conditions Conventional techniques, conditions, and reagents used for the preparation of polymers by RAFT polymerization can be advantageously used according to the present invention. As a general guide in selecting conditions for polymerization, the concentration of initiator(s), monomer, and other reaction conditions (solvent(s), if present, reaction temperature, reaction pressure, surfactants, if present, other additives) should be selected to optimize polymer properties, e.g., narrowly dispersed polymers (good control / livingness based on a satisfactory RDRP (RAFT) process).

[0075] Suitable ratios for the monomers of block [A] (M1:M2) include 1:100 to 100:1, or about 1:100 to 1:1, or about 1:1 to 1:100, or about 5. The amount of the glycerol in the solution may be 0:1 to 1:50, or may be about 1:100, 1:95, 1:90, 1:85, 1:80, 1:75, 1:70, 1:65, 1:60, 1:55, 1:50, 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:15, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1: It may be 1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1 or 100:1, or any range therein.

[0076] Suitable ratios for the monomers of block [B] (M1:M2) include 1:100 to 100:1, or may be about 1:100 to 1:1, or about 1:1 to 1:100, or about 50:1 to 1:50, or may be about 1:100, 1:95, 1:90, 1:85, 1:80, 1:75, 1:70, 1:65, 1:60, 1:55, 1:50, 1:45, 1:40, 1:35, 1:30, 1:25, 1:20, 1:15 , 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1 or 100:1, or any range therein.

[0077] The chain transfer agent is, for example, about 1 mmol L -1 ~Approx. 1000mmol·L -1 , or about 10 mmol L -1 ~Approx. 1000mmol·L -1 , for example, about 5 mmol L -1 ~20 mmol L -1 , or about 7 mmol L -1 ~Approx. 13mmol·L -1, or about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mmol L -1 or any suitable concentration within any range therein.

[0078] In one embodiment, the ratio of [hydrophobic monomer]:[chain transfer agent] ranges from about 10 to about 400, or from about 100 to about 150, or from about 75 to about 100, or it can be about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200, or any range therein. In one preferred embodiment, the ratio ranges from about 40 to about 200.

[0079] The polymerization temperature may be optimized by one of ordinary skill in the art taking into account the particular monomer(s) being polymerized and the other components of the polymerization or reaction medium.

[0080] The polymerization is generally carried out at a temperature in the range of 20 to 100°C, for example, about 0 to 180°C, or about 50 to 150°C, or about 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100°C, or any range therein, preferably in the range of 40 to 100°C.

[0081] The reaction time can be from 1 to 48 hours, for example, from 1 to 20 hours, from 1 to 12 hours, or from 1 to 8 hours, or about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours, or any range therein.

[0082] The polymerization can be carried out at any suitable pH range, in one embodiment, the pH is in the range of 3 to 8, or it can be about 3.5 to about 6, or about 4 to about 7, or about 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, or 8, or any range therein.

[0083] In one embodiment, the polymerization was carried out at 80° C. in an oil bath with a stirring speed of 350 rpm for 6 hours.

[0084] The reaction medium may be selected from a wide range of media to suit the monomer(s) being used, such as water and alcohols, such as methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol, n-pentanol, and mixtures thereof.

[0085] The reaction medium may further include one or more of an acid, a base, a catalyst, a surfactant, and / or a coupling agent, or any other suitable components.

[0086] Hydrophobic and Hydrophilic Those skilled in the art will appreciate that the terms "hydrophilic" and "hydrophobic" as used herein are not intended to define the absolute properties of a particular substance, but rather are indicators of favorable or unfavorable interactions (i.e., attractive or repulsive interactions). In other words, the terms "hydrophilic" and "hydrophobic" are used herein as primary indicators to define properties such as what attracts and what repels each other.

[0087] Although merely as a convenient reference point, one of skill in the art may consider a "hydrophilic" liquid to have a solubility in water of at least 5 g / L at 25° C., and a "hydrophobic" liquid to have a solubility in water of less than 5 g / L at 25° C. From the perspective of solids, the terms "hydrophilic" and "hydrophobic" may be considered by one of skill in the art to refer to solids that may be capable of being wetted (i.e., not repelled) by hydrophilic and hydrophobic liquids, respectively.

[0088] Molecular weight and dispersion index Those skilled in the art will understand that polymers exist as a distribution of chain lengths and molecular weights, and therefore the molecular weight of a polymer must be stated as the average molecular weight calculated from the molecular weights of all the chains in a sample.

[0089] In the present invention, the molecular weight (MW) of block [A] or block [B] may be in the range of 5000 to 100,000, or it may be about 10,000 to 100,000, or about 25,000 to about 75,000, or it may be about 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 3800, 3900, 4000, 41000, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, 5000, 5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6000, 6000, 6000, 6000, 6000, 6000 The molecular weight of the block [A] or block [B] may be in the range of 5,000 to 40,000. In a preferred embodiment, the molecular weight of the block [A] or block [B] is in the range of 5,000 to 40,000.

[0090] In the present invention, the average degree of polymerization (DP) of the block copolymer as described herein ranges from about 10 to about 1000, or from about 20 to about 500, or from about 50 to about 750, or from about 300 to about 800, or from about 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200, or any number therein. In a preferred embodiment, the degree of polymerization (DP) of the block copolymer is in the range of about 50 to about 300.

[0091] Polymers prepared according to the present invention may advantageously exhibit well-defined molecular architecture, predetermined molecular weight, weight, and narrow molecular weight distribution, or low polydispersity (D).

[0092] Nanofiber dimensions As will be appreciated by one of ordinary skill in the art, nanofibers of the present invention are defined as having a length that is greater than or significantly greater than the width of the nanofiber. The ratio of length to width of a nanofiber can be greater than 5:1, or greater than 10:1, or greater than 25:1, or greater than 50:1, or greater than 100:1, or greater than 250:1, or greater than 500:1, or greater than 1000:1, or it can be from 5:1 to 200,000:1, or from 100:1 to 10,000:1, or from 500:1 to 5,000:1, or any range therein.

[0093] The width of the nanofibers may be from about 1 nm to about 250 nm, or from about 3 nm to about 100 nm, or from 5 nm to about 50 nm, or from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, It may be 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245 or 250 nm, or any range therein.

[0094] The length of each of the nanofibers is about 5 nm to 2 mm, or about 10 nm to about 1 mm, or about 50 nm to about 500 μm, or about 20 nm to about 100 μm, or about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 600, 700, 8 100, 900 or 1000 nm, or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900 or 1000 μm, or about 1.5 or 2 mm, or any range therein.

[0095] Crosslinking Agent In certain embodiments, the amphiphilic block copolymers may be crosslinked to durably stabilize the resulting nanofibers and thus provide them with long-term stability. The crosslinker may provide covalent crosslinks between two different polymer chains. Any suitable crosslinker may be used. As will be appreciated by those skilled in the art, the crosslinker must have two end groups that are capable of radical polymerization and thus incorporation into the polymer chains of the present invention. Examples of suitable crosslinkers include, but are not limited to, ethylene glycol diacrylate esters (e.g., ethylene glycol dimethyl acrylate) when the monomeric material is an acrylate ester, or ethylene glycol diacrylic acid (e.g., ethylene glycol dimethacrylic acid) when the monomeric material is an acrylic acid. In embodiments where a crosslinker is present, the ratio of monomeric material to crosslinker in the solvent may be from 10:1 to 50:1, for example, from 20:1 to 40:1.

[0096] Non-limiting examples of crosslinking agents include (meth)acrylic anhydride, ethylene glycol, divinyl ethers of compounds selected from the group consisting of ethylene glycol diacrylate, poly(ethylene glycol) diacrylate, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and combinations thereof; divinyl ethers of diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, heptaethylene glycol, octaethylene glycol, nonaethylene glycol, decaethylene glycol, and polyalkylene glycols; methylene bis(meth)acrylamide; ethylene glycol di(meth)acrylate; butanediol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate; t)acrylate;Polyethylene glycol di(meth)acrylamide;Dipropylene glycol diallyl ether;Polyglycol diallyl ether;Hydroquinone diallyl ether;Trimethylolpropane tri(meth)acrylate;Trimethylolpropane diallyl ether;Pentaerythritol triallyl ether;Allyl (meth)acrylate;Trialyl cyanurate;Diallyl maleate, polyallyl ester;Tetraallyloxyethane;Triallylamine;Tetraallyloxyethane 1,13-tetradecadiene; divinylbenzene; diallyl phthalate; triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; N,N'-divinylimidazolidone, 1-vinyl-3(E)-ethylidenepyrrolidone; 2,4,6-triallyloxy-1,3,5-triazine; and combinations thereof.

[0097] In one non-limiting embodiment, the crosslinker is selected from the group consisting of (meth)acrylic anhydride, methylene bis(meth)acrylamide, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylamide, dipropylene glycol diallyl ether, polyglycol diallyl ether, hydroquinone diallyl ether, trimethylolpropane tri(meth)acrylate, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, and combinations thereof.

[0098] In the present invention, the crosslinker can be added at any time during the polymerization of the second block, including at the beginning, middle, or end. In one embodiment, the crosslinker is added at t=0 hours. In another embodiment, the crosslinker is added at t=2 hours. It is expected that a person skilled in the art can optimize the timing of the addition of the crosslinker depending on the effect desired, for example, adding the crosslinker later in the polymerization process may have less effect on the final morphology, and vice versa.

[0099] In one non-limiting embodiment, the crosslinker(s) can be present in an amount of about 0.001% to about 20% by weight of the block copolymer. In another non-limiting embodiment, the crosslinker(s) can be present in an amount of about 0.001% to about 10% by weight of the block copolymer. In yet another non-limiting embodiment, the crosslinker(s) can be present in an amount of about 0.001% to about 5% by weight of the block copolymer. The crosslinker can be present at about 0.001, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 weight percent, or any range therein.

[0100] In one embodiment, the crosslinker is ethylene glycol diacrylate (EGDA) or ethylene glycol dimethacrylate (EGDMA).

[0101] In another embodiment, the crosslinker is poly(ethylene glycol) diacrylate (PEGDA).

[0102] Uses of the Nanofibers of the Invention The nanofibers disclosed herein may be used as vehicles for active agents. In other words, the nanofibers may further include an active agent encapsulated in the nanofiber. As used herein, the term "encapsulated" refers to the inclusion of an active agent within the core of the body of the nanofibers described herein. For example, in embodiments of the invention where the nanofiber has a solid core, the active agent will be held within the polymer matrix of the nanofiber within the core of the nanofiber.

[0103] In embodiments of the invention, the nanofiber composition further comprising an active agent may contain 0.01-50 wt% of the active agent based on the weight of the nanofiber as a whole. For example, the active agent may be present in an amount of 1-30 wt%, such as 5-10 wt%, based on the weight of the nanofiber as a whole. The active agent may be selected from one or more of the group consisting of vitamin C, peptides, glycerol, dyes, flavors, perfume oils, citronellal, silicon oils, organosilicons, pesticides, beta-carotene, and pharmacologically active agents.

[0104] The term "pharmacologically active agent" as used herein may refer to a substance useful for the treatment or prevention of a condition affecting a human or other animal. The condition may be a disease, a disorder, or a physiological condition. It will be understood that an active agent may not directly affect the underlying condition, but may be used as an adjuvant with an additional active agent to enhance the effectiveness of the other active agent. Thus, the term "pharmacologically active agent" as used herein includes all classes of pharmacologically active agents, whether adjuvant or therapeutic, that may be provided to a subject through oral administration. As used herein, the terms "pharmacologically active agent" and "drug" may be used interchangeably, and therefore the term "drug" may be interpreted based on the definition of "active agent." Examples of pharmacologically active agents include, but are not limited to, ibuprofen, fenofibrate, and isotretinoin.

[0105] Further active agents that may be mentioned herein include, but are not limited to, carbon metabolites (e.g., glucose, fructose, fumarate, etc.), electron acceptors (e.g., nitrates, peroxides, etc.), and vitamins, such as vitamins A, B1, B2, B3, B6, B12, D, E, biotin, folate, and panothenate; minerals, such as calcium, magnesium, selenium, and zinc; amino acids, such as asparagine, carnitine, glutamine, and serine; antioxidants selected from coenzyme Q10, glutathione, and cysteine; or metabolites, such as lipoic acid, oleic acid, choline, inositol, fructose, glucose, insulin, epigallocatechin gallate, and mixtures thereof.

[0106] In an embodiment of the invention, the nanofibers may have a core region that may include an active agent. The nature of the active agent in the core will be determined by the nature of the nanofiber formed. For example, a nanofiber formed such that the hydrophilic block of the amphiphilic block copolymer is disposed at the surface of the nanofiber may be suitable for encapsulation of a hydrophobic active agent (as described above). Alternatively, a nanofiber formed such that the hydrophobic block of the amphiphilic block copolymer is disposed at the surface of the nanofiber may be suitable for encapsulation of a hydrophilic active agent (as described above). The nanofibers of the invention may have an average diameter of 50 to 200 nm, for example, 70 to 150 nm.

[0107] In some materials, the hydrophobic repeat units form the surface of the nanofiber and the hydrophilic repeat units form the core. In other embodiments having the opposite arrangement, the hydrophilic repeat units form the surface of the nanofiber and the hydrophobic repeat units form the core. In still further embodiments, the hydrophobic repeat units form the surface of the nanofiber and the hydrophobic repeat units also form the core.

[0108] Other uses of the nanofibers of the present invention relate to sun care compositions, face care compositions, lip care compositions, eye care compositions, skin care compositions, after-sun compositions, body care compositions, nail care compositions, anti-aging compositions, insect repellents, oral care compositions, deodorant compositions, hair care compositions, conditioning compositions, color cosmetic compositions, color protection compositions, self-tanning compositions, and foot care compositions.

[0109] The nanofibers disclosed herein may also be used as fillers and / or reinforcing agents for composite materials. In other words, the nanofibers may be encapsulated in or dispersed throughout a matrix material. The nanofibers may modify the physical properties of the composite material formed. The nanofibers may be added to or dispersed throughout a matrix during the manufacture of a composite material, such as when the matrix is ​​dissolved or dispersed throughout a solvent, such as water, or when melted. In one example, the matrix may include a polymer as described herein to form a composite polymer material, such as a film, or coating, or formed article. The polymer matrix may preferably be hydrophilic or formed from an aqueous dispersion, such that the hydrophilic shell of the nanofibers is wetted by the matrix during production. If the polymer matrix is ​​formed from an aqueous dispersion (i.e., a latex), the nanofibers may be mixed with the aqueous dispersion before curing. If the polymer matrix is ​​melted, the nanofibers may be added to an extruder along with the polymer pellets and mixed during or after melting of the polymer matrix material.

[0110] In another example, the matrix may include a hydraulic binder such as cement (e.g., Portland cement) or fly ash, where the nanofibers can be added to the hydraulic binder and then mixed before the addition of water, after the addition of water, or sequentially with water to produce a cementitious material comprising the nanofibers of the present invention.

[0111] In another example, the matrix may include mineral materials such as calcium sulfate (ie, gypsum) in the production of gypsum-based articles such as gypsum board / drywall.

[0112] In yet another example, the matrix can be any material that benefits from modifying the viscosity and / or rheology of the matrix. In other words, the nanofibers can be used as viscosity modifiers for a range of liquid or semi-solid materials, such as gels, hydraulic fluids, etc.

[0113] As one skilled in the art will appreciate, the nanofibers of the present invention may be used to replace fillers and / or reinforcing agents in other known materials where the effects of the low Tg core may have beneficial effects.

[0114] Preferred features, embodiments, and variations of the present invention can be identified from the following detailed description, which provides sufficient information for one skilled in the art to practice the present invention. The detailed description should not be construed as limiting the scope of the foregoing summary in any manner. The detailed description makes reference to several drawings, as follows: [Brief description of the drawings]

[0115] [Figure 1] Total monomer conversions for RAFT aqueous emulsion polymerizations of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent at pH 3.5, pH 5, and pH 7 (see also Table 1). [Diagram 2] Molecular weight distributions (w(logM) vs. logM) for RAFT aqueous emulsion polymerizations of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent at pH 3.5, pH 5, and pH 7 (see also Table 1). [Diagram 3] TEM images of RAFT aqueous emulsion polymerizations of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent ([styrene] / [nBA]=70 / 30, [hydrophobic monomer]0 / [macroRAFT]0=200) carried out at pH 3.5, pH 5, and pH 7 (see also Table 1). Scale bars: A-1=500 nm, A-2=2 μm, A-3=500 nm. [Figure 4]Molecular weight distributions (w(logM) vs. logM) of RAFT aqueous emulsion polymerizations of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent with different [hydrophobic monomer]0 / [macroRAFT]0 (macroRAFT agents, from left to right: [hydrophobic monomer]0 / [macroRAFT]0 = 50 (B-1), 100 (B-2), 130 (B-3), 150 (B-4), 170 (B-5), 200 (B-6)) (see also Table 2). [Diagram 5] TEM images of RAFT aqueous emulsion polymerizations of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent with different [hydrophobic monomer]0 / [macroRAFT]0 ([hydrophobic monomer]0 / [macroRAFT]0=50 (B-1), 100 (B-2), 130 (B-3), 150 (B-4), 170 (B-5), 200 (B-6)) (see also Table 2). Scale bars: B-1=200 nm, B-2=1 μm, B-3=1 μm, B-4=2 μm, B-5=2 μm, B-6=2 μm. [Figure 6] TEM images of nanoparticles synthesized via RAFT aqueous emulsion polymerization of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent with EGDA or PEGDA at pH 5 in method (i) (items Cx and Dx; top panel) at t=0 h and method (ii) (items Ex and Fx; bottom panel) at t=2 h ([hydrophobic monomer]0 / [macroRAFT]0=100). Scale bars: B-2=1 μm, C-1=1 μm, C-2=1 μm, D-1=1 μm, D-2=1 μm, D-3=100 nm, E-1=1 μm, E-2=1 μm, F-1=1 μm, F-2=1 μm, F-3=500 nm. [Figure 7]EGDA or PEGDA crosslinked P(AA-stat-PEGA)-bP(S-stat-nBA) nanoparticles dissolved in THF: (a) no crosslinker, 1 mol% PEGDA at t = 0 h, and 2.5 mol% PEGDA at t = 0 h (top left to right); (b) no crosslinker, 0.5 mol% EGDA at t = 0 h, 1 mol% EGDA at t = 0 h, and 10 mol% EGDA at t = 0 h (top left to right); (c) no crosslinker, 1 mol% PEGDA at t = 2 h, and 10 mol% PEGDA at t = 2 h (bottom left to right); (d) no crosslinker, 3 mol% EGDA at t = 2 h, 5 mol% EGDA at t = 2 h, and 10 mol% EGDA at t = 2 h (bottom left to right). [Figure 8] TEM images of nanoparticles synthesized via RAFT aqueous emulsion polymerization of styrene and nBA ([styrene]0 / [nBA]0=20 / 80) in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent at pH 5 with 5 mol% EGDA (relative to macroRAFT agent) after 2 h polymerization at different solid contents ([hydrophobic monomer]0 / [macroRAFT]0=130, solid contents 15.2% (H-1), 24.7% (H-2), 32.7% (H-3)). Scale bars: H-1=200 nm, H-2=200 nm, H-3=200 nm. [Figure 9] Molecular weight distribution (w(logM) vs. logM) of the P(AA-stat-PEGA)-TTC macroRAFT agent (Mn = 13,400 g / mol; D = 1.20). [Figure 10]TEM images of nanoparticles synthesized via RAFT aqueous emulsion polymerization of styrene and nBA ([styrene]0 / [nBA]0=20 / 80) in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent at pH 5 with 5 mol% EGDA (relative to the macroRAFT agent) at different [hydrophobic monomer]0 / [macroRAFT]0 ([hydrophobic monomer]0 / [macroRAFT]0=80 (G-1), 100 (G-2), 115 (G-3), 130 (G-4), 150 (G-5), 180 (G-6), 200 (G-7), 250 (G-8), 300 (G-9)) after 2 h polymerization. Scale bar: G-1=200nm, G-2=1μm, G-3=100nm, G-4=1μm, G-5=1μm, G-6=1μm, G-7=2μm, G-8=1μm, G-9=2μm. [Figure 11] Schematic diagram of a block copolymer having a first hydrophilic block and a second hydrophobic block self-assembled into a nanofiber having a hydrophilic outer "shell" portion and a hydrophobic inner "core" portion used in the preparation of nanofiber-reinforced nanocomposite polymer materials. [Figure 12] (A) TEM micrograph of PMMA-bP(EHMA-stat-MMA) and (B) SEM micrograph of PMMA-b-PBzMA.

[0116] definition In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to be limiting.

[0117] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0118] Unless the context clearly requires otherwise, throughout the specification and claims, the terms "comprise," "comprising," and the like are intended to be construed in an inclusive sense, i.e., "including, but not limited to," as opposed to an exclusive or exhaustive sense. For example, a composition, mixture, process, or method that includes a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, mixture, process, or method.

[0119] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. When present in a claim, such would close the claim to the inclusion of materials other than those recited, except for impurities normally associated therewith. When the phrase "consisting of" appears in a clause in the body of a claim rather than immediately following a preamble, it limits only the elements recited in that clause and does not exclude other elements from the claim as a whole.

[0120] The transitional phrase "consisting essentially of" is used to define a composition, process, or method that includes materials, steps, features, components, or elements in addition to those literally disclosed, provided that these additional materials, steps, features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention. The term "consisting essentially of" occupies a compromise between "comprising" and "consisting of."

[0121] It should be readily understood that where applicants have defined an invention or portions thereof using open-ended terms such as "comprising," the specification should also be construed (unless otherwise indicated) as describing such invention using the terms "consisting essentially of" or "consisting of." In other words, with respect to the terms "comprising," "consisting of," and "consisting essentially of," when one of these three terms is used in the present specification, The disclosed and claimed subject matter may include use of either of the other two terms. Thus, in some embodiments not expressly recited otherwise, any instance of "comprising" may be replaced with "consisting of" or alternatively "consisting essentially of."

[0122] Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not an exclusive or. For example, a condition "A or B" is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0123] Also, the indefinite articles "a" and "an" preceding an element or component of the invention are intended to be open-ended regarding the number of instances (i.e., occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural, unless a numerical value is clearly intended to be in the singular.

[0124] Except in the operating examples or where otherwise indicated, all numbers expressing amounts of ingredients or reaction conditions used herein should be understood in all cases to be modified by the term "about". The examples are not intended to limit the scope of the invention. Hereinafter, or where otherwise indicated, "%" means "% by weight", "ratio" means "ratio by weight", and "parts" means "parts by weight".

[0125] As used herein, the terms "majority" and "substantially" are intended to mean including greater than 50% by weight, unless otherwise indicated.

[0126] As used herein, in connection with a range of numerical values, the terms "about," "approximately," and "substantially" are understood to refer to a range of -10% to +10% of the referenced numerical value, preferably -5% to +5% of the referenced numerical value, more preferably -1% to +1% of the referenced numerical value, and most preferably -0.1% to +0.1% of the referenced numerical value. Furthermore, in connection with numerical ranges, these terms should be interpreted as providing support for a claim regarding any number or subset of numbers within that range. For example, a disclosure of 1 to 10 should be interpreted as supporting ranges such as 1 to 8, 3 to 7, 1 to 9, 3.6 to 4.6, 3.5 to 9.9, 8 to 10, etc.

[0127] As used herein, weight percent refers to the weight of a particular component relative to the total weight of the reference composition.

[0128] The term "and / or" used in the context of "X and / or Y" should be interpreted as "X", or "Y", or "X and Y". Similarly, "at least one of X or Y" should be interpreted as "X", or "Y", or "both X and Y".

[0129] The terms "preferred" and "preferably" refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0130] The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety. No. 6,394,411 and the like, all of which are incorporated by reference in their entireties as if fully set forth herein.

[0131] As used herein, the term "nanofiber" refers to a solid nanoparticle material that is similar to a micelle in that it has a solid core and a solid shell / corona (i.e., the cylindrical interior portion is not hollow). In other words, the core and shell are formed from a polymeric material, with the hydrophilic block on the outer surface of the nanofiber (to form the shell) and the hydrophobic block forming the core of the nanofiber (or vice versa). In another embodiment, the hydrophobic block is on the outer surface of the nanofiber, and the hydrophobic block also forms the core of the nanofiber. While the shell is solid, these nanofibers may have the ability to be used as carriers, since other molecules (e.g., active agents) can still be dispersed (e.g., by diffusion or other suitable means) into the core of the cylindrical nanofiber, thereby allowing the cylindrical nanofiber to function as a carrier for the active agent.

[0132] The term "each independently selected from the group consisting of" means that when a group occurs more than one time in a structure, the group may be independently selected at each occurrence.

[0133] The term "alkyl" refers to a functionalized or non-functionalized monovalent straight, branched, or cyclic C1-C6 alkyl group, optionally with one or more heteroatoms. 60 In one non-limiting embodiment, alkyl is a C1-C 45 In another non-limiting embodiment, the alkyl is a C to C hydrocarbyl group. 30 It is a hydrocarbyl group. Non-limiting examples of alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, tert-octyl, iso-norvomyl, n-dodecyl, tert-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. The definition of "alkyl" also includes groups resulting from a combination of linear, branched, and / or cyclic structures.

[0134] The term "aryl" refers to a functionalized or non-functionalized monovalent aromatic hydrocarbyl group, optionally having one or more heteroatoms. The definition of aryl includes carbocyclic and heterocyclic aromatic groups. Non-limiting examples of aryl groups include phenyl, naphthyl, indenyl, indanyl, azulenyl, fluorenyl, anthracenyl, furyl, thienyl, pyridyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, 2-pyrazolinyl, pyrazolidinyl, isoxazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,3-triazolyl, 1,3,4-thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, 1,3,5-triazinyl, 1,3,5-trithianyl, indolizinyl, indolyl, isoinyl, and the like. dolyl, 3H-indolyl, indolinyl, benzo[b]furanyl, 2,3-dihydrobenzofuranyl, benzo[b]thiophenyl, 1H-indazolyl, enzimidazolyl, benzothiazolyl, purinyl, 4H-quinolizinyl, isoquinolinyl, cinnolinyl, phthalazinyl group, quinazolinyl, quinoxalinyl, 1,8-naphthridinyl, pteridinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxyazinyl, pyrazolo[1,5-c]triazinyl, and the like.

[0135] The term "alkylene" refers to a functionalized or non-functionalized, divalent, straight-chain, branched-chain, or cyclic C1-C6 alkylene group, optionally with one or more heteroatoms. 40 In one non-limiting embodiment, alkylene is a C1-C 30 In another non-limiting embodiment, the alkylene is a C1-C 20 Non-limiting examples of alkylene groups include: [ka]

[0136] The term "heteroatom" refers to oxygen, nitrogen, sulfur, silicon, phosphorus, or halogen. The heteroatom(s) may be present as part of one or more heteroatom-containing functional groups. Non-limiting examples of heteroatom-containing functional groups include ether, hydroxy, epoxy, carbonyl, carboxamide, carboxylic acid ester, carboxylic acid, imine, imide, amine, sulfone, sulfonamide, phosphone, and silane groups. The heteroatom(s) may also be present as part of a ring, such as heteroaryl and heteroarylene groups.

[0137] As used herein, the term "alkenyl" refers to an ethylenically mono-, di-, or polyunsaturated alkyl or cycloalkyl group as defined above, preferably C 2~20 Alkenyl (e.g., C 2~10 Or C 2~6 Examples of alkenyl include vinyl, allyl, 1-methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl, cyclopentenyl, 1-methyl-cyclopentenyl, 1-hexenyl, 3-hexenyl, cyclohexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, cyclooctenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1- Examples of alkenyl groups include decenyl, 3-decenyl, 1,3-butadienyl, 1,4-pentadienyl, 1,3-cyclopentadienyl, 1,3-hexadienyl, 1,4-hexadienyl, 1,3-cyclohexadienyl, 1,4-cyclohexadienyl, 1,3-cycloheptadienyl, 1,3,5-cycloheptatrienyl, and 1,3,5,7-cyclooctatetraenyl. Alkenyl groups may be optionally substituted by one or more optional substituents as defined herein.

[0138] As used herein, the term "alkynyl" refers to a group derived from a straight-chain, branched, or cyclic hydrocarbon residue containing at least one carbon-carbon triple bond, including an ethylenically monovalent, divalent, or polyvalent unsaturated alkyl or cycloalkyl group as defined above. Unless the number of carbon atoms is specified, the term preferably refers to any one of C 2~20 Alkynyl (e.g., C 2~10 Or C 2~6 ), examples include ethynyl, 1-propynyl, 2-propynyl, and butynyl isomers, and pentynyl isomers. It may be optionally substituted by one or more optional substituents as defined in the specification.

[0139] The term "carbocyclyl" refers to a non-aromatic monocyclic, polycyclic, fused, or conjugated hydrocarbon residue, preferably C 3~20 (For example, C 3~10 Or C 3~8 ). The ring may be saturated, e.g., cycloalkyl, or may have one or more double bonds (cycloalkenyl) and / or one or more triple bonds (cycloalkynyl). Particularly preferred carbocyclyl moieties are 5-6 membered or 9-10 membered ring systems. Suitable examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctatetraenyl, indanyl, decalinyl, and indenyl. Carbocyclyl groups may be optionally substituted by one or more optional substituents as defined herein. The term "carbocyclylene" is intended to indicate the divalent form of carbocyclyl.

[0140] The term "heterocyclyl" refers to a stable 3- to 18-membered ring (radical) which consists of carbon atoms and from one to five heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur. The heterocycle can be a monocyclic or polycyclic ring system, which can include fused, bridged, or spiro ring systems, in which the nitrogen, carbon, or sulfur atoms in the heterocycle can be optionally oxidized, the nitrogen atom can be optionally quaternized, and the ring can be partially or fully saturated. Examples of such heterocycles include, but are not limited to, azepinyl, azocanyl, pyranyl, dioxanyl, dithianyl, 1,3-dioxolanyl, tetrahydrofuryl, dihydropyrrolidinyl, decahydroisoquinolyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxoazepinyl, oxazolidinyl, oxiranyl, piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydropyranyl, thiamorpholinyl, thiamorpholinyl sulfoxide, and thiamorpholinyl sulfone.

[0141] The term "heteroaryl" refers to an aromatic monocyclic or polycyclic ring system of about 5 to about 19 ring atoms, or about 5 to about 10 ring atoms, in which one or more of the atoms in the ring system is an element(s) other than carbon, such as nitrogen, oxygen, or sulfur. In the case of polycyclic ring systems, only one of the rings must be aromatic for the ring system to be defined as "heteroaryl". Certain heteroaryls contain about 5 to 6 ring atoms. The prefix aza, oxa, thia, or thio before heteroaryl, respectively, means that at least one nitrogen, oxygen, or sulfur atom is present as a ring atom. The nitrogen, carbon, or sulfur atom in a heteroaryl ring may be optionally oxidized, and the nitrogen may be optionally quaternized. Representative heteroaryls include pyridyl, 2-oxo-pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, furanyl, pyrrolyl, thiophenyl, pyrazolyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, indolyl, isoindolyl, benzofuranyl, benzothiophenyl, indolinyl, 2-oxoindolinyl, dihydrobenzofuranyl, dihydrobenzothiophenyl, indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzisoxazolyl, benzoisothiazolyl, benzotriazolyl, benzo[1,3]dioxolyl, quinolinyl, isoquinolinyl, quinazolinyl, cinnolinyl, phthalazinyl, quinoxalinyl, and the like.

[0142] The term "acyl" means C(O)-R e It indicates a group containing a moiety C=O such as The "syl" group also functions as an oxygen atom -C(O)OR in carboxylic acids, esters, amides, etc. e The preferred acyl group is R e is hydrogen, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, carbocyclyl or heterocyclyl residue. Examples of acyls include formyl, straight-chain or branched alkanoyl (e.g., C 1~20), for example, acetyl, propanoyl, butanoyl, 2-methylpropanoyl, pentanoyl, 2,2-dimethylpropanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl, octadecanoyl, nonadecanoyl, and icosanoyl; cycloalkylcarbonyl, for example, cyclopropylcarbonyl, cyclobutylcarbonyl, cyclopentylcarbonyl, and and cyclohexylcarbonyl; aroyl, for example, benzoyl, toluoyl, and naphthoyl; aralkanoyl, for example, phenylalkanoyl (e.g., phenylacetyl, phenylpropanoyl, phenylbutanoyl, phenylisobutyryl, phenylpentanoyl, and phenylhexanoyl), and naphthylalkanoyl (e.g., naphthylacetyl, naphthylpropanoyl, and naphthylbutanoyl); aralkenoyl, for example, phenylalkenoyl (e.g., phenylpropenoyl, phenylbutenoyl, , phenylmethacryloyl, phenylpentenoyl, and phenylhexenoyl), and naphthylalkenoyl (e.g., naphthylpropenoyl, naphthylbutenoyl, and naphthylpentenoyl); aryloxyalkanoyl, for example, phenoxyacetyl and phenoxypropionyl; arylthiocarbamoyl, for example, phenylthiocarbamoyl; arylglyoxyloyl, for example, phenylglyoxyloyl and naphthylglyoxyloyl; arylsulfonyl, for example, phenylsulfonyl and naphthylsulfonyl; heterocyclic alkanoyl, such as thienylacetyl, thienylpropanoyl, thienylbutanoyl, thienylpentanoyl, thienylhexanoyl, thiazolylacetyl, thiadiazolylacetyl, and tetrazolylacetyl; heterocyclic alkenoyl, such as heterocyclic propenoyl, heterocyclic butenoyl, heterocyclic pentenoyl, and heterocyclic hexenoyl; and heterocyclic glyoxyloyl, such as thiazolyglyoxyloyl and thienylglyoxyloyl. R e The residues can be optionally substituted as described herein.

[0143] The term "sulfoxide" means R f is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl; f Preferred examples of R include C 1~20 Examples include alkyl, phenyl, and benzyl.

[0144] The term "sulfonyl" means R f is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl; f The preferred R f An example of this is C 1~20 Includes alkyl, phenyl, and benzyl.

[0145] The term “sulfonamide” refers to each R f is independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, carbocyclyl, and aralkyl; f R f The preferred R f An example of this is C 1~20 In one embodiment, at least one R f is hydrogen. In another embodiment, both R f is hydrogen.

[0146] Herein, the term "amino" is used in its broadest sense as understood in the art and has the formula NR a R b wherein R a and R b may be independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, heterocyclyl, arylalkyl, and acyl. a and R b teeth, Together with the nitrogen to which they are attached, they may form a monocyclic or polycyclic ring system, for example a 3-10 membered ring, particularly 5-6 and 9 membered ring systems. Examples of "amino" include NH, NHalkyl (e.g., C 1~20 alkyl), NHaryl (e.g., NHphenyl), NHaralkyl (e.g., NHbenzyl), NHacyl (e.g., NHC(O)C 1~20 alkyl, NHC(O)phenyl), N-alkylalkyl (each alkyl, e.g., C 1~20 may be the same or different), and 5- or 6-membered rings optionally containing one or more of the same or different heteroatoms (e.g., O, N, and S).

[0147] Herein, the term "amide" is used in its broadest sense as understood in the art and has the formula C(O)NR a R b wherein R a and R b is as defined above. Examples of amides include C(O)NH, C(O)NH alkyl (e.g., C 1~20 alkyl), C(O)NHaryl (e.g., C(O)NHphenyl), C(O)NHaralkyl (e.g., C(O)NHbenzyl), C(O)Nacyl (e.g., C(O)NHC(O)C 1~20 alkyl, C(O)NHC(O)phenyl), C(O)Nalkylalkyl (each alkyl, e.g., C 1~20 The terms "halogen" or "halo" refer to Cl, Br, I, or F.

[0148] The term written "[group A][group B]" refers to group A when linked through a divalent form of group B. For example, "[group A][alkyl]" refers to a particular group A (e.g., hydroxy, amino, etc.) when linked through a divalent alkyl, i.e., alkylene (e.g., hydroxyethyl is intended to denote HO-CH2-CH-). Thus, the term written "[group]oxy" refers to a particular group when linked through an oxygen, e.g., the terms "alkoxy" or "alkyloxy", "alkenoxy" or "alkenyloxy", "alkynoxy" or "alkynyloxy", "aryloxy", and "acyloxy" respectively refer to alkyl, alkenyl, alkynyl, aryl, and acyl groups as defined above when linked through an oxygen. Similarly, the term written "[group]thio" refers to that particular group when linked through a sulfur; for example, the terms "alkylthio", "alkenylthio", "alkynylthio", and "arylthio" respectively refer to alkyl, alkenyl, alkynyl, and aryl groups, as defined above, when linked through a sulfur.

[0149] The term "substituted" or "optionally substituted" is used to indicate that a group may have a substituent at each substitutable atom of the group (including more than one substituent on a single atom), provided that the normal valence of the designated atom is not exceeded and the identity of each substituent is independent of the others. Combinations of substituents and / or variables are permissible only if such combinations result in stable compounds. The term "stable compound" or "stable structure" refers to a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture and formulation into an efficacious pharmaceutical agent.

[0150] The term "functionalized" in reference to any moiety refers to the presence of one or more functional groups on the moiety. Various functional groups can be introduced to a moiety by one or more functionalization reactions known to those skilled in the art. Non-limiting examples of functionalization reactions include alkylation, epoxidation, sulfonation, hydrolysis, amidation, esterification, hydroxylation, dihydroxylation, amination, ammonolysis, acylation, nitration, oxidation, dehydration, elimination, hydration, dehydrogenation, hydrogenation, acetalization, halogenation, dehalogenation, Michael addition, aldol condensation, Cannizzaro reaction, Mannich reaction, Classien condensation, Suzuki coupling, and the like. In one non-limiting embodiment, the term "functionalized" in reference to any moiety refers to the presence of one or more functional groups on the moiety. It refers to the presence of one or more functional groups selected from the group consisting of alkenyl, hydroxyl, carboxyl, halogen, alkoxy, amino, imino, and combinations thereof.

[0151] The term "monomer" refers to a small molecule that is chemically bonded to one or more monomers of the same or different type during polymerization to form a polymer.

[0152] The term "polymer" refers to a large molecule that contains one or more types of monomeric residues (repeating units) connected by covalent chemical bonds. By this definition, polymers encompass compounds that can range in number of monomeric units from very few (which may be more commonly called oligomers) to very many. Non-limiting examples of polymers include homopolymers, copolymers, terpolymers, tetrapolymers, and higher analogs. Polymers can have random, block, and / or alternating architectures.

[0153] The term "homopolymer" refers to a polymer composed of a single monomer type.

[0154] The term "copolymer" refers to a polymer that contains at least two different monomer types.

[0155] The term "terpolymer" refers to a copolymer containing three different monomer types.

[0156] The term "branched" refers to any non-linear polymer structure. The term includes both branched and hyperbranched structures.

[0157] The term "block copolymer" refers to a polymer that includes at least two blocks of polymerized monomers. Any block can be derived from either a single monomer resulting in a homopolymeric subunit, or from two or more monomers resulting in a copolymeric (or non-homopolymeric) subunit within the block copolymer. Block copolymers can be diblock copolymers (i.e., polymers containing two blocks of monomers), triblock copolymers (i.e., polymers containing three blocks of monomers), multiblock copolymers (i.e., polymers containing more than three blocks of monomers), and combinations thereof. Block copolymers can be linear, branched, star-shaped, or comb-shaped and can have structures such as [A][B], [A][B][A], [A][B][C], [A][B][A][B], [A][B][C][B], etc. Exemplary representations of block copolymers are [A]x[B]y or [A]x[B]y[C]z, where x, y, and z are the degree of polymerization (DP) of the corresponding blocks [A], [B], and [C]. Further insight into the chemistry, properties, and applications of block copolymers can be found in the book 'Block Copolymers: Synthetic Strategies, Physical Properties, and Applications', by Nikos Hadjichristidis, Stergios Pispas, and George Floudas, John Wiley and Sons (2003), the contents of which are incorporated herein by reference in their entirety.

[0158] The terms "reversible deactivation radical polymerization" (RDRP), "controlled radical polymerization" or "controlled / living radical polymerization" refer to a specific radical polymerization process, also denoted by the term "living radical polymerization", in which a control agent is used so that the polymer chains that are formed are functionalized with end groups that can be reactivated in the form of free radicals by reversible transcription or termination, thus allowing, for example, the synthesis of block copolymers.

[0159] The term "addition-fragmentation" refers to a two-step chain transfer mechanism during polymerization in which radical addition is followed by fragmentation to generate new radical species.

[0160] The term "residue of at least one crosslinker" refers to one or more crosslinking moieties that become part of the polymer backbone after polymerization. The residues can be monovalent, divalent, or multivalent.

[0161] The term "radical addition polymerization initiator" refers to a compound used in catalytic amounts to initiate radical addition polymerization. The choice of initiator depends primarily on its solubility and its decomposition temperature.

[0162] The term "alkyl acrylate" refers to an alkyl ester of acrylic acid or alkylacrylic acid.

[0163] The term "alkylacrylamide" refers to the alkyl amides of acrylic acid or alkylacrylic acid.

[0164] The term "moiety" refers to a portion or functional group of a molecule.

[0165] The term "pharmaceutical composition" refers to any composition containing at least one pharma- ceutically active ingredient, as well as any product that results directly or indirectly from the combination, complexation, or aggregation of any two or more ingredients, or from the dissociation of one or more ingredients, or from any other type of reaction or interaction of one or more ingredients.

[0166] The term "coating composition" refers to an aqueous or solvent-based liquid composition that can be applied to a substrate and then solidified (e.g., by radiation, air curing, post-crosslinking, or ambient temperature drying) to form a cured coating on the substrate.

[0167] As used herein, the term "degree of polymerization" (DP) generally refers to the average number average degree of polymerization, as would be readily understood by one of ordinary skill in the art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0168] Those skilled in the art will understand that the present invention includes the embodiments and features disclosed herein, and all combinations and / or permutations of the disclosed embodiments and features. EXAMPLES

[0169] The present invention will now be described with reference to the following examples, which are to be considered in all respects as illustrative and not limiting.

[0170] material Acrylic acid ("AA", 99%, Sigma-Aldrich), poly(ethylene glycol) methyl ether acrylate ("PEGA", with an average of 9 ethylene glycol units, M n =480gmol -1 , Sigma-Aldrich), 4,4'-azobis-(4-cyanopentanoic acid) ("ACPA", 98%, Aesar), sodium bicarbonate ("NaHCO3", Sigma-Aldrich), 1,3,5-trioxane (99%, Sigma-Aldrich), diethyl ether (100%, Chem Supply), ethanol (EtOH, 100%, Chem Supply), tetrahydrofuran ("THF", 100%, RCL Labscan), poly(ethylene glycol) diacrylate ("PEGDA", with an average of 3 ethylene glycol units, M n =250gmol -1, Sigma-Aldrich), and ethylene glycol di Acrylates ("EGDA", 90%, Sigma-Aldrich) were used as received. Inhibitors in styrene ("S", 99%, Sigma-Aldrich), n-butyl acylate ("nBA", 99%, Sigma-Aldrich), methyl methacrylate ("MMA", 99%, Sigma-Aldrich), benzyl methacrylate ("BzMA", 99%, Sigma-Aldrich), and 2-ethylhexyl methacrylate ("EHMA", 99%, Sigma-Aldrich) were removed by passage through an aluminum oxide column prior to use. Azobis(isobutyronitrile) ("AIBN", Sigma-Aldrich) in acetone was precipitated in water. Water was deionized (milli-Q water) prior to use. The RAFT agents 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid ("DDMAT") and 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid ("CPADB") were synthesized according to the literature.

[0171] Two-step synthesis of P(AA-stat-PEGA)-bP(S-stat-nBA) amphiphilic block copolymers The experiments are labeled Ax, Bx, Cx, Dx, Ex, and Fx (x is the experiment number). Item Ax is the RAFT aqueous emulsion polymerization of styrene and nBA carried out at different pH. Item Bx is the RAFT aqueous emulsion polymerization of styrene and nBA with different molar ratios [hydrophobic monomer]:[macroRAFT] carried out at pH 5 (Scheme 1). Item Cx, Dx, Ex, and Fx refer to the synthesis of crosslinked P(AA-stat-PEGA)-bP(S-stat-nBA) nanofibers (Scheme 2).

[0172] Synthesis of P(AA-stat-PEGA)-DDMAT macro RAFT agent The macro RAFT agent was prepared by solution copolymerization of AA (0.8882 g, 12.3 mmol) and PEGA (5.9164 g, 12.3 mmol) (molar ratio = 50 / 50) in the presence of DDMAT RAFT agent (0.2 g, 0.55 mmol) (monomer / RAFT agent molar ratio = 44), ACPA (0.0154 g, 0.055 mmol) and EtOH (5.0309 g) as solvent. 1 1,3,5-trioxane (0.1650 g, 1.8 mmol) was added to the polymerization mixture as an internal standard for H NMR analysis. The solution was mixed in a 25 mL glass vial at ambient temperature for 10 min, followed by purging with nitrogen for 30 min in an ice bath. The polymerization was carried out at 70° C. in an oil bath with a stirring speed of 500 rpm for 3 h. The final total conversion of AA and PEGA was 1 The purity was 95% as determined by H NMR. The resulting final polymerization mixture was added dropwise to 35 mL of diethyl ether in a 50 mL centrifuge tube and centrifuged at 7000 rpm for 5 minutes. After centrifugation, the product was precipitated in diethyl ether and the supernatant was discarded. It was then refilled with 35 mL of fresh diethyl ether and mixed thoroughly before centrifugation. This process was repeated three times. The purified sample was dried overnight in a vacuum oven at 50 °C.

[0173] RAFT aqueous emulsion polymerization of styrene and nBA ([styrene]0 / [nBA]0=70 / 30) (items Ax and Bx) P(AA-stat-PEGA)-bP(S-stat-nBA) amphiphilic block copolymers were prepared by RAFT-mediated aqueous emulsion polymerization of styrene and nBA ([styrene]0 / [nBA]0=70 / 30). In this example, ACPA, NaHCO3, P(AA-stat-PEGA)-DDMAT, and milli-Q water were added to a 25 mL glass vial. The solution was mixed using a sonication bath for 10 minutes. To observe the effect of pH, different amounts of 1 M NaOH were added in items Ax. For A-1, the pH of the solution was not adjusted (0 μL of 1 M NaOH). For A-2 and A-3, 1 M NaOH solution was added to adjust the pH (A For A-2, 290 μL of 1M NaOH was added, and for A-3, 930 μL was added). To the solution, styrene and nBA ([hydrophobic monomer]0 / [macroRAFT]0=200) were added after pH adjustment. The effect of DP on the hydrophobic block was investigated in section Bx. The pH of the solution was adjusted to pH 5 by adding 290 μL of 1M NaOH. After adjusting the pH, styrene and nBA with different [hydrophobic monomer]0 / [macroRAFT]0 were added to the solution. The polymerization was carried out at 80° C. in an oil bath with a stirring speed of 350 rpm for 6 h (section Ax) and 4 h (section Bx). The polymerization mixture was subsequently quenched by placing the flask in an ice bath. The conversion of styrene and nBA was determined by gravimetric analysis. All experiments are summarized in Table 1 (section Ax) and Table 2 (section Bx).

[0174] Theoretical number average molecular weight (M n,th ) is expressed by the formula (1):

number

[0175] Synthesis of crosslinked P(AA-stat-PEGA)-bP(S-stat-nBA) nanofibers ([styrene]0 / [nBA]0=70 / 30) (items Cx, Dx, Ex, and Fx) Crosslinked P(AA-stat-PEGA)-bP(S-stat-nBA) nanofibers were prepared by the crosslinker EGDA (170.16 gmol -1 ) or PEGDA(M n =250gmol -1 ) as a crosslinker. Two different approaches were used. The first was to introduce EGDA before the RAFT aqueous emulsion polymerization of styrene and nBA, and the second was to introduce EGDA after 2 h of polymerization (conversion >90%). The ratio [hydrophobic monomer]0 / [macroRAFT]0 was fixed at 100. After polymerization, 120 μL of latex was added to 1 mL of THF (volume ratio ≈ 10 / 90) to observe whether the polymer particles were soluble in THF. Insolubility indicates that crosslinking has been achieved.

[0176] Synthesis of crosslinked P(AA-stat-PEGA)-bP(S-stat-nBA) nanofibers ([styrene]0 / [nBA]0=20 / 80) (items Gx and Hx) The synthesis was carried out for RAFT aqueous emulsion polymerization of styrene and nBA as above, except that the molar ratio of styrene to nBA was 20 / 80 ([styrene]0 / [nBA]0=20 / 80), and the nanoparticles were crosslinked by adding 5 mol% EGDA (relative to the macroRAFT agent) after 2 hours of polymerization. The pH of the solution was adjusted to pH 5 by adding 290 μL of 1 M NaOH for item Gx (Table SI-1), and 290 μL, 580 μL, and 870 μL of 1 M NaOH for H-1, H-2, and H-3 (Table SI-2). After adjusting the pH for item Gx, styrene and nBA with different [hydrophobic monomer]0 / [macroRAFT]0 were added to the solution. Styrene and nBA with different solids content at a fixed ([hydrophobic monomer]0 / [macroRAFT]0=130) were carried out for item Hx. The conversion of styrene and nBA was determined by gravimetric analysis. n,th was determined by formula (SI-1). All experiments are summarized in Table SI-1 (item Gx) and Table SI-2 (item Hx).

[0177] gravimetric analysis The total conversion of styrene and nBA was determined by gravimetric analysis. The latex was sampled at different time intervals to observe the progress of monomer conversion over time. 950 μL of latex was weighed into a pre-weighed aluminum pan and dried overnight in a vacuum oven at 50 °C.

[0178] nuclear magnetic resonance (NMR) The final total conversion of AA and PEGA at t=3 hours was determined using a Bruker Avance III 300 MHz NMR with 1,3,5-trioxane as an internal standard. 1 Determined by H NMR spectroscopy. Samples were prepared by dissolving 50 μL of the reaction mixture (t=0 h and t=3 h) in 600 μL of deuterated dimethylsulfoxide (d6-DMSO).

[0179] Gel Permeation Chromatography (GPC) Number average (M n) and weighted average (M w The molecular weight and dispersity (D) of the olefins were determined by gel permeation chromatography (GPC) using a Shimadzu modular system equipped with a SIL-10AD autoinjector, LC-10AT pump, DGU-12A degasser, CTO-10A column oven, and RID-10A refractive index detector. A Polymer Laboratories 5.0 μm bead size guard column (50 × 7.8 mm) was used, followed by four linear PL columns (300 × 7.8 mm, 500, 10 3 , 10 4 , and 10 5 A column configuration consisting of N,N-dimethylacetamide (DMAc, 0.03% w / v LiBr, 0.05% w / v 2,6-dibutyl-4-methylphenol (BHT)) was used for the analysis at 50 °C and 1 mL min. -1 The SEC system was used with a mobile phase of 500 to 10 6 gmol -1 The chromatograms were processed using Cirrus2.0 software (Polymer Laboratories). The samples were methylated to modify the carboxylic acid groups in the acrylic acid and reduce their interaction with the column. The dried latex (10 mg) was added to 1 mL of milli-Q water in a 25 mL glass vial and HCl was added to adjust the pH to 3-4. Then, 20 mL of THF was added to the mixture. Trimethylsilyldiazomethane methylating agent was added dropwise to the vial. The mixture was stirred at room temperature for 4 h. After methylation, the solution was dried overnight at ambient temperature in an aluminum pan. It was further dried at 35 °C using a high vacuum oven for 1 h to remove the water. The sample was dissolved in DMAc and filtered using a syringe filter (0.45 μm) before injection into the GPC system.

[0180] Transmission electron microscope (TEM) TEM samples were prepared by dropping 10 μL of diluted latex (10 μL latex in 1 mL milli-Q water) onto glow-discharged formvar-coated copper grids, which were allowed to dry at ambient temperature. The grids were glow-discharged to modify the grid surface from hydrophobic to hydrophilic to avoid accumulation of block copolymer nanoparticles around the grid. TEM images were obtained using a JEOL1400 transmission electron microscope under an accelerating voltage of 100 kV.

[0181] Effect of pH PISA was synthesized using the macro RAFT agent P(AA-stat-PEGA)-TTC (hydrophilic block; M n = 13,400 g / mol; D = 1.20) and ACPA as initiators, at 80 °C as an aqueous emulsion polymerization (Scheme 1). In this example, the macro RAFT agent was prepared by solution polymerization in EtOH at 70 °C (Scheme 1, Figure 1). 9;M n = 13,400 g / mol; D = 1.20). A weight ratio of 65.5:34.5 in RAFT aqueous emulsion polymerization (item Ax) (theoretical T of 27.1 °C for full conversion based on the Fox equation) g Copolymerization of styrene and nBA at pH 7.0 (corresponding to pH 7.0) was carried out at three different pHs (3.5, 5, and 7) to determine the most suitable pH for the formation of nanofibers. The target degree of polymerization (DP) was fixed at [hydrophobic monomer]0 / [macroRAFT]0 = 200 (Table 1).

[0182] [ka] Scheme 1. RAFT aqueous emulsion polymerization of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macro-RAFT agent. For all three pH values, the total monomer conversion after 6 h reached over 90%, with the highest conversion being reached at pH 3.5 (Table 1, Figure 1). Without wishing to be bound by theory, it is believed that the self-assembly behavior itself may be influenced by pH.

[0183] At pH 3.5, the molecular weight distribution (MWD) shifted toward higher molecular weights with low dispersity (D = 1.18), indicating good control / living properties (Table 1, Figure 2). However, at pH 5 (Figure 2.A-2) and pH 7 (Figure 2.A-3), a significant low molecular weight shoulder was present, consistent with residual unreacted macro-RAFT agent.

[0184] TEM images show that only spherical morphology was obtained at pH 3.5 (Figure 3.A-1) and pH 7 (Figure 3.A-3), with particle diameters of about 50 nm and 120 nm, respectively. However, a mixture of nanofibers and vesicles was obtained at pH 5 (Figure 3.A-2). It is possible that at pH 3.5, due to the protonation of the AA units of the macroRAFT, this block did not drive the reorganization into higher-order morphology because the segments became hydrophobic enough to be buried within the particle. Furthermore, the absence of charges on the macroRAFT agent could lead to a reduction in the strength of separation between the macroRAFT agent (hydrophilic block) and the core-forming block (hydrophobic block). The formation of spherical micelles without higher-order morphology has also been previously reported for the copolymerization of styrene and MMA using poly(methacrylic acid-stat-poly(ethylene oxide) methyl ether methacrylate) at pH 3.5. At pH 5, partial ionization of the hydrophilic block could lead to the ionization of the AA units buried within the particle. It is believed that the hydrophobic block length was long enough to minimize the occurrence of α-hydroxybutyric acid moieties, thus resulting in the transformation into nanofibers / vesicles. Without wishing to be bound by theory, the spherical morphology obtained at pH 7 could possibly be rationalized by the negative charges generated by the deprotonation of AA, which prevents the reorganization of the spheres into higher order morphologies due to electrostatic repulsion. [Table 1]

[0185] Effect of DP of hydrophobic block Subsequently, polymerizations were carried out at various [hydrophobic monomer]0 / [macroRAFT]0 at a fixed macroRAFT agent concentration (item Bx, Table 2) and pH 5 with the aim of obtaining pure nanofibers as opposed to mixed forms (Figure 3.A-2). The target DP was varied from 50 to 200 and the solids content was consequently increased from 10 wt% to 17.5 wt%. The color of the final dispersion changed from yellow to white as the amount of hydrophobic monomer was increased. Experiment M n The value is M n,th with D = 1.54–1.93 (Table 2). A low molecular weight shoulder in the MWD was present in all cases demonstrating the presence of unreacted macro-RAFT for the reasons discussed above (Figure 4).

[0186] TEM imaging revealed that the morphology changed from spheres (Figure 5.B-1) to nanofibers (Figures 5.B-2 and B-3) and finally to vesicles (Figures 5.B-4, B-5, and B-6) with the expected increase in target DP. Without wishing to be bound by theory, this is believed to occur due to an increase in the packing parameter (P) due to the increase in the length of the core-forming blocks. The viscosity of the latex increased as nanofibers were obtained. All latexes remained stable without coagulation and sedimentation. Nanofibers were observed over a wide range of DP from 100 to 200, but the parameter window corresponding to relatively pure nanofibers was narrow. In most cases, nanofibers were present along with a small amount of spheres (Figure 5.B-2) or vesicles (Figures 5.B-3 to B-6). The amount of vesicles increased as the DP increased from 130 to 200. Relatively pure nanofibers were obtained at DP=100 (Figure 5.B-2) and 130 (Figure 5.B-3).

[0187] A narrower MWD was achieved with a reduced target DP, when spheres (Fig. 5B-1, D = 1.54) or relatively pure nanofibers (Fig. 5B-2, D = 1.56) (Table 2 and Fig. 4) were obtained. Higher dispersity was obtained for a mixture of nanofibers and vesicles (Figs. 5B-3 to 5B-6). ), resulting in a broader MWD. ​​Previous reports have reported similar results for the homopolymerization of styrene in the presence of hydrophilic macro-RAFT agents in RAFT aqueous emulsion polymerizations. [Table 2]

[0188] Synthesis of crosslinked nanofibers ([styrene]0 / [nBA]0=70 / 30) Polymer nanofibers prepared by PISA can be crosslinked using various approaches. In one example, the present invention utilized the divinyl crosslinkers EGDA and PEGDA to crosslink the core cross-section of nanofibers (Scheme 2). Two simple in situ crosslinking methods were investigated: (i) addition of crosslinker at the beginning of emulsion polymerization (items Cx and Dx), and (ii) addition of crosslinker after 2 hours of polymerization (conversion > 90%) (items Ex and Fx). Depending on the crosslinking method, different crosslinking structures can be expected. The entire core-forming block is crosslinked based on method (i), while the core-forming block is only partially crosslinked using method (ii) (only the part of the block that forms at the highest conversion range, i.e., the segment of the chain closest to the RAFT end group).

[0189] [ka] Scheme 2. Schematic of the crosslinking step of the RAFT aqueous emulsion polymerization of styrene and nBA in the presence of P(AA-stat-PEGA)-TTC macroRAFT agent using EGDA or PEGDA as crosslinkers ([hydrophobic monomer]0 / [macroRAFT]0=100, pH 5). The basic conditions without crosslinker correspond to TEM image B-2 (Figure 5), which produced relatively pure nanofibers in the absence of crosslinker ([hydrophobic monomer]0 / [macroRAFT]0=100). When added at the beginning of the polymerization (method (i)), EGDA and PEGDA (items Cx and Dx) interfered with the PISA process and influenced the final morphology. In the case of PEGDA, thinner (Figure 6; C-2) and shorter (Figure 6; C-3) nanofibers were obtained with 1 or 2.5 mol% PEGDA. In the case of EGDA (item Dx), relatively pure nanofibers (Figure 6; D-1 and D-2) were obtained with 0.5 or 1 mol% EGDA, while spherical micelles were obtained when 10 mol% EGDA was introduced (Figure 6; D-3). Without wishing to be bound by theory, it is believed that crosslinking influences the final morphology.

[0190] When added 2 hours after polymerization (method (ii)), EGDA and PEGDA (items Ex and Fx) had relatively less effect on the final morphology than in method (i), except for 10 mol% EGDA. Again, nearly pure nanofibers were obtained without crosslinker (Figure 6.B-2). In the case of PEGDA, nanofibers and small amounts of vesicles were obtained for 1 and 10 mol% PEGDA (Figure 6; E-2 and E-3). Relatively pure nanofibers were obtained for 3 and 5 mol% EGDA (Figure 6; F-1 and F-2). However, 10 mol% EGDA led to the formation of vesicles (Figure 6; F-3). Crosslinked nanofibers / vesicles can be obtained by introducing the crosslinker at the beginning of the polymerization (method (i)) and delaying the introduction of the crosslinker once the desired morphology has been formed (method (ii)).

[0191] Crosslinking was confirmed by mixing the nanoparticle latexes with THF. THF is a good solvent for linear diblock copolymers, i.e., a clear solution indicates minimal (if any) crosslinking, while a cloudy solution is consistent with significant crosslinking. Nearly pure nanofibers were obtained when 3 and 5 mol% EGDA were introduced at t = 2 h (method (ii)) (Figure 6; F-1 and F-2). Addition of THF to these latexes resulted in a cloudy solution (Figure 7; (d)), confirming successful crosslinking. Crosslinking was successful in all cases for both EGDA and PEGDA, as cloudy solutions (Figure 7; (a) and (b)) were observed in all cases when added at t = 0 h (method (i)). When added at t=2 h (method (ii)), crosslinking was successful with EGDA (Figure 7; (d)), while PEGDA did not result in significant crosslinking, as evidenced by the clear solution upon addition of THF (Figure 7; (c)).

[0192] EGDA and PEGDA were prepared by dissolving the final dispersion in THF (Figure 7). As determined by the experimental setup, the crosslinking behavior was different. Crosslinking was successful with EGDA when added at t=0 or t=2 hours (methods (i) and (ii)), whereas PEGDA only resulted in successful crosslinking when added at t=0 hours (method (i)). Without wishing to be bound by theory, a possible explanation could be the difference in hydrophobicity between these crosslinkers. The crosslinker is initially present as droplets in the continuous phase and, as the polymerization proceeds, gradually diffuses into the polymer particles following an emulsion polymerization mechanism. Due to the higher hydrophilicity (higher water solubility) of PEGDA, excessive partitioning into the aqueous phase could limit the degree of crosslinking.

[0193] Overall, it can be concluded that 1 mol% EGDA added at t=0 h by using method (i) or 3 and 5 mol% EGDA added at t=2 h by using method (ii) are the best methods to achieve crosslinked nanofibers.

[0194] Synthesis of crosslinked nanofibers ([styrene]0 / [nBA]0=20 / 80) T of core-forming blocks below 0 °C g Based on the methods of Schemes 1 and 2, polymer nanoparticles having a weight ratio of 16.9:83.1 (theoretical T of −37.6 °C for complete conversion based on the Fox equation) were prepared. g The copolymerization of styrene and nBA at 1000 rpm (corresponding to T value) was achieved by introducing 5 mol% EGDA (method (ii)) after 2 h of polymerization (conversion >90%). g Nevertheless, structural stability was achieved by cross-linking, thereby allowing TEM imaging without the need for cryo-TEM.

[0195] First, polymerizations were performed by varying [hydrophobic monomer]0 / [macroRAFT]0 at a fixed macroRAFT agent concentration ([macroRAFT]0 = 6.2 mmol / L) at pH 5 to target nanofibers (item Gx, Table SI-1). The target DP was varied from 80 to 300, and the solids content increased from 12.2% to 23.5%. In all cases, monomer conversion was greater than 90% (Table SI-2). The morphology changed with increasing target DP from spheres (Figure 10; G-1, G-2, and G-3) to nanofibers (Figure 10; G-4), and finally to vesicles (Figure 10; G-8, and G-9). Nanofibers were observed over a range of target DPs from 130 to 180 (Figure 10). In most cases, nanofibers were present along with vesicles, and the amount of vesicles increased with increasing DP (Figure 10; G-5, G-6, G-7, G-8, and G-9). Nanofibers with a small amount of spheres and vesicles were obtained at DP = 130 (Figure 10; G-4). The final dispersion was stable without settling or coagulation, and the viscosity increased with increasing amount of nanofibers, as expected. Dissolving the final dispersion (item Gx) in THF gave a cloudy solution in all cases indicating successful crosslinking.

[0196] When the solid content was 15.2% ([macroRAFT]0 = 6.2 mmol / L), nanofibers with spheres and vesicles were obtained at DP = 130 (Figure 10; G-4) as described above. The solid content was then further increased to 24.7% ([macroRAFT]0 = 11.5 mmol / L) and 32.7% ([macroRAFT]0 = 17.7 mmol / L) and the target DP was fixed at 130 (item Hx, Table SI-2). The monomer conversion was above 90% in all cases (Table SI-2) and the obtained latex was stable. When the solid content was 24.7%, almost pure nanofibers were formed (Figure 8.H-2), whereas at 32.7%, a large amount of spheres with almost no nanofibers were obtained (Figure 8.H-3). A turbid solution was obtained in THF (item Hx), indicating successful crosslinking.

[0197] conclusion As demonstrated herein, PISA, practiced as aqueous RAFT emulsion polymerization, has been shown to provide low T g Nona Macro-RAFT agents have been utilized to synthesize nano-sized polymer fibers. However, it will be understood that different types of macro-RAFT agents can be used as alternatives. As shown above, two types of nanofibers were prepared using core-forming blocks consisting of different molar ratios of S:nBA, i.e., 70:30 and 20:80, corresponding to theoretical glass transition temperatures of 27.1° C. (S:nBA=70:30) and −37.6° C. (S:nBA=20:80). In the preferred embodiment that produced high yields of nanofibers, the pH was 5. In addition, the preferred embodiment utilized cross-linking of the core block using the divinyl monomers poly(ethylene glycol) diacrylate (PEGDA) and ethylene glycol diacrylate (EGDA), respectively, introduced either at the beginning of the PISA process or at the end of the growth of the core-forming block. The nature of the cross-linking agent and the time of addition can affect the morphology of the nanofibers. In the preferred embodiment, addition of the cross-linking agent at the beginning or later in the polymerization successfully cross-linked while maintaining the morphology of the nanofibers.

[0198] Supplementary Information [Table 3]

[0199] Theoretical number average molecular weight (M n,th ) was determined by equation (SI-1).

number

[0200] Example SI-1. In this example, block copolymers containing hydrophobic monomers were prepared by dispersion polymerization. Previous studies have shown that PISA can be carried out in non-polar solvents such as dodecane and mineral oil using hydrophobic monomers. However, such non-polar solvents usually have high boiling points and are difficult to remove. Herein, the preparation of hydrophobic block copolymers in a mixture of water and alcohol is described. In a preferred embodiment, the hydrophobic monomer is substantially insoluble in water and / or substantially soluble in an 80 / 20 vol.% ethanol / water mixture.

[0201] Synthesis of PMMA-CPADB macro RAFT agent The macro RAFT agent was prepared by solution polymerization of MMA (6.0926 g; 60.8 mmol) in the presence of CPADB RAFT agent (0.2 g; 0.72 mmol; monomer / RAFT agent molar ratio=85), AIBN (0.0117 g; 0.07 mmol; CPADB / AIBN molar ratio=10.0) using toluene (6.0 g) as solvent. The solution was mixed in a 25 mL glass vial at ambient temperature for 10 min, followed by purging with nitrogen in an ice bath for 30 min. The polymerization was carried out in an oil bath at 70° C. with a stirring speed of 500 rpm for 20 h. The final conversion of MMA was 1The purity was 78%, as determined by H NMR. The final polymerization mixture was added dropwise to 35 mL of diethyl ether in a 50 mL centrifuge tube and centrifuged at 7000 rpm for 5 minutes. After centrifugation, the precipitated product was collected and the supernatant was discarded. After precipitation, the product was redissolved in toluene and then added dropwise to 35 mL of fresh diethyl ether and mixed thoroughly before centrifugation. This process was repeated three times. The purified sample was dried overnight in a vacuum oven at 50° C. THF GPC analysis using a refractive index detector and poly(methyl methacrylate) standards revealed 8,200 gmol -1 M n and 1.17 M w / M n was shown.

[0202] RAFT dispersion polymerization of EHMA and MMA ([EHMA]0 / [MMA]0=90 / 10) PMMA-bP (EHMA-stat-MMA) block copolymers were prepared by RAFT-mediated dispersion polymerization of EHMA and MMA ([EHMA]0 / [MMA]0=90 / 10) in EtOH and milli-Q water mixture (EtOH / water=80 / 20 v / v). PMMA-bP (EHMA) with a target degree of polymerization (DP) of 100 at 10% w / w solids was obtained. The following example of PMMA-CPADB (0.2624 g; 0.04 mmol), 1,3,5-trioxane (0.0477 g; 0.53 mmol), EtOH (6.3120 g), and milli-Q water (2.0 g) were weighed into a 25 mL glass vial. The 1,3,5-trioxane was dissolved in water at 20° C. for 1 hour. 1 H was added as an internal standard for determining monomer conversion by H NMR. The solution was stirred in a preheated oil bath at 70° C. for 10 min. EHMA (0.6299 g; 3.18 mmol), MMA (0.0353 g; 0.35 mmol), and AIBN (0.0029 g; 0.02 mmol; macroRAFT / AIBN=2.0) were then added to the solution, followed by purging with nitrogen in an ice bath for 30 min. The polymerization was carried out in an oil bath at 70° C. with a stirring speed of 300 rpm for 21 h.

[0203] RAFT dispersion polymerization of BzMA PMMA-b-PBzMA block copolymer was prepared by dispersion polymerization of BzMA in the presence of PMMA-CPADB macro RAFT agent and AIBN in an EtOH / water mixture. In this example, BzMA (0.4603 g, 2.6 mmol), PMMA-CPADB macro RAFT agent (0.4650 g, 0.065 mmol), AIBN (5.4 mg, 0.033 mmol), and 10 ml of EtOH / water mixture (80 / 20 by volume) were mixed in a 25 ml glass vial to give a [BzMA]:[RAFT]:[AIBN] molar ratio of 40:1:0.5. The mixture was purged with nitrogen gas in an ice bath for 30 min and then placed in a 70 °C oil bath with magnetic stirring. After 18 h, the polymerization was stopped by removing from the oil and opening to air. Monomer conversion was determined by the addition of 1000 g of PBzMA in d6-DMSO. 1 It was determined to be about 98% via 1 H NMR. The as-synthesized block copolymer was analyzed by TEM / SEM.

[0204] Polymer nanofibers containing hydrophobic corona and core were synthesized via dispersion polymerization of hydrophobic monomers in EtOH and water mixtures. The block polymers self-assembled into nanofibers and the morphology were confirmed by TEM / SEM (Figure 12). [ka] Scheme SI-1. RAFT dispersion polymerization of hydrophobic monomer(s) in the presence of PMMA macro RAFT agent

[0205] Although the present invention has been described with reference to specific examples, it will be understood by those skilled in the art that the present invention may be embodied in many other forms, and in particular that a particular feature of any one of the various described examples may be provided in any combination of any of the other described examples. Various modifications and alterations to the present invention will become apparent to those skilled in the art without departing from the scope and spirit of the present invention. It should be understood that the present invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein, and that such examples and embodiments are presented only as examples with respect to the scope of the present invention, which is intended to be limited only by the claims set forth herein below.

Claims

1. 1. A polymer nanofiber having a core-shell morphology, wherein the shell comprises a hydrophilic homopolymer or copolymer, and the core comprises: a) a hydrophobic copolymer having a Tg of less than about 65°C, or b) a hydrophobic homopolymer having a Tg of less than 16°C.

2. a block [A] containing a hydrophilic homopolymer or copolymer; a) a hydrophobic copolymer having a Tg of less than about 65°C, or b) a block [B] comprising a hydrophobic homopolymer having a Tg of less than 16°C; optionally a cross-linking agent, Amphiphilic block copolymers when self-assembled into nanofibers.

3. 10. A method for producing the amphiphilic block copolymer of claim 2, said method comprising: a) reacting at least one hydrophilic monomer using RDRP to form a hydrophilic block [A]; b) adding a hydrophobic block [B] comprising at least one hydrophobic monomer to the hydrophilic block [A] using RDRP; c) optionally adding a cross-linking agent in step b).

4. The method of claim 3 further comprising the step of self-assembling the block copolymer into the nanofiber of claim 1.

5. 4. The method of claim 3, wherein the polymerization is carried out as RAFT, ATRP, or NMP.

6. 6. The polymeric nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3 to 5, wherein the hydrophilic homopolymer or copolymer is prepared from one or more of poly(ethylene glycol) methyl ether acrylate (PEGA), poly(ethylene glycol) methyl ether methacrylate (PEGMA), and acrylic acid.

7. The hydrophobic homopolymer or copolymer is one or more of styrene, n-butyl acrylate, methyl acrylate, and methyl methacrylate, preferably styrene, The polymer nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3 to 5, prepared from n-butyl acrylate (nBA) and tert-butyl acrylate (tBA).

8. 6. The polymeric nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3 to 5, wherein the hydrophobic copolymer is selected to have a Tg in the range of -70°C to 65°C.

9. 6. The polymer nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3 to 5, wherein the hydrophobic homopolymer is selected to have a Tg in the range of -70°C to 16°C.

10. The method according to any one of claims 3 to 5, wherein the cross-linking agent is ethylene glycol diacrylate (EGDA) or poly(ethylene glycol) diacrylate (PEGDA).

11. The method of any one of claims 3 to 5, wherein the crosslinking agent of step c) is introduced either at the beginning of the polymerization or at the end of the polymerization.

12. The process according to any one of claims 3 to 5, wherein the polymerization is carried out at a pH in the range of about 3 to about 8, preferably about 5.

13. The method of any one of claims 3 to 5, wherein the block copolymer has an average degree of polymerization (DP) of from about 50 to about 300.

14. 6. The polymeric nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3-5, wherein the nanofiber has a width of from about 1 nm to about 100 nm.

15. 6. The polymeric nanofiber of claim 1, the amphiphilic block copolymer of claim 2, or the method of any one of claims 3-5, wherein the nanofiber has a length of from about 5 μm to about 1000 μm.

16. Nanofibers when self-assembled from the amphiphilic block copolymer produced by the method of any one of claims 3 to 5.

17. 6. Use of the nanofibers of any one of claims 1, 2 or 4-5 for at least partially producing a film or coating.

18. 18. A method of forming the film or coating of claim 17, said method comprising: Dispersing the nanofibers of any one of claims 1, 2, or 4-5 in a solvent to form a dispersion; applying the dispersion to a surface; allowing or causing the solvent to substantially or completely evaporate; thereby forming the film.

19. a matrix or binder; and the nanofibers of any one of claims 1, 2, or 4-5 dispersed throughout the matrix or binder.

6. Use of nanofibers according to any one of claims 5.

20. 6. Use of the nanofibers of any one of claims 1, 2 or 4-5 to modify or improve the mechanical properties of a matrix or binder.

21. 1. A method of producing a composite material, said method comprising: providing a polymer dispersion; Dispersing the nanofibers of any one of claims 1, 2, or 4-5 in the polymer dispersion to form a mixture; and drying the mixture to form the composite material.

22. 10. A method for producing a composite material comprising a polymer and the nanofibers of any one of claims 1, 2, or 4-5 by melt extrusion, said method comprising: heating the polymer and the nanofibers to a temperature above the melting temperature of the polymer; mixing the polymer and the nanofibers; and extruding the mixture to form the composite material.

23. 1. Use of polymer nanofibers as viscosity or rheology modifiers, wherein the polymer nanofibers comprise a core-shell morphology, the shell being hydrophilic and the core comprising a hydrophobic homopolymer or copolymer.

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