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We report a green solvent-to-polymer upgrading transformation of chemicals of the lactic acid portfolio into water-soluble lower critical solution temperature (LCST)-type acrylic polymers. Aqueous Cu(0)-mediated living radical polymerization (SET-LRP) was utilized for the rapid synthesis of N-substituted lactamide-type homo and random acrylic copolymers under mild conditions. A particularly unique aspect of this work is that the water-soluble monomers and the SET-LRP initiator used to produce the corresponding polymers were synthesized from biorenewable and non-toxic solvents, namely natural ethyl lactate and BASF's Agnique (R) AMD 3L (N,N-dimethyl lactamide, DML). The pre-disproportionation of Cu(I) Br in the presence of tris[2-(dimethylamino)ethyl]amine (Me6TREN) in water generated nascent Cu(0) and Cu(II) complexes that facilitated the fast polymerization of N-tetrahydrofurfuryl lactamide and N,N-dimethyl lactamide acrylate monomers (THFLA and DMLA, respectively) up to near-quantitative conversion with excellent control over molecular weight (5000 < M-n < 83 000) and dispersity (1.05 < D < 1.16). Interestingly, poly(THFLA) showed a degree of polymerization and concentration dependent LCST behavior, which can be fine-tuned (T-cp = 12-62 degrees C) through random copolymerization with the more hydrophilic DMLA monomer. Finally, covalent cross-linking of these polymers resulted in a new family of thermo-responsive hydrogels with excellent biocompatibility and tunable swelling and LCST transition. These illustrate the versatility of these neoteric green polymers in the preparation of smart and biocompatible soft materials.

A middle-chain cleavable telechelic poly(oligoethylene glycol) methyl ether acrylate) (MCCT-POEGA-Br) was synthesized by single-electron transfer living radical polymerization (SET-LRP) initiated from an acetal-containing hydrophobic sequence-defined difunctional initiator. In aqueous medium, above a certain concentration, this hydrophilic homopolymer self-assembled into nanogel-like large micelles that exhibit an encapsulating capacity for both hydrophobic and hydrophilic cargo. The sequence-defined cleavage pattern encoded in the initiator residue allowed precise middle-chain cleavage, leading to quantitative disassembly of the corresponding nanoobjects. Dye release studies performed in an acidic environment demonstrated the potential of this new design concept in the preparation of pH-responsive nanocarriers. In addition, fluorescently tagged nanoassemblies could also be obtained via the thio-bromo "click" modification of MCCT-POEGA-Br prior to self-assembly. This strategy may provide facile access to a diversity of multistimuli-responsive nanocarriers based on commercially available hydrophilic monomers and sequence-defined difunctional initiators synthesized by this simple design strategy.

A recent communication from our laboratory demonstrated that the presence of a small hydrophobic initiator residue (core) in water-soluble telechelic dibromo homopolymers can drive their self-assem...

The design of stimuli-responsive lignin nanoparticles (LNPs) for advanced applications has hitherto been limited to the preparation of lignin-grafted polymers in which usually the lignin content is low (25 wt.%) and its role is debatable. Here, the preparation of O

We report a new strategy toward the development of block copolymer surfactants from chemicals of the lactic acid family. A particularly unique aspect of this work is the use of green solvents as biobased platform chemicals to generate well-defined and nanostructure-forming materials. Herein, efficient functionalization of ethyl lactate (EL) and N,N-dimethyl lactamide (DML) solvents with acrylate groups generated monomers that could be polymerized by the photoinduced copper-catalyzed living radical polymerization process to yield polymeric materials with different water solubilities. These lactic acid-derived monomers were used as a major component in well-defined diblock copolymers composed of poly(EL acrylate) and poly(DML acrylate) segments as hydrophobic and hydrophilic building blocks, respectively. The resulting amphiphilic copolymers could self-assemble in aqueous solution to form nanoparticles with different morphologies (e.g., large-compound micelles and vesicles). Subsequently, the formed amphiphilic polymers were employed as efficient stabilizers in the emulsion polymerization of methyl methacrylate and styrene, offering a facile method for the synthesis of well-defined and stable polymer latexes in the range of 100-200 nm, demonstrating the practical significance of these biobased polymers in nanomaterial synthesis.

Single-electron transfer-living radical polymerization (SET-LRP) in “programmed” aqueous organic biphasic systems eliminates the judicious choice of solvent and also provides accelerated reaction rates. Herein, we report efforts to expand the monomer scope for these systems by targeting methacrylic monomers and polymers. Various environmentally friendly aqueous alcoholic mixtures were used in combination with Cu(0) wire catalyst, tris(2-dimethylaminoethyl)amine (Me6-TREN) ligand, and p-toluenesulfonyl chloride (Ts-Cl) initiator to deliver well-defined polymethacrylates from methyl methacrylate, butyl methacrylate, and other monomers derived from biomass feedstock (e.g., lactic acid, isosorbide, furfural, and lauric acid). The effect of water on the nature of the reaction mixture during the SET-LRP process, reaction rate, and control of the polymerization is discussed. The control retained under the reported conditions is demonstrated by synthesizing polymers of different targeted molar mass as well as qua...

We report the synthesis and solution properties of novel biobased thermoresponsive amphiphilic copolymers prepared using N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA) as hydrophilic and hydrophobic monomers, respectively. Copolymers with similar overall molecular weight but different monomer distribution profiles, such as random, diblock, triblock, and random-blocks, were prepared using photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization activated by a Zn-based photoredox catalyst. The synthesized polymers show interesting self-assembly and thermoresponsive behavior in water, depending on the monomers distribution along the chain. Different critical solution temperatures, in the range of 13-70 °C, were observed by tuning the monomers molar ratio and distribution. The formation of aggregates of various types was proven by transmission electron microscopy (TEM). The prepared polymers also display different surface activity with the fully random copolymer being significantly more surface active than block systems. A study of emulsion stabilization was performed with oils of various polarity, showing promising results for applications of these novel polymers as biobased surfactants and water/oil (w/o) emulsion stabilizers.

13 pags., 8 figs., 1 tab., 1 sch., Well-defined hydrophilic telechelic dibromo poly(triethylene glycol monomethyl ether acrylate)s were prepared by single-electron transfer living radical polymerization employing a hydrophobic difunctional initiator containing acetal and disulfide linkages. Although the resulting homopolymers have low hydrophobic contents (, Spanish Ministerio de Ciencia, Innovacion y Universidades through project MAT2017-82669-R (to G.L. and J.C.R) and FPI grant BES-2015-072662 (to A.M.) and the Serra Hunter Programme of the Government of Catalonia (to G.L.) are acknowledged for supporting and funding this work. Miguel Servet Program from Instituto de Salud Carlos III (CPII13/ 00017 to O.A.); Fondo de Investigaciones Sanitarias from Instituto de Salud Carlos III; European Union (ERDF/ESF, ‘Investing in your future’) (PI18/00343 to O.A.); Diputacioń General de Aragon (Predoctoral Research Contract 2019 to A.J- ́ A., ‘Digestive Pathology Group’ B25_20R to O.A.); and Centro de Investigacion Biomedica en Red en Enfermedades Hepaticas ́ y Digestivas (CIBERehd). V.P. gratefully acknowledges the support from the National Science Foundation Grants DMR1066116 and DMR-1807127 and the P. Roy Vagelos Chair at the University of Pennsylvania.

Biological macromolecules such as proteins and nucleic acids are monodisperse just as low-molar-mass organic compounds are. However, synthetic macromolecules contain mixtures of different chain lengths, the most uniform being generated by living polymerizations, which exhibit a maximum of 1–3% of chains with the desired length. Monodisperse natural and synthetic oligomers can be obtained in low quantities by tedious, multistep iterative methods. Here we report a methodology to synthesize monodisperse synthetic macromolecules by self-interrupted living polymerization. This methodology relies on a concept that combines supramolecular and macromolecular chemistry and differs from the conventional reactivity principles employed in the synthesis of polymers for over 100 years.

Branched polyesters with acid degradable and oxidation responsive β-thiopropionate groups have been obtained by lipase catalyzed polycondensation of diester and hydroxyester monomers from heptanal, a castor oil derivative. Their polymerization behavior has been investigated and poly(ethylene glycol)-b-poly(β-thioether ester) amphiphilic block copolymers have been obtained. SEC, NMR and FTIR have been employed to confirm the structure of the polymers and copolymers and DSC and TGA have been used to characterize their thermal properties. The block copolymers containing aliphatic pendant moieties self-assemble into micelles in aqueous solution, showing potential application as dual responsive systems in drug delivery.

To expand the range of hydrolytically degradable functional polymers, copolyacetals of various compositions were synthesized and fully characterized, and their self-assembly into nanoparticles was studied. First, functionalized copolyacetals were obtained by polyaddition of alkyne- and activated ester-functionalized diols with 1,4-butanediol divinyl ether (DVE). Second, the copolymers were functionalized by using two orthogonal chemical reactions, the thiol–yne click reaction and transesterification/amidation. Amphiphilic copolymers of varying compositions, i.e. different hydrophilic/hydrophobic balance, were obtained and self-assembled in water to afford well-defined nanostructures. The size of the micelles and the critical micelle concentration were correlated to the chemical nature and to the modification degree of the copolymers. The micelles displayed high drug loading capacity and encapsulation efficiency and could be disassembled in mildly acidic media showing a pH-dependent drug release behavior. Subsequent orthogonal modification to introduce folic acid moieties allowed the preparation of site-specific drug delivery systems, showing the versatility of this approach.

The synthesis of a partially renewable hydroxyl hyperbranched polyester: poly(10,11-dihydroxyundecanoic acid) (PDHU), by polycondensation using CALB as catalyst, has been described. The synthesized polymers were structurally characterized in detail, using model compounds previously synthesized, by 1H, 13C and 19F NMR. The synthesis of amphiphilic copolymers by incorporation of mPEG moieties and utilizing CALB, was carried using two methods: by copolymerization of mPEG-OH and 10,11-dihydroxyundecanoic to produce block hyperbranched copolymers, and grafting onto hydroxyl groups of linear and hyperbranched PDHU, mPEG containing carboxylic acid. The microstructure of block and grafted copolymers was determined in detail by NMR spectroscopy by using models and 1H-13C heteronuclear bidimensional correlations. The self-assembly of these amphiphilic polyesters form well-defined multimolecular micelles ranging 100–300 nm in very diluted aqueous solutions, showing potential application in drug delivery among other applications.

Synthetic protocols to prepare new diols were developed to revalorize heptanal and 10-undecenoic acid castor oil derivatives. The Acetal Metathesis Polymerization of these diols yielded linear and branched renewable polyacetals and copolyacetals with number average molecular weights in the range 14,000–27,000 g mol−1. Thermally robust semicrystalline or amorphous materials were obtained. Polyacetals were hydrolytically degradable down to parent diols under slightly acidic media and no significant differences on the degradation pattern were observed among them.

The fluorinated alcohol 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is an especially effective solvent for solubilizing a wide range of polymers. However, the performance of HFIP as SET-LRP solvent has classically been questioned due to its poor Cu(I)X disproportionating properties. Taking advantage of the fast and quantitative disproportionation of Cu(I)X in water, SET-LRP in organic solvent/water mixtures rids the organic solvent of mediating this fundamental event. Here, the Cu(0) wire-catalyzed SET-LRP synthesis of well-defined poly(methyl acrylate)s and poly(butyl acrylate)s with narrow molecular weight distribution and near perfect bromine chain end functionality is reported in HFIP/water mixtures. The results reported here support the potential of HFIP/water mixtures in the preparation of more complex architectures including polymers with dual control over molecular weight and tacticity. Since HFIP is also a classic solvent for the denaturation of proteins this SET-LRP system is also expected to find applications in the grafting of protein.

The hydrolytic and enzymatic degradations of aliphatic polyesters: poly (10,11-epoxyundecanoic acid) (PEAU) bearing hydroxyl groups along the main chain and poly (11-hydroxyundecanoate)diol (PHU), were studied and compared to that of commercial poly (e-caprolactone)diol (PCL). Changes taking place after polyester degradation in sample weight, molecular weight (Mn), chemical constitution, thermal properties, crystallinity and morphology were monitored by size exclusion chromatography (SEC), 1H nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-Ray diffraction (XRD) and environmental scanning electron and atomic force microscopies (ESEM and AFM). A significant decrease of PEUA Mn in both hydrolytic and enzymatic degradation was detected versus PHU and PCL, and related to its hydrophilic character, by the presence of hydroxyl pendant groups, and the superior amorphous character. An accelerated degradation in acidic media, monitored by SEC and 1H NMR spectroscopy to study in detail all residual material of three polyesters, showed the complete degradation only in the case of PEUA and PCL.

A simple synthetic route is used for the preparation of hydroxyl functionalized polyesters from an AB-type monomer carrying an epoxy and carboxylic acid group. A systematic study of the reaction conditions suggested that tetrabutylphosphonium bromide was the better polymerization catalyst to obtain the highest conversion of linear polymers with moderate molecular weights. Enzymatic catalyst (CALB), in contrast, yielded branched polymers with polyether units. The synthesized polymers were structurally characterized in detail, using model compounds previously synthesized, by 1H, 13C, and 19F NMR. Polyesters were characterized by FTIR, SEC, DSC and TGA too. The post-polymerization modification of the reactive hydroxyl sites present along the polymer backbone with N-Boc protected l -phenylalanine and l -serine was essayed to test the ability of these polyesters to prepare polymer bioconjugates.

Cu(0) wire-catalyzed single electron transfer–living radical polymerization (SET-LRP) of (−)-menthyl acrylate, a biobased hydrophobic monomer, was investigated at 25 °C in ethanol, isopropanol, ethyl lactate, 2,2,2-trifluoroethanol (TFE), and 2,2,3,3-tetrafluoropropanol (TFP). All solvents are known to promote, in the presence of N ligands, the mechanistically required self-regulated disproportionation of Cu(I)Br into Cu(0) and Cu(II)Br2. Both fluorinated alcohols brought out their characteristics of universal SET-LRP solvents and showed the proper polarity balance to mediate an efficient polymerization of this bulky and hydrophobic monomer. Together with the secondary alkyl halide initiator, methyl 2-bromopropionate (MBP), and the tris(2-dimethylaminoethyl)amine (Me6-TREN) ligand, TFE and TPF mediated an efficient SET-LRP of MnA at room temperature that proceeds through a self-generated biphasic system. The results presented here demonstrate that Cu(0) wire-catalyzed SET-LRP can be used to target polyMnA...

Block copolymers containing poly(trimethylene carbonate) (PTMC) middle block and poly(furfuryl methacrylate) PFMA end blocks were synthesized through sequential organocatalytic ring opening polymerization (ROP) of trimethylene carbonate and thermal and photoinitiated metal-free atom transfer radical polymerizations (ATRP) of furfuryl methacrylate. The thermal and mechanical properties of the triblock copolymers were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamical mechanical analysis (DMA). The crosslinking via Diels-Alder (DA) reaction between the furan groups of the block copolymers and bismaleimide and bisitaconimide was proved by FTIR and DSC and the thermoreversibility properties of the crosslinked polymer were subsequently investigated using DSC and solubility testing.

Single electron transfer-living radical polymerization (SET-LRP) provides excellent control over polymer chain-end functionality. The chain ends of poly(butyl acrylate) (PBA), prepared by biphasic SET-LRP in an acetone/water mixture using a non-activated Cu(0) wire/TREN/Cu(II)X2 catalytic system, could not be reacted quantitatively using a biphasic reaction mixture of potassium acrylate (KA) in acetonitrile at 75 °C. This procedure was previously successfully applied to poly(methyl acrylate). The PBA chain ends showed lower reactivity due to their higher hydrophobicity and sterically hindered nature. However, the chain extension of α-bromo and α,ω-dibromo PBA with a few monomeric units of MA dramatically changed the reactivity of PBA. Thus, acrylate-functionalized macromonomers and telechelics based on PBA could be successfully prepared by merging biphasic SET-LRP, chain extension with MA and heterogeneous esterification with KA in acetonitrile at 75 °C. This three step methodology, that can be simplified by carrying out two or even three steps in one pot, is expected to become a general route for the preparation of acrylate-functionalized polyacrylates derived from monomers with hydrophobic and sterically hindered substituents.

Depending on the order of addition to the reaction mixture during biphasic SET-LRP performed in acetone/water mixtures, acetone can serve as a solvent or as a reagent brominated by CuBr2 to provide the electrophilic bromoacetone initiator as well as aldol condensation products.

The high bromine chain end functionality of polyacrylates synthesized by single electron transfer living radical polymerization (SET-LRP) mediated by TREN in a biphasic acetone–water mixture containing Cu(II)Br2 can be exploited to introduce specific functional groups to the chain-ends of these polymers. Here, the α-bromoester end groups of poly(methyl acrylate) (PMA) synthesized in this biphasic SET-LRP system using non-activated Cu(0) wire as catalyst were reacted also under heterogeneous biphasic conditions with potassium acrylate to yield PMA macromonomers and telechelics with α- and α,ω-acrylate chain ends. The reagents used in both steps are air insensitive and inexpensive. 500 MHz 1H NMR, GPC and MALDI-TOF analyses in combination with the thio-bromo “click” reaction were used to confirm the high efficiency of this two-step protocol. The reactive nature of these macromonomers by the preparation of a PMA-g-PMA more complex architecture was also demonstrated.

Biphasic-binary mixtures of 2,2,2-trifluoroethanol (TFE) or 2,2,3,3-tetrafluoropropanol (TFP) with water were used as reaction media to synthesize well-defined poly(methyl acrylate) (PMA) with chain end functionality close to 100% by SET-LRP. Non-activated Cu(0) wire was used as a catalyst, taking advantage of the Cu(0)-activation property that these fluorinated alcohols possess. Biphasic-binary mixtures of water, containing a ligand and Cu(II)Br2 either generated by disproportionation of Cu(I)Br or externally added, and an organic solvent, containing a monomer and a polymer, were studied. Two N-ligands were investigated: the classic tris(2-dimethylaminoethyl)amine (Me6-TREN) and tris(2-aminoethyl)amine (TREN), as a more economically attractive alternative for technological purposes. The results reported here support the replacement of Me6-TREN by TREN, taking into account the fact that the latter requires small loadings of an externally added Cu(II)Br2 deactivator and a ligand in the water phase to mediate a living radical polymerization process. Both catalytic systems ensure efficient SET-LRP processes with first order kinetics to high conversion, linear dependence of experimental Mn on conversion, narrow molecular weight distribution, and near-quantitative chain end functionality.

Depending on the order of their addition to the reaction mixture, acrylates can undergo SET-LRP or dibromination by Cu(II)Br2 and spontaneously dehydrohalogenate to provide the corresponding highly reactive α-bromoacrylate monomer and Michael acceptor.

The most fundamental aspects of single-electron transfer (SET) principles are presented. They are discussed according to different definitions used by expert practitioners and are applied to SET living radical polymerization (SET-LRP) according to the definition of the division of organic chemistry of IUPAC that relies on principles elaborated by Taube, Eberson, Chanon, and Kochi. Additional definitions are also discussed to help clarify for the nonexpert contradictory literature reports. Subsequently, the principles and evolution of SET-LRP together with the methodologies currently available to practice it are discussed. It is expected that this Perspective will be able to help experts and nonexperts practice, develop, and invent new concepts and methodologies for SET-LRP to advance its status and the status of other living radical polymerization methods to the level of the most precise living polymerization methods.

Intensive research has recently been carried out to synthesize non-isocyanate polyurethanes (NIPUs) from five-membered cyclic carbonates and amines as a sustainable route to industrial relevant polyurethanes. Herein, an activated disubstituted cyclic carbonate and methyl ester containing monomer CE was prepared using castor oil based heptanal and CO 2 . Good results for the catalytic cycloaddition have been obtained using renewable sugar cane bagasse in combination with TBAB, and this system has been shown to be recyclable. A novel poly(amide-hydroxyurethane) ( PAHU ) was obtained by bulk ring-opening and amidation polymerization of high reactive CE with 1,6-diaminohexane at low temperature and in absence of catalyst. PAHU contains aliphatic pendant moieties allowing its self-assembling into nanoparticles in aqueous solution, showing potential application in catalysis or drug delivery among other applications.

A mixed-ligand effect was observed for mixtures of tris(2-dimethylaminoethyl)amine (Me

Lactic acid is one of the key biobased chemical building blocks, given its readily availability from sugars through fermentation and facile conversion into a range of important chemical intermediates and polymers. Herein, well-defined rubbery polymers derived from butyl lactate solvent were successfully prepared by reversible addition&ndash, fragmentation chain transfer (RAFT) polymerization of the corresponding monomeric acrylic derivative. Good control over molecular weight and molecular weight distribution was achieved in bulk using either monofunctional or bifunctional trithiocarbonate-type chain transfer agents. Subsequently, poly(butyl lactate acrylate), with a relative low Tg (&minus, 20 &deg, C), good thermal stability (5% wt. loss at 340 &deg, C) and low toxicity was evaluated as a sustainable middle block in all-acrylic ABA copolymers using isosorbide and vanillin-derived glassy polyacrylates as representative end blocks. Thermal, morphological and mechanical properties of copolymers containing hard segment contents of &lt, 20 wt% were evaluated to demonstrate the suitability of rubbery poly(alkyl lactate) building blocks for developing functional sustainable materials. Noteworthy, 180&deg, peel adhesion measurements showed that the synthesized biosourced all-acrylic ABA copolymers possess competitive performance when compared with commercial pressure-sensitive tapes.

The mixed-ligand system consisting of tris(2-aminoethyl)amine (TREN) and tris(2-dimethylaminoethyl)amine (Me

The precise synthesis of polymers derived from alkyl lactate ester acrylates is reported for the first time. Kinetic experiments were conducted to demonstrate that Cu(0) wire-catalyzed single electron transfer-living radical polymerization (SET-LRP) in alcohols at 25 °C provides a green methodology for the LRP of this forgotten class of biobased monomers. The acrylic derivative of ethyl lactate (EL) solvent and homologous structures with methyl and n-butyl ester were polymerized with excellent control over molecular weight, molecular weight distribution, and chain-end functionality. Kinetics plots in conventional alcohols such as ethanol and methanol were first order in the monomer, with molecular weight increasing linearly with conversion. However, aqueous EL mixtures were found to be more suitable than pure EL to mediate the SET-LRP process. The near-quantitative monomer conversion and high bromine chain-end functionality, demonstrated by matrix-assisted laser desorption ionization time-of-flight analysis, further allowed the preparation of innovative biobased block copolymers containing rubbery poly(ethyl lactate acrylate) poly(ELA) sequences. For instance, the poly(ELA)- b-poly(glycerol acrylate) block copolymer self-assembled in water to form stable micelles with chiral lactic acid-derived block-forming micellar core as confirmed by the pyrene-probe-based fluorescence technique. Dynamic light scattering and transmission electron microscopy measurements revealed the nanosize spherical morphology for these biobased aggregates.

A set of (poly-α-methylene-γ-butyrolactone)–co-(poly-δ-decalactone)–co-(poly-α-methylene-γ-butyrolactone) (PMBL-co-PDL-co-PMBL) ABA block copolymers containing different stimuli cleavable groups at the central point of the poly(δ-decalactone) (PDL) block were synthesized by a combination of Ring Opening Transesterification Polymerization (ROTEP) of DL, diol end-group functionalization as α-bromoester and Atom Transfer Radical Polymerization (ATRP) of α -methylene-γ-butyrolactone (MBL). Diols containing acetal, spiroacetal, thioacetal and disulphide units were used as initiators for the bulk room temperature controlled polymerization of δ-decalactone (DL) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. PDL diols were functionalized in a one-pot two-steps procedure using N-(2-bromoisobutyryl)imidazole (BiB-Im). The resulting macroinitiators were chain extended by atom transfer radical polymerization (ATRP) in DMF at 50 °C using MBL as methacrylic-like monomer and the conventional CuCl/CuCl2/2,2′-bipyridine catalyst system. The cleavage behaviour of the copolymers under reductive, acidic and photooxidative conditions has been studied and the resulting AB block copolymers structurally characterized.

The recently developed “programmed” water/organic solvent biphasic reaction medium is the most efficient approach to expand the advantages of SET-LRP to next generation solvents and to enhance the performance of the current solvents employed in this polymerization methodology. This system has been successfully applied to families of solvents not accessible so far by SET-LRP such as polar and nonpolar non-disproportionation solvents. Here we report a series of screening experiments on biphasic mixtures of water with linear diethyl and dimethyl carbonates, cyclic propylene and ethylene carbonates, the cyclic ethers THF and dioxane, and with dipolar aprotic solvents. Two general methodologies were applied in the catalytic process: the accelerated “multicomponent” Cu(0) generated by the in situ reduction of Cu(II)Br2 with NaBH4 and the “single component” Cu(0) wire. All carbonates and ethers provide linear kinetic SET-LRP experiments when solvent/water = 8/2, v/v were used while under the same conditions dipolar aprotic solvents increased their apparent rate constant of polymerization up to about 3.5 times from the values obtained in the absence of water. These remarkable results demonstrate the power of the biphasic water/organic solvent mixture to the elaboration of new solvent systems for SET-LRP.

Tris(2-aminoethyl)amine (TREN) has been used as a replacement for tris(dimethylaminoethyl)amine (Me6-TREN) in the non-activated Cu(0) wire catalyzed SET-LRP of methyl and n-butyl acrylates performed in biphasic-binary mixtures containing an aqueous solution of Cu(II)Br2 and a ligand with water miscible or water immiscible organic solvents containing a monomer and a polymer. Dipolar aprotic solvents (DMF, DMSO, NMP, DMAc and sulfolane), cyclic carbonates (ethylene carbonate and propylene carbonate), cyclic ethers (THF and dioxane), alcohols (methanol, ethanol, and isopropanol), acetone, acetonitrile and 2-butanone were used as water soluble solvents while hexane, anisole, toluene and ethyl acetate were used as water insoluble solvents. The chain end functionality of the resulting polymers is close to 100%. All reagents used in this process including the ligand, the Cu(0) wire catalyst, the solvent and Cu(II)Br2 are air insensitive, and can be recycled and reused. In addition, since TREN is 80 times less expensive than Me6-TREN and some of these solvents are the least expensive commercial solvents available, we expect that this methodology, which most probably is the most economical and efficient metal-catalyzed living radical polymerization, can be transplanted to a continuous process of interest for technological applications.

Polyurethanes and polyureas from renewable castor oil-derived 10-undecenoic acid were synthesized using the AB-type self-condensation approach. ω-Hydroxy- or ω-amino methyl carbamate ester precursor monomers were prepared under mild conditions from cysteamine methyl carbamate by thiol-ene addition. Synthesis of cysteamine carbamate and the self-condensable monomers derived of 10-undecenol or 10-undecenylamine was studied by using different synthetic conditions. Two different polymers, a polyurethane and a polyurea, were prepared using conventional catalysts thus following a non-isocyanate route. The proposed synthetic approach constitutes a general route that allows for the easy preparation of methyl carbamate monomers not only from renewable (limonene, myrcene, geraniol, etc.), but also from petroleum-derived unsaturated substrates.

A series of monofunctional benzoxazine monomers with terminal unsaturated alkyl chains was synthesized from fatty acid-derived renewable compounds: 10-undecenoic acid, 4-pentenoic acid and 10-undecen-1-ol. The monofunctional monomers were dimerized by self-metathesis under mild conditions. Different metathesis catalysts and conditions were tested to obtain the desired dimers in good yields and purity that were characterized by 1H, 13C NMR and ESI-TOF. The structure, properties affecting processing ability and thermal polymerization behavior of the resulting α,ω-bis-benzoxazines were studied. The properties of the obtained flexible materials were evaluated by DSC, TGA, DMTA and contact angle measurements.

Biological macromolecules such as nucleic acids and proteins are homochiral, display monodisperse chain length with mega, multimillion, molecular weight and encode functions by their precise sequence via self-organization. The functions of biological macromolecules are either independent on molecular weight or, like in the case of ribosome, are programmed by the self-organization of their mega molecular weight. In spite of the fact that Staudinger coined the name macromolecule 100 years ago, self-organizable synthetic covalent and supramolecular mega macromolecules exhibiting the symptoms of biological macromolecules started to emerge only recently. This personal perspective will discuss, with examples mostly from our laboratory, methodologies for the synthesis of self-organizable covalent and supramolecular mega macromolecules for which functions are encoded, programmed and perfected via homochiral, sequence-defined and monodisperse components. Methodologies to generate them together with historical developments will be briefly discussed.

The synthesis of oxidation-responsive biodegradable amphiphilic block copolymers by Candida Antarctica Lipase B (CALB)-catalyzed self-polycondensation of 11-((2-hydroxyethyl)-thio)undecanoic acid (TEHA) initiated by methoxy polyethyleneglycol (mPEG-OH) of different molecular weights has been described. SEC and mono and bidimensional NMR have been used to confirm the molecular weight and structure of the polymers and copolymers. DSC and TGA have been employed to characterize their thermal properties. The oxidation behaviour in front of H2O2 as well as the structure of the oxidized products has been established using NMR, FTIR and Raman spectroscopies. The different block copolymers could self-assemble to form nanosized micelles in aqueous solution with low critical micelle concentration (CMC), showing potential application as dual responsive systems in drug delivery. Micellar characteristics were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). These micelles are prone to undergo a H2O2-triggered disassembly due to the oxidizable thioether groups in the hydrophobic core. Nile Red was used as model for hydrophobic drugs to test the oxidative triggered release of a copolymer, which showed progressive release in few hours upon the addition of H2O2.

A series of novel aliphatic copolyesters bearing vinylsulfide and ketone functional groups were synthesized via lipase catalyzed polycondensation of vegetable oil derivatives. The vinylsulfide-containing hydroxyacid (VSHA) from 10-undecenoic fatty acid and the ketone-containing hydroxyester (KHE) from methyl oleate were used to obtain random copolymers and further sequential and single-step strategies involving the reactions with thiol and oxyamine were investigated. Good agreement between product and feed stoichiometries was achieved in both reactions for sequential modification, and the order of addition seems not to be a significant parameter. One pot functionalization allows for the single step modification, but not quantitative reactions were achieved.

This work reports a series of versatile post-polymerization modifications of an aliphatic functional polyester obtained by enzymatic polycondensation of dimethyl 2,9-dibromosebacate and 1,10-decanediol, both derived from castor oil. The alkyl halide functionality has shown to react with thiols, amines and carboxylic acids under mild conditions obtaining high modification degrees. Moreover, functionalization using NIPAAm-COOH terminated polymer has been carried out.

A series of monofunctional benzoxazine monomers with terminal unsaturated alkyl chains were synthesized from two renewable platform chemicals: 10-undecenoic and 4-pentenoic acids. The monofunctional monomers were dimerized under mild conditions by hydrosilylation using two difunctional silanes. Different hydrosilylation conditions and catalysts were tested in order to produce the desired dimmers in good yields and high purity. The structure, properties affecting processing ability and thermal polymerization behavior of the resulting α,ω- bis -benzoxazines were studied. The properties of the resulting flexible materials were evaluated by DSC, TGA, DMTA and CA.

A novel biobased α,ω-diene bearing a thermally curable benzoxazine group is synthesized and polymerized via acyclic diene metathesis (ADMET) using Hoveyda–Grubbs second generation catalyst. The benzoxazine-containing diene monomer was designed based on 10-undecenoic acid, a castor oil derived platform chemical. The Mn and crosslinker content can be modulated by using a monofunctional comonomer to end-cap polymer chains. Differential scanning calorimetry was used to demonstrate that obtained thermoplastic prepolymers are able to yield thermosets after thermally activated ring opening polymerization just simply by heating up to around 200 °C. Thermal and mechanical properties of the cured polybenzoxazines are also discussed.

The synthesis and characterization of fully biobased ABA triblock copolyesters from PLA and castor oil derivatives are described. The synthetic strategy uses a dihydroxy telechelic polyester as a macroinitiator for the ring opening polymerization of l -lactide. This macroinitiator was obtained from a sulfur-containing hydroxyacid derivative of 10-undecenoic acid, which undergoes self-polycondensation with low amounts of biobased 1,4-butanediol, enables the obtention of two prepolymers of different weight. Two series of triblock copolyesters with different percentage of PLA contents were prepared and the resulting thioether-bearing copolyester oxidized to polysulfones. Both series of copolyesters showed improved thermal stability, decrease of crystallinity and a similar hydrophilicity with respect to the PLA homopolymer.

Ethyl lactate (EtLa), a green and safe agrochemical solvent, is gifted with some properties that make it a good candidate for SET-LRP. It dissolves CuBr2, mediates an efficient disproportionation of CuBr in the presence of tris(2-(dimethylamino)ethyl)amine (Me6-TREN), and is capable to dissolve both aqueous (polar) and hydrocarbon (nonpolar) soluble monomers and polymers. Here, we report that EtLa is an excellent solvent for the Cu(0) wire-catalyzed SET-LRP to produce both hydrophilic and hydrophobic polyacrylates that exhibit precise chain end functionality. These results will expand the table of SET-LRP solvents with a new green member of biological origin that is also biodegradable and, therefore, are expected to contribute to continue expanding the use of SET-LRP in the field of biomacromolecules, bioconjugates, and other biology and medicine related disciplines.

DOI: 10.1021/acs.biomac.7b00722 URL: https://pubs-acs-org.sabidi.urv.cat/doi/abs/10.1021/acs.biomac.7b00722 Filiació URV: SI To continue expanding the use of Single Electron Transfer-Living Radical Polymerization (SET-LRP) in applications at the interface between macromolecular science, biomacromolecules, biology and medicine, it is essential to develop novel initiators that do not compromise the structural stability of synthesized polymers in biological environments. Here, we report that stable 2-bromopropionyl peptoid-type initiators such as 1,4-bis(2-bromopropionyl)piperazine and 4-(2-bromopropionyl)morpholine are an alternative that meets the standards reached by the well-known secondary and tertiary ¿-haloester-type initiators in terms of excellent control over molecular weight evolution and distribution as well as polymer chain ends. SET-LRP methodologies in organic, aqueous, and biphasic organic-aqueous media were evaluated for this purpose.

DOI: 10.1021/acs.biomac.7b00197 URL: http://pubs.acs.org/doi/abs/10.1021/acs.biomac.7b00197 Filiació URV: SI Single electron transfer-living radical polymerization (SET-LRP) represents a robust and versatile tool for the synthesis of vinyl polymers with well-defined topology and chain end functionality. The crucial step in SET-LRP is the disproportionation of the Cu(I)X generated by activation with Cu(0) wire, powder, or nascent Cu(0) generated in situ into nascent, extremely reactive Cu(0) atoms and nanoparticles and Cu(II)X2. Nascent Cu(0) activates the initiator and dormant chains via a homogeneous or heterogeneous outer-sphere single-electron transfer mechanism (SET-LRP). SET-LRP provides an ultrafast polymerization of a plethora of monomers (e.g., (meth)-acrylates, (meth)-acrylamides, styrene, and vinyl chloride) including hydrophobic and water insoluble to hydrophilic and water soluble. Some advantageous features of SET-LRP are (i) the use of Cu(0) wire or powder as readily available catalysts under mild reaction conditions, (ii) their excellent control over molecular weight evolution and distribution as well as polymer chain ends, (iii) their high functional group tolerance allowing the polymerization of commercial-grade monomers, and (iv) the limited purification required for the resulting polymers. In this Perspective, we highlight the recent advancements of SET-LRP in the synthesis of biomacromolecules and of their conjugates.

A novel and efficient strategy for the synthesis of nonisocyanate polyurethanes has been developed via thiol–ene self-photopolymerization. An aliphatic thiol–ene carbamate monomer (allyl(2-mercaptoethyl)carbamate, AMC) was synthesized by a one-step synthesis procedure, from cysteamine and allyl chloroformate. The urethane group was therefore incorporated directly into the monomer precursor, avoiding the problems associated to toxic isocyanates. AMC was successfully stabilized with the radical inhibitor pyrogallol (1% wt). In addition, the use of phenyl phosphonic acid as coadditive allowed its stabilization for lower concentrations of pyrogallol (0.1% wt). AMC was directly transformed into thermoplastic polyurethane (TPU) through thiol–ene photopolymerization by UV-irradiation at 365 nm. The obtained TPU presented semi-crystalline nature and very high thermal stability (T5% ∼325 °C). It was found that high concentrations of pyrogallol decreased the reaction rate and final conversion of photopolymerization. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3017–3025