Vinyl phenylboronic acid controlling co‐monomer for nitroxide mediated synthesis of thermoresponsive poly(2‐N morpholinoethyl methacrylate)

Abstract

Low concentrations of 4-vinylphenylboronic acid (VPBA) were copolymerized with 2-N-morpholinoethyl methacrylate (MEMA) by nitroxide mediated polymerization using BlocBuilder TM unimolecular initiator at 80 to 90 8C. The MEMA/VPBA copolymerizations were performed at initial feed compositions (f VPBA,0 ) of 0.05 to 0.10 VPBA, with f VPBA,0 5 0.10 using dimethylacetamide (DMAc) solvent being most effective, as seen by a linear increase in number average molecular weight, M n , versus conversion and low dispersity, -D < 1.40. The copolymers were further chain-extended with a second batch of VPBA, resulting in a block copolymer with monomodal molecular weight distribution and -D 5 1.66. For MEMA/VPBA copolymers, increases in VPBA composition and polymer solution concentration resulted in decreases in the cloud point temperature (CPT, typically varied between 27.4-37.8 8C) and CPT increased from 31.2 to 33.8 8C to about 88 8C with decreases in pH from 7 to 4. Rheological tests with small angle light scattering (SALS) confirmed CPTs measured by UV-Vis and DLS. These copolymers were targeted as models to combine possible glucose-sensing boronic acid functionality the thermoresponsiveness provided by MEMA groups. V C 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016Chem. , 54, 1560Chem. -1572

History of nitroxide mediated polymerization in Canada

“…We also used 4‐vinylphenylboronic acid (VPBA), which can be applied towards glucose sensing in combination with a thermoresponsive DMAEMA co‐monomer. [ 144 ] One particular interesting aspect concerning VBK was the very low concentration required for it to be an effective controlling co‐monomer ~1 mol%, [ 145 ] compared to ~8 mol% for styrene, and using a combination of kinetic studies and ESR studies revealed the subtle role of the reactivity ratios in increasing the probability of a terminal VBK monomer unit attached to the nitroxide. [ 146 ] Other controlling co‐monomers like 2‐vinylpyridine were successfully implemented to provide added pH‐responsiveness and tuning to the resulting copolymer LCST.…”

Lignin‐based polymers via graft copolymerization

“…Condensation reaction is a chemical reaction in which multiple reactants produce a desired product with accompanying formation of small molecules . In a recent study, boronate ester formation was used to synthesis lignin graft copolymers [Scheme (e)] . The copolymers were prepared by covalent linkage between aryl boronic acid end functionalized PCL and organosolv lignin in the presence of 1,2‐dichloroethane for 17 h at 65 °C.…”

Stimuli-responsive 4-acryloylmorpholine/4-acryloylpiperidine copolymers via nitroxide mediated polymerization

“…Traditionally, NMP was restricted to the polymerization of styrenic monomers using 2,2,6,6‐tetramethyl‐piperidine 1‐oxyl initiator (TEMPO) . NMP's recent development has been accelerated by the development of initiators based on alkoxyamines such as N ‐tert‐butyl‐ N ‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)]nitroxide (SG1) and 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide (TIPNO), which have allowed the controlled polymerization of a wider range of monomers including acrylates, acrylamides, and methacrylates (with a small addition of “controlling” comonomers) . NMP controls the radical concentration for a significant period of the polymerization, thereby minimizing irreversible termination reactions.…”

“…8 NMP's recent development has been accelerated by the development of initiators based on alkoxyamines such as N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)]nitroxide (SG1) 9 and 2,2,5-trimethyl-4-phenyl-3-azahexane-3nitroxide (TIPNO), 10 which have allowed the controlled polymerization of a wider range of monomers including acrylates, [11][12][13][14] acrylamides, [15][16][17] and methacrylates (with a small addition of "controlling" comonomers). [18][19][20][21][22][23] NMP controls the radical concentration for a significant period of the polymerization, thereby minimizing irreversible termination reactions. Consequently, chain end fidelity and narrow molecular weight distributions are the result, which superficially resemble the features of truly living polymerizations.…”