Nitroxide‐Mediated Copolymerization of 2‐Hydroxyethyl Acrylate and 2‐Hydroxypropyl Acrylate: Copolymerization Kinetics and Thermoresponsive Properties

Abstract

Poly(2-hydroxyethyl acrylate) (PHEA) is an interesting biomaterial with similar biocompatibility as the widespread used poly(2-hydroxyethyl methacrylate). Poly(2-hydroxypropyl acrylate) (PHPA) is a less frequently studied polymer that exhibits thermoresponsive behavior in water. Therefore, copolymers of HEA and HPA are interesting thermoresponsive polymers to evaluate as potential biomaterials. Here, we report the copolymerization kinetics of HEA and HPA by nitroxide-mediated polymerization, employing Blocbuilder® initiator and SG-1 free nitroxide, revealing an ideal random copolymerization. Furthermore, the thermoresponsive properties of the resulting copolymers are discussed, whereby the cloud points are related to both polymer composition as well as polymer concentration.

Amphiphilic Poly(4‐acryloylmorpholine)/Poly[2‐(N‐carbazolyl)ethyl acrylate] Random and Block Copolymers Synthesized by NMP

“…These values are very similar to those obtained by the FR46 method ( r VAK = 0.67 ± 0.34 and r 4AM = 1.19 ± 0.08) or the KT47 method ( r VAK = 0.67 ± 0.21 and r 4AM = 1.13 ± 0.53). Similar pseudo‐ideal reactivity ratios have been previously observed for 2‐hydroxyethyl acrylate/2‐hydroxypropyl acrylate random copolymerizations 13. For comparison, the corresponding fits to the various models (using the reactivity ratios) were plotted along with the experimentally obtained values (Figure 8).…”

“…Ever since the pioneering work by Georges et al and Hawker et al,3, 4 nitroxide‐mediated polymerization (NMP) has been used to synthesize a variety of polymer architectures with controlled microstructure, encompassing linear homopolymers, random copolymers, block copolymers, hyperbranched polymers, and comb polymers 5, 6. NMP's growth in the past 15 years has been accelerated by the development of initiators based on alkoxyamines such as N ‐ tert‐ butyl‐ N ‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)]nitroxide (SG1, Scheme )7, 8 and 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide (TIPNO),9 which have allowed the controlled polymerization of acrylates,10–14 acrylamides,9, 15, 16 1,3‐dienes,17 and methacrylates (with a small addition of “controlling” comonomers) 18–22. Previous to the development of such initiators, NMP was largely restricted to the controlled polymerization of styrenic monomers.…”

One‐Pot Synthesis of Multifunctional Polymers by Light‐Controlled Radical Polymerization and Enzymatic Catalysis with Candida antarctica Lipase B

“…In contrast to this, ATRP and RAFT processes in most cases need elevated temperatures to proceed and would need to be cooled down for enzymatic transacylation reactions. [12][13][14] This signifi cant difference opens up opportunities to synthesize various polymeric microstructures, such as block copolymers in an elegant manner. We chose the synthesis of a block copolymer to demonstrate that the polymers from light-controlled polymerizations can also be used as macro initiators, proving chain-end functionality.…”

Poly(meth)acrylates Obtained by Cascade Reaction

“…The nitroxide‐mediated polymerization of the new hydroxy functional acrylates was investigated using the optimized conditions: 110 °C polymerization temperature and 10 mol‐% excess SG‐1 free nitroxide relative to the Blocbuilder alkoxyamine initiator 114, 115. Since the acrylate monomers have a high propagation rate constant, excess of free nitroxide is required to reduce the polymerization rate and retain control over the polymerization.…”