Understanding the effect of monomer structure of oligoethylene glycol acrylate copolymers on their thermoresponsive behavior for the development of polymeric sensors

Abstract

Oligoethylene glycol acrylate polymers present an interesting class of polymers, combining biocompatibility with a thermoresponsive behavior, which can be tuned by copolymerization of the defined oligoethylene glycol acrylates, which differ in length or functionality. Within this contribution, the copolymerization kinetics of various oligoethylene glycol acrylate monomers via controlled radical polymerization techniques will be discussed, including nitroxide mediated polymerization (NMP) method and reversible addition–fragmentation chain transfer (RAFT) polymerization. Herein several novel comonomer combinations are presented, providing valuable insights in the copolymerization kinetics and structure–property relationship of the LCST-behavior. The effect of the comonomer ratios on the thermoresponsive properties will be discussed in detail using turbidimetry in aqueous solution in order to highlight the extensive range of possible temperature sensing regions and the highly predictable tuneability. Here different relationships could be identified, which were dependent on the monomer combination, whereby a relationship between hydroxyl hydration and the relative length of the given oligoethylene glycol acrylate is highlighted. Finally, these copolymers are functionalized with a polymerizable dye to highlight their potential use as polymeric thermometers with a visible output signal.