Thermoresponsive Polyurethane Bearing Oligo(Ethylene Glycol) as Side Chain Without Polyol at Polymer Backbone Achieved Excellent Hydrophilic and Hydrophobic Switching

Abstract

In order to prepare thermoresponsive polyurethane gels, a novel polyurethane bearing oligo(ethylene glycol) (OEG) as the side chain is successfully synthesized with hexamethylene diisocyanate and OEG tartrate ester. The aqueous solution of the polyurethane shows sharp and clear lower critical solution temperature behavior at 34 °C. Furthermore, a hydrogel based on the same polyurethane is also successfully prepared using glycerol as the crosslinker. This polyurethane hydrogel including 10 mol% of glycerol presents a large swelling ratio change between 4 °C and 37 °C from 250% to 40%.

Remarkable diastereomeric effect on thermoresponsive behavior of polyurethane based on lysine and tartrate ester derivatives

“…7a and c). 21,28 On the other hand, the T cp of D-PU showed a steep decrease at low NaCl concentration and moderated as the concentration increased (Fig. 7b and d).…”

“…l -Tartaric acid and d -tartaric acid were purchased from Nacalai Tesque, Inc. Anhydrous tetrahydrofuran (THF) and anhydrous N , N -dimethylformamide (DMF) were purchased from Kanto Chemical Co., Inc. Diethyl ether and benzene were purchase from Wako Pure Chemical Industries. The chiral diol monomer, l -OEG 3 TA and d -OEG 3 TA, were synthesized following the literature procedure 21 by condensation between tartaric acid and mOEG 3 using TsOH as an acid catalyst.…”

“…In this context, we previously reported thermoresponsive polyurethane (PU) consisting of hexamethylene diisocyanate (HDI) and chiral l -tartrate ester with OEG side chains. 21 However, the long-distance diastereomeric effect did not appear because the chiral relationship between reported PUs was composed of an achiral diisocyanate and symmetric chiral l -/ d -tartrate diols.…”

Thermoresponsive Polypeptoids

“…Due to the reversible hydration and dehydration of the oligo(ethylene glycol) (OEG) moieties upon temperature change, LCST-type thermoresponsive polymers can be obtained by introducing OEG pendants to the side chain [63]. Aoshima [64] and Lutz [65] investigated a range of biocompatible and thermoresponsive polymers based on (OEG) moieties. The T cp of these copolymers could be tuned by adjusting the fraction of OEG units and molecular weight [66,67].…”

Cell Adhesion on UV‐Crosslinked Polyurethane Gels with Adjustable Mechanical Strength and Thermoresponsiveness

“…[18] Nevertheless, it should be noted that their turbidity measurements showed a rather broad (≈10 °C) and partially incomplete LCST transition in comparison to pNiPAm. This has been strongly improved through the introduction of charged comonomers, which further allowed an even more flexible variation of the LCST, as demonstrated by Sardon et al [13,20] To transfer the obtained insights from linear chains to 3D crosslinked networks, PU hydrogels have either been obtained in a crosslinking polymerization in the presence of a trifunctional comonomer [17,21,22] or through the consecutive crosslinking of linear precursor polymers with reactive side-groups. [20,23] As shown in the studies of Frydrych et al and Li et al, the absolute swelling ratio of such PU gels can be variated through the molar mass of the polyether soft segment in both cases.…”