Synthesis of shape memory bio-based crosslinked polymer: Poly(arbutin)-co-poly(tosyl arbutin)-co-poly(ethylene glycol)

Abstract

Oxidative copolymerization of arbutin (Arb) with 6-O-tosyl-Arb (TArb) was performed in water media in the presence of a di-μ-hydroxo-bis[(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride (Cu[tmeda]) catalyst under oxygen to produce the corresponding copolymer PArbxPTArby (where, x and y indicate the molar ratio) with a number-average molecular weight (Mn) ranging from 4.2 to 9.3 kDa depending on the polymerization temperature and the time. This copolymer was further reacted with poly(ethylene glycol) (PEG) with amino groups at the terminals (Mn = 8.0 kDa) (PEG8.0k2NH2) in a silicone mould at 100 °C for 24 h to give the bio-based PArbxPTArbyPEGz crosslinked copolymer (z indicates the molar equivalent of the NH2 functions in the PEG to TArb units). The results of differential scanning calorimetry, wide-angle X-ray analysis and polarizing optical microscope image measurements determined that the PEG domain was homogeneously dispersed within the film. The degree of crystallization of the PEG domain was calculated to be 59%–78% and the film swelled over 2100 vol% after immersion in water for 12 h. This bio-based film showed good shape memory after being moulded at 80 °C, maintaining its shape at 20 °C and quickly recovering its original shape upon reheating.