Triple-Shape Memory Polymers Based on Self-Complementary Hydrogen Bonding

Abstract

Triple shape memory polymers (TSMPs) are a growing subset of a class of smart materials known as shape memory polymers, which are capable of changing shape and stiffness in response to a stimulus. A TSMP can change shapes twice and can fix two metastable shapes in addition to its permanent shape. In this work, a novel TSMP system comprised of both permanent covalent cross-links and supramolecular hydrogen bonding cross-links has been synthesized via a one-pot method. Triple shape properties arise from the combination of the glass transition of (meth)acrylate copolymers and the dissociation of self-complementary hydrogen bonding moieties, enabling broad and independent control of both glass transition temperature (Tg) and cross-link density. Specifically, ureidopyrimidone methacrylate and a novel monomer, ureidopyrimidone acrylate, were copolymerized with various alkyl acrylates and bisphenol A ethoxylate diacrylate. Control of Tg from 0 to 60 °C is demonstrated: concentration of hydrogen bonding moieties is varied from 0 to 40 wt %; concentration of the diacrylate is varied from 0 to 30 wt %. Toughness ranges from 0.06 to 0.14 MPa and is found to peak near 20 wt % of the supramolecular cross-linker. A widely tunable class of amorphous triple-shape memory polymers has been developed and characterized through dynamic and quasi-static thermomechanical testing to gain insights into the dynamics of supramolecular networks.

Recent progress in shape memory polymer: New behavior, enabling materials, and mechanistic understanding

“…12d) [157]. When the T g does not overlap with the UPy thermal activation temperature, they found that both the amorphous phase and the supramolecular molecular switch could be used to record two independent shapes, thus achieving a triple-SME.…”

Intrinsic self-healing thermoset through covalent and hydrogen bonding interactions

“…These advantages have recently triggered the research on thermoset systems with tuneable chemical reversibility and mechanical properties (e.g. polymers containing reversible [20,26,28] and non-reversible [29][30][31] covalent interactions in combination with hydrogen bonding). However, the design of this kind of materials still faces problems in terms of lengthy, costly and cumbersome synthetic steps, thus hindering any application at industrial scale.…”

Semi-degradable poly(β-amino ester) networks with temporally controlled enhancement of mechanical properties

“…the network continues to lose mass), the network’s toughness begins to decrease as more of the PBAE departs from the system and the network transitions to a more glassy, brittle state. Comparatively, these PBAE-MMA networks have toughness similar to the initial toughness of nondegradable crosslinked acrylic polymers, 0.14 to 50 MJ/m 3 , crosslinked polyurethanes, 50.2 MJ/m 3 , swollen chitosan-PVA hydrogels, 1.76 MJ/m 3 , and PLA, 2.13 MJ/m 3 [22, 39–43]. To the authors’ knowledge, there are few comparable studies of degradable polymers that examine the toughness of degradable polymers over the degradation time course.…”