Shape-Memory Polymers with Adjustable High Glass Transition Temperatures

Abstract

Shape-memory polymers (SMPs) are synthesized with adjustable glass transition temperature (T g ) ranging from 299 to 322 °C, higher than those reported previously. The polyimide containing thermal stable but flexible linkages within the backbone act as reversible phase, and high molecular weight (M n ) is necessary to form physical cross-links as fixed phase of thermoplastic shape-memory polyimide. The critical M n is 21.3 kg/mol, and the relationship between M n and T g is explored. Thermoset polyimides show higher storage modulus and better shape-memory effects than thermoplastic counterparts due to covalent cross-linking, and the effective cross-link density with the influence on their physical properties is studied. The mechanism of high-temperature shape-memory effect of polyimide on the basis of chain flexibility, molecular weight, and cross-link density is proposed, which will benefit further research on high-temperature SMPs.

Shape memory properties and unusual optical behaviour of an interpenetrating network of poly(ethylene oxide) and poly(2‐hydroxyethyl methacrylate)

“…Shape memory polymers (SMPs) are a new class of smart materials which can be given a temporary shape and recover their permanent shape on demand using heat or any other external stimuli such as light, electric field etc . The advantage of SMPs over shape memory alloys are that SMPs offer higher recoverable strain and a wider range of mechanical properties .…”

Three-dimensional constitutive model for shape memory polymers using multiplicative decomposition of the deformation gradient and shape memory strains

“…Many experimental studies have been carried out to characterize the macro-and microscopic material properties of SMPs and to investigate one-way shape memory in SMPs. Various SMPs have been studied, including epoxy resin (Chen et al, 2014;Song et al, 2011), polyurethanes (Hong et al, 2007;Tobushi et al, 1996;Wang et al, 2010), polyimide (Xiao et al, 2015), commercially available SMPs (Richard and Lisa Mauck, 2008), and poly(cyclooctene) (PCO) (Liu et al, 2002). Two-way shape memory, i.e., reversible deformation behavior in response to an on-off stimulus, has also been demonstrated using one-way SMPs and bias loads (Chung et al, 2007;Hong et al, 2010;Pandini et al, 2012).…”

Tunable Triple‐Shape Memory Binary Mixtures with High Transition Temperature and Robust Mechanical Properties

“…The tremendous attention on thermal‐triggered SMPs is focused on polymers with low switching temperatures. However, high temperature SMPs, especially high temperature multiple‐SMPs with wide potential applications in some severe conditions and used as shape morphing structures, smart jet propulsion systems, deployable space structures, and high temperature sensors and actuators, have rarely been reported …”