A new strategy to prepare polymer composites with versatile shape memory properties

Abstract

A new strategy to prepare multi-shape memory polymers, which utilizes the confined co-crystallization characteristics of small molecules to construct tunable switch, has been proposed. On the basis of this strategy, a novel shape memory polymer comprising paraffin molecules with different chain lengths and styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) was prepared. As paraffin molecules tend to form continuous series of solid solution over a wide range of chain lengths, deemed as co-crystallization, a broad thermal transition may be obtained through mixing paraffin molecules with distinct melting points, and for our shape memory composites, a broad transition is essential for tunable abilities. Thermal properties of the SEBS-paraffin composites have been characterized by differential scanning calorimetry, suggesting excellent confined co-crystallization characteristics, and such characteristics have been further verified by wide angle X-ray diffraction and successive self-nucleation and annealing thermal fractionation analysis. The results of a series of shape memory testing demonstrate that the composites possess versatile shape memory properties, such as temperature memory and multi-shape memory effect. Compared with the reported methods to prepare multi-shape memory polymers, this method not only simplifies the fabrication procedure from raw materials to processing, paving the way for large-scale fabrication, but also offers a controllable approach for adjusting the mechanical properties as well as tailoring the transition temperature.

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

“…Two paraffins with different T m s (32 °C and 60 °C, respectively) were incorporated into a physically crosslinked styrene-b-(ethylene-co-butylene)-b-styrene network. Within this network, the two paraffins exhibited a co-crystallization effect, yielding a broad T m and a tunable multi-SME [177].…”

Ultrafast Digital Printing toward 4D Shape Changing Materials

“…The cross-linked network and the wax provided netpoints and switching segments required for shape memory functions. [1,[27][28][29] In principle, such a material can be deformed at a high temperature upon melting of the wax and then fixed into a temporary shape when cooled to room temperature. The permanent shape can be recovered upon reheating.…”

Design of Triple-Shape Memory Polyurethane with Photo-cross-linking of Cinnamon Groups

“…Generally, TSMPs include either the multiphase polymer networks which have obvious differences between transition temperatures, 18−20 or the polymers with a wide range of temperature changes. 21,22 To date, TSMPs have been widely applied in intelligent medical devices, assembling systems, and minimally invasive surgery. 18,23 However, in the face of everincreasing complex demands on the use of intelligent medical devices, TSMPs can be used under two transition temperatures which provide more flexible application in intelligent medical devices compared to the traditional SMPs with only one particular transition temperature.…”