Enhancement in Mechanical and Shape Memory Properties for Liquid Crystalline Polyurethane Strengthened by Graphene Oxide.

Yueting Li,Wei Chang,Yang Liu,Yanou Hu,Huiqin Lian,Xiuguo Cui

doi:10.3390/polym8070236

Abstract

Conventional shape memory polymers suffer the drawbacks of low thermal stability, low strength, and low shape recovery speed. In this study, main-chain liquid crystalline polyurethane (LCPU) that contains polar groups was synthesized. Graphene oxide (GO)/LCPU composite was fabricated using the solution casting method. The tensile strength of GO/LCPU was 1.78 times that of neat LCPU. In addition, shape recovery speed was extensively improved. The average recovery rate of sample with 20 wt % GO loading was 9.2°/s, much faster than that of LCPU of 2.6°/s. The enhancement in mechanical property and shape memory behavior could be attributed to the structure of LCPU and GO, which enhanced the interfacial interactions between GO and LCPU.

Highlights

Shape-memory polymers (SMPs) are smart materials that have attracted much attention in fields ranging from the scientific to the industrial
Graphene oxide (GO) was obtained from graphite power through oxidation
The creating polar groups on the surface of graphite benefitted the dispersion of GO in solution

Summary

Introduction

Shape-memory polymers (SMPs) are smart materials that have attracted much attention in fields ranging from the scientific to the industrial. SMPs have the ability to memorize a permanent shape and to be programmed for one or many temporary shapes. They recover their original permanent shapes from temporary deformations under external stimuli of heat, light, electricity, and solution [2]. SMPs contain at least two separate phases: a crosslink phase, which determines the permanent shape, and a switching segment, which is responsible for the temporary shape [3]. Polyurethane (PU)-based SMP offers many advantages in terms of structure designable, higher shape recoverability, a wider range of shape recovery temperature, and better biocompatibility. Neat SMP materials suffer from relatively low thermal stability, strength, and stiffness, which hinders their applications as functional and structural materials [5,6]

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Results

Conclusion