Flexible liquid crystal polyurethane for the regulation of the interfacial, mechanical, and electrical properties of silicone rubber/conductive carbon black composites

Abstract A synthetic biphenyl flexible liquid crystal polyurethane (FLCPU) is used in a methyl vinyl silicone rubber (VMQ)/conductive carbon black (CCB) composite via two decoration methods. CCB modified with moderate amounts of FLCPU under liquid way dispersion undergoes ammonia esterification in a rubber matrix, but the coating effect of PU on CCB leads to a decrease in the mechanical properties and electrical conductivity of the material. Conversely, CCB modified with 4 wt% FLCPU via solid mixing is well distributed in VMQ because of polar interactions, such as hydrogen bonding, which enhance the mechanical properties of the composite. In addition, the volume resistivity of the composite decreases by 41.7% compared with that of pure VMQ/CCB for improved filler distribution. Furthermore, the energy consumption decreases sharply by more than 60% in the liquid‐crystal temperature transition range, assisted by the synergistic effect of the biphenyl‐conjugated π electron clouds of FLCPU, which enhance the ability to move electrons. Thus, FLCPU could be an interfacial regulator of VMQ temperature sensors or smart materials potentially. Highlights FLCPU exhibited the liquid crystallinity around 70 ~ 130°C. FLCPU improved the distribution of CCB in the VMQ matrix significantly. Ammonia esterification and polar interactions existed in the matrix. Liquid crystal phase promoted the materials' electrical conductivity obviously. FLCPU endowed the material with the feature of thermal stimulus response.