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Synthesis And Properties Of Novel Light-Responsive Liquid Crystal Elastomers Based On α-Cyanostilbene

Posted on:2021-03-06Degree:MasterType:Thesis
Country:ChinaCandidate:L F HeFull Text:PDF
GTID:2381330614453655Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
Photo-responsive liquid crystal elastomers(LCEs)are a class of LCEs that respond to light stimuli.Because of the advantages of no contact,no pollution,and adjustable performance parameters,photo-responsive liquid crystal elastomers have become a hotspot in the research of LCEs.However,most of the photo-responsive LCEs are used azobenzene as the photo-responsive group,and there are few types of photo-responsive groups and single performance.In this dissertation,a series of novel photo-responsive liquid crystal elastomers with different crosslink density,different flexible spacer lengths and alkoxy tail chain lengths were designed and synthesized by using α-cyanostilbene as the mesogen,fluorescent light emitting and photo-responsive groups.The effects of crosslink density,flexible spacers and alkoxy tail chain length on the phase structure and photo-response behavior of LCEs were investigated in detail,and the relationship between the chemical structure and properties of liquid crystal elastomers based on α-cyanostilbene.The main research work of this paper are as follows:1.A series of liquid crystal elastomers LCE-M(x)-L(y)(M represents the cyanodistyrene component,L represents the hydrogen bond crosslinker component,x : y = 96: 4,94: 6,92: 8,90: 10,88: 12)with different crosslinking density based on α-cyanostilbene were synthesized by radical polymerization.The results showed that all LCEs samples formed smectic liquid crystal and the clearing point temperature of LCE-M(x)-L(y)gradually decreases with the increasing crosslinking density.At the same time,LCE-M(x)-L(y)also showed excellent AIEE characteristic.The results of the research on the photodeformation of LCE-M(x)-L(y)single domain oriented liquid crystal elastomers fibers showed that single domain oriented liquid crystal elastomer fibers underwent light bending deformation under UV irradiation,and the maximum bending angle and bending speed of the fibers increased with the increasing crosslinking density.Then the single domain oriented LCE-M(x)-L(y)fibers also exhibited excellent shape memory function.2.A series of liquid crystal elastomers LCE-PMm PVPC12(m represents the flexible spacer length of α-cyanostilbene,m = 2,4,6,8,10)with different flexible spacer lengths based on α-cyanostilbene were synthesized by radical polymerization.The results showed that LCE-PMm PVPC12 samples formed smectic liquid crystal,and the clearing point temperature gradually decreases with the increasing spacer length.At the same time,LCE-PMm PVPC12 also have excellent AIEE characteristic.The results of the research on the photodeformation of LCE-PMm PVPC12 single domain oriented liquid crystal elastomers fibers showed that single domain oriented liquid crystal elastomer fibers underwent light bending deformation under UV irradiation,and the maximum bending angle and bending speed increased with the increasing spacer length.Then the single-domain oriented LCE-PMm PVPC12 fibers have good shape memory function,and were expected to be applied to brakes and anti-counterfeiting materials.3.A series of liquid crystal elastomers LCE-PM10PVPCm(m represents the alkoxy tail chain length of α-cyanostilbene,m = 4,6,8,12,16)with different alkoxy tail chain lengths based on α-cyanostilbene were synthesized by radical polymerization.The results showed that LCE-PM10 PVPCm samples formed smectic liquid crystal and the clearing point temperature gradually increases with the increasing of alkoxy tail chain length.At the same time,LCE-PM10 PVPCm also have excellent AIEE characteristic.The results of the research on the photodeformation of LCE-PM10 PVPCm single domain oriented liquid crystal elastomers fibers showed that single domain oriented liquid crystal elastomer fibers underwent light bending deformation under UV irradiation,and the maximum bending angle and bending speed increased with the increasing alkoxy tail chain length.In addition,the single domain oriented LCE-PM10 PVPCm fibers also have excellent shape memory function.
Keywords/Search Tags:photoresponsive liquid crystal elastomers, α-cyanostilbene, photoinduced deformation, shape memory
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