Synthesis of well-defined PS-based Azo-liquid crystals with control of phase transitions and photo-behaviors for liquid crystal networks with photomechanical deformation
Synthesis of well-defined PS-based Azo-liquid crystals with control of phase transitions and photo-behaviors for liquid crystal networks with photomechanical deformation
复制标题
合成明确的 PS 基偶氮液晶，控制具有光机械变形的液晶网络的相变和光行为
DOI：
10.1016/j.polymer.2020.122749
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发表时间：
2020-08-26
期刊：
影响因子：
4.6
通讯作者：
Li, Yang
中科院分区：
文献类型：
--
作者：
Lei, Lan;Han, Li;Li, Yang
利用Si-H和乙烯基功能化的聚苯乙烯（ps），即聚-（4-乙烯基苯基）-二甲硅烷（PVPDMS/PS-SiH）和聚-（4-乙烯基苯基）-1-丁烯（PVSt/ ps -乙烯基），利用其良好的机械加工性和高可调性，用四种端乙烯和端硅基偶氮苯中间体（偶氮-乙烯基、偶氮- sih、偶氮-乙烯基和偶氮- sih，简称M-1、M-2、M-3和M-4）进行处理。分别)通过硅氢化反应制备了含有不同间隔剂的PS-SiC/ sisi - azo /AzoB的ps基侧链液晶聚合物（SCLCPs）。作为基于ps的SCLCPs的基本分子控制策略，探讨了间隔剂和聚合度（DP）对介形转变的协同影响。相位转变可以根据DP稍微调整，但通过调整间隔器可以显着调整。其中，亚晶形成的温度范围为PS[SiOSi]- azo （δ T = 34 ~ 49℃）< PS- [SiC]- azo （δ T = 49 ~ 60℃）< PS- [SiOSi]- azob （δ T = 154 ~ 164℃）< PS- [SiC]- azob （δ T = 162 ~ 193℃）。利用基于ps的sclcp的定量结构-性能相关性，进一步设计了用于光力学变形的基于ps的液晶网络。基于ps的lcnn具有良好的力学性能，其存储模量为120 MPa，相变可控，玻璃化温度（Tg）在室温左右。具有选择性交联的刚性PS均聚物的交联PS基lcn在拉伸后在50℃的紫外线照射下可以表现出定向弯曲，这被证明是一种光力学变形，这扩大了这些材料的适用性。
Benefiting from their good mechanical processability and high tunability, Si-H and vinyl-functionalized poly-styrenes (PSs), i.e., poly-(4-vinylphenyl)-dimethyl-silane (PVPDMS/PS-SiH) and poly-(4-vinylphenyl)-1-butene (PVSt/PS-Vinyl), produced by living anionic polymerization (LAP) were treated with four vinyl- and Si-Hterminated azobenzene mesogens (Azo-Vinyl, Azo-SiH, AzoB-Vinyl, and AzoB-SiH, referred to as M-1, M-2, M-3, and M-4, respectively) via hydrosilylation for the fabrication of PS-based side-chain liquid crystal polymers (SCLCPs) containing different spacers, i.e., PS-SiC/SiOSi-Azo/AzoB. As a strategy for basic molecular control in PS-based SCLCPs, the cooperative influences of the spacers and the degree of polymerization (DP) on the mesomorphic transitions were explored. The phase transitions could be tuned slightly based on the DP but dramatically by adjusting the spacers. For example, the temperature ranges of mesomorphic formation (AT) were in the order PS[SiOSi]-Azo (Delta T = 34-49 degrees C) < PS- [SiC]-Azo (Delta T = 49-60 degrees C) < PS- [SiOSi] -AzoB (Delta T = 154-164 degrees C) < PS- [SiC]-AzoB (Delta T = 162-193 degrees C). Taking advantage of the quantitative structure-property correlation of PS-based SCLCPs, PS-based liquid crystal networks (LCNs) were further designed for the photomechanical deformation. PS-based LCNs show good mechanical properties with a storage modulus of 120 MPa, controlled phase transitions, and glass transition temperatures (Tg) around room temperature. Crosslinked PS-based LCNs of rigid PS homopolymers with selective crosslinking can exhibit directional bending upon irradiation with UV light at 50 degrees C after stretching, and this was shown to be a photomechanical deformation, which expands the applicability of these materials.