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Meltable copolymeric elastomers based on polydimethylsiloxane with multiplets of pendant liquid-crystalline groups as physical crosslinker: A self-healing structural material with a potential for smart applications
European Polymer Journal ( IF 5.8 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.eurpolymj.2020.109962
Sabina Horodecka , Adam Strachota , Beata Mossety-Leszczak , Miroslav Šlouf , Alexander Zhigunov , Michaela Vyroubalová , Dana Kaňková , Miloš Netopilík

Abstract Elastomers with strong physical crosslinks were prepared, based on alternating polydimethylsiloxane (PDMS) spacer segments and pendant quartets of mesogenic building blocks (LC) of azobenzene type. They are structurally related to the well-studied polymers with pendant-chain LC units (light-sensitive actuators), but are generally highly different: The LC units make up only a small volume fraction in our materials and they do not generate elastic energy upon irradiation, but they act as physical crosslinkers with thermotropic properties. Our elastomers lack permanent chemical crosslinks – their structure is fully linear (with some dangling units). The aggregation of the relatively rare and spatially separated LC quartets (of small mesogen units) nevertheless proved to be an efficient crosslinking mechanism: The most attractive product displays a rubber plateau extending over 100 °C, melts near 70 °C and is soluble in organic solvents. The LC nano-aggregates were also found to be responsible for a continuous temperature region of phase transitions, e.g. two gel points observed by rheology. The physical crosslinks are reversibly disconnected by large mechanical strain at room temperature, but they undergo self-healing, also after sample disruption. The elastomers might be of interest for the development of passive smart materials (e.g. meltable rubbers for 3D-printing, or thermo-reversible visco-elastic mechanical coupling). Our study focuses on the comparison of physical properties and structure-property relationships in two systems, with long and with short PDMS spacer segments.

中文翻译:

基于聚二甲基硅氧烷的可熔融共聚弹性体,具有多个液晶侧基作为物理交联剂:一种具有智能应用潜力的自修复结构材料

摘要 基于交替的聚二甲基硅氧烷 (PDMS) 间隔链段和偶氮苯型介晶结构单元 (LC) 的悬垂四重体,制备了具有强物理交联的弹性体。它们在结构上与具有悬链 LC 单元(光敏致动器)的经过充分研究的聚合物相关,但通常有很大不同:LC 单元在我们的材料中仅占很小的体积分数,并且它们不会产生弹性能量辐射,但它们充当具有热致特性的物理交联剂。我们的弹性体缺乏永久性化学交联——它们的结构是完全线性的(带有一些悬空单元)。然而,相对稀有且空间分离的 LC 四重奏(小介晶单元)的聚集被证明是一种有效的交联机制:最吸引人的产品表现出超过 100 °C 的橡胶高原,在 70 °C 附近熔化,并且可溶于有机溶剂。还发现LC纳米聚集体负责相变的连续温度区域,例如通过流变学观察到的两个凝胶点。物理交联在室温下被大的机械应变可逆地断开,但它们也会在样品破裂后进行自我修复。弹性体可能对开发被动智能材料(例如用于 3D 打印的可熔橡胶或热可逆粘弹性机械耦合)感兴趣。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。熔点接近 70 °C,可溶于有机溶剂。还发现LC纳米聚集体负责相变的连续温度区域,例如通过流变学观察到的两个凝胶点。物理交联在室温下被大的机械应变可逆地断开,但它们也会在样品破裂后进行自我修复。弹性体可能对开发被动智能材料(例如用于 3D 打印的可熔橡胶或热可逆粘弹性机械耦合)感兴趣。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。熔点接近 70 °C,可溶于有机溶剂。还发现LC纳米聚集体负责相变的连续温度区域,例如通过流变学观察到的两个凝胶点。物理交联在室温下被大的机械应变可逆地断开,但它们也会在样品破裂后进行自我修复。弹性体可能对开发被动智能材料(例如用于 3D 打印的可熔橡胶或热可逆粘弹性机械耦合)感兴趣。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。流变学观察到的两个凝胶点。物理交联在室温下被大的机械应变可逆地断开,但它们也会在样品破裂后进行自我修复。弹性体可能对开发被动智能材料(例如用于 3D 打印的可熔橡胶或热可逆粘弹性机械耦合)感兴趣。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。流变学观察到的两个凝胶点。物理交联在室温下被大的机械应变可逆地断开,但它们也会在样品破裂后进行自我修复。弹性体可能对开发被动智能材料(例如用于 3D 打印的可熔橡胶或热可逆粘弹性机械耦合)感兴趣。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。或热可逆粘弹性机械耦合)。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。或热可逆粘弹性机械耦合)。我们的研究侧重于比较两个系统的物理特性和结构-性能关系,长和短 PDMS 间隔段。
更新日期:2020-08-01
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