Nanoscale Particle Motion in Attractive Polymer Nanocomposites

Abstract

Using x-ray photon correlation spectroscopy, we examined the slow nanoscale motion of silica nanoparticles individually dispersed in an entangled poly (ethylene oxide) melt at particle volume fractions up to 42%. The nanoparticles, therefore, serve as both fillers for the resulting attractive polymer nanocomposites and probes for the network dynamics therein. The results show that the particle relaxation closely follows the mechanical reinforcement in the nanocomposites only at the intermediate concentrations below the critical value for the chain confinement. Quite unexpectedly, the relaxation time of the particles does not further slow down at higher volume fractions-when all chains are practically on the nanoparticle interface-and decouples from the elastic modulus of the nanocomposites that further increases orders of magnitude.

Dynamics of soft nanoparticle suspensions at hard X-ray FEL sources below the radiation-damage threshold

“…Thus, an effect of size and shape polydispersity on the dynamics that leads dynamical heterogeneities with <1 as well (Andrews et al, 2018) can be neglected. The results are in qualitative agreement with various XPCS studies on polymeric systems where stretched exponentials together with p<2 suggesting super-diffusive dynamics are reported frequently (Nogales & Fluerasu, 2016;Hoshino et al, 2013;Ruta et al, 2014;Conrad et al, 2015;Senses et al, 2017).…”

From Femtoseconds to Hours—Measuring Dynamics over 18 Orders of Magnitude with Coherent X-rays

“…During the last decades XPCS was typically performed using CCD detectors with repetition rates in the range of seconds. Therefore, slow dynamics of condensed matter have been investigated frequently, with special attention on colloidal glasses, gels and polymer melts [47,[66][67][68][69][70][71][72]. Faster dynamics have been probed using fast diodes, such as for studying capillary waves [73][74][75][76][77] or hydrodynamic functions [41][42][43][44].…”

From polymer configuration and dynamics to protein folding

“…尽管关于纳 米颗粒对聚合物纳米复合物体系的玻璃化相变温 度、黏性、弹性和力学增强的影响的实验研究越来 越多 [29][30][31][32][33] , 然而, 由于在聚合物纳米复合物的微观 行为和宏观性能之间缺乏确定的关系, 功能特定的 聚合物纳米复合材料的生产和商业化的发展存在很 大的障碍. 另一个困难是需要涉及的参数空间规模 巨大, 使得单纯通过实验进行筛选变得十分昂贵, 但 未来可以通过模拟帮助缩小在实验室中可能探索的 参数范围 [34][35][36][37][38][39][40][41][42] . 仅进行实验研究很难阐明在与纳米颗粒和聚 合物线团的大小相比拟的小尺度上纳米颗粒和聚 合物基质之间的相互作用机理, 从而由此得出纳米 尺度填料对相应的聚合物纳米复合材料微观行为 和宏观性能的影响 [43][44][45][46][47][48] [46] .…”

“…这些生命体系中的 生物大分子凝胶在剪切应力下表现出黏性流动, 然 而在施加的应力放松时能够迅速恢复以自愈合恢复 其生物学功能. 因此, 人们开始仿照生物大分子凝胶 的自组装, 通过非共价交联来设计制造具有结构可 逆性、剪切稀释和自愈合等性能特征的可塑高分子 凝胶材料 [34,46,47] . 至今, 仿生高分子凝胶材料的实 验研究大部分都是用了具有动态连接行为的非共价 分子间相互作用来实现其自组装.…”

“…至今, 仿生高分子凝胶材料的实 验研究大部分都是用了具有动态连接行为的非共价 分子间相互作用来实现其自组装. 然而, 该类仿生凝 胶材料的应用目前仍受到其自愈合进展缓慢的限 制 [26,34] . 最近, 实验研究表明纳米颗粒对聚合物链 的吸附能够被用来实现不同高分子链之间的强、快 030008-4 https://engine.scichina.com/doi/10.1360/SSPMA-2020-0427 速黏附, 以增强增多高分子链之间的非共价物理交 联 [27,37]…”