Department of Polymer Engineering, The University of Akron, Akron, Ohio 44325-0301, United States.
Langmuir. 2013 May 21;29(20):6156-65. doi: 10.1021/la4007394. Epub 2013 May 6.
Proper selection of silane precursors and polymer reinforcements yields more durable and stronger silica aerogels. This paper focuses on the use of silane-end-capped urethane prepolymer and chain-extended polyurethane for reinforcement of silica aerogels. The silane end groups were expected to participate in silica network formation and uniquely determine the amounts of urethanes incorporated into the aerogel network as reinforcement. The aerogels were prepared by one-step sol-gel process from mixed silane precursors tetraethoxysilane, aminopropyltriethoxysilane (APTES), and APTES-end-capped polyurethanes. The morphology and mechanical and surface properties of the resultant aerogels were investigated in addition to elucidation of chemical structures by solid-state (13)C and (29)Si nuclear magnetic resonance. Modification by 10 wt % APTES-end-capped chain-extended polyurethane yielded a 5-fold increase in compressive modulus and 60% increase in density. APTES-end-capped chain-extended polyurethane was found to be more effective in enhancement of mechanical properties and reduction of polarity.
适当选择硅烷前体和聚合物增强剂可得到更耐用、更强的二氧化硅气凝胶。本文重点研究了硅烷封端的聚氨酯预聚物和链扩展型聚氨酯在二氧化硅气凝胶增强方面的应用。预计硅烷端基将参与二氧化硅网络的形成，并独特地决定作为增强剂掺入气凝胶网络中的聚氨酯的量。通过一步溶胶-凝胶工艺，使用混合硅烷前体四乙氧基硅烷、氨丙基三乙氧基硅烷（APTES）和 APTES 封端的聚氨酯制备了气凝胶。除了通过固态（13）C 和（29）Si 核磁共振阐明化学结构外，还研究了所得气凝胶的形态以及机械和表面性能。用 10wt%的 APTES 封端的链扩展型聚氨酯改性后，压缩模量增加了 5 倍，密度增加了 60%。发现 APTES 封端的链扩展型聚氨酯在增强机械性能和降低极性方面更为有效。
