Maleki Hajar, Whitmore Lawrence, Hüsing Nicola
Chemistry and Physics of Materials , Paris-Lodron University Salzburg , Jakob-Haringer-Strasse 2a , 5020 , Salzburg , Austria . Email:
J Mater Chem A Mater. 2018 Jul 14;6(26):12598-12612. doi: 10.1039/c8ta02821d. Epub 2018 Jun 12.
The development of aerogels with improved mechanical properties, to expand their utility in high-performance applications, is still a big challenge. Besides fossil-fuel based polymers that have been extensively utilized as platforms to enhance the mechanical strength of silsesquioxane and silica-based aerogels, using green biopolymers from various sustainable renewable resources are currently drawing significant attention. In this work, we process silk fibroin (SF) proteins, extracted from silkworm cocoons, with organically substituted alkoxysilanes in an entirely aqueous based solution a successive sol-gel approach, and show for the first time that it is possible to produce homogeneous interpenetrated (IPN) polymethylsilsesquioxane (PMSQ)-SF hybrid aerogel monoliths with significantly improved mechanical properties. Emphasis is given to an improvement of the molecular interaction of the two components (SF biopolymer and PMSQ) using a silane coupling agent and to the design of pore structure. We succeeded in developing a novel class of compressible, light-weight, and hierarchically organized meso-macroporous PMSQ-SF IPN hybrid aerogels by carefully controlling the sol-gel parameters at a molecular level. Typically, these aerogels have a compressive strength ( ) of up to 14 MPa, together with high flexibility in both compression and bending, compressibility up to 80% strain with very low bulk density ( ) of 0.08-0.23 g cm. By considering these promising properties, the superhydrophobic/oleophilic PMSQ-SF aerogel hybrids exhibited a high competency for selective absorption of a variety of organic pollutants (absorption capacities ∼500-2600 g g %) from water and acted as a high-performance filter for continuous water/oil separation. Moreover, they have demonstrated impressive thermal insulation performance ( = 0.032-0.044 W m K) with excellent fire retardancy and self-extinguishing capabilities. Therefore, the PMSQ-SF aerogel hybrids would be a new class of open porous material and are expected to further extend the practical applications of this class of porous compounds.
开发具有改进机械性能的气凝胶以扩大其在高性能应用中的用途仍然是一个巨大的挑战。除了广泛用作增强倍半硅氧烷和二氧化硅基气凝胶机械强度平台的基于化石燃料的聚合物外，使用来自各种可持续可再生资源的绿色生物聚合物目前正受到广泛关注。在这项工作中，我们采用连续溶胶 - 凝胶法，在完全基于水的溶液中，用有机取代的烷氧基硅烷处理从蚕茧中提取的丝素蛋白（SF），并首次表明可以制备出具有显著改善机械性能的均匀互穿（IPN）聚甲基倍半硅氧烷（PMSQ） - SF杂化气凝胶整体材料。重点是使用硅烷偶联剂改善两种组分（SF生物聚合物和PMSQ）之间的分子相互作用以及孔结构的设计。通过在分子水平上仔细控制溶胶 - 凝胶参数，我们成功开发出了一类新型的可压缩、轻质且具有分级结构的介观 - 大孔PMSQ - SF IPN杂化气凝胶。通常，这些气凝胶的抗压强度（ ）高达14 MPa，在压缩和弯曲方面都具有高柔韧性，可压缩性高达80%应变，体积密度（ ）非常低，为0.08 - 0.23 g/cm³。考虑到这些有前景的性能，超疏水/亲油的PMSQ - SF气凝胶杂化物对从水中选择性吸收各种有机污染物（吸收容量约为500 - 2600 g/g）表现出很高的能力，并作为连续水/油分离的高性能过滤器。此外，它们还表现出令人印象深刻的隔热性能（ = 0.032 - 0.044 W/(m·K)），具有出色的阻燃性和自熄能力。因此，PMSQ - SF气凝胶杂化物将是一类新型的开放多孔材料，有望进一步扩展这类多孔化合物的实际应用。
