Silica aerogel (SA) has shown great promise in constructing thermal insulation composites in various forms. However, it is still challenging to disperse a huge amount of SA particles into other matrices for fabricating superior thermal insulation materials or highly filled masterbatch, owing to its high specific surface area and ultra-low density. Herein, inspired by high internal phase emulsion (HIPE), we successfully prepare processable SA/polyvinyl alcohol (PVA) composites (SA-PVA dough) with over 74 vol% dispersed SA, using a PVA aqueous solution as a binder. This is achieved by gradually mixing a large amount of hydrophobic SA filler into a small amount of PVA aqueous solution. The resulting SA-PVA dough exhibits an internal structure resembling that of HIPEs, with hydrophobic SA particles stabilized in the water phase by amphiphilic PVA chains, tightly packed within the thin continuous PVA aqueous phase. Benefiting from such a HIPE structure, the SA-PVA dough can be easily shaped into various forms and exhibits good applicability in further processing. The dried dough inherits the excellent properties of SA, including ultra-low density, superhydrophobicity (water contact angle: 153°), thermal insulation (thermal conductivity: 0.03 W m K), and flame resistance. Moreover, the continuous PVA network structure, combined with the nanoscale pore structure of SA, provides the dough with excellent gas barrier properties, greatly expanding the application scope of SA-based composites.

中文翻译：

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二氧化硅气凝胶-PVA 面团：具有优异隔热性和阻气性的高内相复合材料

二氧化硅气凝胶（SA）在构建各种形式的隔热复合材料方面显示出巨大的前景。然而，由于其高比表面积和超低密度，将大量SA颗粒分散到其他基体中以制造优质隔热材料或高填充母料仍然具有挑战性。在此，受高内相乳液（HIPE）的启发，我们使用PVA水溶液作为粘合剂，成功制备了可加工的SA/聚乙烯醇（PVA）复合材料（SA-PVA面团），其分散的SA含量超过74 vol%。这是通过将大量疏水性SA填料逐渐混合到少量PVA水溶液中来实现的。所得的 SA-PVA 面团表现出类似于 HIPE 的内部结构，疏水性 SA 颗粒通过两亲性 PVA 链稳定在水相中，紧密堆积在薄的连续 PVA 水相中。得益于这种HIPE结构，SA-PVA面团可以很容易地成型为各种形状，并在进一步加工中表现出良好的适用性。干燥后的面团继承了SA的优异性能，包括超低密度、超疏水性（水接触角：153°）、隔热性（导热系数：0.03 W·m·K）、阻燃性。而且，连续的PVA网络结构与SA的纳米级孔隙结构相结合，为面团提供了优异的气体阻隔性能，大大扩展了SA基复合材料的应用范围。