可修复纤维损伤的防霜和防雾聚合物复合膜

Frost-resistant and Antifogging Polymeric Composite Films Capable of Healing Fractured Nanofibers

聚合物材料内部具有的微/纳米尺度的结构赋予了它们独特的功能.然而,聚合物材料在使用时不可避免地会遭受机械损伤,这会使得聚合物材料的微/纳米结构受到破坏,导致聚合物材料自身功能的丧失.为了解决上述问题,我们利用聚丙烯酸(PAA)与聚丙烯酰胺(PAAm)的嵌段共聚物(PAA-b-PAAm)和聚二烯丙基二甲基氯化铵(PDDA)形成的复合物溶液,通过提拉成膜,然后在25℃、相对湿度为~100%的环境中退火处理,制备了可修复纳米纤维损伤的防霜和防雾聚合物复合膜(PAA-b-PAAm/PDDA).亲水的PAA-b-PAAm/PDDA膜的纳米纤维结构可以增加水滴和膜表面的接触面积并促进膜对水分子的快速吸收,从而赋予了该膜优异的防雾防霜性能.得益于聚合物链间静电与氢键作用的动态性,PAA-b-PAAm/PDDA膜具有优异的自修复性能,不仅能修复宽度为几十微米的划痕,还能使断裂的纤维重新连接并恢复其原有的纳米纤维结构.

Micro-and/or nanoscaled structures have endowed artificial polymeric materials with various unique functions.However,these materials are vulnerable to mechanical damage,which can destroy their inherent micro-and/or nanoscaled structures and result in the loss of their original functions.Therefore,to extend the service life of artificial polymeric materials whose functions depend on micro/nanostructures,it is highly important to fabricate polymeric materials that can heal damaged micro/nanoscaled structures.In this work,we report the fabrication of self-healing antifogging and frost-resisting films capable of healing the fractured nanofibrils.The films are fabricated by dip-coating of clean substrate from aqueous solution of poly(acrylic acid)-block-poly(acrylamide)(PAA-b-PAAm)and poly(diallyldimethylammonium chloride)(PDDA)complexes,followed by annealing under a humid environment of~25℃and relative humidity of~100%(denoted as PAA-b-PAAm/PDDA).The complexation of PAA-b-PAAm and PDDA in aqueous solutions can assemble into nanorods,which are comprised of electrostatically cross-linked PAA blocks and PDDA chains as the hydrophobic cores and hydrogen-bonded PAAm chains as the hydrophilic coronas.These nanorods in the complex solutions can fuse into oriented nanofibers in the dip-coated PAA-b-PAAm/PDDA films during the dip-coating and the annealing processes.Nanofibrillar structures of the hydrophilic PAA-b-PAAm/PDDA film can increase the contact area between water droplets and film surfaces to facilitate water dispersion and adsorption,thereby endowing the film with excellent antifogging and frost-resisting properties.Because of the dynamic nature of electrostatic and hydrogen-bonding interactions,the PAA-b-PAAm/PDDA films can not only heal physical cuts with several tens of micrometer width,but also reconnect the fractured nanofibers to restore their original ordered nanostructures.The ability to heal macroscopic damages and restore inherent nanostructures can largely extend the service life and enhance the reliability of the antifogging and frost-resisting PAA-b-PAAm/PDDA films.The present work paves a way for the fabrication of polymeric materials that can heal micro/nanostructures and thus restore their original functions.