具有光热存储与释放功能的偶氮苯侧链接枝聚降冰片烯  

Photo-thermal Storage and Release of an Azobenzene-grafted Polynorbornene Film

作　　者：符林霞 冯奕钰[1] 封伟[1] Lin-xia Fu;Yi-yu Feng;Wei Feng(School of Materials Science and Engineering,Tianjin University,Tianjin 300072)

机构地区：[1]天津大学材料科学与工程学院

出　　处：《高分子学报》2019年第12期1272-1279,共8页Acta Polymerica Sinica

基　　金：国家重点基础研究发展计划(973计划,项目号2016YFA0202302);国家自然科学杰出青年基金(基金号51425306);国家自然科学基金(基金号51573125,51573147,51803151)资助项目

摘　　要：将甲氧基和羧基取代偶氮苯共价接枝到开环易位聚合方法制备的聚降冰片烯侧链上,制备了具有光热存储与释放功能的偶氮基聚降冰片烯(PNB-Azo).结果表明,当偶氮苯在聚合物上的接枝密度为31%(偶氮苯与聚合物结构单元摩尔比)时,可获得具有良好柔韧性和自支撑性的光热膜,拉伸强度和最大应变分别可达21.5 MPa和120%.通过在波长365 nm的紫外充热后,PNB-Azo膜光热存储的能量密度可达34 Wh/kg.该薄膜在波长为550 nm的绿光照射和50°C条件下,能实现存储热量的可控释放,与未充热的膜相比,温差可达1.25℃.该结果为制备具有光热循环利用功能的柔性光热膜提供了材料基础.The poor film-formation ability of azobenzene carbon thermal storage materials with graphene as templates limits their practical application due to the rigid structure of graphene sp2 hybridization. In this study,we addressed this issue by employing polynorbornene as the templelate given that polymers much outperform graphene in terms of film formation, flexibility, and self-supporting property. Herein, azobenzene attached with two methoxy and two carboxyl groups was firstly synthesized to regulate the photoisomerization and energy density. Next, polynorbornene(PNB) templates with various molecular weights were prepared by ring-opening metathesis polymerization(ROMP) with different molar ratios between monomer and catalyst. Azobenzene was then grafted onto the side chain of PNB through amidation reaction to afford azobenzene-grafted polynorbornenes with diverse grafting densities. Experimental results showed that with the increasing molecular weight of PNB template, the graft density of azobenzene rose first but subsequently fell. As for the film formation ability, PNBAzo-500 with the highest graft density(36%) could hardly form an intact film, while PNB-Azo-900 exhibited the best film formation ability despite a slightly lower graft density(31%). Therefore, PNB-Azo-900 was involved in the following measurements. Tensile testing indicated that the PNB-Azo-900 film possessed good flexibility and self-supporting behavior by achieving a strain of 120% and a tensile strength of 21.5 MPa. Photoisomerization and energy density was characterized by UV-absorption spectroscopy and differential scanning calorimetry,respectively, which suggested that the film effectuated energy storage under 365 nm UV-light irradiation and the energy density reached 34 Wh/kg. The stored energy could be released as heat when the film was expoed to 550 nm green light or heat source stimulation, during which the highest temperature was 1.25 ℃. Such excellent energy storage and light responsiveness endowed this PBN film with potential applica

关 键 词：开环易位聚合 聚合物模板 柔性薄膜 偶氮苯 热释放 

分 类 号：TQ317[化学工程—高聚物工业] TB383.2[一般工业技术—材料科学与工程]