立构规整性偶氮苯聚醚的制备及储能性质

Preparation and energy storage properties of azobenzene based isotactic-enriched polyethers

摘要:

太阳能热燃料可以实现在一个封闭的循环系统中,通过分子构象的转换捕获和储存太阳能,并按需以热的形式释放能量。本文通过外消旋偶氮苯基环氧烷烃对映选择性均聚,合成出一系列具有主链手性的立构规整性偶氮苯聚醚,深入研究了偶氮苯聚醚的热性质、光异构化和作为新一代太阳能热燃料的储能性质。结果表明,等规反式偶氮苯聚醚均为半结晶材料,熔点为230~259 ℃,结晶温度为197~219 ℃；聚醚中的偶氮苯基团在光照下可实现高效可逆的顺反异构化转变。由于等规聚醚自结晶的特点,其储能密度较无定形聚醚有明显提高,最高可达193.7 J/g,说明结晶性对偶氮苯聚合物的储能密度中起着重要作用。本文利用立构规整性聚合物的自结晶特点提高偶氮苯类聚合物的储能密度,为聚合物储能材料的研究提供了新思路。

Abstract:

Solar thermal fuels can harvest and store solar energy through the conversion of molecular conformation in a closed circulation system and release energy in the form of heat on demand. In this paper, a series of isotactic azobenzene-based polyethers (azopolyethers) with main-chain chirality were synthesized via highly enantioselective resolution polymerization of racemic azobenzene-containing epoxides. The thermal properties, photoisomerization, and energy-storage properties of these resultant azopolyethers as a new generation of solar thermal fuels were investigated in detail. These isotactic-enriched azopolyethers with trans-azobenzene moieties were found to be semicrystalline materials with melting temperatures in the range of 230-259 ℃ and crystallization temperature within the scope of 197-219 ℃. The azobenzene groups in the polyethers exhibited reversible trans-to-cis and cis-to-trans photoisomerization upon irradiation with light. Due to the crystallization characteristic of isotactic polyethers, their energy storage densities are significantly higher than that of the corresponding amorphous polyethers, and the maximum energy storage density is up to 193.7 J/g. This provides a new idea for the research of polymer energy storage materials.