立构规整性偶氮苯聚醚的制备及储能性质

Preparation and energy storage properties of stereoregular azobenzene-based polyethers

以合成的具有不同碳链长度的含偶氮苯基的外消旋端位环氧化合物为单体,双金属Salen钴配合物[(S,S,R,S,S)-Salen Co(Ⅲ)Cl]/双-(三苯基正膦基)氯化铵(PPNCl)为催化剂,通过对映选择性均聚反应,合成出一系列具有主链手性的立构规整性偶氮苯聚醚。采用GPC、13CNMR对其进行了表征,通过DSC和UV-Vis考察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,全同反式偶氮苯聚醚均为半结晶材料,熔点为230~259℃,结晶温度为197~221℃;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。由于全同聚醚自结晶的特点,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醚的储能密度起着重要作用。

A series of stereoregular azobenzene-based polyethers(azopolyethers) with main-chain chirality were synthesized via highly enantioselective resolution polymerization of racemic azobenzene-containing epoxides with different carbon chain lengths using bimetallic Salen cobalt complex [(S,S,R,S,S)-Salen Co(Ⅲ)Cl]/bis(triphenylphosphine)iminium chloride(PPNCl) as catalyst,and then characterized by GPC and 13CNMR.The thermal properties,photoisomerization effciency,and energy-storage performance of the obtained 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 197~221 ℃.The azobenzene groups in the polyethers exhibited reversible trans-to-cis and cis-to-trans photoisomerization upon light irradiation.Due to the crystallization characteristic of isotactic polyethers,their energy storage densities were significantly higher than those of the corresponding amorphous polyethers,and the maximum energy storage density reached up to 193.7 J/g.This provides new ideas for future research of polyether energy storage materials.