Crystallization and thermal performance of poly(acrylonitrile-co-alkyl acrylate) comb-like polymeric phase change materials with various side-chain lengths

A series of comb-like poly(n-alkyl acrylate) and poly(acrylonitrile-co-alkyl acrylate) phase change materials (PCMs), denoted as PAn and PANAn, with alkyl carbon atoms varying from n = 14 to 16 and 18, are synthesized through the free-radical polymerization of n-alkyl acrylates without or with acrylonitrile, respectively. Structure and thermal properties such as phase change enthalpy, thermal repeatability and shape stability of the PM and PANAn comb-like PCMs were investigated by H-1 NMR, FTIR, DSC, and TGA. With n changing from 14 to 18, the phase change temperature and enthalpy of the PANAn PCMs increase from 26.4 to 51.4 degrees C and from 29.3 to 71.2 J g(-1), respectively. Compared to those of pristine PM, an enhanced shape-stabilization performance and thermal stability of the PANAn series are observed owing to the good support role of the PAN component, and PANA18 shows the maximum form-stable temperature of 240 degrees C followed by an excellent thermal reliability and structure stabilization after 100 thermal cycles. Three-point temperature measurement supports the good thermal energy storage/release capability of PANA18, and fabric coated with PANA18 gives a thermoregulated effect. The good shape-stabilized performance and excellent structural stability tuned by varying the alkyl side-chain lengths demonstrate their prospective application as thermal management materials.