Fractional complexation in a miscible polymer blend. Calorimetry and size exclusion chromatography

Abstract

Poly(N-methyldodecano-12-lactam) (PMDL) is miscible with poly(4-vinylphenol) (PVPh). In the system PMDL + PVPh + tetrahydrofuran containing low-molar-mass polymer pair, this miscible blend is soluble in the solvent. In this work, it has been found that the system containing high-molar-mass polymer pair undergoes associative phase separation into a gel-like interpolymer complex and a soluble residual phase (RP). The complex and RP samples were characterized using differential scanning calorimetry, size exclusion chromatography and thermogravimetric analysis. The average molar ratio of PMDL to PVPh in the complex is 1:2, considered an optimum composition of the interpolymer complex. The complex shows higher glass transition temperature and higher thermal stability than the RP. Formation of the interpolymer complex in the studied system and differences in its properties from the RP are caused by higher molar mass/length of associated polymer chains as a result of fractionation during which the high-molar-mass fraction forms the gel-like interpolymer complex and the low-molar-mass fraction forms the soluble RP. © 2014 Society of Chemical Industry