Crystallisation of nanohybrids of poly(ϵ-caprolactone) and hydrotalcites containing antimicrobial species

Abstract

New composites of poly(ϵ-caprolactone) containing Zn/Al hydrotalcites [layer double hydroxide (LDH)] and ‘active’ antimicrobial anions (benzoate, dichlorobenzoate, o-hydroxybenzoate and p-hydroxybenzoate) prepared with two different techniques have been characterised through differential scanning calorimetry and dynamic mechanical analysis. The method of preparation of the samples has a strong influence on the dispersion of the nanolayers within the polymeric matrix, and, in turn, on the crystallisation kinetics: in fact, the samples prepared by high energy ball milling crystallise much faster than those prepared by casting. The different ‘active’ anions strongly affect the value of the LDH interlamellar distance, which, in turn, affects their capacity of dispersion in the polymer. As a consequence of the different kinds of dispersion, the sample containing benzoate LDH or dichlorobenzoate LDH crystallises faster than that containing p-hydroxybenzoate LDH. Such results are of great importance in the definition of processing and use conditions of such materials of potential interest in food ‘active’ packaging.