Crystalline and spectroscopic characterization of poly(2-aminoethyl methacrylate hydrochloride) chains grafted onto poly[(R)-3-hydroxybutyric acid]

• Gamma radiation induced graft polymerization of PAEMA chains onto P(3HB) are evaluated in solution of different solvents.
• Successful grafting by 1H NMR and FTIR spectroscopy has been demonstrated. A structure of the grafted copolymer was proposed based on spectroscopic results.
• The calculus of the degree of grafting was surveyed, and the products are characterized by FTIR, Raman and WAXS techniques.
• Three different methods were established to compare the variation of degree of crystallinity with the degree of grafting.

The present study is aimed to investigate the degree of crystallinity of poly(3-hydroxybutyrate) P(3HB) grafted with poly(2-aminoethyl methacrylate hydrochloride) (PAEMA) chains using WAXS, micro Raman, and FTIR spectroscopy. The samples were obtained by radiation induced graft polymerization of the monomer in the substrate using different solvents for comparison. The results of crystallinity are consistent with those obtained of lower crystallinity in grafting copolymer relative to the substrate P(3HB). The low crystallinity is directly related to the increase of the degree of grafting, meaning that although the P(3HB) amorphous region is grafted, the crystalline zone is also affected in some extent by the grafting process and the environment of the new molecule. Three different methods were surveyed to determine the variation of crystallinity degree with the grafting degree. It is shown that all methods provide linear relationships between these variables, but WAXS method was found more acceptable than the others (FTIR and Raman). A detailed characterization of the vibrational bands characteristic of amorphous and helical crystalline structure of the grafting copolymers are also highlighted.