Structural characteristics of 2‐hydroxyethylmethacrylate (HEMA)/methacrylamide (MAA)‐grafted silk fibers

A series of 2‐hydroxyethylmethacrylate (HEMA)/methacrylamide (MAA)‐grafted silk fibers obtained in various comonomer compositions was prepared and their structural characteristics were studied by X‐ray diffractometry, differential scanning calorimetry, and scanning electron microscopy. HEMA/MAA‐grafted silk fibers with a graft yield of about 60% obtained in a HEMA/MAA mixture system containing 20% of HEMA and 80% of MAA on a weight basis showed endothermic peaks at 280 and 420°C (shoulder form), which are attributed to the thermal decomposition of the MAA and HEMA polymers, respectively, in addition to the thermal decomposition peak of the silk fibroin fiber which appeared at 323°C. These DSC results suggest that the HEMA/MAA‐grafted silk fiber showed a low compatibility in the relation between the silk fibroin molecules and HEMA and/or MAA polymers. The crystalline structure of the HEMA/MAA‐grafted silk fiber remained unchanged regardless of the HEMA/MAA grafting ratio even when the graft yield value reached 120%.