Synthesis of silyl-terminated polylactides for controlled surface immobilization of polylactide macromolecular chains

Poly(D-lactide)s (PDLA) having an end group of trimethoxysilyl (P(x)-Si-(OMe)(3)) or monoethoxydimethylsilyl (P(x)-Si-OEt) group were synthesized to immobilize macromolecular chains of polylactide onto a flat silicon surface by the "grafting onto" mechanism. Both the end-functional PDLAs were efficiently immobilized on the flat surface of silicon wafers to create different nano-ordered structures. The P(x)-Si-OEt having the monofunctional siloxyl group formed a homogeneous dot morphology consisting of homogeneously dispersed particles of 20-30 nm in diameter while the P(x)-Si-(OMe)(3) having the trifunctional siloxyl group formed a heterogeneous morphology consisting of both spots and fibrous strands. The former homogeneous morphology was attributed to the lack of the intermolecular cross-linking reaction that was evident in P(x)-Si-(OMe)(3).