Silylation of poly-L-lysine hydrobromide to improve dissolution in apolar organic solvents

Abstract

Bis(trimethylsilyl)acetamide (BSA) was used to trimethylsilylate the hydrobromide salt of the synthetic polyamide poly-L-lysine (PLL-HBr) to improve its solubility in apolar organic solvents. The resulting trimethylsilylated derivative of PLL (PLL-SiMe 3 ) was found to be soluble in methylene chloride, tetrahydrofuran, and xylenes. The PLL-SiMe 3 was eventually used in the formation of an interpenetrating polymer network (IPN) with ultrahigh molecular weight polyethylene via xylenes. Elemental analysis, FTIR, and NMR spectroscopic evidence supported highly efficient (81.7%) silylation for the BSA-treated PLL-SiMe 3 product. Spectral data also showed complete silylation at the carboxyl, N-terminal α-amine, and the e-amine groups. This chemistry provides solvent processing accessibility for PLL blends or grafting reactions not possible for the commercial hydrobromide salt of PLL.