Random multiblock poly(ester amide)s containing poly (L-lactide) and cycloaliphatic amide segments: Synthesis and biodegradation studies

Novel multiblock poly(ester amide)s containing poly(L-lactide) and cycloaliphatic amide segments were synthesized from telechelic oligomer of χ,ω-hydroxyl terminated poly(L-lactide), 1,3- cyclohexylbis(methylamine), and sebacoylchloride by the "two-step" interfacial polycondensation method. The blocky nature of PEAs was established by FTIR and ¹H NMR spectroscopies. The effect of relative content of ester and amide segments on the crystallization nature of PEAs was investigated by WAXD and DSC analyses. PEAs having lower content of PLLA, PEA 1 and PEA 2, showed a crystallization pattern analogous to polyamides, whereas PEA 3, having higher content of PLLA, showed two crystalline phases characterized by polyester and polyamide segments. Random nature of PEAs was observed from single T _g values. Biodegradation studies using the enzyme lipase from Candida Cylindracea showed higher degradation rate for PEA 3 than that for PEA 1 and PEA 2. FTIR, ¹H NMR, and DSC analyses of the degraded products indicated the involvement of ester linkages in the degradation process.