Stereocomplexation of quaternary or ternary monomer units and dual stereocomplexation in enantiomeric binary and quaternary polymer blends of poly(2-hydroxybutanoic acid)s, poly(2-hydroxybutanoic acid-co-lactic acid)s, and poly(lactic acid)s

Abstract

The solution- and melt-crystallized binary polymer blends from L- and D-configured poly(2-hydroxybutanoic acid) homopolymers [P(L-2HB) and P(D-2HB), respectively], L- and D-configured poly(2-hydroxybutanoic acid-co-lactic acid) random copolymers [P(L-2HB-LLA) and P(D-2HB-DLA), respectively], and L- and D-configured poly(lactic acid) homopolymers (PLLA and PDLA, respectively) and the solution- and melt-crystallized quaternary homopolymer blend of P(L-2HB), P(D-2HB), PLLA, and PDLA were prepared and their crystallization behavior was investigated by wide-angle X-ray diffractometry (WAXD), differential scanning calorimetry, and polarized optical microscopy. The WAXD profiles and the interplane distance values first revealed the stereocomplexation of quaternary or ternary monomer units of optically active 2-hydroxybutanoic acid and lactic acid units in binary polymer blends of the random copolymer with the random copolymer or the homopolymer and the dual homo-stereocomplexation of P(L-2HB) and P(D-2HB) and of PLLA and PDLA in the quaternary homopolymer blends.