Hetero-stereocomplex formation of stereoblock copolymer of substituted and non-substituted poly(lactide)s

Cocrystallization of monomer units in lactic acid-based biodegradable copolymers, poly(l-lactic acid-co-l-2-hydroxybutanoic acid)s

“…1 H NMR peaks at around 5.06, 1.99, and 1.04 ppm are ascribed to methine (c) (not that at hydroxyl terminal), methylene (b), and methyl (a) protons of P(L-2HB), whereas those at around 5.16 and 1.59 ppm are attributed to methine (e) (not that at hydroxyl terminal) and methyl (d) protons of PLLA. The observed chemical shift values agree well with the reported values [32]. The copolymers including HB44 had both 1 H NMR peaks observed for P(L-2HB) and PLLA, confirming the incorporation of both LLA and L-2HB units in the copolymers.…”

“…However, cocrystallization is not reported for the blend composed of L-(or D)-P(2HA) polymers with different types of side chains and same configurations and the block P(2HA) copolymer with L-(or D-) segments with different types of side chains and same configurations. In poly(L-lactide) [i.e., poly(L-lactic acid), PLLA]/poly(L-2-hydroxybutanoic acid) [P(L-2HB)] blend [31] and poly(D-2-hydroxybutanoic acid) [P(D-2HB)]-b-poly(D-lactide) [poly(D-lactic acid), PDLA] [32], respectively separate homo-crystallization of constituent polymers and sole homo-crystallization of PDLA segments occurred.…”

Stereocomplex crystallization and homo-crystallization of enantiomeric substituted poly(lactic acid)s, poly(2-hydroxy-3-methylbutanoic acid)s

“…Hetero-stereocomplex is formed between L-and D-forms (and vice versa) of PLA and P(2HB) [15][16][17][18] and those of P(2HB) and P(2H3MB) [19]. Also, ternary and quaternary SC formation is reported to take place in ternary [P(D-2H3MB)] blends [22].…”

Hetero‐Stereocomplex Crystallization between Star‐Shaped 4‐Arm Poly(l‐2‐hydroxybutanoic acid) and Poly(d‐lactic acid) from the Melt

“…Also, the polymers with different chemical structures and the opposite configurations are known to form hetero‐stereocomplex (HTSC). Examples of polymer pairs which can form HTSC crystallites include S‐ and R‐polyketones such as (+)‐poly(propylene‐carbon monoxide) and (‐)‐poly(1‐butene‐carbon monoxide), l ‐ and d ‐polyesters such as poly( l ‐2‐hydroxybutanoic acid) [P(L‐2HB)] and PDLA (or PLLA and poly( d ‐2‐hydroxybutanoic acid) [P( d ‐2HB)]) and poly( l ‐2‐hydroxybutanoic acid) [P(L‐2HB)] and poly( d ‐2‐hydroxy‐3‐methylbutanoic acid) [P( d ‐2H3MB)] . Furthermore, ternary SC crystallization was reported to occur in ternary P(L‐2HB)/P(D‐2HB)/PDLA blends …”

“…In a previous study, we reported that HTSC crystallization between substituted and unsubstituted PLAs can be used as a versatile preparation method for biodegradable materials having a wide variety of physical properties and biodegradability and that HTSC crystallites are formed also in P(L‐2HB)‐ b ‐PDLA block copolymer . However, HTSC crystallization was investigated only for linear 1‐arm polymer blends or linear 1‐arm diblock copolymer and not for star‐shaped (branched) polymer blends.…”