Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers

Abstract

D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as “a configurational or helical molecular glue” for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers.

Effects of Amphiphilic Chitosan on Stereocomplexation and Properties of Poly(lactic acid) Nano-biocomposite

“… 17 to synthesize scPLA using supercritical fluids. Synthesis of stereoblock PLA, sintering and compression of enantiomeric PLA 18 , ternary stereocomplex formation via configurational molecular glue 19 or use of fillers 20 or biofillers, such as cellulose nano/micro crystals 21 , 22 , clays 23 , chitosan, hydroxyapatite 24 etc. into the matrix of scPLA can be the possible routes for preventing the formation of homocrystals.…”

Stereocomplex‐ and Homo‐Crystallization and Phase‐Transition Behavior of Relatively High‐Molecular‐Weight Linear One‐ and Two‐Armed and Star‐Shaped Four‐Armed Poly(l‐lactide)/Poly(d‐lactide) Blends

“…In the case of blends, that the molecular architectures such as molecular weight and tacticity or optical purity of PLA polymers have crucial effects on SC crystallization and high molecular weight and low optical purity should be avoided because these factors disturb SC crystallization . On the other hand, binary, ternary, and quaternary SC crystallization of optically active unsubstituted and/or substituted PLAs, and copolymers having opposite configurations and the identical or two different chemical structures have been reported and extensively studied . Very recently, ternary SC crystallization of PDLA, poly( l ‐2‐hydroxybutanoic acid), poly( l ‐2‐hydroxy‐3‐methylbutanoic acid) having three different chemical structures was reported …”

“…On the other hand, binary, ternary, and quaternary SC crystallization of optically active unsubstituted and/or substituted PLAs, and copolymers having opposite configurations and the identical or two different chemical structures have been reported and extensively studied . Very recently, ternary SC crystallization of PDLA, poly( l ‐2‐hydroxybutanoic acid), poly( l ‐2‐hydroxy‐3‐methylbutanoic acid) having three different chemical structures was reported …”

Synthesis and stereocomplex formation of enantiomeric alternating copolymers with two types of chiral centers, poly(lactic acid-alt-2-hydroxybutanoic acid)s

“…60 Hetero SC formation occurred between PLA and P(2HB), P(2HB) and P(2H3MB) with the different chemical structures and opposite congurations. Ternary SC formation took place in the blends of L-and D-congured P(2HB)s and L-or D-congured PLA, 18 L-and D-congured P(2H3MB)s and L-or D-congured P(2HB), 61 and D-congured PLA, L-congured P(2HB), and D-congured P(2H3MB) [or L-congured PLA, D-congured P(2HB), and L-congured P(2H3MB)], 62 whereas quaternary SC occurred in the blend of L-and D-congured P(2HB)s and L-and D-congured P(2H3MB)s. 18 Also, SC formation took place in enantiomeric random copolymer blends of poly(L-lactic acid-co-L-2-hydroxybutanoic acid) [P(LLA-co-L-2HB)] (56/44) and poly(D-lactic acid-co-D-2hydroxybutanoic acid) [P(DLA-co-D-2HB)] (52/48) 63 and of poly(L-lactic acid-co-L-2-hydroxy-3-methylbutanoic acid) [P(LLA-co-L-2H3MB)] (47/53) and poly(D-lactic acid-co-D-2-hydroxy-3methylbutanoic acid) [P(DLA-co-D-2H3MB)] (47/53), 64 and the staggered random copolymers, L-congured P(LLA-co-L-2HB) (50/50) and D-congured poly(D-2-hydroxybutanoic acid-co-D-2hydroxy-3-methylbutanoic acid) (50/50). 65 It should be noted that in these cases, all types of monomer units were conrmed to be packed in the SC crystalline lattice by wide-angle X-ray diffractometry (WAXD).…”