Enhanced impact properties of polylactide by poly(lactide-b-butadiene-b-lactide) triblock copolymer

Abstract

Polylactide (PLA) was copolymerized with polybutadiene (PBD) to improve its impact properties. Triblock copolymers of poly(lactide-b-butadiene-b-lactide) (PLBDL) were obtained by the ring opening polymerization of lactide using tin 2-ethylhexanoate (Sn(Oct) 2 ) and hydroxyl terminated polybutadiene (HTPBD) as a catalyst and macroinitiator, respectively. PLA and PLBDL were blended at 5, 10, and 15 wt% PLBDL. After blending, the samples exhibited a shift in the T g of PLA, which means that PLBDL and PLA are compatible. The tensile strength and Young's modulus decreased with increasing PLBDL. On the other hand, the PLA/PLBDL blend containing 10 wt% PLBDL showed a 4 fold increase in impact strength. In addition, the elongation at break of the blend containing 10 wt% PLBDL was 467%, showing a 27 fold increase compared to neat PLA. This suggests that the PBD chains on the PLBDL backbone have a significant effect on the impact properties of PLA.

ABA-Type Thermoplastic Elastomers Composed of Poly(ε-caprolactone-co-δ-valerolactone) Soft Midblock and Polymorphic Poly(lactic acid) Hard End blocks

“…2 In this regard, PLAs with different stereostructures are the ideal candidates to use as the end blocks of ABA-type TPEs, which can also render the TPEs biodegradability and biocompatibility. Many nonbiodegradable soft midblocks such as polyisobutylene, 3 poly-(dimethylsiloxane), 4 polybutadiene (PB), 5,6 polyisoprene (PI), 7 poly(ethylene-co-butylene) (PEB), 8 and a variety of biodegradable or biobased midblocks such as poly(1,3trimethylene carbonate), 9 poly(1,5-dioxepan-2-one), 10 poly(εcaprolactone) (PCL), 11,12 poly(6-methyl-ε-caprolactone) (PMCL), 13 poly(ε-decalactone) (PεDL), 14 polymenthide (PM), 15 poly(butylene succinate), 16 poly(3-methyl-1,5-pentylene succinate), 17 poly(ricinoleic acid), 18 and poly(ε-caprolactone-stat-D,L-lactide) 19 have been conjugated with PLAs to prepare the ABA-type TPEs. A particular phenomenon of PLA is the stereocomplex formation between its two enantiopure stereoisomers, that is, PLLA and PDLA.…”

Polylactide-b-poly(ethylene-co-butylene)-b-polylactide thermoplastic elastomers: role of polylactide crystallization and stereocomplexation on microphase separation, mechanical and shape memory properties

“…Because the amorphous, racemic PLA has relatively high T g and the enantiopure PLA is semicrystalline, they are ideal candidates used as the endblocks of TPEs. [13][14][15][16][17][18][19][20][21][22][23][24] A lot of so midblocks such as polyisobutylene, 13 poly(dimethylsiloxane), 14 poly(1,3-trimethylene carbonate), 15 poly(1,5-dioxepan-2-one), 16 polyisoprene (PI), 18 polymenthide (PM), 19,20 and poly(6-methyl-3-caprolactone) (PMCL) 21 have been incorporated into PLA to prepare TPEs, which were demonstrated to be highly effective to overcome the brittleness of PLA. Furthermore, the physical properties of TPEs can be readily modulated through varying the tacticity, crystallizability, and crystalline polymorphs of PLA blocks.…”

Combining block copolymers and hydrogen bonding for poly(lactide) toughening

“…30 This is in contrast with previous reports where higher molar mass PB effectively toughens PLA. 8,9 The mechanical properties of UPy-LBL triblock copolymers showed a molar mass dependence (Table 2). UPy-LBL copolymers with a molar mass lower than 100 kg mol À1 and lower than 0.6 wt% UPy (see Table 1), exhibited brittle character with similar tensile strengths to their non-functionalized counterparts.…”

“…8 Polymer blends of PLA with a similar triblock system exhibited a 27-fold increase in the fracture strain of PLA when 10 wt% of the triblock copolymer was used. 9 Non-covalent interactions (e.g., ionic, metal coordination, hydrogen bonding) are widely used to improve the mechanical performance of materials. Hydrogen bonding interactions are thermoreversible and allow for property tuning by heating the material above the hydrogen bond dissociation temperature.…”