Polylactide–Poly(6-methyl-ε-caprolactone)–Polylactide Thermoplastic Elastomers

Abstract

Amorphous ABA type block aliphatic polyesters can be useful as degradable and biorenewable thermoplastic elastomers. These materials can be prepared by sequential ringopening transesterification polymerization (ROTEP) reactions and can exhibit a range of physical properties and morphologies. In this work a set of amorphous polylactideÀpoly(6-methyl-ε-caprolactone)Àpolylactide aliphatic polyester ABA triblock copolymers were prepared by consecutive controlled ring-opening polymerizations. Ring-opening polymerization of neat 6-methyl-εcaprolactone in the presence of 1,4-benzenedimethanol and tin(II) octoate afforded α,ω-hydroxyl-terminated poly(6-methyl-εcaprolactone). High conversions of 6-methyl-ε-caprolactone (>96%) afforded polymers with molar masses ranging from 12 to 98 kg mol À1 , depending on monomer-to-initiator ratios, polymers with narrow, monomodal molecular weight distributions. An array of polylactideÀpoly(6-methyl-ε-caprolactone)Àpolylactide triblock copolymers with controlled molecular weights and narrow molecular weight distributions were synthesized using the telechelic poly(6-methyl-ε-caprolactone) samples as macroinitiators for the ring-opening polymerization of D,L-lactide. The morphological, thermal, and mechanical behaviors of these materials were explored. Several triblocks adopted well-ordered microphase-separated morphologies, and both hexagonally packed cylindrical and lamellar structures were observed. The FloryÀHuggins interaction parameter was determined, χ(T) = 61.2T À1 À 0.1, based on the order-to-disorder transition temperatures of two symmetric triblocks using the calculated mean field theory result. The elastomeric mechanical behavior of two high molecular weight triblocks was characterized by tensile and elastic recovery experiments.

Scalable production of mechanically tunable block polymers from sugar

“…With the bioderived βMδVL in hand, we demonstrated that bulk ROTEP using an organocatalyst proceeds at room temperature to high conversion, yielding an amorphous polyester with T g = -51°C (26,28). Simple chain extension through reaction with lactide (LLA or LA) leads to P(L)LA-PβMδVL-P(L)LA triblock polymers that can be tuned to have mechanical properties ranging from stiff tough plastics to soft and highly extendible elastomers (Fig.…”

“…In this paper we address this challenge by combining the efficient bioproduction of β-methyl-δ-valerolactone with controlled polymerization techniques to produce economically viable block polymer materials with mechanical properties akin to commercially available thermoplastics and elastomers. offer exceptional mechanical properties (26,27). βMδVL can be generated by direct fermentation of glucose or through the production of the intermediate compound mevalonate.…”

“…This design results in outstanding mechanical properties and has been the basis for the commercially successful poly(styrene)-poly(diene) variants (23). Many PLA-containing block polymers have been reported; several have been shown to be flexible, tough, elastic, and hydrolytically degradable (24)(25)(26)(27). Unfortunately the starting materials used to prepare these polymers are either derived from fossil fuels or from natural products that are prohibitively expensive.…”

Thermoplastic Elastomers Based on Block, Graft, and Star Copolymers

“…Sample PLLA-PM-PLLA (13-33-13) displayed a strain at break of 765% with ultimate tensile strength of 19.5 MPa [51,52]. With 30 vol% of poly(6-methyl-ε-caprolactone) (PMCL) as the elastic block, 1880% strain at break was achieved with 10.2 MPa ultimate stress [53].…”

Fully bio-renewable multiblocks copolymers of poly(lactide) and commercial fatty acid-based polyesters polyols: Synthesis and characterization

“…The dihydroxyl terminated polymer is then used as a macro-initiator for the subsequent ring-opening polymerization of lactide. A variety of polymers can be used as soft block [16,17,21,27,31,38,41], provided that they have a suitably low glass transition temperature, and that they can be obtained with proper terminal functional groups. Recently, the research focused on the development of fully biobased PLA-containing triblocks copolymers, by employing biorenewable soft blocks, such as amorphous polyhydroxyalkanoates [18,26], polymethide [28] and polyesters derived from castor oil [44].…”