Synthesis and characterization of well‐defined random and block copolymers of ε‐caprolactone with l‐lactide as an additive for toughening polylactide: Influence of the molecular architecture

Abstract

Well-defined multiarmed star random and block copolymers of e-caprolactone with L-lactide with controlled molecular weights, low polydispersities, and precise numbers of arms were synthesized by the ring-opening polymerization of respective cyclic ester monomers. The polymers were characterized by 1 H-NMR and 13 C-NMR to determine their chemical composition, molecular structure, degree of randomness, and proof of block copolymer formation. Gel permeation chromatography was used to establish the degree of branching. Star-branched random copolymers exhibited lower glass-transition temperatures (T g 's) compared to a linear random copolymer. When the star random copolymers were melt-blended with poly(L-lactic acid) (PLA), we observed that the elongation of the blend increased with the number of arms of the copolymer. Six-armed block copolymers, which exhibited higher T g 's, caused the maximum improvement in elongation. In all cases, improvements in the elongation were achieved with no loss of stiffness in the PLA blends.

Toughening modification of PLLA with PCL in the presence of PCL‐b‐PLLA diblock copolymers as compatibilizer

“…In order to obtain PLLA/PCL blends with high toughness, several strategies had been employed to improve the compatibility between PLLA and PCL . Reactive blending was an effective route to enhance compatibility for PLLA/PCL blends through using lysine triisocyanate or dicumyl peroxide, because the PLA‐based block or graft polymers were directly obtained in the process .…”

“…[23][24][25] In order to obtain PLLA/PCL blends with high toughness, several strategies had been employed to improve the compatibility between PLLA and PCL. [26][27][28][29][30] Reactive blending was an effective route to enhance compatibility for PLLA/PCL blends through using lysine triisocyanate or dicumyl peroxide, because the PLA-based block or graft polymers were directly obtained in the process. 26,27 Tensile toughness of these blends was significantly enhanced through reactive processing, but the application of these blends was limited in the fields with high biomedical safety requirements, because of possible toxicities derived from the residual triisocyanate incorporated.…”

The Effects of Blending Ratio of Poly(lactic acid)/POSS Cored Star Poly(ε-caprolactone) Biopolymers

“…The star-shaped polymers are generally characterized by lower glass transition temperature (Tg) and melt viscosity. They are more compact and less crystalline in comparison to linear counterparts of the same molecular weights (3,9). The starbranched block and random copolymers of LA and ε-CL are a candidate for enhancing the toughness of PLA.…”

“…The starbranched block and random copolymers of LA and ε-CL are a candidate for enhancing the toughness of PLA. Several studies in the literature prepared blends of PLA with synthesized star-shaped polymers (3,9,10). Deokar et al prepared three, four, and six-armed random and block star polymers of PCL-PLA and blended with PLA.…”

Novel green route towards polyesters-based resin by photopolymerization of star polymers

“…The hyperbranched star-like PCL resins tend towards lower melt viscosity, which decreases the solvent content of coating and in turn reduces or eliminates the volatile organic compounds (VOC)s emission suitable for the film formation for powder coating [4,5]. Typically, star-like PCL are synthesized from polyhydric alcohols (such as pentaerythritol [6][7][8][9], di-trimethylolpropane [10], D-sorbitol [11], dipentaerythritol [10] etc.) as initiators that constitute the core of the star.…”