Easy access to ultra-high molecular weight polylactones using a bismuth catalyst

Synthesis and Characterization of Well-Defined High-Molecular-Weight PDLA-b-PLLA and PDLA-b-PLLA-b-PDLA Stereo-Block Copolymers

“…To recall, the melting point of the PLLA or PDLA homo-crystal is below 180 °C. The estimated crystallinity (32–48%) from the enthalpic relaxation of the di- and triblock copolymers is similar to that of the PLLA/PDLA homo-crystal. , The observations are that independent of the molar masses, at a heating rate of 10 °C/min, and all nascent di- and triblock copolymers (run 1 to run 11, Table ) show a high melting temperature peak, anticipated for the PLLA/PDLA SCs. In a broad generality, the high-molar-mass di- and triblock copolymers tend to crystallize at higher temperatures than the low-molar-mass PLLA/PDLA block copolymers, when cooled from the melt at 10 °C/min.…”

“…Very recently, in our group, we have reported the facile synthesis of ultra-high-molecular-weight PLLA and PDLA using diphenyl bismuth bromide (Ph 2 BiBr) as a catalyst that does not require monomer purification and was obtained from the supplier Purasorb, Corbion Co., Ltd. The catalytic system seems to tolerate a low water content in the monomer, resulting in the synthesis of polymers having extraordinarily high molar masses with a relatively low polydispersity index ( D̵ ) . Density functional theory (DFT) calculations in Figure of ref in the manuscript shows a higher energy demand of the chain transfer to the water than that of the ROP.…”

“…The catalytic system seems to tolerate a low water content in the monomer, resulting in the synthesis of polymers having extraordinarily high molar masses with a relatively low polydispersity index ( D̵ ) . Density functional theory (DFT) calculations in Figure of ref in the manuscript shows a higher energy demand of the chain transfer to the water than that of the ROP. This allows an enhancement in the molar mass of PLA during polymerization.…”

Planar bismuth triamides: a tunable platform for main group Lewis acidity and polymerization catalysis

“…In contrast, compared to other bismuth systems utilized for this polymerization, 3b is able to produce polymers with high molecular weights and lower dispersity. 88–94 For example, diphenyl bismuth bromide or bismuth subsalicylate are able to proceed at greater rates and produce polymers of similar (or higher) molecular weights, the dispersities reported for these systems are higher (1.5–2) than observed here. 93,94…”

“…In contrast, compared to other bismuth systems utilized for this polymerization, 3b is able to produce polymers with high molecular weights and lower dispersity. [88][89][90][91][92][93][94] For example, diphenyl bismuth bromide or bismuth subsalicylate are able to proceed at greater rates and produce polymers of similar (or higher) molecular weights, the dispersities reported for these systems are higher (1.5-2) than observed here. 93,94 To probe the degree of control over molecular weight control which could be achieved using 3b, the catalyst loading of polymerizations of 3-caprolactone and rac-lactide were varied to observe the effect on M n .…”