Organocatalytic Ring Opening Polymerization of Trimethylene Carbonate

Abstract

A variety of organocatalysts has been surveyed in the ring opening polymerization of trimethylene carbonate. Excellent control was found for several of these catalysts yielding well-defined polycarbonates with molecular weights up to 50 000 g mol-1, polydispersities below 1.08, and high end-group fidelity. Melt or bulk polymerization was accomplished without loss of control of molecular weight or polydispersity, and random ester−carbonate bulk polymerizations were also demonstrated. Furthermore, by combining disparate polymerization techniques using bifunctional initiators, the mild polymerization conditions allow for the preparation of new block copolymers. Hydrogen-bond activation of monomer and initiator/propagating species is proposed as the underlying mechanism, which can be tuned to mitigate adverse side reactions.

Modern Synthesis and Thermoresponsivity of Polyphosphoesters

“…When TBD was used as a catalyst, the conversion of PIPP reached a level of more than 75% within 20 min. The heightened activity of TBD for the polymerization of lactone and TMC was also observed (Nederberg et al, 2007). Vol.…”

“…One of the most successful procedures for making biodegradable polymers is polymerization using guanidine and amidine bases, both in bulk and in solution. Nederberg and Hedrick prepared poly(trimethylene carbonate (TMC)) (PTMC) with the base catalysts in the presence of benzyl alcohol (Nederberg et al, 2007). Excellent controlled polymerization conditions were present with several catalysts, and PTMCs with relatively high molecular weight, narrow distribution, and high yield were obtained.…”

“…The molecular weight distribution of PIPP was narrow and stable during polymerization. The mechanism of ROP with organocatalysts was characterized using 1 H NMR by Hedrick and co-workers (Nederberg et al, 2007;Pratt et al, 2006). They indicated that DBU and TBD form hydrogen bonds to the alcohol of an initiator.…”

Synthesis and Thin-film Self-assembly of Cylinder-Forming High-χ Block Copolymers

“…Mn = 6200, Mw = 8700, PDI = 1.40. The product Sty:HEMA:GMA x:y:z mole ratio was calculated by 13 C inverse gated NMR as x:y:z = 88:6:6 (mole ratio). Based on the Mn and the product monomer mole ratio, the degree of polymerization (DP) ratio of the repeat units was calculated to be x': y': z' = 50.5: 3.5: 3.5 (Sty:HEMA:GMA, respectively).…”

“…To enable sub-10 nm half-pitch resolution for future patterning applications, polycarbonate-based BCP platform was developed by ring opening polymerization (ROP) of cyclic carbonyl monomers from hydroxyl-functional polystyrene macroinitiator using DBU as the base catalyst [13,14]. Two BCPs were synthesized and used in this work -PS-b-PTMC (6.6k-b-3.2k, PDI = 1.05, Vf PTMC ~ 0.27) and PS-b-PMTC-Me (12.5k-b-5.6k, PDI = 1.03, Vf PMTC-Me ~ 0.27) (Figure 1).…”