High‐molecular‐weight aliphatic polycarbonates by melt polycondensation of dimethyl carbonate and aliphatic diols: synthesis and characterization

Abstract

Aliphatic polycarbonates (APCs) synthesized by polycondensation of dialkyl carbonates and aliphatic diols have often been used as precursors for the preparation of novel polyurethanes. However, they could not be applied in plastics directly because of poor mechanical properties caused by low molecular weight. In the work reported in this paper, three kinds of fairly high molecular weight (M w ≥ 166 000 g mol −1 ) APCs with narrow dispersity ( -D ≤ 1.86) were successfully synthesized via a successive two-step polycondensation of dimethyl carbonate and diols, using a novel TiO 2 /SiO 2 -based catalyst. This process gave a high yield of above 85%. 1 H NMR spectra indicated that there was no detectable decarboxylation happening during polycondensation at high temperature. The effects of molecular weight on the mechanical properties of the APCs are discussed. APCs with M w greater than 70 000 g mol −1 showed useful mechanical properties. Especially, poly(butylene carbonate) and poly(hexamethylene carbonate) exhibited excellent tensile strengths of 34.1 and 40.0 MPa, respectively, when their M w was ca 170 000 g mol −1 . All the APCs showed appreciable biodegradability under enzymatic degradation.

Vegetable Oil Derived Solvent, and Catalyst Free “Click Chemistry” Thermoplastic Polytriazoles

“…The odd-even effect's influence in crystallinity has also been well documented in polyurethanes [46]. Similar findings for a variety of hydrogen bonding systems, including nylon [47], glucoseamide polymers [48], polycarbonate [45], fatty acids [49], fatty alcohols [50], and polyesters [37], describe similar trends. The findings of this study are consistent with the polymer chains of C18C9 being adapted into contracted, sterically unfavourable configurations forming disordered or reduced hydrogen bonding, similar to what has been reported for nylon [45] and polyurethane [46].…”

Effect of chemical structure of polycarbonates on entanglement spacing

“…The synthetic procedure has been described in detail elsewhere [8] . The chemical structure of the repeat unit is shown as Scheme 1.…”

“…Recently a series of high MW APCs with different lengths of methylene segments were synthesized via the two-step condensation polymerization [8] . They are also good model polymers to build the structure and rheological properties relationship for this novel biodegradable polymer.…”

Polycarbonates from biorenewable diols via carbonate metathesis polymerization

“…26 Li and coworkers were able to address this shortcoming and produce reasonably higher molecular weight polycarbonates using a novel TiO 2 /SiO 2 -based catalyst. 27 Recently, enzymatic 28 and organocatalytic 29 routes converting dialkyl carbonates and diols to a limited number of polycarbonates have also been demonstrated.…”