Degradable polyester based on long alkane diesters and diols

Abstract

Long alkane diesters and diols were prepared and condensed to synthesize poly(triacontamethylene triacontanedioate)(PTRM), poly(dodecamethylene triacontanedioate) (PDDT), poly(butylene triacontanedioate) (PBUT), poly (tetratriacontamethylene tetratriacontanedioate) (PTTM), poly(tetracosamethylene tetracosanedioate) (PTEM). All the polymers were soluble only in toluene and decalin at elevated temperature. All the polyesters showed not only high melt-transition of the range from 95℃ up to 113℃ but also high thermal stability, which are comparable to thermal properties of low density polyethylene (LDPE). Their enthalpy of melting were 88.1-203.8 kJ/mol larger than that of LDPE. Films were prepared from PTRM and PDDT by melting-casting and subjected to testing. Higher molecular weight PTRM could be obtained by solid state polymerization and melt post-polymerization by the addition of MgO. Their elongation values were low (5%) and tensile strengths were around 12.5 MPa above the compared LDPE value. The small contact angles indicate that these polyesters exhibit good wettability in comparison with polyethylene. The evidences of biodegradation of these polyester films were obtained with Rhizopus arrhizus lipase, in activated sludges, and in soil. From the increases of total organic carbon concentration, carboxy end group, and turbidity, the decreases of molecular weight, weight losses, and the breakdowns of surface morphology, we confirmed that these polyesters are biodegraded. The narrowing of molecular weight distribution after degradation suggests that these polyesters are exogenously (degrading from terminal groups to inward in the chain) degraded. The three differently treated PTRM films were prepared: the quenched sample (PTRM-Q); the sample formed under room temperature (PTRM-R); the annealed sample (PTRM-A). The degree of crystallinity and crystallite size were in order: $PTRM-A > PTRM-R > PTRM-Q$. The biodegradability was in order: $PTRM-Q > PTRM-R > PTRM-A$.