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A series of biodegradable isosorbide-based copolyesters poly(butylene succinate-co-isosorbide succinate-co-polyethyleneoxide succinate) (PB x I y E z S) were synthesized via bulk polycondensation in the presence of dimethyl succinate (DMS), 1,4-butanediol (BDO), poly-(ethylene glycol) (PEG) and isosorbide (ISO). The crystallization behaviors, crystal structure and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization behavior of the copolyesters was influenced by the content of isosorbide succinate (IS) and polyethyleneoxide succinate (PEOS) units, which further tuned the mechanical and biodegradable properties of the copolyesters. The PB x I y E z S copolyesters, compared to pure poly(butylene succinate), showed lower crystallization temperature, melting temperature, degree of crystallinity and degradation rate while a significant increase in glass transition temperature with increasing isosorbide content.

Biodegradable poly(butylene succinate-co-ethylene glycol) (PBSG)/multiwalled carbon nanotube (MWCNT) nanocomposites were successfully prepared through physical blending and silication between PBSG and acyl aminopropyltriethoxysilane functionalized multiwalled carbon nanotube (MWCNT-APTES). Nuclear magnetic resonance (NMR) spectra observations revealed that the PBSG chains were covalently attached to the MWCNT-APTES by hydrolysis. PBSG/ MWCNT-APTES nanocomposites after hydrolysis showed excellent interfacial compatibility between PBSG and MWCNT-APTES, which was helpful for the dispersion of MWCNT in the PBSG matrix. The incorporation of MWCNT-APTES accelerated the crystallization of PBSG in the nanocomposites for both approaches of physical blending and hydrolysis due to the heterogeneous nucleation effect of MWCNT while the crystal structure of PBSG was remained. Furthermore, the crystallization rate of PBSG in PBSG/MWCNT-APTES nanocomposites after hydrolysis was slower than that in the nanocomposite by physical blend. The tensile strength and modulus of the nanocomposites increased about 6% and 11% with the addition of only 1 wt% MWCNT-APTES compared with that of neat PBSG, and was larger for the PBSG/MWCNT-APTES nanocomposites after hydrolysis.

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A series of aliphatic biodegradable poly (butylene succinate-co-ethyleneoxide-co-DL-lactide) copolyesters were synthesized by the polycondensation in the presence of dimethyl succinate, 1,4-butanediol, poly(ethylene glycol), and DL-oligo(lactic acid) (OLA). The composition, as well as the sequential structure of the copolyesters, was carefully investigated by 1 H-NMR. The crystallization behaviors, crystal structure, and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry, wide angle X-ray diffraction, and polarizing optical microscopy, respectively. The results indicate that the sequence length of butylene succinate (BS) decreased as the OLA feed molar ratio increasing. The crystallization behavior of the copolyesters was influenced by the composition and sequence length of BS, which further tuned the mechanical properties of the copolyesters. The copolyesters formed the crystal structures and spherulites similar to those of PBS. The incorporation of more content of ethylene oxide (EO) units into the copolyesters led to the enhanced hydrophilicity. The more content of lactide units in the copolyesters facilitated the degradation in the presence of enzymes. The morphology of the copolyester films after degradation was also studied by the scanning electron microscopy.