Synthesis and Characterisation of Sorbitol Based Copolyesters for Biomedical Applications

In this investigation we report on the synthesis and characterisation of certain polyester elastomers namely as Poly（Sorbitol succinate-co-ethylene glycol succinate） （PSSEG）, Poly（sorbitol succinate-co-butane diol succinate） （PSSBD） and Poly（sorbitol succinate-co-hexane diol succinate） （PSSHD） by carrying out catalyst free melt polycondensation.. The synthesised polyesters were characterised by solubility, FT-IR, -H NMR and 13C NMR spectral methods. The thermal properties were analysed by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties evaluated for the polyester films in the tensile mode shows that the polymer has characteristics of elastomers and stiff thermosets. We demonstrate that the chemical structure, physical integrity and mechanical property of synthesized copolyester can be controlled by simply changing the monomers and suit them for the requirements of various biomedical and soft tissue engineering applications.

MORPHOLOGY, CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY(ε-CAPROLACTONE)/GRAPHENE OXIDE NANOCOMPOSITES

A series of nanocomposites based on poly（ε-caprolactone） （PCL） and graphene oxide （GO） were prepared by in situ polymerization. Scanning electron microscopy observation revealed not only a well dispersion of GO but also a strong interfacial interaction between GO and the PCL matrix, as evidenced by the presence of some GO nanosheets embedded in the matrix. Effects of GO nanofillers on the crystal structure, crystallization behavior and spherulitic morphology of the PCL matrix were investigated in detail. The results showed that the crystallization temperature of PCL enhanced significantly due to the presence of GO in the nanocomposites, however, the addition of GO did not affect the crystal structure greatly. Thermal stability of PCL remarkably increased with the addition of GO nanosheets, compared with that of pure PCL. Incorporation of GO greatly improved the tensile strength and Young＇s modulus of PCL without a significant loss of the elongation at break.

Polyurethane foam-supported three-dimensional interconnected graphene nanosheets network encapsulated in polydimethylsiloxane to achieve significant thermal conductivity enhancement

Polyurethane(PU)foams are widely used in thermal management materials due to their good flexibility.However,their low thermal conductivity limits the efficiency.To address this issue,we developed a new method to produce tannic acid(TA)-modified graphene nanosheets(GTs)-encapsulated PU(PU@GT)foams using the soft template microstructure and a facile layer-by-layer(L-B-L)assembly method.The resulting PU@GT scaffolds have ordered and tightly stacked GTs layers that act as three-dimensional(3D)highly interconnected thermal networks.These networks are further infiltrated with polydimethylsiloxane(PDMS).The through-plane thermal conductivity of the polymer composite reaches 1.58 W·m^(−1)·K^(−1) at a low filler loading of 7.9 wt.%,which is 1115%higher than that of the polymer matrix.Moreover,the mechanical property of the composite is~2 times higher than that of the polymer matrix while preserving good flexibility of the polymer matrix owing to the retention of the PU foam template and the construction of a stable 3D graphene network.This work presents a facile and scalable production approach to fabricate lightweight PU@GT/PDMS polymer composites with excellent thermal and mechanical performance,which implies a promising future in thermal management systems of electronic devices.