Two synthesis routes to graphene/polycaprolactone composites are introduced and the properties of the resulting composites compared. In the first method, mixtures are produced using solution processing of polycaprolactone and well dispersed, chemically reduced graphene oxide and in the second, an esterification reaction covalently links polycaprolactone chains to free carboxyl groups on the graphene sheets. This is achieved through the use of a stable anhydrous dimethylformamide dispersion of graphene that has been highly chemically reduced resulting in mostly peripheral ester linkages. The resulting covalently linked composites exhibit far better homogeneity and as a result, both Young's modulus and tensile strength more than double and electrical conductivities increase by 14 orders of magnitude over the pristine polymer at less than 10 per cent graphene content. In vitro cytotoxicity testing of the materials showed good biocompatibility resulting in promising materials for use as conducting substrates for the electrically stimulated growth of cells. Two synthesis routes to graphene/polycaprolactone composites are introduced and the properties of the resulting composites compared. In the first method, mixtures are produced using solution processing of polycaprolactone and well dispersed, chemically reduced graphene oxide and in the second, an esterification reaction covalently links polycaprolactone chains to free carboxyl groups on the graphene sheets. This is achieved through the use of a stable anhydrous dimethylformamide dispersion of graphene that has been highly chemically reduced resulting in mostly peripheral ester linkages. The resulting covalently linked composites exhibit far better homogeneity and as a result, both Young's modulus and tensile strength more than double and electrical conductivities increase by ≈ 14 orders of magnitude over the pristine polymer at less than 10 % graphene content. In vitro cytotoxicity testing of the materials showed good biocompatibility resulting in promising materials for use as conducting substrates for the electrically stimulated growth of cells.

Problem statement: Jatropha curcas is a wonder plant with a variety of applications and enormous economic potentials. Oil from the seeds can be used as alternative fuel and for making biodiesel which aims to overcome energy crisis problems. In this study, extraction of Jatropha oil from seeds was optimized using organic solvent based on the amount of the extracted oil. The kinetics of extraction was also investigated and its parameters were determined based on a second order model. Approach: The effects of five operating parameters on the oil extraction namely type of solvents, temperature, solvent to solid ratio, processing time and particle size of the meal were investigated to optimize the processing conditions for achieving maximum oil yield. The kinetics of extraction was assumed based on a second order mechanism. The initial extraction rate, the saturated extraction capacity, the rate constant of extraction and the activation energy were calculated using the model. Results:The optimum conditions were found at 8 h reaction time, temperature of around 68°C, coarse particle size (0.5-0.75 mm), solvent to solid ratio of 6:1 and hexane as solvent. The activation energy was found to be 8021.9 J moL −1 . Conclusion: Hexane was found to be the best solvent for the process as compared to petroleum ether, the kinetics of extraction conforms well to the second order model and the extraction of Jatropha seeds was an endothermic process.

Composites of graphene in a chitosan-lactic acid matrix were prepared to create conductive hydrogels that are processable, exhibit tunable swelling properties and show excellent biocompatibility. The addition of graphene to the polymer matrix also resulted in significant improvements to the mechanical strength of the hydrogels, with the addition of just 3 wt% graphene resulting in tensile strengths increasing by over 200%. The composites could be easily processed into three-dimensional scaffolds with finely controlled dimensions using additive fabrication techniques and fibroblast cells demonstrate good adhesion and growth on their surfaces. These chitosan-graphene composites show great promise for use as conducting substrates for the growth of electro-responsive cells in tissue engineering. Composites of graphene in a chitosan-lactic acid matrix were prepared to create conductive hydrogels that are processable, exhibit tunable swelling properties and show excellent biocompatibility. The addition of graphene to the polymer matrix also resulted in significant improvements to the mechanical strength of the hydrogels, with the addition of just 3 wt% graphene resulting in tensile strengths increasing by over 200 %. The composites could be easily processed into threedimensional scaffolds with finely controlled dimensions using additive fabrication techniques and fibroblast cells demonstrate good adhesion and growth on their surfaces. These chitosan-graphene composites show great promise for use as conducting substrates for the growth of electro-responsive cells in tissue engineering.

A 3D iron porphyrin/graphene hydrogel electrocatalyst affords highly efficient, durable and selective CO2 reduction to CO at a low overpotential.