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We have fabricated high-energy-density all-solid-state flexible asymmetric supercapacitor by using a facile novel 3D hollow urchin-shaped coaxial manganese dioxide@polyaniline (MnO@PANI) composite as positive electrode and 3D graphene foam (GF) as negative electrode materials with polyvinyl alcohol (PVA)/KOH gel electrolyte. The coaxial MnO@PANI composite was fabricated by hydrothermal route followed by oxidation without use of an external oxidant. The formation mechanism of the 3D hollow MnO@PANI composite occurs first by nucleation and growth of the MnO crystal species via dissolution-recrystallization and oriented attachment mechanisms followed by the oxidation of aniline monomers on the MnO crystalline template. The self-assembled 3D graphene block was synthesized by hydrothermal route using vitamin C as a reducing agent. The microstructures of the composites are analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The morphology is characterized by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), which clearly showed the formation of urchin-shaped coaxial MnO@PANI composite. The electrochemical studies are explored by cyclic voltammetry, electrochemical impedance spectrometry, and cyclic charge-discharge tests. The symmetric all-solid-state flexible MnO@PANI//MnO@PANI and GF//GF supercapacitors exhibit the specific capacitance of 129.2 and 82.1 F g at 0.5 A/g current density, respectively. The solid-state asymmetric supercapacitor shows higher energy density (37 Wh kg) with respect to the solid-state symmetric supercapacitors MnO@PANI//MnO@PANI and GF//GF, where the obtained energy density are found to be 17.9 and 11.4 Wh kg, respectively, at 0.5 A/g current density. Surprisingly, the asymmetric supercapacitor shows a high energy density of 22.3 Wh kg at a high current density of 5 A g. The solid-state asymmetric supercapacitor shows a good cyclic stability in which ∼11% capacitance loss was observed after 5000 cycles.

A porous 3D RGO/MnO2@PANI hybrid film and a 3D graphene aerogel were developed to fabricate a high-performance all-solid-state flexible asymmetric supercapacitor.

This report studies the surface modification of cyclic olefin copolymer (COC) by 2-methacryloyloxyethyl phosphorylcholine (MPC) monomer using photografting technique for the purpose of biointerface applications, which demonstrate resistance to both protein adsorption and cell adhesion in COC-based microfluidic devices. This is essential because the hydrophobic nature of COC can lead to adsorption of specific compounds from biological fluids in the microchannel, which can affect the results during fluidic analysis and cause clogging inside the microchannel. A correlation was found between the irradiation time and hydrophobicity of the modified substrate. Static water contact angle results show that the hydrophilicity property of the MPC-grafted substrate improves with increasing irradiation time. The contact angle of the modified surface decreased to 20 6 5 from 88 6 3 for the untreated substrate. The surface characterization of the modified surface was evaluated using x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR spectroscopy). Attenuated total reflection-FTIR and XPS results show the presence of the phosphate group (P-O) on modified COC substrates, indicating that the hydrophilic MPC monomer has successfully grafted on COC. Finally, it was demonstrated that cell adhesion and protein adsorption on the MPC modified COC specimen has reduced significantly.

Microfabrication of polymer using hot embossing technique are becoming increasingly important and considered as low-cost alternative to the silicon or glassbased micro-electro-mechanical systems technologies. This report is based on a parametric study on the hot embossing of cyclic olefin copolymer (COC) (Topas-6015 grade).The key process parameters in hot embossing such as the embossing temperature, load, the holding time and the demolding temperature significantly impact the quality of the embossed product. The work was performed to understand the influence of the various process parameters on the embossed micro-size patterns with the aim to develop the capability for microfluidic devices manufacturing. Microembossed polymer replicates were measured using a PLl confocal microscope and inspected using a scanning electron microscope. It was established that the optimal embossing temperature for COC is 10°C above its T g , while an optimal embossing load of 2.94 kN and holding time of 180 s are required. We have also demonstrated the effective sealing of the microchannel without destroying the channel integrity by thermal bonding technique.