17 research outputs found
Treatment of lumbar degenerative disc disease-associated radicular pain with culture-expanded autologous mesenchymal stem cells: a pilot study on safety and efficacy
Preparation and evaluation of ionomeric membranes based on sulfonated-poly (styrene_isobutylene_styrene) membranes for proton exchange membrane fuel cells (PEMFC)
Diffusivity of alkanes in polystyrene
Gravimetry is used to study the diffusivity of a homologous series of linear alkanes (Cn, with n=8, 10, 12,14 and 16) in amorphous polystyrene at temperatures ranging from 45 °C to 145 °C, i.e. both below and above the polymer glass transition temperature (100 °C). All the mass uptake results obtained are well described by a simple
Fickian model (for t<t1/2) and are used to calculate the corresponding diffusion coefficients (D) using the thin-film approximation of the Fickian equation. For all the alkanes considered, the temperature dependency of the diffusion coefficients is non-Arrhenius in character, over the broad
temperature intervals considered. For any particular temperature log(D) varies linearly (R2>0.993, for all temperatures) with respect to the number of carbon atoms (n) in the alkyl chain, log(D) decreasing when n increases. For each liquid penetrant, over the temperature intervals considered, its log
(D) also increases linearly (R2>0.996 for all the systems) with the decrease in the penetrant’s liquid viscosity.Gabriel Bernardo acknowledges financial support from the IPC's (Institute for Polymers and Composites) strategic project: "PEst-C/CTM/LA0025/2011" (Projecto Estrategico -LA 25 - 2011-2012 - Strategic Project - LA 25 - 2011-2012)
Self-assembled highly ordered acid layers in precisely sulfonated polyethylene produce efficient proton transport
Oriented MOF-polymer Composite Nanofiber Membranes for High Proton Conductivity at High Temperature and Anhydrous Condition
Fast low-voltage electroactive actuators using nanostructured polymer electrolytes
Electroactive actuators have received enormous interest for a variety of biomimetic technologies ranging from robotics and microsensors to artificial muscles. Major challenges towards practically viable actuators are the achievement of large electromechanical deformation, fast switching response, low operating voltage and durable operation. Here we report a new electroactive actuator composed of self-assembled sulphonated block copolymers and ionic liquids. The new actuator demonstrated improvements in actuation properties over other polymer actuators reported earlier, large generated strain (up to 4%) without any signs of back relaxation. In particular, the millimetre-scale displacements obtained for the actuators, with rapid response (<1 s) at sub-1-V conditions over 13,500 cycles in air, have not been previously reported in the literature. The key to success stems from the evolution of the unique hexagonal structure of the polymer layer with domain size gradients beneath the cathode during actuation, which promotes the bending motion of the actuators