Mahendra Thunga

PMMA-g-SOY as a sustainable novel dielectric material

Soy protein (and associated carbohydrate) (SOY) is graft copolymerized with poly(methyl methacrylate) (PMMA) to synthesize novel low cost dielectric materials for multifunctional applications. Graft copolymerization of methyl methacrylate onto pre-activated SOY is carried out using a simple reflux method to form covalently bonded PMMA-g-SOY copolymers. The resulting PMMA-g-SOY is processed into films without employing any toxic chemical solvents. The PMMA-g-SOY films exhibited enhanced storage modulus and a low loss tangent together with promising dielectric properties compared to the pristine PMMA polymer. This strategy may open a new avenue to efficiently use green co-products for multifunctional applications in traditional and structural capacitors.

Micro-structured smart hydrogels with enhanced protein loading and release efficiency.

A series of temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with highly porous microstructures were successfully prepared by using hydrophobic polydimethylsiloxane (PDMS) and sodium dodecyl sulfate as liquid template and stabilizer, respectively. These newly prepared hydrogels possess highly porous structures. In contrast to the conventional PNIPAAm hydrogel, the swelling ratios of the porous gels at room temperature were higher, and their response rates were significantly faster as the temperature was raised above the lower critical solution temperature. For example, the novel hydrogel prepared with 40% PDMS template lost over 95% water within 5 min, while the conventional PNIPAAm gel only lost approximately 14% water in the same time. The improved properties are achieved due to the presence of liquid PDMS templates in the reaction solutions, which lead to the formation of porous structures during the polymerization/crosslinking. Lysozyme and bovine serum albumin (BSA) as protein models were for the first time loaded into these micro-structured smart hydrogels through a physical absorption method. The experimental results show that the loading efficiency of BSA with a higher molecular weight is lower than that of lysozyme due to the size exclusion effect, and the loading efficiencies of both proteins in the porous hydrogel are much higher than those in the conventional PNIPAAm hydrogel. For example, the loading efficiency of BSA in porous hydrogel is 0.114, approximately 200% higher than that in conventional hydrogel (0.035). Both lysozyme and BSA were completely released from the porous hydrogel at 22 degrees C. Furthermore, the release kinetics of the proteins from the porous hydrogel could be modulated by tuning the environmental temperature. These newly prepared porous materials provide an avenue to increase the loading efficiency and to control the release patterns of macromolecular drugs from hydrogels, and show great promise for application in protein or gene delivery.

Bio-inspired sensory membrane: Fabrication processes for full-scale implementation

In this paper, we investigate the influence of processing methods that dictate the performance enhancement in a nanocomposite soft capacitor. Styrene Ethylene Butylene Styrene (SEBS)/Titanium dioxide (TiO2) based nanocomposites are used as model substrates for preparing the soft capacitors. The efficiency of ultrasonic probe and high-shear melt mixing methods in dispersing TiO2 nanoparticles in SEBS polymer matrix is studied, and scanning electron microscopic (SEM) images are used to reveal fine-dispersion of TiO2 particles. After dispersion, films are prepared by compression-molding and drop-cast processing. The compression-molding method shows highly promising for engineering applications by enhancing fabrication speed, safety, and improving control over the film thickness.

Enhanced Polymer Nanocomposites for Condition Assessment of Wind Turbine Blades

Damages in composite components of wind turbine blades and large-scale structures can lead to increase in maintenance and repair costs, inoperability, and structural failure. The vast majority of condition assessment of composite structures is conducted by visual inspection and non-destructive evaluation (NDE) techniques. NDE techniques are temporally limited, and may be further impeded by the anisotropy of the composite materials, conductivity of the fibers, and the insulating properties of the matrix. In previous work, the authors have proposed a novel soft elastomeric capacitor (SEC) sensor for monitoring of large surfaces, applicable to composite materials. This soft capacitor is fabricated using a highly sensitive elastomer sandwiched between electrodes. It transduces strain into changes in capacitance. Here, we present a fabrication method for fabricating the SEC. Different surface treatment techniques for the nanoparticles are investigated and the effects on the mechanical and the electrical properties of the produced film are studied. Results show that using melt mixing fabrication method was successful at dispersing the nanoparticles without using any surface treatment, including coating the particles with PDMS oil or the use of Si-69 coupling agent. Yet, treating the surface would result in increasing the stiffness of the matrix as well as improving the interaction between the filler particles and the matrix.