Soft transient electronics of polymeric substrates and silver-ink electronics are studied for correlated mechanical-electrical properties. Experimental and predictive finite element analysis are used to understand, explain and predict delamination, cracking, buckling, and failure of printed conductive components of such systems. An active transient polymer system consisting of poly(vinyl alcohol) and sodium bicarbonate is introduced that results in byproducts (alkaline and bubbles) when undergoing transiency. These byproducts are facilitated to control and expedite transiency of the electronic components based on redispersion of metallic nano/micro materials. Complete mechanical and electrical characterization of such systems is reported.

Resistive switching behaviors in Aloe vera films are being explored for nonvolatile memory applications. A simple structure in which the Aloe vera films sandwiched in between a top and bottom electrode are used. The switching behaviors of the devices in which the Aloe vera film is dried at different temperatures and the roles of top electrode materials (Al and Ag) are investigated. Current density–voltage measurements reveal that filamentary conduction is the dominant conduction process inducing resistive switching characteristics in Aloe vera films. Device with Al-top electrode requires a forming voltage higher than devices with Ag-top electrode, due to the tendency of oxide formation of these materials. The resistive switching behaviors are highly reproducible, as demonstrated by the data retention performance over an interval of 104 s and endurance capability of over 100 cycles.

The present work demonstrates a novel technique for dispersing nanofillers in a thermoplastic polymer, where polymerization and dispersion of the nanofillers occur simultaneously via dynamic emulsion polycondensation at ambient temperature. The composite is manufactured in the form of a uniform powder, which can then be molded into desired shape by melting or sintering. The technique is demonstrated for Ag nanowire / Nylon 66 composites. In this demonstration, Ag nanowires are synthesized by the polyol process. Polyvinylprrolidone (PVP) is used to functionalize the Ag nanowires. Nanocomposites with varying Ag content are prepared and investigated. The nanowires are found to be monodispersed and hydrogen-bonded to the Nylon 66 matrix through PVP. Glass transition temperature of the composites decreases from 61 to 48 °C with Ag weight fraction increasing from 0 to 6.47%. The depression of the glass transition temperature is owed to the plasticizer effect as well as heterogeneous nucleation effect of the nanowires for polymerization leading to shorter chain length.

Self-assembling systems of amphiphilic molecules display structures similar to those of biomineralization natural systems. This allows to somehow mimic nature to synthesize nanomaterials with low polidispersity and with diverse morphologies. In this work we describe the synthesis and characterization of gold-copper, silver-copper, and gold-silver bimetallic nanoparticles by chemical reduction in self-assembling systems of two surfactants. The nanoparticles were characterized by Transmission Electron Microscopy and UV-Vis spectroscopy. We have prepared a composite material using mesoporous silica as support of the AuAg bimetallic nanoparticles. The system was used in photocatalysis experiments for water remediation applications. Our results show that the AuAg/SBA15 composite material degrades methyl orange in water from 17 ppm to 4 ppm in 30 minutes.

Reversible, suction based adhesion employed by many marine organisms may provide unique, adaptable technologies for biologically inspired grasping devices that function in difficult submerged environments. Here a theoretical framework based on measurable structural, material, and topological properties is developed to better understand a critical aspect of suction based attachment strategies: the leakage rate. The utility of the approach is demonstrated on an experimental apparatus designed to mimic the flow conditions experienced by a suction-based attachment device. Furthermore, the sealing effectiveness of a remora fish on sharkskin is investigated as a biological example.

Polyphenol in mango seed kernel extraction has been demonstrated to show benefits against skin disorders. In this study, micro-cellulose sponges (MCS) from waste cotton are used as the carrier for polyphenol to produce a controlled release system. Polyphenol loaded micro-cellulose sponges were produced by acid hydrolysis and a freeze drying method. The microparticles were characterized in terms of size and morphology, total polyphenol loading, and physical state of the encapsulated polyphenol. Polyphenol release from the microparticles was assessed by dissolution tests. The particles had spherical shapes with amorphous form. The controlled drug release was tested by using different polyphenol concentration. The results showed that the structure of micro-cellulose sponges, the media type and the solubility of the polyphenol influenced the polyphenol-release behavior. Since the release of the polyphenol is controlled by the structure and interactions between the microparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These structures of micro-cellulose sponges can be very useful in many pharmaceutical micro-particle applications.

At the MRS Fall 2014 Meeting, Symposium E, we reported on morphologies, fragmentation, and hardness in synthetic hydrogen urate monohydrate (monosodium urate monohydrate, MSUM, or MSU) crystals. We are now presenting further characterization results, including some from the biomaterial that forms in humans with gout disease: The fanning of radiating blades (needles) in spherulitic grains of synthetic MSUM was examined by microscopy techniques. These and previous data are consistent with an interpretation in terms of the crystallographic parameters in the unit cell, and the presence of dislocation arrays at low angle boundaries. The kinetics of such branched growth is here related to thermodynamic properties and super-saturation levels. Secondary nucleation is an additional mechanism leading to more complex morphologies. Differences in overall growth rates, under conditions of either branched or single needle growth, are considered in relation to gout. Novel powder XRD and solid state NMR data show, respectively, preferred orientation in the biomaterial, and the potential of NMR for identifying and characterizing MSUM in specific environments, helping to resolve pending questions in gout. Present results are anticipated to be useful for designing bio-inspired and bio-mimetic materials, regarding morphologies, overall growth rates, and mechanical properties.

Carbonate intercalated Mg-Al layered double hydroxides (Mg-Al-CO3-LDH) were successfully produced by mechanical alloying process using different starting raw chemicals. Two distinct chemical reactions were activated at different milling times. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Results revealed that the structural characteristics of Mg-Al-CO3-LDH such as lattice parameters, unit cell volume, and the interlayer spacing were affected strongly by milling time. Based on the XRD data, the formation rate of pure Hydrotalcite (HT) was strongly influenced by the chemical composition of raw materials. Electron microscopic observation displayed that the final product had a platelet-like structure with an average particle size of 20-100 nm. Therefore, the synthesis of Mg-Al-CO3-LDH via a cost-effective solid-state method owing to simplicity and reproducibility can be a promising candidate especially for use in biomaterials and catalyst industries.

Tissue engineering scaffolding is the external media or structure in which cell growth, migration and reproduction is enabled in order to stimulate tissue regeneration. In order to promote tissue regeneration, scaffolding materials are required to have certain properties such as biocompatibility, adequate mechanical properties and surface topographical features in order to provide specific biological signals to promote cell attachment and proliferation [1].

Cellulose is the most abundant, inexpensive and readily available carbohydrate polymer in the world and it is traditionally extracted from plants or their wastes [2]. Although the plant itself is the major contributor of cellulose, various types of bacteria are able to produce cellulose and it is termed bacterial cellulose [3]. Bacterial cellulose is a well suited scaffold for tissue regeneration due to its biocompatibility, mechanical properties and its ability to be combined with other structures such calcium phosphates [4], which can create composites with intrinsic properties that meet the requirements of the different tissues of the human body [5].

Through additive manufacturing, highly complex structures can be created which are similar to those found in nature. This work will explore the different ways to produce biomimetic structures for tissue engineering applications through the combination of bacterial cellulose and additive manufacturing producing complex structures of a highly a biocompatible material for a range of different biomedical applications [6]. In addition to the manufacturing and processing techniques, the use of mango (juice/peel) as a complex carbon source for the production of bacterial cellulose was investigated.

Chlorella is a green, photosynthetic single-celled genus of algae. It can be 3D printed as a suspension in sodium alginate and gelled with calcium solutions. We have made “log pile” structures with channels between the gel lines to allow easy transport of nutrients and products. Under white light and immersed in solutions of bicarbonate and phosphate and urea “plant food” the algae multiply with the gel and produce oxygen at a rate comparable to that reported for suspensions of Chlorella. The system is stable for one or two weeks at least. In principle this can be extended to other plant tissues but there are concerns relating to bacterial and fungal infection and toxicity of the gel components. In addition a tougher gel is needed if this was to be converted to a practical bioreactor system.