Chitin, the second most abundant biopolymer after cellulose, is an important resource for biosourced materials. The global demand for chitin is rapidly increasing, however, the majority of industrial chitin is sourced from crustacean shells, which may be less accessible in regions without seafood waste. Therefore, it is crucial to explore alternative chitin sources, such as those derived from beetles and other arthropods.
View Article and Find Full Text PDFChitosan, a natural polysaccharide, has attracted considerable attention as an environmentally friendly and highly efficient adsorbent for dye removal. It is usually produced by deacetylation or partial deacetylation of chitin. However, conventional sources of chitin and chitosan are limited, prompting the need for alternative sources with improved adsorption capabilities.
View Article and Find Full Text PDFPolymer gels are comprised of a three-dimensional, cross-linked network that can typically withstand the mechanical deformation associated with both swelling and de-swelling. Thus, gels can be designed with smart behaviors that require both stress generation and dissipation, making them well-suited to many applications including membrane technology, water capture devices, and drug delivery systems. In contrast to the fully swelled equilibrium state, limited research characterizes the unsteady-state swelling regime prior to equilibrium.
View Article and Find Full Text PDFPhotopolymerization induced phase separation (PIPS) is a platform capable of creating heterogeneous materials from initially miscible resin solutions, where both the reaction's governing thermodynamics and kinetics significantly influence the resulting phase composition and morphology. Here, PIPS is used to develop materials in a single photopolymerization step that are hydrophobic on one face and hydrophilic on the other. These two faces possess a water contact angle difference of 50°, bridged by a bulk-scale chemical gradient.
View Article and Find Full Text PDFThermal conductivity (TC) and thermal stability are the basic requirements and highly desirable properties in thermal management, heat storage and heat transfer applications. This work is regarding the fabrication of polystyrene/boron nitride composites and melt extruded to produce good thermal stability, increased thermal conductivity and enhanced mechanical properties. Our strategy is potentially applicable to produce thermally conductive composites of low cost over large scale.
View Article and Find Full Text PDFThe lack of drinkable water is one of the most significant risks for the future of the humanity. Estimates show that in the near future, this risk will become the origin of massive migrations leading to humanitarian disaster. As consequence, the development of solutions to provide water is becoming ever more critical, and a significant effort is devoted to identifying new sources of water.
View Article and Find Full Text PDFPolystyrene (PS)/sepiolite clay nanocomposites were prepared via the melt extrusion technique using vinyl tri-ethoxy silane (VTES) as the compatibilizer and cross-linking agent. Mechanical, thermal, and flame-retardant properties of the newly developed polystyrene-based nanocomposites were determined. Surface morphology was investigated using scanning electron microscopy (SEM), examining the distribution of the filler in various compositions of fabricated composites.
View Article and Find Full Text PDFSimultaneous photopolymerization of radical and cationic systems is one strategy to generate polymer network architectures named interpenetrating polymer networks (IPNs). In these hybrid systems, phase separation and final polymer morphology are ultimately governed by thermodynamic incompatibility and polymerization kinetics. This behavior is quite complex, as numerous factors can affect polymerization kinetics including monomer/oligomer viscosity and structure, light intensity, photoinitiator content and absorbance, cross-linking, vitrification, etc.
View Article and Find Full Text PDFThe aim of the present work was to synthesize magnetite (Fe3O4) nano hollow spheres (NHS) via simple, one-pot, template-free, hydrothermal method. The structural, morphological, and surface analysis of Fe3O4 NHS were studied by scanning electron microscopy (SEM), x-ray diffraction technique (XRD), Fourier transform infrared spectroscopy FTIR and burner-Emmett-teller (BET). The as obtained magnetic (Fe3O4) NHS were used as an adsorbent for treating industrial trinitrotoluene (TNT) wastewater to reduce its Chemical Oxygen Demand (COD) values.
View Article and Find Full Text PDFBiopolymers and their derivatives are materials with increasing interest for industry and especially for sustainable engineering development. Among such kind of materials, carbohydrate polymer like highly deacetylated chitin (chitosan) is widely used for a wide range of applications, including material and biomedical developments. The majority of industrially produced chitosan is based on chitin extracted from crustacean exoskeleton.
View Article and Find Full Text PDFDesertification is a growing risk for humanity. Studies show that water access will be the leading cause of massive migration in the future. For this reason, significant research efforts are devoted to identifying new sources of water.
View Article and Find Full Text PDFCO and O gas permeability are paramount concerns in food packaging. Here, the permeability of cellulose nanocrystals (CNCs) and polyvinyl alcohol (PVA) coatings was explored as it relates to varied CNC content. Specifically, this work focuses on the role of PVA in rheology and barrier performance of the CNC films.
View Article and Find Full Text PDFHypothesis: The formation of porous nanostructures on surfaces and the control of their size and shape is fundamental for various applications. The creation of nanotubes is particularly difficult to implement without the aid of hard and rigid templates. Recently, methods that form nanotubular structures in a straightforward manner and without direct templating, e.
View Article and Find Full Text PDFNaturally derived polymers, such as cellulose or chitin, are materials with increasing interest for a sustainable future. Considering the pollution associated with plastics recycling, natural and fully biocompatible materials like cellulose and chitin are becoming increasingly more relevant for sustainable engineering applications. Chitin and highly deacetylated chitin (chitosan) are already implemented in a wide range of materials applications, especially in biomedical fields.
View Article and Find Full Text PDFChitosan is a polymer obtained by deacetylation of chitin, and chitin is one of the major components of the arthropod cuticle. Chitin and chitosan are both polysaccharides and are considered to be an interesting class of biosourced materials. This is evident as chitosan has already demonstrated utility in various applications in both industrial and biomedical domains.
View Article and Find Full Text PDFHere, a bioinspired strategy is used to prepare well-ordered nanotubular structures, as observed in animals and plants, such as gecko toe pads or corals. The nanotubes are obtained by templateless electropolymerization of thieno[3,4-]thiophene-based monomers with various aromatic groups in an organic solvent (dichloromethane). The most interesting and robust structures were obtained with carbazole and pyrene substituents to the base monomer structure, since these groups participate significantly in the polymerization and also have strong -stacking interactions.
View Article and Find Full Text PDFIn this work, we present the synthesis of original thieno[3,4-]thiophene monomers with rigid substituents (e.g., perfluorinated chains, and aromatic groups) and demonstrate the ability to prepare nanotubular and nanoporous structures via templateless, surfactant-free electropolymerization in organic solvents (dichloromethane).
View Article and Find Full Text PDFAmong the different species of flower beetles, there is one of particular notoriety: the Goliath beetle. This large insect can grow up to 11 cm long and is well-known for its distinctive black and white shield. In this paper, we focus on a particular species: (Moser, 1909).
View Article and Find Full Text PDFIn the animal kingdom, macroscopic variations in size, color, and even hairiness are frequently observed between male and female, making the sex of various species easy to discern. In the case of insects, similar variances also exist. While direct observation is a quick and efficient way to differentiate between sexes, there are also variations which are unseen to the naked eye and occur on a micro- or nanoscopic scale.
View Article and Find Full Text PDFParahydrophobic surfaces are an interesting class of materials that combines both high contact angles and very strong adhesion with wetting fluids, most commonly water. This unique set of properties makes parahydrophobic surfaces attractive for a variety of applications, including water harvesting and collection, guided fluid transport, and membrane development, amongst many others. Taking inspiration from natural surfaces that display this same behavior such as rose petals and gecko feet, synthetic approaches aim to incorporate the nano- and micro-scale topography as well as the low surface energy chemistry found on these interfaces.
View Article and Find Full Text PDFWhile the development of polymer coatings with controlled surface topography is a growing research topic, a fabrication method that does not rely on lengthy processing times, bulk solvent solution, or secondary functionalization has yet to be identified. This study presents a facile, rapid, in situ method to develop parahydrophobic coatings based on phase separation during photopolymerization. A comonomer resin of ethylene glycol diacrylate (EGDA) and 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) is modified with a thermoplastic additive (PVDF) to induce phase separation during polymerization.
View Article and Find Full Text PDFPolymerization-induced phase separation (PIPS) was studied in ambient photopolymerizations of triethylene glycol dimethacrylate (TEGDMA) modified by poly(methyl methacrylate) (PMMA). The molecular weight of PMMA and the rate of network formation (through incident UV-irradiation) were varied to influence both the promotion of phase separation through increases in overall free energy, as well as the extent to which phase development occurs during polymerization through diffusion prior to network gelation. The overall free energy of the polymerizing system increases with PMMA molecular weight, such that PIPS is promoted thermodynamically at low loading levels (5 wt%) of a higher molecular weight PMMA (120 kDa), while a higher loading level (20 wt%) is needed to induce PIPS with lower PMMA molecular weight (11 kDa), and phase separation was not promoted at any loading level tested of the lowest molecular weight PMMA (1 kDa).
View Article and Find Full Text PDFThis work presents an approach to extend the period for phase separation, independent of temperature, in ambient phase-separating photopolymerizations based on the copolymerization of structurally similar mono- and di-vinyl monomers. Copolymer resins composed of triethylene glycol dimethacrylate (TEGDMA) and ethylene glycol methyl ether methacrylate (EGMEMA) were modified with a thermoplastic prepolymer, poly(butyl methacrylate). With increasing EGMEMA modification into the bulk TEGDMA resin, there is a decrease in the initial reaction rate, which increases the time for development of compositionally different phases prior to network gelation.
View Article and Find Full Text PDFA mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed via ambient, photo-initiated polymerization-induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three non-reactive, linear prepolymers (poly-methyl, ethyl and butyl methacrylate). At higher prepolymer loading levels (10-20 wt%) an enhanced reduction in both shrinkage and polymerization stress is observed.
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