PMMA@SCNC composite microspheres prepared from pickering emulsion template as curcumin delivery carriers

We demonstrate a facile route to prepare novel composite microspheres based on Pickering emulsion template stabilized by cellulose nanocrystals prepared from sisal fiber (SCNCs). The oil phase of the Pickering emulsions contains hydrophobic drug curcumin and poly(methyl methacrylate) (PMMA). Curcumin loaded PMMA composite microspheres coated by SCNCs (Cur‐loaded PMMA@SCNC CMs) were obtained after the evaporation of dichloromethane. The structure and morphology of CMs were characterized by polarized optical microscope (POM), confocal laser scanning microscope, scanning electric microscope, and Fourier transform infrared spectroscopy. The stability and release kinetics of curcumin were evaluated based on spectrophotometric measurements. Overall, these results show that Cur‐loaded PMMA@SCNC CMs display long‐term photostability and good encapsulating ability for curcumin. This work offers an effective route of preparing new functional microsphere for the delivery of bioactive compounds. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46127.     

Reinforced soy protein isolate–based bionanocomposites with halloysite nanotubes via mussel‐inspired dopamine and polylysine codeposition

Fully renewable soy protein isolate (SPI)–based film with rigid strength and sufficient water resistance is difficult to attain. In this study, the mussel‐inspired surface chemistry of ?‐poly‐L‐lysine (?‐PL)/dopamine was exploited for codeposition onto halloysite nanotubes (HNTs) to engineer a multinetwork of HNT/SPI bionanocomposite films via physicochemical bonds. A series of ?‐PL/dopamine aqueous solutions at different concentration ratios were employed. The ?‐PL with abundant cationic amine groups could prevent the overoxidation of dopamine on HNT surfaces, thus maintaining sufficient free catechol groups for highly active reactions that improve the biphase interfacial adhesion. Moreover, HNTs surface entangled by ?‐PL chains could be more compatible with peptides. This codeposition of ?‐PL/dopamine on HNT (DLHNT) surfaces was analyzed by X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. Compared to the control SPI film, the tensile strength of the nanocomposite film (DLHNTs0.5/SPI) was increased from 5.9 MPa to 8.25 MPa, the Young's modulus was improved by 166.4%, and the moisture absorption was reduced to 56.1% (87.2% of the control). In summary, a facile and mild bioinspired surface chemistry of ?‐PL/dopamine codeposition onto HNT surfaces was performed to prepare SPI‐based nanocomposite films with improved interfacial adhesion and benign compatibility. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46197.     

Melt processing of polyamide 12 and cellulose nanocrystals nanocomposites

The fabrication of nanocomposites of polyamide 12 (PA12) and cellulose nanocrystals (CNCs) isolated from cotton and tunicates is reported. Through a comparative study that involved solution‐cast (SC) and melt‐processed materials, it was shown that PA12/CNC nanocomposites can be prepared in a process that appears to be readily scalable to an industrial level. The results demonstrate that CNCs isolated from the biomass by phosphoric acid hydrolysis display both a sufficiently high thermal stability to permit melt processing with PA12, and a high compatibility with this polymer to allow the formation of nanocomposites in which the CNCs are well dispersed. Thus, PA12/CNC nanocomposites prepared by melt‐mixing the two components in a co‐rotating roller blade mixer and subsequent compression molding display mechanical properties that are comparable to those of SC reference materials. Young's modulus and maximum stress could be doubled in comparison to the neat PA12 by introduction of 10% (CNCs from tunicates) or 15% w/w (CNCs from cotton) CNCs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42752.     

Influence of the nanofiber dimensions on the properties of nanocellulose/poly(vinyl alcohol) aerogels

The investigation of aerogels made from cellulose nanofibers and poly(vinyl alcohol) (PVOH) as a polymeric binder is reported. Aerogels based on different nanocellulose types were studied to investigate the influence of the nanocellulose dimensions and their rigidity on the morphology and mechanical properties of the resulting aerogels. Thus, cellulose nanocrystals (CNCs) with low (10), medium (25), and high (80) aspect ratios, isolated from cotton, banana plants, and tunicates, respectively, microfibrillated cellulose (MFC) and microcrystalline cellulose (MCC) were dispersed in aqueous PVOH solutions and aerogels were prepared by freeze‐drying. In addition to the cellulose type, the PVOH‐ and the CNC‐concentration as well as the freeze‐drying conditions were varied, and the materials were optionally cross‐linked by an annealing step or the use of a chemical cross‐linker. The data reveal that at low PVOH content, rigid, high‐aspect ratio CNCs isolated from tunicates afford aerogels that show the least amount of shrinking upon freeze‐drying and display the best mechanical properties. However, with increasing concentration of PVOH or upon introduction of a chemical cross‐linker the differences between materials made from different nanocellulose types decrease. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41740.     

Biodegradation of PHBV/GNS nanocomposites by Penicillium funiculosum

Biodegradable polymer nanocomposites are an essential alternative to minimize the generation of polymeric solid waste that shows short shelf life and difficult degradation. In this study, nanocomposites based on poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) were prepared by the incorporation of different contents, 0.25, 0.50, 0.75, and 1.00 wt % of graphite nanosheets (GNS), using a solution casting method. The investigation of the PHBV samples biodegradation was made using filamentous fungi (Penicillium funiculosum) in solid medium. Characterization of the material was performed by weight loss, differential scanning calorimetry, carbonyl index determined by Fourier transformed infrared spectroscopy, contact angle, roughness, and scanning electron microscopy. Results revealed that PHBV/GNS nanocomposites can be totally degraded in the presence of Penicillium funiculosum; however, it will be necessary high incubation period. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44234.     

Fabrication of cellulose nanofiber‐based ultrafiltration membranes by spray coating approach

Ultrafiltration membranes containing a cellulose nanofiber barrier layer were fabricated by the spray coating method, where the thickness and uniformity of the barrier layer were systematically investigated as a function of air pressure, flow rate and concentration of the cellulose nanofiber suspension. In specific, the surface morphology of the barrier layer was studied by scanning electron microscopy and its uniformity was examined by the fluorescence dye imaging method. The ultrafiltration performance of the membranes fabricated by the spray coating method was also compared with that of the membranes made by the knife coating approach using dextran molecules as probe, where the former consistently exhibited significantly higher permeation flux while remaining the same rejection ratio. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44583.     

A novel polymer composite with a small optical band gap: New approaches for photonics and optoelectronics

In this article, a novel approach is presented for the preparation of small band‐gap polymer composites. The intensity of the surface plasmon resonance (SPR) peak increased from 0.64 to 3.2 for the chitosan–silver nitrate sample containing 1 wt % titanium dioxide (TiO₂). In the cases of 3 and 5 wt % added TiO₂ particles, the SPR peak disappeared. A wide shift of the absorption coefficient from 4.36 to 0.93 eV was observed. The smallest optical band gap of about 0.98 eV was achieved for the sample containing 3 wt % TiO₂ filler. The wide shift in the optical band gap was interpreted on the bases of the formation of metal‐induced gap states between the metallic silver particles and the TiO₂ structure. A novel approach was achieved that was an alternative method to Tauc's semi‐empirical model for band‐gap estimation. The optical dielectric loss parameter for the band‐gap study was easily calculated and analyzed, whereas it unfolded a deep knowledge from the physics point of view. The established quantum mechanical expression revealed a strong relationship between the energy band gap and the optical dielectric loss parameter. The scanning electron microscopy results show the leakage of white aggregated silver particles and distinguishable intense peaks of metallic silver particles between 3 and 3.3 keV appearing in the energy‐dispersive X‐ray spectrum. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44847.     

Modeling of tensile strength in polymer particulate nanocomposites based on material and interphase properties

In this work, a simple model is presented to determine tensile/yield strength in polymer nanocomposites containing spherical nanofillers based on material and interphase properties. The accuracy of the proposed model is estimated by comparing with the experimental strength of several samples from the literature. In addition, the effects of thickness (t) and tensile strength (σ_i) of the interphase as well as the radius (R) and volume fraction ( ) of the nanoparticles on the tensile strength are explained according to the proposed model. The high level of nanoparticle strength (more than 100 GPa) commonly leads to overestimates of the tensile strength of nanocomposites, whereas the assumption of correct interphase properties produces accurate calculations. The tensile strength of nanocomposites does not change at σ_i < 38 MPa, while it increases by 140% at t = 20 nm and σ_i = 90 MPa. However, a maximum 14% growth in tensile strength is obtained with the optimum values of = 0.04 and R = 10 nm. Therefore, the concentration and size of the nanoparticles have minor effects on the tensile strength of nanocomposites, but the major influences of interphase thickness and strength are pronounced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44869.     

Reinterpretation of the mechanical reinforcement of polymer nanocomposites reinforced with cellulose nanorods

The mechanical reinforcement of nanocomposites containing nanorods‐like fillers such as cellulose nanocrystals (CNCs) is often interpreted by adapting the classical parallel–series model, assuming a simple hyperbolic dependence between the percolation threshold and aspect ratio. However, such assumptions are valid only for nanorods with high aspect ratio and often are misinterpreting the reinforcement obtained at low volume fraction of filler loading. To elucidate this intriguing scenario, we proposed a new approach and validated it by compiling and reinterpreting some of available literature that represent the experimental reinforcement with CNCs. Our approach showed better accuracy, specifically for the cases of CNC nanorods with lower aspect ratio. We conclude that this route permits a more realistic evaluation of the mechanical reinforcement, where a physical parameter accounting the polymer filler association is introduced. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45254.     

Ionic‐liquid‐assisted three‐dimensional caged silica ablative nanocomposites

In this study, we demonstrated a novel three‐dimensional network of thermally stable fumed silica (FS)–resorcinol formaldehyde (RF) nanocomposites via an ionic‐liquid (IL)‐assisted in situ polycondensation process. The study involved subjecting the tailored nanocomposites to thermogravimetric analysis and oxyacetylene flame environment as per ASTM test standards for thermal ablative performance. X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, Raman spectroscopy, and wettability studies were undertaken to underline the improvement correlation in the microstructure and material properties. Significant reductions in the linear ablation rate (66%) and mass ablation rate (26.6%), along with lower back‐face temperature profiles, marked enhanced ablative properties. The increased char yield (33.3%) and higher temperatures for weight losses evinced the improved thermal stability of the modified RF resin. The uniformly dispersed fused nanosilica with a glassy coating morphology on the ablative surface acted as barrier to oxidation. The results signify that the IL‐assisted modification of the RF resin with FS significantly enhanced ablative performance. A viable replacement to the conventional phenolic nanocomposites for thermal ablative applications to buy critical time for the containment and suppression of thermal‐heat‐flux threats is of paramount importance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45328.