This is an editorial article. It has no abstract.
The presented research shows the results of the investigations on the synthesis of polymeric materials through the fusion reaction of modified palm oil derivatives. First, raw palm oil was subjected to epoxidation. In order to determine the best reaction conditions, the process was conducted under four different conditions. In the next stage, the polyaddition products were obtained by the reaction of epoxidized palm oil (EOP) and bisphenol A (BPA), through the epoxy fusion process. On the basis of the performed studies, using both analysis of the content of functional groups, as well as data obtained from FT-IR, GPC, 1H NMR and 13C NMR analyses of the chemical structure of all obtained palm oil derivatives was determined. It was found that during the polyaddition process, after the reaction of the oxirane group of EOP with the hydroxyl group of BPA, a subsequent reaction occurred, involving the reaction of a free phenolic group with the following macromolecule of modified oil. Finally, obtained bio-polyaddition products were used: (1) to obtain ‘stand-alone’ epoxy-polyurethane materials and (2) as modifiers of a commercial bisphenol A-based low molecular weight epoxy resin.
We designed a series of thermo- and electro-induced double-stimulus shape-memory composites comprising natural Eucommia ulmoides rubber (EUR) and conductive carbon blacks (CCBs). This paper discusses the mechanical, cure, thermal, and shape-memory properties of the composites. The shape-memory properties of the composites were investigated under two stimulation conditions, heat and electricity. In these composites, the crosslinked networks acted as the fixed domain, and the crystalline regions of EUR worked as the reversible domain during the shape-memory process. CCBs were embedded in the composites as a conductive component, which endowed their electrical stimulation response. These composites exhibited excellent thermal and electrical shape-memory properties. We studied the shape-memory behavior of composites under different voltage conditions during the electrical stimulation process. Due to its excellent electrical stimulation response, natural EUR can be used in intelligent and multi-response shape-memory applications.
Herein, a grafted copolymer composed of carboxymethylcellulose (CMC) and polyethylene-glycol-aminated (PEG-NH2) was successfully synthesized via a facile ionic interaction and scalable route in the presence of EDC/NHS (N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide) activators. From Fourier transform infrared (FTIR) spectroscopy, the absorption peak at 1652 cm–1 corresponded to –NH groups of PEG-NH2. After grafting, the grafted CMC-PEG was characterized for surface morphology, crystallinity, functional groups determination, and thermal analysis. No cytotoxicity effect was observed in normal human dermal fibroblasts (NHDFs) cells following exposure to the grafted CMC-PEG up to 2 mg/ml. The rheological studies suggested that the optimized 10% (w/v) grafted CMC-PEG hydrogels crosslinked with 5% (w/v) citric acid (CA) exhibited better mechanical properties compared to the non-grafted CMC. This work highlights the characterizations of grafted CMC-PEG and demonstrates the potential of grafted CMC-PEG hydrogels crosslinked with CA for advanced 3D-bioprinting or as injectable hydrogels in various biomedical applications such as tissue engineering, wound dressing materials, and drug delivery systems.
The immiscible polymeric blend of polypropylene (PP) and polyvinyl alcohol (PVA) was manufactured into multifilament fibers via the melt-spinning process, of which the mass ratio of PP to PVA was selected as 30%/70%. The PP micro/nanofibers were accessible with the removal of PVA in hot water. Kaolinite particles were also incorporated to modify the micro/nanofibers surface, for functionalization efficiencies play a useful role with the aid of a high specific surface area. The octahedral layers of kaolinite particles were grafted with a regioselective process by octadecyl (C18H37-) groups modified into Janus particles to better localize the fillers at the biphasic interface. As a result, the kaolinite particles having a Janus morphology are more distributed at the interface of the polymers, as observed by SEM. The knitting structures are capable of being maintained after the selective phase extraction leaving numbers of micro/nanofibers. After the incorporation of kaolinite particles, there are still some amounts of particles appearing on the surface of PP micro/nanofibers. Besides, there is a mechanical enhancement of the knitted fabrics, especially when the Janus particles are used, even after the selective phase extraction, which the conventional chemical treatment cannot bring. This study sets an example of fabricating PP micro/nanofiber fabrics surface-modified and mechanically enhanced using Janus kaolinite particles.
Poly-ε-caprolactone (PCL) microspheres containing graphene nanopowders were prepared by oil-in-water (o/w) emulsion solvent- evaporation technique. For the emulsification study, an oil phase (PCL solution in dichloromethane or chloroform) and a water phase (3 wt% aqueous polyvinyl alcohol solution) was utilized. Effect of solvent type, stirring speed, and graphene addition on the structural and morphological properties of the prepared microspheres was investigated. Results showed that stable emulsification of oil in water (o/w) was achieved with a 5 wt% PCL. A decrease in particle size was observed for the PCL microspheres prepared by chloroform (19.02±6.41 µm) compared to the microspheres obtained by dichloromethane (59.81±23 µm) under the same conditions. Results also revealed that the addition of graphene changed the morphology and particle size of the microspheres significantly. Hollow PCL microspheres were obtained in the presence of graphene nanopowders when chloroform was utilized as the solvent. Drug release experiments indicated that hollow PCL-graphene composite microspheres have improved release behavior compared to bare solid PCL microspheres. The particles prepared in the study have the potential to be used in drug delivery and tissue engineering applications.
Molecularly imprinted polymers (MIP) are materials capable of recognizing specific molecules, usually through non-covalent bonds. In this work, gallic acid (GA) was selected as the imprinting molecule, and MIP for GA (MIP-GA) was synthesized by bulk polymerization. X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) confirmed the MIP-GA recognition property. Poly(caprolactone) mat containing MIP-GA particles (MIM-GA) was produced by electrospinning, which was morphologically characterized by Scanning electron microscopy (SEM). Functionalized MIM-GA was obtained by washes sequence in methanol for the GA removal from MIM-GA. The GA removal was confirmed by High-performance liquid chromatography (HPLC) with UV-Vis detection at 214 and 268 nm. The functionalized MIM-GA immersed in GA methanolic solution with a concentration of 1.0 mM extracted 96±1.5% of GA at t =150 minutes. The vibrational modes obtained from FT-IR spectra confirmed the chemical composition of MIM-GA and its functionalization through of band at 770 cm–1. The contact angle measurements were 134.0±1.0° for electrospun MIM-GA and 125.0±1.2° for functionalized MIM-GA. The decrease was due to the absence of GA after the functionalization process. The produced MIM-GA by electrospinning acquired the recognition property of the GA imprinted polymer synthesized, which can be used for the specific detection, extraction, and purification of this important natural polyphenol.
Elucidating the role of clay-modifier on the properties of silica- and silica/nanoclay-reinforced natural rubber tire compounds
S. Sattayanurak, K. Sahakaro, W. Kaewsakul, W. K. Dierkes, L. A. E. M. Reuvekamp, A. Blume, J. W. M. Noordermeer
Vol. 15., No.7., Pages 666-684, 2021
Vol. 15., No.7., Pages 666-684, 2021
Organoclay (OC) is one of the potential secondary fillers to be applied in silica-reinforced rubber compounds for tire applications. Commercial OC contains a large proportion of surface modifier, i.e., dimethyl dihydrogenated tallow ammonium chloride (2HT) type, that has an influence on the compound properties. To elucidate the effect of 2HT on the properties of silica-Natural Rubber (NR) compounds, a silica-only system, silica/OC, and silica/montmorillonite (MMT)/2HT added in situ during mixing, were comparatively studied. Irrespective in which form 2HT is added, it has potential to further enhance the performance of silica-NR compounds. Incorporation of 2HT suppresses filler flocculation and improves processability. Overall, the silica-only filled compound shows better mechanical properties than the silica/clay dual filler systems. The use of a small amount (2.4–4.7 phr) of 2HT improves 300% modulus, tear strength and abrasion resistance. The silica/OC gives better mechanical properties than the silica/MMT/2HT. With the optimum content of 2HT, a higher tan δ at –20 °C and lower tan δ at 60 °C can be achieved, all showing the beneficial potential of utilization of the modifying agent to improve wet traction and rolling resistance of silica-based tire tread compounds.