Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity

Polymeric nanofibers are materials that can be used as scaffolds in tissue engineering. Quercetin and curcumin are antioxidants because of scavenge free radicals and chelate metal ions properties, protecting tissues of lipid peroxidation. The objective of this study was to develop a scaffold with potential antioxidant activity that was produced from nanofibers consisting of polycaprolactone (PCL) and a blend of PCL/poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHB‐HV) with the addition of quercetin or curcumin as the bioactive compound. Curcumin and quercetin were integrated into the solution at a concentration of 3%. The electrospun nanofibers were characterized using calorimetry and thermogravimetric analysis, and the addition of bioactive compounds did not alter the thermal properties of the biomaterial. The antioxidant activity of scaffolds with the active compounds was evaluated by hydrate 2,2‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) methods. The scaffolds with PCL and PCL/PHB‐HV blend with quercetin exhibited higher antioxidant activity than curcumin with both methods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43712.     

Suture Fiber Reinforcement of a 3D Printed Gelatin Scaffold for Its Potential Application in Soft Tissue Engineering

Gelatin has excellent biological properties, but its poor physical properties are a major obstacle to its use as a biomaterial ink. These disadvantages not only worsen the printability of gelatin biomaterial ink, but also reduce the dimensional stability of its 3D scaffolds and limit its application in the tissue engineering field. Herein, biodegradable suture fibers were added into a gelatin biomaterial ink to improve the printability, mechanical strength, and dimensional stability of the 3D printed scaffolds. The suture fiber reinforced gelatin 3D scaffolds were fabricated using the thermo-responsive properties of gelatin under optimized 3D printing conditions (−10 °C cryogenic plate, 40–80 kPa pneumatic pressure, and 9 mm/s printing speed), and were crosslinked using EDC/NHS to maintain their 3D structures. Scanning electron microscopy images revealed that the morphologies of the 3D printed scaffolds maintained their 3D structure after crosslinking. The addition of 0.5% (w/v) of suture fibers increased the printing accuracy of the 3D printed scaffolds to 97%. The suture fibers also increased the mechanical strength of the 3D printed scaffolds by up to 6-fold, and the degradation rate could be controlled by the suture fiber content. In in vitro cell studies, DNA assay results showed that human dermal fibroblasts’ proliferation rate of a 3D printed scaffold containing 0.5% suture fiber was 10% higher than that of a 3D printed scaffold without suture fibers after 14 days of culture. Interestingly, the supplement of suture fibers into gelatin biomaterial ink was able to minimize the cell-mediated contraction of the cell cultured 3D scaffolds over the cell culture period. These results show that advanced biomaterial inks can be developed by supplementing biodegradable fibers to improve the poor physical properties of natural polymer-based biomaterial inks.     

Fabrication of tissue engineering scaffold from poly(vinylalcohol-co-ethylene)/poly(D,L-lactic-co-glycolic acid) blend: Miscibility,thermomechanical properties,and morphology

A series of poly(DL-lactide-co-glycolic acid) (PLGA) with poly(vinylalcohol-co-ethylene) (PEVAL) blends were prepared by solution casting method. The miscibility, thermal and mechanical properties have been investigated using FTIR, DSC, and DMA techniques. The miscibility of this pair of polymers throughout compositions was proved by these methods through the single T_g and the presence of interactions between the constituents. The TGA analysis revealed three degradation zones and no sensible enhancement in the thermal stability of PLGA was noted with addition of PEVAL content. The SEM analysis revealed that the draying method dramatically influence the surface morphology of copolymers and blend. The cross section micrograph of blend scaffold containing 50 wt% of PEVAL presents microcavities of diameter pores ranged between 70 and 170 µm interconnected and uniformly distributed in the polymer matrix.     

Effect of natural polyphenols on physicochemical properties of crosslinked gelatin‐based polymeric biocomposite

This work was aimed to study the effect of natural polyphenols extract (Acacia nilotica bark) on physicochemical properties of crosslinked gelatin‐poly(acrylamide‐co‐acrylic acid), Gel‐poly(AAm‐co‐Ac), polymeric biocomposite film. Gelatin‐based composite films have extensive application as biocompatible biomaterial as drug carriers, cosmetics, and agricultural food packaging. The prepared composite films were characterized using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC), in addition to the swelling and degradation behavior. UV‐Vis absorption spectra and scanning electron microscopy (SEM) were also applied to observe the interaction between Gel‐poly(AAm‐co‐Ac) and natural polyphenol (catechin). The study has demonstrated that the involvement of hydrogen bonding and hydrophobic interactions as the major forces involved in the stabilization of gelatin‐based polymeric biocomposite film by the plant polyphenols (catechin and gallic acid derivatives). Thermal stability studies of crosslinked gelatin‐based composite film revealed that A. nilotica bark extract stabilizes the gelatin molecules and leads to moderate increase of the denaturation temperatures relative to the uncrosslinked one. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Tailoring the swelling and glass‐transition temperature of acrylonitrile/hydroxyethyl acrylate copolymers

Novel polyacrylonitrile (PAN)‐co‐poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8, 12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy. Intrinsic viscosity measurements revealed that the molecular weights of the copolymers were quite enough to form ductile films. The influence of the molar fraction of hydroxyethyl acrylate on the glass‐transition temperature (T_g) and mechanical properties was demonstrated by differential scanning calorimetry and tensile test results, respectively. Additionally, thermogravimetric analysis of copolymers was performed to investigate the degradation mechanism. The swelling behaviors and densities of the free‐standing copolymer films were also evaluated. This study showed that one can tailor the hydrogel properties, mechanical properties, and T_g's of copolymers by changing the monomer feed ratios. On the basis of our findings, PAN‐co‐PHEA copolymer films could be useful for various biomaterial applications requiring good mechanical properties, such as ophthalmic and tissue engineering and also drug and hormone delivery. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of polyhydroxybutyrate‐co‐hydroxyvalerate/silk fibroin nanofibrous scaffolds for skin tissue engineering

Nanofibrous scaffolds were obtained by co‐electrospinning poly (3‐hydroxybuty‐rate‐co‐3‐hydroxyvalerate) (PHBV) and fibroin regenerated from silk in different proportions using 1,1,1,3,3,3‐hexafluoro‐2‐isopropanol (HFIP) as solvent. Field emission scanning electron microscope (FESEM) investigation showed that the fiber diameters of the nanofibrous scaffolds ranged from 190 to 460 nm. X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy analysis (FT‐IR) showed that the main structure of silk fibroin (SF) in the nanofibrous scaffold was β‐sheet. Compared to the PHBV nanofibrous scaffold, the surface hydrophilicity and water‐uptake capability of the PHBV/SF nanofibrous scaffold with 50/50 were improved. The results of cell adhesion experiment showed that the fibroblasts adhered more to the PHBV/SF nanofibrous scaffold with 50/50 than the pure PHBV nanofibrous scaffold. The proliferation of fibroblast on the PHBV/SF nanofibrous scaffold with 50/50 was higher than that on the pure PHBV nanofibrous scaffold. Our results indicated that the PHBV/SF nanofibrous scaffold with 50/50 may be a better candidate for biomedical applications such as skin tissue engineering and wound dressing. POLYM. ENG. SCI., 55:907–916, 2015. © 2014 Society of Plastics Engineers     

A Novel NIR Laser Switched Nanocomposite Hydrogel as Remote Stimuli Smart Valve

Thermosensitive nanocomposite (NC) hydrogels are considered as a significant kind of intelligent material to be utilized as sensor, biomaterial, drug carrier, etc. Recently, preparation of remotely controlled NC hydrogel with high‐performance attracts more and more concern. To produce facile remote‐stimuli thermosensitive NC hydrogel, a novel near‐infrared (NIR) laser switched CuS/clay/poly(OEGMA‐co‐MEO₂MA) hydrogel is demonstrated, which can be precisely remote‐stimulated by NIR irradiation based on the excellent NIR photothermal conversion property of CuS nanoparticle. The temperature change of hydrogel is related to the NIR intensity, CuS content, and crosslinking density. Moreover, the influences on dimensional variation of hydrogel on macroscale are systematically studied, and the hydrogel as smart liquid valve is further utilized which can be remotely controlled by NIR switch on/off successfully. Cyclic test illustrates that this novel CuS/clay/poly(OEGMA‐co‐MEO₂MA) hydrogel exhibits stable cyclic volume transition property which has promising applications in the areas of sensors, valves, and intelligent switches.     

Compressive properties and creep resistance of a novel,porous, semidegradable poly(vinyl alcohol)/poly(lactic‐co‐glycolic acid) scaffold for articular cartilage repair

Tissue engineering for articular cartilage repair has shown success in ensuring the integration of neocartilage with surrounding natural tissue, but the rapid restoration of biomechanical functions remains a significant challenge. The poly(vinyl alcohol) (PVA) hydrogel is regarded as a potential articular cartilage replacement for its fair mechanical strength, whereas its lack of bioactivity limits its utility. To obtain a scaffold possessing expected bioactivity and initial mechanical properties, we herein report a novel salt‐leaching technique to fabricate a porous PVA hydrogel simultaneously embedded with poly(lactic‐co‐glycolic acid) (PLGA) microspheres. Through the investigation of environmental scanning electron microscopy, we found that the porous PVA/PLGA scaffold was successfully manufactured. The compression and creep properties were also comprehensively studied before and after cell culturing. The relationship between the compressive modulus and strain ratio of the porous PVA/PLGA scaffold showed significant nonlinear behavior. The elastic compressive modulus was influenced a little by the porogen content, whereas it went higher with a higher PLGA microsphere content. The cell‐cultured scaffolds presented higher compressive moduli than the initial ones. The creep resistance of the cell‐cultured scaffolds was much better than that of the initial ones. In all, this new scaffold is a promising material for articular cartilage repair. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40311.     

Synthesis and characterization of poly(HEMA‐co‐MMA)‐g‐POSS nanocomposites by combination of reversible addition fragmentation chain transfer polymerization and click chemistry

New hybrid poly(hydroxyethyl methacrylate‐co‐methyl methacrylate)‐g‐polyhedral oligosilsesquioxane [poly(HEMA‐co‐MMA)‐g‐POSS] nanocomposites were synthesized by the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and click chemistry using a grafting to protocol. Initially, the random copolymer poly(HEMA‐co‐MMA) was prepared by RAFT polymerization of HEMA and MMA. Alkynyl side groups were introduced onto the polymeric backbones by esterification reaction between 4‐pentynoic acid and the hydroxyl groups on poly(HEMA‐co‐MMA). Azide‐substituted POSS (POSS? N₃) was prepared by the reaction of chloropropyl‐heptaisobutyl‐substituted POSS with NaN₃. The click reaction of poly(HEMA‐co‐MMA)‐alkyne and POSS? N₃ using CuBr/PMDEATA as a catalyst afforded poly(HEMA‐co‐MMA)‐g‐POSS. The structure of the organic/inorganic hybrid material was investigated by Fourier transformed infrared, ¹H‐NMR, and ²⁹Si‐NMR. The elemental mapping analysis of the hybrid using X‐ray photoelectron spectroscopy and EDX also suggest the formation of poly(HEMA‐co‐MMA)‐anchored POSS nanocomposites. The XRD spectrum of the nanocomposites gives evidence that the incorporation of POSS moiety leads to a hybrid physical structure. The morphological feature of the hybrid nanocomposites as captured by field emission scanning electron microscopy and transmission electron microscopic analyses indicate that a thick layer of polymer brushes was immobilized on the POSS cubic nanostructures. The gel permeation chromatography analysis of poly(HEMA‐co‐MMA) and poly(HEMA‐co‐MMA)‐g‐POSS further suggests the preparation of nanocomposites by the combination of RAFT and click chemistry. The thermogravimetric analysis revealed that the thermal property of the poly(HEMA‐co‐MMA) copolymer was significantly improved by the inclusion of POSS in the copolymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Design and Synthesis of Imidazo[2,1‐b]thiazole–Chalcone Conjugates: Microtubule‐Destabilizing Agents

A series of chalcone conjugates featuring the imidazo[2,1‐b]thiazole scaffold was designed, synthesized, and evaluated for their cytotoxic activity against five human cancer cell lines (MCF‐7, A549, HeLa, DU‐145 and HT‐29). These new hybrid molecules have shown promising cytotoxic activity with IC₅₀ values ranging from 0.64 to 30.9 μM . Among them, (E)‐3‐(6‐(4‐fluorophenyl)‐2,3‐bis(4‐methoxyphenyl)imidazo[2,1‐b]thiazol‐5‐yl)‐1‐(pyridin‐2‐yl)prop‐2‐en‐1‐one ( 11 x ) showed potent antiproliferative activity with IC₅₀ values ranging from 0.64 to 1.44 μM in all tested cell lines. To investigate the mechanism of action, the detailed biological aspects of this promising conjugate ( 11 x ) were carried out on the A549 lung cancer cell line. The tubulin polymerization assay and immunofluoresence analysis results suggest that this conjugate effectively inhibits microtubule assembly in A549 cells. Flow cytometric analysis revealed that this conjugate induces cell‐cycle arrest in the G2/M phase and leads to apoptotic cell death. This was further confirmed by Hoechst staining, activation of caspase‐3, DNA fragmentation analysis, and Annexin V–FITC assay. Moreover, molecular docking studies indicated that this conjugate ( 11 x) interacts and binds efficiently with the tubulin protein.     

Towards skin tissue engineering using poly(2-hydroxy ethyl methacrylate)-co-poly(N-isopropylacrylamide)-co-poly(ε-caprolactone) hydrophilic terpolymers

Poly(2-hydroxy ethyl methacrylate)-co-poly(N-isopropylacrylamide)-co-poly(ε-caprolactone) (PHEMA-co-PNIPAAm-co-PCL) terpolymers and polyaniline (PANI) were applied to develop hydrophilic, conductive, and biocompatible fibroblast scaffolds. Reversible addition of fragmentation chain transfer (RAFT) and ring opening polymerizations were the synthesis methods. PHEMA and PNIPAAm segments reflected hydrophilicity and biocompatibility, PCL led to appropriate mechanical characteristics, and presence of PANI induced conductivity to scaffolds. Scaffolds imitated natural microenvironment of extra cellular matrix (ECM) to regulate cell attachment, proliferation, and differentiation for electrical conductivity (0.04?S cm^?1) and hydrophilicity (50?±?5°). In vitro cytocompatibility investigations performed over 168?h indicated that nanofibers were non-toxic to mouse fibroblast L929 cells.     

Studies on comonomer compositional distribution and its effect on some physical properties of bacterial poly(3‐hydroxybutyric acid‐co‐3‐hydroxypropionic acid)

Comonomer compositional distribution of bacterially synthesized poly(3‐hydroxybutyric acid‐co‐3‐hydroxypropionic acid) [P(3HB‐co‐3HP)] was investigated via solvent/non‐solvent fractionation techniques. The result indicates the presence of extremely broad comonomer compositional distribution in the original bacterial product. Furthermore, utilizing compositionally fractionated bacterial copolyesters with much narrower comonomer compositional distributions, the 3HP comonomer content‐dependence of their thermal and crystallization behavior was studied by means of differential scanning calorimeter (DSC) and polarized optical microscopy and the results compared with those of unfractionated copolyesters. It was revealed that the physical features of the fractionated copolyester P(3HB‐co‐3HP)s strongly depends on the 3HP comonomer content. In addition, to clarify the effect of the compositional distribution on the properties of the unfractionated copolyester, the miscibility between bacterial poly(3‐hydroxybutyric acid) [P(3HB)] and two fractionated P(3HB‐co‐3HP) samples with 11.3 and 14.9% 3HP was investigated for blends obtained by solvent casting techniques. The evidence of thermal analysis and spherulitic growth rates imply miscibility of the P(3HB)/3HB‐rich P(3HB‐co‐3HP) binary blends. © 1999 Society of Chemical Industry     

Application of polymeric nanofibers in medical designs,part III: Musculoskeletal and urological tissues

Nanotechnology has potential applications in different sciences, especially in the biological sciences and medicine. The nanomaterials are applicable materials with different morphologies such as nanoparticles, nanotubes, nanowires, nanorods, and nanofibers. The development of nanofibers has greatly enhanced the scope for fabricating designs that can be potentially used in medical sciences. In part III the author summarizes the currently available applications of nanofibers in musculoskeletal and urologic tissues. The graphical abstract shows computed tomography analysis and macroscopic images of calvarial defects in rat, with the regeneration result, after four weeks, of bone healing upon implantation of scaffolds in the defect. (A and D) Control group; (B and E) poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/nanohydroxyapatite (PHBV/nHAp) scaffold; and (C and F) PHBV/nHAp scaffold with unrestricted somatic stem cells precultured in vitro.     

Aromatic Linkers Unleash the Antiproliferative Potential of 3-Chloropiperidines Against Pancreatic Cancer Cells

In this study, we describe the synthesis and biological evaluation of a set of bis-3-chloropiperidines (B−CePs) containing rigid aromatic linker structures. A modification of the synthetic strategy also enabled the synthesis of a pilot tris-3-chloropiperidine (Tri-CeP) bearing three reactive meta-chloropiperidine moieties on the aromatic scaffold. A structure–reactivity relationship analysis of B−CePs suggests that the arrangement of the reactive units affects the DNA alkylating activity, while also revealing correlations between the electron density of the aromatic system and the reactivity with biologically relevant nucleophiles, both on isolated DNA and in cancer cells. Interestingly, all aromatic 3-chloropiperidines exhibited a marked cytotoxicity and tropism for 2D and 3D cultures of pancreatic cancer cells. Therefore, the new aromatic 3-chloropiperidines appear to be promising contenders for further development of mustard-based anticancer agents aimed at pancreatic cancers.     

Miscibility and crystallization behaviors of poly(3‐hydroxybutyrate‐co‐11%‐4‐hydroxybutyrate)/Poly(3‐hydroxybutyrate‐co‐33%‐4‐hydroxybutyrate) blends

Biopolyesters poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) with an 11 mol % 4HB content [P(3HB‐co‐11%‐4HB)] and a 33 mol % 4HB content [P(3HB‐co‐33%‐4HB)] were blended by a solvent‐casting method. The thermal properties were investigated with differential scanning calorimetry. The single glass‐transition temperature of the blends revealed that the two components were miscible when the content of P(3HB‐co‐33%‐4HB) was less than 30% or more than 70 wt %. The blends, however, were immiscible when the P(3HB‐co‐33%‐4HB) content was between 30 and 70%. The miscibility of the blends was also confirmed by scanning electron microscopy morphology observation. In the crystallite structure study, X‐ray diffraction patterns demonstrated that the crystallites of the blends were mainly from poly(3‐hydroxybutyrate) units. With the addition of P(3HB‐co‐33%‐4HB), larger crystallites with lower crystallization degrees were induced. Isothermal crystallization was used to analyze the melting crystallization kinetics. The Avrami exponent was kept around 2; this indicated that the crystallization mode was not affected by the blending. The equilibrium melting temperature decreased from 144 to 140°C for the 80/20 and 70/30 blends P(3HB‐co‐11%‐4HB)/P(3HB‐co‐33%‐4HB). This hinted that the crystallization tendency decreased with a higher P(3HB‐co‐33%‐4HB) content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of orotic acid as a nucleating agent on the crystallization of bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) copolymers

The kinetics of crystallization induced by orotic acid (OA) and boron nitride (BN) as nucleating agents were investigated for bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s (P(HB‐co‐HH)s) containing from 0 to 18% HH monomer units. The nucleation efficiency of these two chemicals was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that both orotic acid and boron nitride are able to nucleate the crystallization of PHB. In the case of P(HB‐co‐HH) copolymers, orotic acid showed an outstanding nucleating effect. The comparison of half‐crystallization times shows that for P(HB‐co‐10% HH), the crystallization initiated by orotic acid is more than three time faster than the one induced by boron nitride (t_1/2BN/t_1/2OA(60°C) = 3.7 and t_1/2BN/t_1/2OA(90°C) = 4.5). According to the fact that orotic acid is a biodegradable, biocompatible and a nontoxic chemical, this nucleating agent is a promising solution for PHAs used in medical applications such as implants. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

High tensile strength fiber of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] processed by two‐step drawing with intermediate annealing

High tensile strength fibers of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] [P(3HB‐co‐3HH)], a type of microbial polyesters, were processed by one‐step and two‐step cold‐drawn method with intermediate annealing. Thermal degradation behaviors were characterized by differential scanning calorimeter and gel permeation chromatography measurements. Thermal analyses were revealed that molecular weights decreased drastically within melting time at a few minute. One‐step cold‐drawn fiber with drawing ratio of 10 showed tensile strength of 281 MPa, while tensile strength of as‐spun fiber was 78 MPa. When two‐step drawing was applied for P(3HB‐co‐3HH) fibers, the tensile strength was led to 420 MPa. Furthermore, the optimization of intermediate annealing condition leads to enhance the tensile strength at 552 MPa of P(3HB‐co‐3HH) fiber. Wide‐angel X‐ray diffraction measurements of these fibers suggest that the fibers with high tensile strength include much amount of the planer‐zigzag conformation (β‐form) as molecular conformation together with 2₁ helix conformation (α‐form). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41258.     

A parametric study on the processing parameters and properties of a porous poly(DL‐lactide‐co‐glycolide) acid 85/15 bioscaffolds

This study presents a comprehensive parametric study on the effects of processing parameters on the poly(DL‐lactide‐co‐glycolide) acid (PLGA) 85/15 scaffold's physical properties. Porous PLGA 85/15 scaffolds were prepared using a gas foaming/salt leaching technique. The processing parameters under examination for the gas foaming/salt leaching method included: gas saturation pressure (SP), gas saturation time, and NaCl/polymer mass ratio (NaCl/PMR). The physical properties considered in this study were the scaffold density, the scaffold porosity, and the average pore size of the scaffold. Young's moduli in compression, as well as the pore density (PD) inside the scaffold, were also studied. The results demonstrated optimum correlations of processing parameters are required to produce a scaffold with a high level of interconnectivity. In general, all scaffolds yielded by this experiment exhibited a porosity more than 90%, a relative density ranging from 0.0534 to 0.149 g/cm³, a PD ranging from 1.51 × 10⁶ to 6.72 × 10⁶ pores/cm³, and a compressive modulus ranging from 0.07 to 0.84 MPa. It was determined that the NaCl/PMR was the parameter that had the most significant effect on the physical properties of the scaffold. The average pore size was affected slightly by the SP only, and it was observed that the pore size was equivalent to the size of the NaCl particles used to make the scaffold. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Preparation and characterization of polystyrene/titanium dioxide composite particles containing organic ultraviolet‐stabilizer groups

Polystyrene/titanium dioxide (TiO₂) composite particles containing organic ultraviolet (UV)‐stabilizer groups were prepared by the emulsion copolymerization of styrene and 2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylpropoxy)benzophenone with sodium sulfopropyl lauryl maleate as a surfactant in the presence of rutile TiO₂ modified with 3‐(trimethoxysilyl) propyl methacrylate, and the product was poly[styrene‐co‐sodium sulfopropyl lauryl maleate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylpropoxy) benzophenone] [poly(St‐co‐M12‐co‐BPMA)]/TiO₂ composite particles. The structures of the composite particles were characterized with Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The Fourier transform infrared and UV–vis measurements showed that poly(St‐co‐M12‐co‐BPMA) was grafted from the surface of TiO₂, and this copolymer possessed a high absorbance capacity for UV light, which is very important for improving the UV resistance of polystyrene. The thermogravimetric analysis measurements indicated that the percentage of grafting and the grafting efficiency could reach 513.9 and 59.9%, respectively. The differential scanning calorimetry measurement indicated that the glass‐transition temperature of the poly(St‐co‐M12‐co‐BPMA)/TiO₂ composite particles was higher than that of poly (St‐co‐M12‐co‐BPMA).These research results are very important for preparing polystyrene with high UV resistance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Gold deposition on Fe3O4/(co)Poly(N‐octadecyl methacrylate) hybrid particles to obtain nanocomposites With ternary intrinsic features

Here, nanocomposite particles with three domains including magnetite nanoparticles, poly(N‐octadecyl methacrylate) (PODMA) or poly(N‐octadecyl methacrylate‐co‐1‐vinylimidazole) (P(ODMA‐co‐VIMZ)), and gold nanoparticles were prepared. Fe₃O₄ nanoparticles with narrow particle size distribution were prepared through a synthetic route in an organic phase in order to achieve good control of the size and size distribution and prevent their aggregation during their preparation. These magnetite nanoparticles, ～ 5 nm in size, were then encapsulated and well‐dispersed in PODMA and P(ODMA‐co‐VIMZ) matrices via a miniemulsion polymerization process to obtain the corresponding nanocomposite particles. The results revealed that Fe₃O₄ nanoparticles were encapsulated and did not migrate towards the monomer/water interface during polymerization. The resulting latex was used as a precursor for the adsorption of Au³⁺ ions on the surface of the polymeric particles and subsequent reduction to produce Fe₃O₄/P(ODMA‐co‐VIMZ)/Au nanocomposite particles. The morphology of the particles from each step was fully characterized by TEM and AFM, and the results of DLS analysis showed their size and size distribution. Measurement of magnetic properties illustrated the superparamagnetic characteristic of the products and it was observed that the encapsulation process and deposition of gold had no effect on the magnetic properties of the resulting particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013