Simultaneously reinforcing and toughening poly(lactic acid) by incorporating reactive melt-functionalized silica nanoparticles

Simultaneously reinforcing and toughening poly(lactic acid) (PLA) was carried out by adding a small amount of functionalized SiO₂ (f-SiO₂) with grafting degraded PLA chains in this work. Typically, the high shear force and high temperature condition of melt blending were employed to accelerate the degradation of PLA and graft the degraded PLA chains onto SiO₂.The structure characterizations revealed that large quantity of degraded PLA chains were grafted onto the surface of SiO₂ by transesterification, condensation, and esterification reactions during melt blending. Due to the improvement in dispersion and interfacial interaction in PLA matrix, the f-SiO₂ exhibited an effective reinforcing and toughening effect for PLA, where the tensile strength, elongation at break, and impact toughness of PLA/f-SiO₂ nanocomposite increased by 14.9, 47.8, and 30.3% compared to neat PLA. Besides, the degree of crystallinity of PLA was significantly improved by the added f-SiO₂, which also contributed to improving mechanical properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48834.     

Facile modification of polysulfone hollow-fiber membranes via the incorporation of well-dispersed iron oxide nanoparticles for protein purification

Protein existence in wastewater is an important issue in wastewater management because proteins are generally present as contaminants and foulants. Hence, in this study, we focused on designing a polysulfone (PSf) hollow-fiber membrane embedded with hydrophilic iron oxide nanoparticles (IONPs) for protein purification by means of ultrafiltration. Before membrane fabrication, the dispersion stability of the IONPs was enhanced by the addition of a stabilizer, namely, citric acid (CA). Next, PSf–IONP–CA nanocomposite hollow-fiber membranes were prepared via a dry–wet spinning process and then characterized in terms of their hydrophilicity and morphology. Ultrafiltration and adsorption experiments were then conducted with bovine serum albumin as a model protein. The results that an IONP/CA weight ratio of 1:20 contributed to the most stable IONP dispersion. It was also revealed that the membrane incorporated with IONP–CA at a weight ratio of 1:20 exhibited the highest pure water permeability (58.6 L m⁻² h⁻¹ bar⁻¹) and protein rejection (98.5%) while maintaining a low protein adsorption (3.3 μg/cm²). The addition of well-dispersed IONPs enhanced the separation features of the PSf hollow-fiber membrane for protein purification. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47502.     

Controllable preparation of uniform polystyrene nanospheres with premix membrane emulsification

The expansion of polymer nanosphere applications requires facile and versatile preparation techniques. In this study, combining circled premix membrane emulsification and thermally initiated miniemulsion polymerization, we developed a new strategy for preparing uniform polystyrene nanospheres within a duration as short as 1 h. The size of the nanospheres, ranging from 40 to 120 nm, was dependent on the premix membrane emulsification cycle number, the transmembrane flow rate, and the membrane pore size; this was almost consistent with characterizations of droplet size evolution. The coefficient of variation, around 15%, indicated that the size distribution of the nanospheres was still narrow, even as the monomer‐to‐water ratio was as high as 0.2. This method may be competitive for further applications because of its high production efficiency and low system requirements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Highly antibacterial and toughened polystyrene composites with silver nanoparticles modified tetrapod‐like zinc oxide whiskers

In this work, high‐performance multifunctional composites were obtained by melt blending silver deposited tetrapod‐like zinc oxide whiskers (Ag‐ZnOw) with polystyrene (PS). The chemical, spectroscopic, antibacterial, mechanical, and morphological properties of the PS/Ag‐ZnOw composites were carefully investigated and discussed. The obtained PS/Ag‐ZnOw composites characterized remarkable antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Moreover, it is found that impact strength of the composite increase with increasing nanofiller concentration (up to 0.25 wt %). Morphological characterization of the impact fractured surface of composites revealed that toughening was achieved through uniform filler distribution in the polymer matrix, and anchoring effect was imparted by the tetrapod‐like shape of ZnO whiskers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40900.     

Synthesis of Fe3O4@SiO2@MPS@P4VP nanoparticles for nitrate removal from aqueous solutions

In this study, synthesis of Fe₃O₄@SiO₂@MPS@poly(4‐vinylpyridine) core‐shell‐shell structure was investigated as an efficient adsorbent for removal of nitrate ions from aqueous solutions. Fe₃O₄ nanoparticles were initially prepared by co‐precipitation method, then the surface of Fe₃O₄ was coated with SiO₂ through a modified St öber method. Finally, the Fe₃O₄@SiO₂ nanoparticles were modified by 3‐(trimethoxysilyl) propyl methacrylate followed by emulsion polymerization of 4‐vinylpyridine. The resultant material was acidified in HCl solution to be effective for nitrate removal. The synthesized sample was characterized by X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, Fourier‐transform infrared spectra, thermogravimetric analysis (TGA), and vibrating sample magnetometer. The removal efficiency was optimized for some experimental parameters such as pH, contact time, and amount of sorbent loading. The maximum predictable adsorption capacity was 80.6 (mg nitrate/g sorbent) at optimum conditions. Also, regeneration of the nitrate adsorbed particles was possible with NaOH solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44330.     

Textile with a hydrogel and iron oxide nanoparticles for wastewater treatment after reactive dyeing

In this work, we describe for the first time the synthesis of a hydrogel with iron oxide nanoparticles, uniformly distributed in its structure on a polyamide fabric by surface initiated photopolymerization. The type of outgoing iron ions Fe(II), Fe(III), and the combination between them influences the properties of the iron oxide particles and the obtained composite materials (PAF2, PAF3, and PAF32). All composite materials have been investigated as catalysts in heterogeneous Fenton process for treating real industrial wastewater after dyeing of cotton fabric with reactive dye Drimarene K-7B. Different conditions on the degradation of this dye have been investigated. The best result for discoloration has been obtained with PAF2 at concentration 9.4 g L⁻¹ and pH = 2.2 in the presence of H₂O₂ (93.3 mmol L⁻¹, where 78% of dye was degraded for 24 h and 90.5%-for 48 h. The high salinity of wastewaters, typical for dyeing with reactive dyes favors discoloration, while surface-active agents hinder the process. The obtained material is reusable and is more effective in less polluted water solutions. It has been found that the composite material can be used repeatedly.     

Synergistic effect of silica nanoparticles in the matrix of a poly(ethylene glycol) diacrylate coating layer for the surface modification of polyamide nanofiltration membranes

In this study, a commercial polyamide nanofiltration membrane was modified by a combination of poly(ethylene glycol) diacrylate (PEGDA) in situ polymerization and silica (SiO₂) nanoparticles. The PEGDA layer was polymerized on the surface of the membranes alone or mixed with SiO₂ nanoparticle. The surface modification influence on the water flux, salt rejection, and antifouling behavior was investigated. The effects of the nanoparticles and PEGDAylation on the membrane properties were characterized by Fourier transform infrared spectroscopy, contact angle measurement, and scanning electron microscopy analyses. The membranes that were in contact with 30 wt % PEGDA and then treated with ultraviolet light for 5 min had a better water flux than the unmodified membrane. The fouling resistance of the membranes to a foulant solution containing bovine serum albumin, humic acid, and sodium sulfate were studied, and the results show that the membrane with 30 wt % PEGDA had better antifouling properties. After the weight percentage of PEGDA for the prepolymerization solution was optimized (30 wt % was the best), the SiO₂ nanoparticle concentration in the prepolymerization matrix was optimized. The presence of SiO₂ nanoparticles in the PEGDA layer increased the membrane flux. The maximum water flux and good antifouling properties were obtained for 0.5 wt % SiO₂ nanoparticles in a 30 wt % PEGDA layer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43793.     

Thin film composite forward osmosis membranes with poly(2‐hydroxyethyl methacrylate) grafted nano‐TiO2 as additive in substrate

The poly(2‐hydroxyethyl methacrylate) grafted titanium dioxide nanoparticles were synthesized and added to the substrate of flat‐sheet thin film composite forward osmosis (TFC‐FO) membranes. The hydrophilicity of substrate was improved, which was advantageous to enhance the water flux of TFC‐FO membranes. The membranes containing a 3 wt % TiO₂‐PHEMA in the substrate exhibited a finger‐like structure combined with sponge‐like structure, while those with lower or without TiO₂‐PHEMA content showed fully finger‐like structures. As for FO performance, the TFC‐FO membranes with 3 wt % TiO₂‐PHEMA content achieved the highest water flux of 42.8 LMH and 24.2 LMH against the DI water using 2M NaCl as the draw solution tested under the active layer against draw solution (AL‐DS) mode and active layer against feed solution (AL‐FS) mode, respectively. It was proven that the hydrophilic property of membrane substrates was a strong factor influencing the water flux in FO tests. Furthermore, the structural parameter was remarkably decreased with an increase of TiO₂‐PHEMA content in membrane substrate, indicating the reducing of internal concentration polarization. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43719.     

Conversion of expanded polystyrene waste to nanoparticles via nanoprecipitation

The conversion of polymeric waste into useful, value added material is considered as an efficient method for polymeric waste management because of the environmental issues caused by such materials. This work proposes a simple, cost‐effective strategy for the conversion of expanded polystyrene waste into polystyrene nanoparticles via nanoprecipitation. In this method, expanded polystyrene is dissolved in a suitable solvent for example, tetrahydrofuran and added to a nonsolvent, such as water, to precipitate polystyrene nanoparticles of diameter less than 500 nm. The study also investigates the influence of various process parameters such as, initial concentration of expanded polystyrene, the speed of stirring, the solvent to water volume ratio and the solvent type used for nanoprecipitation, on the size and polydispersity of the precipitated PS nanoparticles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42904.     

Synthesis of polyacrylonitrile/polystyrene latex particles that contain platinum

Studies on the incorporation of highly dispersed platinum (Pt) nanoparticles into proton‐exchange membrane fuel cells (PEMFC) as a possible catalyst have gained tremendous attention in the past decade. The major obstacle to fully commercialize PEMFCs is the high cost of Pt as the catalyst. In this study, the incorporation of highly dispersed platinum molecules into poly(acrylonitrile) (PAN) or polystyrene (PS)/PAN latex particles was carried out to form a possible a catalyst precursor for fuel‐cell applications. Pt‐containing PAN/PS particles were prepared using miniemulsion polymerization. Both transmission electron microscopy (TEM) and induction coupled plasma (ICP) measurements indicated that Pt salt was encapsulated into PAN/PS copolymer latex particles. In addition, the encapsulation percentages of Pt salt are all above 90% for different PAN/PS ratios. Additional experiments have been carried out to convert these Pt molecules into nanoparticles and will be elaborated upon subsequent studies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41933     

Sorption of propylene and propane in polyurethane membranes containing silver nanoparticles

The preparation of a facilitated transport membrane of polyurethane (PU) containing silver nanoparticles is reported. The propylene and propane sorption was investigated aiming at the selective separation from C3s mixtures. The silver particles were photogenerated in situ into the polyurethane matrix using UV light radiation and silver triflate (AgCF₃SO₃) as precursor. The morphological properties of these membranes (PUAg) reveled great dispersion of silver particles, which size was smaller than 110 nm. The propylene solubility in PUAg resulted more than four times superior to the one for the pure PU membrane, revealing the high affinity between silver and propylene. Flory–Huggins theory was more accurate to describe the propylene sorption behavior in PUAg than Henry's model. The ideal solubility selectivity of PUAg membrane resulted 24.4, indicating that there is a good potential for an industrial application aiming at the separation of propylene/propane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42916.     

Preparation of zinc oxide nanocrystals with high stability in the aqueous phase

ZnO nanocrystals (NCs), potential candidates for photoluminescent applications, have attracted increasing attention recently because of their good biocompatibility, low cost, and convenient synthesis. However, their stability and fluorescent quenching, particularly in the aqueous phase, still hampers their use in biological applications. We report herein the synthesis of ZnO NCs modified by amphiphilic methoxy poly(ethylene glycol)‐grafted poly(styrene‐alt‐maleic anhydride) (SMA‐g‐MPEG) copolymer based on the sol–gel method. We demonstrated a simple solution to address those challenges. Compared with unmodified ZnO NCs, SMA‐g‐MPEG modified ZnO NCs exhibited a significantly improvement in the stability and photoluminescent properties in the aqueous phase over current unmodified ones. This simple synthesis provides a novel platform for the preparation of ZnO NCs for biological applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Investigation on carbon nanotube oxide for anhydrous proton exchange membranes application

The widespread participation of polymers in the membrane preparation has been considering to be critical for the development of proton exchange membranes (PEMs). For the polymers without functional groups to conduct protons, the introduction of proton conduction carriers with the formation of composite membranes is an effective strategy to prepare PEMs with the outstanding proton conductivity. However, there remains a potential risk of the components leaking from composite membranes due to the lack of the interaction force. Here, the composite of carbon nanotube oxide (OCNT) assembling with cadmium telluride (CdTe) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆) was introduced into the system of phosphoric acid (PA) doping poly(vinylidene fluoride) (PVDF) with the formation of PVDF/OCNT-CdTe-bmimPF₆/85%PA membranes. PA molecules are anchored by the inorganics of OCNT-CdTe-bmimPF₆ and are stabilized in membranes. The high and stable proton conductivity values at the elevated temperature are obtained comparing the reported PVDF/bmimPF₆/PA membranes. Specifically, the proton conductivity value reached 1.28 × 10⁻¹ S/cm at 160 °C and the value is stable 1.70 × 10⁻² S/cm at 120 °C lasting for 350 h. The fine stability in components could make the membranes extricate from the predicament of proton conductivity decline exceeding 120 °C under anhydrous conditions in PVDF/bmimPF₆/PA membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48833.     

Removal of hexavalent chromium in wastewater by polyacrylamide modified iron oxide nanoparticle

Iron oxide nanoparticle has been successfully modified by polyacrylamide and the polyacrylamide modified magnetic nanoparticles (PMMNs) were applied to remove Cr(VI) in wastewater. The vibrating sample magnetometer (VSM) spectra indicated the large saturation magnetization and superparamagnetic property of the PMMNs. This made the polyacrylamide modified iron oxide easily separate with liquid phase. Scanning electron microscope (SEM) results showed that both the synthesized iron oxide and the PMMNs were nanoscale. Batch adsorption studies had been carried out to determine the effect of pH, contact time, Cr(VI) initial concentration, and coexisting salts on the adsorption of Cr(VI). Maximum removal (98.30%) was observed from an initial concentration of 100 mg L^?1 Cr(VI) at pH 3.0, 30°C. This process followed pseudo‐second‐order kinetics model and the equilibrium time was 40 min. The experimental data fitted the Langmuir isotherm better than Freundlich. Maximum adsorption amount of Cr(VI) by PMMN was 35.186 mg g^?1. The effect of coexisting salts on Cr(VI) removal was not apparent even the concentration of salt was 10 times as big as the low concentration, 0.01M. It had been proposed that the mechanism of Cr(VI) uptake onto PMMN was adsorption‐coupled reduction. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40945.     

Synthesis and comparison of crosslinked peptide nanoparticles based on diphenylalanine derivatives

Self‐assembly is a mechanism that creates novel nanomaterials with amplified properties but with stability challenges. In this report, highly stable and biocompatible anionic zwitterionic diphenylalanine nanoparticles (ZFFNPs), which are novel for the literature, are demonstrated. ZFF was crosslinked with glutaraldehyde (GA) and self‐assembled into nanoparticles in a self‐assembly mechanism like that for diphenylalaninamide nanoparticles (FFANPs). Also, ZFFNPs were compared with FFANPs in aspects of morphology, surface charge, stability, and cytotoxicity. ZFFNPs demonstrate a spherical morphology and homogenicity like FFANPs, but while ZFFNPs have negative surface groups (carboxyl), FFANPs contain polar surface groups (amide). While ZFFNPs exhibit a high stability in extremely acidic environments (pH 3–5), AFFNPs show stability in a wide pH range (pH 4–10). Both NPs are nontoxic and biocompatible. These novel anionic ZFFNPs have great promise for potential utilization in biomedical applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45930.     

Preparation of halogen-free flame-retardant expandable polystyrene foam by suspension polymerization

In this research, using hexaphenoxycyclotriphosphazene (HPCTP) as the halogen-free flame retardant, we prepared flame-retardant expandable polystyrene (EPS) beads by suspension polymerization. The effects of process parameters and the amount of flame retardant on polystyrene (PS)/HPCTP composite beads were investigated. The results show that the change in HPCTP content has little effect on the particle size distribution of composite beads. When the oil–water ratio is 1/4, TCP dosage is 3 wt %, stirring rate is 350 rpm, initiator dosage is 1.25 wt %, and HPCTP dosage is 15 wt %, the size of the composite beads is uniform, and the average particle size is 1.12 mm. HPCTP formed nanodispersed particles in the PS matrix with an average particle size of 44.86 nm. In addition, the thermogravimetric behavior and heat-release properties of composite beads were evaluated. The results showed that HPCTP mainly acted in the gaseous phase, which can effectively decrease the maximum mass-loss rate of the PS/HPTCP composite beads and significantly reduce the heat-release rate and heat-release capacity. The EPS foams were obtained by a prefoaming method. The average cell diameter was 62.15 μm, and the foaming ratio was 11 times. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47779.     

Polymerized high internal phase emulsion monoliths for the chromatographic separation of engineered nanoparticles

PolyHIPEs of ethylene glycol dimethacrylate (EGDMA) and styrene/divinylbenzene were prepared by polymerization of water‐in‐oil high internal phase emulsions (HIPEs) within high pressure liquid chromatography (HPLC) columns. The columns were incorporated into a HPLC system affixed to an inductively‐coupled plasma mass spectrometer, and their potential for the separation of engineered nanoparticles was investigated. Triplicate injections of 5 and 10 nm gold particles injected onto a poly(styrene‐co‐divinylbenzene) polyHIPE column produced an average difference in retention time of 135 s. On a poly(EGDMA) column, triplicate injections of dysprosium containing polystyrene particles of 52 and 155 nm produced a difference in retention time of 8 s. In both cases the smaller particles eluted from the column first. Comparison, using scanning electron microscopy, of the polyHIPE columns after the separations, against freestanding monoliths produced from the same HIPEs, revealed no apparent change in the internal porous structure of the polyHIPEs. © 2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 132, 41229.     

Synthesis and properties of magnetite nanoparticles with peroxide-containing polymer shell and nanocomposites based on them

Magnetite nanoparticles (Fe₃O₄ NPs) with peroxide-containing polymer shell have been synthesized using the method of coprecipitation from the mixture solutions of Fe (II) and Fe (III) salts in the presence of peroxide-containing copolymer (PCC). Polymer shell presence has been proved by elemental and complex thermal analysis. Synthesized Fe₃O₄ NPs possess superparamagnetic properties. Their specific saturation magnetization decreases gradually from 65 to 54 A·m²·kg⁻¹ with increasing PCC concentration owing to the surface spin pinning effect caused by a polymer shell. The average sizes of Fe₃O₄ NPs estimated from the data of XRD analysis and magnetic measurements are in the range of 9–12 nm. The NP sizes determined by the DLS method lie in the range of 150–270 nm; this result is significantly larger than the sizes estimated by the two aforementioned methods evidencing a tendency for Fe₃O₄ NPs toward self-association. Cross-linked composite films based on polyvinyl alcohol have been obtained via radical curing initiated by the PCC shell of nanoparticles. The resulting composite films are magnetically sensitive films with rather high physico-mechanical properties (tensile strength reaches 48–67 MPa and relative elongation – 4%–21% depending on cross-linking degree), a priori non-toxic and biocompatible, which makes them promising materials for various applications.     

Peroxopolyoxometalate nanoparticles blended PES membrane with improved hydrophilicity,anti-fouling,permeability, and dye separation properties

Poly(ethersulfone) (PES) is one of the polymers most widely used for the fabrication of ultrafiltration or nanofiltration membranes in various applications, but its membrane suffers from fouling. In this study, preparation, characterization, and performance of PES nanocomposite membrane comprising peroxopolyoxometalate nanoparticles was studied to provide improved permeability and anti-fouling properties. The high oxygen ratio of the PW₄ nanoparticles could enhance the hydrophilicity of the membranes. The PW₄ nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction analyses. The mixed matrix membranes were fabricated using a non-solvent induced phase-separation method. The fabricated membranes were characterized using atomic force microscopy, attenuated total reflection, SEM, EDX mapping, total average porosity, thermogravimetric analyze, and water contact angle experiments. The dye flux and rejection, pure water permeability and anti-fouling properties of the membranes were investigated. All of the membranes blended by different contents of the PW₄ nanoparticles presented better performance compared to the unmodified membrane. The filtration performance of the membranes in reactive green 19 (RG19) and reactive yellow 160 (RY160) dye separation showed that all of the PW₄ blended membranes possessed dye rejection greater than 86% and 96% for RY160 and RG19, respectively. The reusability test using bovine serum albumin (BSA) protein and RG19 dye solutions in five cycle experiments presented good reproductivity of the PW₄ blended membranes. The PES membrane containing 1 wt% of PW₄ nanoparticles showed the highest flux recovery ratio (75%) as well as reduced irreversible fouling ratio (8%) through BSA protein filtration.     

Synthesis and physicochemical investigation of imide-functionalized silica nanocomposites

The incorporation of inorganic nanoparticles into polymers have gained significant attention to improving functional properties. The ultimate nanocomposite behaviors are influenced by many parameters, such as microstructural distribution that are produced during the treatment process. Herein, a hybrid material integrating a modified network into a polyimide PI matrix was produced via the sol–gel method by the reaction of pyromellitic dianhydride, 4, 4-oxydianaline, and 1, 5-diaminonaphthalene to synthesize copolyimides nanocomposite. The modified polyimide and unmodified polyimide silica (SiO₂) nanoparticles were incorporated in the polyimide matrix to have polyimide silica nanocomposite. In modified silica nanoparticles, 3-aminopropyltriethosilane was introduced to have better compatibility among inorganic–organic hybrid with similar chemical contact due to their flexible alkyl group. The surface morphology or structure of silica and polyimide was affirmed by scanning electron microscopy, Fourier transforms infrared spectroscopy confirmed the synthesis of pure polyimide, unmodified polyimide, and modified polyimide silica via presence and absence of certain peaks. Thermogravimetric analysis (TGA) results showed high thermal stability of nanocomposites as silica content increases. In contrast to unmodified silica, the modified silica provides more thermal stability to the nanocomposites. Dynamic mechanical analysis was used to investigate the tensile stress of pure polyimide, unmodified, and modified silica nanocomposites. Thermal stability, storage modulus, and moisture absorption of these hybrid materials were improved with silica nanoparticles. The TG mass spectrum confirms the successful synthesis of modified silica networks. The substituted silica nanoparticles show higher mechanical toughness and storage in modified compared to unmodified silica nanocomposite, which exhibits stronger binding attraction between silica nanoparticles and polyimide matrix.