Hybrid polydiacetylene/magnetite nanoparticles: Sensing for sodium cetyltrimethylammonium bromide and streptavidin

Hybrid nanoparticles composed of polydiacetylene (PDA) and magnetite (Fe₃O₄) were fabricated by a double‐emulsion method. The structure and composite form of the hybrid nanoparticles were investigated with transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and dynamic light scattering. The successful incorporation of magnetism to an attractive class of colorimetric PDA sensors was demonstrated. Compared with the PDA vesicles, the hybrid nanoparticles showed better colloidal stability with ethanol stimuli. In this study, we explored the colorimetric sensing ability of the hybrid nanoparticles in response to sodium cetyltrimethylammonium bromide (CTAB). The results show a high sensitivity to CTAB with a limit of detection at 30 μM. The biotin–streptavidin interaction was used as a sensing model to test ligand–receptor interactions on the hybrid nanoparticles' response. The concentration dependence of the chromic response was observed with the limit of visual detection at 20 μg/mL. The Fe₃O₄–PDA hybrid nanoparticles might have great potential applications in biosensing because of their advantages, including separation and sensing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40634.     

Cyclopolymerization protocol for the synthesis of a poly(zwitterion‐alt‐sulfur dioxide) to investigate the polyzwitterion‐to‐poly(anion‐zwitterion) transition

The zwitterionic monomer, 3‐(N,N‐diallyl,N‐carboethoxymethylammonio)propanesulfonate, on cocyclopolymerization with sulfur dioxide in DMSO using azoisobutyronitrile as the initiator afforded the polyzwitterion (PZ) copolymer in excellent yields. The PZ on acidic hydrolysis of the ester groups led to the corresponding polyzwitterionic acid (PZA). The pH‐responsive PZA on treatment with sodium hydroxide gave the new poly(eletrolyte‐zwitterion) (PEZ). The solubility, viscosity behaviors, and solution properties of the salt‐tolerant PZ, PZA, and PEZ were studied in detail. Like common PZs, PZ was found to be insoluble in salt‐free but soluble in salt‐added water. The apparent basicity constants of the carboxyl group in PEZ have been determined. As the name implies, the PEZ possesses dual type of structural feature common to both conventional anionic polyelectrolytes and PZs, and its aqueous solution behavior is found to be similar to that observed for a typical alternating anionic‐zwitterionic copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Volume phase transition of a polymer gel induced by phase separation of mixed solvents of water and 2‐butoxyethanol

The occurrence of the volume phase transition triggered by the phase separation of mixed solvents is investigated using polyacrylamide gels in mixtures of water and 2‐butoxyethanol. When the water content of the mixtures is lower than that of the critical composition, the temperature‐dependent swelling curves show a steep change around the phase separation temperatures but remain continuous, although the solvent inside the gel undergoes a discontinuous composition change. This continuous change originates from the critical concentration fluctuation below the spinodal temperature. Hysteresis‐like behavior is also observed for the heating and cooling curves. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46366.     

Electrorheological behavior of side‐chain polysiloxane containing 3‐(4‐amidophenyl) sydnone moieties

Side‐chain polysiloxane containing 3‐(4‐amidophenyl) sydnone moieties at terminal and aliphatic spacer has been synthesized and its structure was confirmed by FTIR and ¹H‐NMR. Low mass molar weight sydnone exhibited electrorheological effect, which was enhanced by electron‐donor substituted group at phenyl, but weakened by electron‐acceptor substituted group. By introducing sydnone into polysiloxane, the polymer displays the higher electrorheological effect due to the increased interaction between sydnone molecules. The oxide states of sydnone affect the electrorheological effect as well as the color of the product. Moreover, the temperature is higher than the glass transfer temperature of the polymer; the electrorheological fluids show a very large leakage current. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2523–2528, 2004     

Preparation and aqueous solution behavior of a ph‐responsive branched copolymer based on 2‐(diethylamino)ethyl methacrylate

pH‐Responsive amphiphilic branched copolymers were prepared from poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2‐(diethylamino)ethyl methacrylate (DEAEMA), 2‐(tert‐butylamino)ethyl methacrylate (tBAEMA), and ethylene glycol dimethacrylate (EGDMA) utilizing a thiol‐modified free radical polymerization. The molecular structures of copolymers were confirmed by proton nuclear magnetic resonance spectroscopy (¹H NMR) and triple‐detection gel permeation chromatography (tri‐GPC). The aqueous solution behaviors of the obtained copolymers were investigated by dynamic light scattering (DLS). The DLS data showed that about 16 nm polymer particles comprising of hydrophobic poly(tert‐butylamino)ethyl methacrylate (PtBAEMA) and poly(diethylaminoethyl methacrylate (PDEAEMA) core, hydrophilic PEGMA corona were formed above pH 8. With the decrease of pH from 8 to 6, a dramatic increase in the hydrodynamic radius of polymer particles from 16 nm to 130 nm was observed resulting from the protonation of the PDEAEMA segment. Moreover, in vitro drug release behaviors of the resulting polymer assemblies at different pH values were also investigated to evaluate their potential as sustained release drug carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42183.     

Synthesis and catalytic activity of the thermoresponsive polymers having pyrrolidine side chains as base functionalities

Optically active polymers having chiral 2‐aminomethylpyrrolidine side chains have been newly synthesized by a radical homopolymerization of the corresponding protected acrylamide monomer and copolymerization with N‐isopropylacrylamide followed by deprotection. The resulting polymers were found to be thermoresponsive showing lower critical solution temperatures (LCSTs) at 27–65°C in their aqueous solutions. The pyrrolidine side chains of the resulting thermoresponsive polymer promoted aldol reaction between cyclohexanone and p‐nitrobenzaldehyde in water, and the reaction proceeded most smoothly at its LCST. Moreover, the diastereomeric ratio (syn : anti) of the aldol adducts obtained at the reaction at 40°C was 22 : 78, whereas the diastereomeric ratio (syn : anti) was 55 : 45 at 20°C. These results indicate that the pyrrolidine side chains catalyze the aldol reactions in the relatively hydrophobic field generated by the thermoresponsive polymer at its LCST. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of comonomer type and concentration on the equilibrium swelling and volume phase transition temperature of N‐isopropylacrylamide‐based hydrogels

The effect of incorporating a hydrophilic monomer into poly(N‐isopropylacrylamide) (polyNIPA) hydrogels on the equilibrium swelling and the volume phase transition temperature is reported here. A nonionizable monomer (acrylamide) and three ionizable monomers (itaconic acid, 2‐ethoxyethyl monoitaconate, and 2,2‐(2‐ethoxyethyl) monoitaconate) were studied. Hydrogels with larger swelling capacity than that of the polyNIPA hydrogel were obtained. With the exception of the hydrogel containing 2,2‐(2‐ethoxyethyl) monoitaconate, which did not exhibit the de‐swelling phenomena, the rest showed a volume phase transition. The hydrogels containing 85 wt % acrylamide and 15 wt % comonomer presented the higher shrinking ratio. For some compositions, the T_c of the polyNIPA hydrogel was within the desired temperature range (38–41°C) for controlled‐drug delivery in the human body. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Interactions of a smart cationic polyelectrolyte based on hydroxypropylcellulose with an anionic surfactant

Novel thermosensitive, cationic polyelectrolyte was obtained by grafting N‐vinylformamide onto hydroxypropylcellulose followed by the hydrolysis of the formamide groups to the amine groups. The effect of the ionic strength on the lower critical solution temperature of the polymers was studied. The interactions of the polymers with sodium dodecyl sulfate (SDS) as a model anionic surfactant were studied. It was found by the measurements of the light scattering and fluorescence spectroscopy that the graft copolymers obtained strongly interact with SDS with the formation of polymer‐surfactant complexes. The values of critical association concentration (cac) of these polymer‐surfactant systems were found to be of the order of 10^?5 mol/dm³ at pH = 6.5 and of the order of 10^?6 mol/dm³ at pH = 2.5. The polymer was shown to be potentially useful for the purification of water from anionic surfactants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Glycidyl methacrylate as a new host material for laser dyes

This article reports on the laser action of pyrromethene 597 and pyrromethene 567 doped in the novel solid polymeric matrix glycidyl methacrylate. Mirrorless lasing was observed when samples with diameters of 10 mm and lengths of 20 mm, with different dyes concentrations, were transversely pumped at 532 nm. The influence of the dye concentration on the laser measurements included the peak wavelengths, output energies, conversion efficiencies, and laser gains. Relatively high lasing efficiencies (up to ～ 60%) were obtained from these new polymeric materials with very good photostability, where a decrease of only 65% in the initial laser output energy was observed after pumping by 60,000 shots of 15 mJ at 10 Hz. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 59–63, 2007     

Novel benzoxazine resins as photoinitiator comprising benzophenone and coinitiator amine for photopolymerization

A novel kind of benzoxazine precursors made of 4‐dihydroxybenzophenone (DHBP), formaldehyde and N, N′‐diethylethylenediamine was developed. The striking feature of this class of precursors is that it can be acted as an effective photo initiator for polymerization of acrylate monomers. In addition, this kind of precursors could be directly dispersed in water and its aqueous solution exhibited very sharp response to temperature, with a well‐defined cloud point. The structure of this precursor has been confirmed by Proton Nuclear Magnetic Resonance Spectroscopy (¹H‐NMR) and Fourier Transform Infrared spectroscopy (FTIR) and its curing behaviors are investigated by Differential Scanning Calorimetry (DSC). The photopolymerization of acylate monomers, initiated by this precursor, was studied through photo‐DSC. The results show that this precursor is dramatically more efficient than benzophenone (BP), in which the polymerization rate is almost four times as high as that of the BP system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Dynamic mechanical and shape memory properties of polybenzoxazines based on aminopropyl‐terminated siloxanes

Four siloxane‐containing benzoxazine monomers and telechelic benzoxazine oligomers were synthesized from 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetramethyldisiloxane, α,ω‐bis(3‐aminopropyl)polydimethylsiloxane, phenol, o‐allylphenol, and formaldehyde. The length of the siloxane segment affects the polymerization reaction of the benzoxazine monomers and telechelic benzoxazine oligomers. The dynamic mechanical properties of the corresponding polybenzoxazines depend primarily on the structure of phenol and the length of the siloxane segment. The polybenzoxazines exhibit one‐way dual‐shape memory behavior in response to changes in temperature. The thermally induced shape memory effects of the polybenzoxazines were characterized by bending and tensile stress–strain tests with a temperature program based on their glass transition temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44121.     

Multi‐responsive microgel of a water‐soluble monomer via emulsion polymerization

Microgel of a water‐soluble monomer [2‐(N‐morpholino)ethyl methacrylate (MEMA)] was successfully prepared in aqueous media via emulsion polymerization by using a novel water‐soluble block copolymer as stabilizer. Characterization studies confirmed monodisperse spherical morphologies of microgels with a diameter of 280 nm at neutral pH. These microgels exhibited multi‐responsive behavior by responding solution pH, temperature, ionic strength, type of dispersing media, and magnetic particles. It swells well at low pH (<6.0) and at low temperature, but shrinks above pH 6.0, or even more shrinks with salt addition at neutral and basic conditions. In addition, the hydrodynamic diameter of PMEMA microgel was decreased gradually at basic and neutral pH when solution temperature was increased up to the lower critical solution temperature of PMEMA (LCST, 35°C), but microgel diameter did not change much above LCST. Multi‐responsive behavior of PMEMA microgel was investigated by using dynamic light scattering, UV‐Vis spectrophotometer and zeta potentiometer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42072.     

A low onset voltage WORM type polymer memory based on functional PES

A high‐performance polymer polyethersulfone (CN‐Azo‐PES), with a flexible ethoxyl linkage between the azobenzene chromophore side chain and the PES backbone, has been designed and successfully synthesized for an application in a WORM type memory device as an active polymer layer. CN‐Azo‐PES has excellent thermal properties with T_g of 151°C and the degradation temperature higher than 373°C, which can contribute to a better performance of the device. The device based on CN‐Azo‐PES exhibits a write‐once read‐many (WORM) type memory performance with an onset voltage as low as ?1.0 V and an ON/OFF current ratio higher than 10² at a reading voltage of 0.4 V. Moreover, the data can be maintained for longer than 4 × 10⁵ s once written and can be read for more than 400 cycles under a reading voltage of 0.4 V. Thus CN‐Azo‐PES can serve as an energy saving memory material in the data storage field of next generation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42644.     

Synthesis and characterization of thermosensitive composite microsphere latex

Monodisperse aqueous latex dispersions, prepared from mixtures of styrene, N‐isopropylacrylamide, and N,N′‐methylenebisacrylamide, were characterized. Thermosensitive composite microspheres with diameters greater than 1.0 μm, consisting of a polystyrene core and a poly(N‐isopropylacrylamide) shell, were prepared. The morphology of the composite microspheres was observed with transmission electron microscopy, and the particle size of the composite microspheres was estimated with dynamic light scattering. The thermosensitive properties of the composite microspheres were evaluated via the hydrodynamic size of the composite microspheres. The particle size of the composite microspheres decreased with increasing temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 824–828, 2005     

Effect of interchain interaction on optical properties of poly(p‐phenylene vinylene) derivative containing oxadiazole in backbone

We have investigated the optical properties of poly [2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene] containing oxadiazole in backbone (MEH‐OPPV) in dilute tetrahydrofuran solution and solid solution films. There is a large dihedral angle between the two adjacent monomer units in MEH‐OPPV, which restrains interchain interactions and destroys the conjugation of the polymer to result in blue shifted absorption and emission spectra. The red shifted photoluminescence (PL) peak is continuously changed in the solid solution films with increasing the concentration of MEH‐OPPV. Comparison with the dilute solution, an obvious shoulder peak at 465 nm is found in the UV–vis absorption and PL excitation (PLE) spectra of the MEH‐OPPV film. The intensity of the PLE shoulder at 465 nm is increased with the concentration of MEH‐OPPV in the solid solution films, which is connected with the aggregation of the MEH‐OPPV chains. The interchain interactions are restrained and the π‐stack aggregates of the polymer chains can not form in the MEH‐OPPV due to the large dihedral angle, and then the interchain species are effectively suppressed in the MEH‐OPPV films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

pH‐responsive core crosslinked polycarbonate micelles via thiol‐acrylate Michael addition reaction

A facile method for the construction of pH‐responsive core crosslinked micelles (CCLMs) based on polycarbonate was developed. Biodegradable amphiphilic block copolymer monomethoxy poly(ethylene glycol)‐b‐Poly(AC) (mPEG‐b‐poly(AC)) with pendant acrylate group was synthesized by means of ring opening polymerization of acryloyl carbonate (AC). Then CCLMs were obtained via thiol‐acrylate Michael addition reaction between the pendant acrylate group in the hydrophobic block and the crosslinker 1,6‐hexanedithiol. DLS results showed that the CCLMs prepared from mPEG‐b‐poly(AC)₂₅ were more stable than uncrosslinked micelles (UCLMs) upon dilution by 10‐fold DMF. Model drug Coumarin 102 was then encapsulated into the micelles. The pH‐responsive release of coumarin 102 from the CCLMs was demonstrated by fluorescence spectroscopy. The core crosslinked polycarbonate micelles have a potential as efficient intracellular smart drug delivery platforms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44421.     

Fabrication and performance of a donut‐shaped generator based on dielectric elastomer

Dielectric elastomers (DEs) have been suggested as generators to harvest electrical energy from natural mechanical energy sources, such as human movements and ocean waves. In this study, a donut‐shaped DE generator (DEG) has been fabricated and its performance is characterized depending on the stretch deformation. A simple new stretchable electrode system using multi‐walled carbon nanotubes has been suggested. Measurements on the resistance, capacitance, and electrical power generation are made depending on the area expansion. The capacitance and harvested energy are parabolically increased with increased area expansions. The theoretical prediction of energy harvesting is in good agreement with measured values of capacitance changes with stretching. FE analysis is also applied for calculation of strains for the DEG to figure out the distribution of strains. It is suggested that the DEG has promising applications in the field of designing an energy harvesting device depending on the type of energy available. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40076.     

pH‐ and temperature‐responsive IPN hydrogels based on soy protein and poly(N‐isopropylacrylamide‐co‐sodium acrylate)

pH‐ and temperature‐responsive interpenetrating polymer network (IPN) hydrogels based on soy protein and poly(N‐isopropylacrylamide‐co‐sodium acrylate) were successfully prepared. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analyzer. The equilibrium and dynamic swelling/deswelling behaviors and the drug release properties of the hydrogels responding to pH and/or temperature were also studied in detail. The hydrogels have the porous honeycomb structures, good miscibility and thermal stability, and good pH‐ and temperature‐responsivity. The volume phase transition temperature of the hydrogels is ca. 40°C. Changing the soy protein or crosslinker content could be used to control the swelling behavior and water retention, and the hydrogels have the fastest deswelling rate in pH 1.2 buffer solutions at 45°C. Bovine serum albumin release from the hydrogels has the good pH and temperature dependence. The results show that the proposed IPN hydrogels may have potential applications in the field of biomedical materials such as in drug delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39781.     

Covalent immobilization of trypsin onto thermo‐sensitive poly(N‐isopropylacrylamide‐co‐acrylic acid) microspheres with high activity and stability

Poly(N‐isopropylacrylamide‐co‐acrylic acid) (P(NIPAM‐co‐AA)) microspheres with a high copolymerized AA content were fabricated using rapid membrane emulsification technique. The uniform size, good hydrophilicity, and thermo sensitivity of the microspheres were favorable for trypsin immobilization. Trypsin molecules were immobilized onto the microspheres surfaces by covalent attachment. The effects of various parameters such as immobilization pH value, enzyme concentration, concentration of buffer solution, and immobilization time on protein loading amount and enzyme activity were systematically investigated. Under the optimum conditions, the protein loading was 493 ± 20 mg g^?1 and the activity yield of immobilized trypsin was 155% ± 3%. The maximum activity (V_max) and Michaelis constant (K_m) of immobilized enzyme were found to be 0.74 μM s^?1 and 0.54 mM, respectively. The immobilized trypsin showed better thermal and storage stability than the free trypsin. The enzyme‐immobilized microspheres with high protein loading amount still can show a thermo reversible phase transition behavior. The research could provide a strategy to immobilize enzyme for application in proteomics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43343.     

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis,characterization, and swelling behavior

Novel thermoresponsive poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) (PVA‐g‐PDEAAm) copolymers were prepared by microwave‐assisted graft copolymerization using a potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine (KPS/TEMED) initiator system. The structures of PVA‐g‐PDEAAm copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, gel permeation chromatography, X‐ray diffraction, and scanning electron microscopy. The effects of various process parameters on grafting were systematically studied: microwave power, KPS, monomer and PVA concentrations, and ultraviolet irradiation. Under optimal conditions, the maximum grafting percent and graft efficiency were 101% and 93%, respectively. Furthermore, a lower critical temperature of copolymers was measured in the range 29–31 °C by ultraviolet spectroscopy. The swelling behavior of graft membranes was carried out at various temperatures, and the results showed that the swelling behavior of membranes was dependent on the temperature. In vitro cell culture studies using L929 fibroblast cells confirmed cell compatibility with the PVA‐g‐PDEAAm copolymer and its membrane, making them an attractive candidate for drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45969.