Surface modification of titanium by using plasma‐induced graft‐polymerization

Plasma‐induced graft‐polymerization (PIGP) method was utilized in this study to improve corrosion behavior and biocompatibility of titanium (Ti) surface. Bioactive molecule polyacrylamide (PAM) was immobilized onto Ti surface by introducing silanederivatized spacer arms as an intermediary for the covalent linkage. Ti was firstly activated by O₂ plasma, and oxygen‐containing groups were introduced on its surface consequently. The intermediary mercapto silane spacer molecules were then covalently linked to the oxidated surface, followed by the covalent binding of PAM and the sulfhydryl‐terminal groups via PIGP. Surface analyses following modification process included water contact angles (CA), SEM, attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR), XPS and atomic force microscope (AFM). The results revealed the effectiveness of this method on immobilizing PAM to Ti surface, and the hydrophilicity of modified surface improved remarkably. In addition, potentiodynamic polarization and cellular proliferation tests were implemented to validate the enhanced corrosion‐resistance and biocompatibility of modified Ti surface, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

On the influence of electron energy on iodine‐doped polyaniline formation by plasma polymerization

The influences that both electron energy and density of a plasma bear on thin film formation are examined in the case of iodine‐doped polyaniline polymerization. The plasma was produced by means of 13.5‐MHz radiofrequency–generated glow discharges in low‐pressure (ca. 10⁻² mbar) air between electrodes. Four representative inner regions of the reactor were selected according to the electron incidence. Given the uneven energy distribution found on the inside of this kind of reactors, variations in the polymer structure formed in the presence of iodine were found and studied by elemental analysis, thermogravimetry, infrared spectroscopy, and X‐ray diffraction. The results indicate that the electric conductivity of polyaniline by plasma is a function of the iodine content and that such content is a function of the combined conditions of both reactor and plasma. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 175–183, 2001     

Effect of initial precursor concentration on TiO2 thin film nanostructures prepared by PCVD system

TiO₂ thin film was prepared on Si substrate by plasma chemical vapor deposition (PCVD) system and the morphologies of TiO₂ thin film were controlled by adjusting the initial precursor concentration. As the initial titanium tetra-isopropoxide (TTIP) concentration increases in PCVD reactor, the shapes of TiO₂ particles generated in PCVD reactor change from the spherical small-sized particles around 20 nm and spherical large-sized particles around 60 nm to aggregate particles around 100 nm. The TiO₂ particles with different shapes deposit on the substrate and become the main building blocks of resulting TiO₂ thin film. We observed the TiO₂ thin film with smooth morphology at low initial TTIP concentration, granular morphology at medium initial TTIP concentration, and columnar morphology at high initial TTIP concentration. It is proposed that we can prepare the TiO₂ thin film with controlled morphologies in one-step process just by adjusting the initial precursor concentration in PCVD.     

Role of vacuum ultraviolet irradiation in plasma‐induced graft polymerization in the pore‐filling polymerization of porous materials

The role of vacuum ultraviolet (VUV) rays contained in the plasma during plasma‐induced graft polymerization in the pores of a porous high‐density polyethylene (HDPE) substrate was investigated through the separation of the VUV rays from the plasma with LiF, CaF₂, and quartz filters. Two characteristic phenomena, the effect of the solvent on the grafting rate and the graft polymerization in the pores of the porous substrate, were observed in the VUV‐induced graft polymerization process. These results provided clear evidence that VUV rays in the plasma played an important role in the formation of grafted layers in the pores of the HDPE substrate. The relationship between the penetration depth of the VUV rays and the distribution of the grafted layer inside the substrate was examined. The calculated penetration depth of the VUV rays (and hence the distribution of radicals) and the distribution of the grafted layer were not consistent. However, this inconsistency could be explained by the fact that the effective density of the radicals that could react with the monomer to grow the grafting polymer was very low because of the steric hindrance of the grafted chains. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2068–2074, 2005     

Effect of reaction conditions on film morphology of polyaniline composite membranes for gas separation

Composite membranes combining polyaniline as an active layer with a polypropylene support have been prepared using an in situ deposition technique. The protonated polyaniline layer with a thickness in the range of 90–200 nm was prepared using precipitation, dispersion, or emulsion polymerization of aniline with simultaneous deposition on top of the porous polypropylene support, which was immersed in the reaction mixture. Variables such as temperature, concentration of reagents, presence of steric stabilizers, surfactants, and heteropolyacid were found to control both the formation and the quality of the polyaniline layers. Both morphology and thickness of the layers were characterized using scanning electron microscopy. Selective separation of carbon dioxide from its mixture with methane is used to illustrate potential application of these composite membranes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Surface nanostructuring of kevlar fibers by atmospheric pressure plasma‐induced graft polymerization for multifunctional protective clothing

Atmospheric plasma‐induced graft polymerization was employed successfully to generate free radical on the surface of Kevlar® (poly‐(p‐phenylene terephthalamide or PPTA), and to initiate and control graft polymerization of cationic antimicrobial precursors diallyldimethylammonium chloride (DADMAC) or 3‐(trimethoxysilyl)propyl‐dimethyloctadecyl ammonium chloride (TMS) onto the fabric surface, which eliminates the need for separate processes that may involve thermal energy or UV irradiation. It was demonstrated that when the radiofrequency of the plasma power was 400 W, the radical density generated on the surface was 10¹⁵ to 10¹⁶ radicals cm^?2, which were enough to generate a poly‐DADMAC or poly‐TMS with surface charge of at least 2 × 10¹⁷ N⁺/cm², which is the minimum threshold for an effective cationic biocidal surface. In both cases, the grafted polymers were characterized and confirmed using SEM, FTIR, and XPS. The antimicrobial activity was measured using the AATCC Test Method 100, which showed that at least 3‐log reduction of bacteria colonies was achieved in the case of grafted poly‐DADMAC or grafted poly‐TMS on Kevlar®. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Electrochemical Synthesis of Chitosan‐co‐polyaniline/WO3⋅nH2O Composite Electrode for Amperometric Detection of NO2 Gas

An electrode of hydrated tungsten oxide (WO₃?nH₂O) embedded chitosan‐co‐polyaniline (CHIT‐co‐PANI) composite was electrochemically prepared on an indium tin oxide (ITO) coated glass surface using mineral acid as a supporting electrolyte. The resulting CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode was characterized using ultraviolet‐visible spectroscopy (UV‐vis), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The composite electrode exhibited a three‐dimensional nanofibrous structure with the diameter of the nanofibers ranging from 20 to 100 nm. The CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode allowed for the low potential detection of NO₂ gas in acidic medium. The NO₂ gas sensing characteristics were studied by measuring change in the current with respect to concentration and time. Using the CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode, NO₂ gas was detected electrochemically without interference at pH 2.0 and 0.25 V vs. Ag/AgCl. The current of the electrochemical cell with the CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode decreased linearly with an increase in NO₂ gas concentration in a range from 100 to 500 ppb with a response time of eight seconds.     

Graphene oxide‐induced polymerization and crystallization to produce highly conductive polyaniline/graphene oxide composite

Graphene oxide (GO)–polyaniline (PANI) composite is synthesized by in situ polymerization of aniline in the presence of GO as oxidant, resulting in highly crystalline and conductive composite. Fourier transform infrared spectrum confirms aniline polymerization in the presence of GO without using conventional oxidants. Scanning electron microscopic images show the formation of PANI nanofibers attached to GO sheets. X‐ray diffraction (XRD) patterns indicate the presence of highly crystalline PANI. The sharp peaks in XRD pattern suggest GO sheets not only play an important role in the polymerization of aniline but also in inducing highly crystalline phase of PANI in the final composite. Electrical conductivity of doped GO–PANI composite is 582.73 S m^?1, compared with 20.3 S m^?1 for GO–PANI obtained by ammonium persulfate assisted polymerization. The higher conductivity appears to be the result of higher crystallinity and/or chemical grafting of PANI to GO, which creates common conjugated paths between GO and PANI. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1545–1554     

Synthesis by plasma and characterization of bilayer aniline–pyrrole thin films doped with iodine

The synthesis by plasma and characterization of aniline–pyrrole bilayer polymers doped in situ with iodine were studied. The objective was to study the electrical conductivity of thin films composed of alternating layers of different polymers. The results indicated that the plasma technique is capable of forming chemically bonded layered polymers with several possible combinations. The electric conductivity was studied during heating–cooling cycles so the dependence of the bilayer polymers on temperature could be observed. The behavior was related with the Arrhenius model, with average activation energies of 0.4 ± 0.1 eV in the heating steps and 0.5 ± 0.1 eV in the cooling steps. The difference in both steps shows the influence of the aniline in the bilayer polymer network because polyaniline presents changes in the structure during heating processes. The bilayer aniline–pyrrole polymers had greater electric conductivity at room temperature than that shown by the separate homopolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1850–1856, 2002     

聚苯胺分子印迹膜电化学传感器检测氯霉素

以苯胺为功能单体和交联剂,氯霉素(chloramphenicol,CAP)为模板分子,采用电化学聚合法(循环伏安法)在金电极上合成了对CAP具有快速响应能力的聚苯胺分子印迹膜;结合差示脉冲伏安法建立了针对氯霉素的检测方法,并将所制备的聚苯胺分子印迹膜用作电化学传感器以测定氯霉素眼药水中的氯霉素.结果表明,所制备的聚苯胺分子印迹膜具有制备简单、响应快速、灵敏度高、再生性能良好等特点;其对氯霉素眼药水中的氯霉素的检测结果令人满意,有望用于实际样品中氯霉素的检测.     

Reusable thin film photocatalyst of Fe‐doped TiO2 deposited by ECR plasma

The paper presents an improved method of depositing nanocrystalline thin films of Fe‐doped TiO₂ to be used as a reusable cyclic photocatalyst for degrading the organic pollutants. The technique of electron cyclotron resonance plasma‐enhanced chemical vapor deposition was employed with titanium tetra‐isopropoxide (C₁₂H₂₈O₄Ti) and ferrocene (C₁₀H₁₀Fe) as precursors of Ti and Fe, respectively. Optical emission spectroscopy was used to identify the reactive species, to determine the electron temperature and the ion density during deposition. The films were characterized using optical absorption and photoluminescence spectra, whereas the morphological analysis was carried out with scanning electron microscopy. Strong adhesion of the deposited films with the substrate ruled out any possibility of TiO₂ particles being leached out. It was confirmed by observing the degradation rate of the same film repeatedly. Cyclic use of the film for the catalytic reactions thus makes the process much user friendly for the water treatment. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of catalysts on thin‐film polymerization of thermotropic liquid crystalline copolyester

Using a novel thin‐film polymerization technique, we have investigated in situ uncatalyzed and catalyzed polycondensation reaction systems for 73/27 (mol ratio) poly(p‐oxybenzoate/2,6‐oxynaphthoate) [P(OBA/ONA)] thermotropic liquid crystalline copolyester. We have also determined the effect of catalysts on the kinetics and morphological changes of the reactions. Because the thin‐film polymerization is conducted on the heating stage and the morphology is observed in situ by a polarizing microscope, we can directly observe and determine the accurate onset time for LC phase generation. The number‐average degree of polymerization (DP) at the onset of this morphological change decreases with decreasing reaction temperature in the range of 230–290 °C. The LC phase may form at a DP as low as 2 at 230 °C. Most importantly and surprisingly, the reaction rate constant obtained from the thin‐film polymerization is much greater (20–30 times) than the previous reported value obtained from the bulk polymerization reaction because the release of acetic acid in the former is much easier and quicker than in the latter. Clearly, the thin‐film polymerization may be a better and accurate technique to observe the approximately inherent properties of polymerization kinetics than the traditional bulk polymerization reaction. Three kinds of catalysts, namely, sodium acetate, calcium acetate, and antimony oxide, have been studied. Sodium acetate has obvious acceleration effect on the reaction. Reaction rate constant increases almost proportionally to the catalyst content in the low catalyst content range, and activation energy slightly decreases with an increase in sodium acetate percentage. Calcium acetate has a higher catalytic effect than sodium acetate when the catalyst content is high, but the trend reverses when the catalyst content is low. Polymerization with high content of calcium acetate produces LCP with undesirable morphology because it suppresses the coalescence process among LC domains. Antimony oxide is a polymerization inhibitor for this reaction. It slows down the reaction, but does not alter the sequence of the morphological changes during the polymerization. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1257–1269, 2000     

Polyaniline thin film optical waveguides for integrated optics and VLSI prepared by vacuum evaporation technique

Polyaniline is emerging as an important polymer material which offers challenging opportunities for both fundamental research and new technological applications in waveguides. Metal doped polyaniline has been prepared initially in the form of powder by a solution growth technique. The emeraldine salt with doped metal was also prepared by solution growth technique. This powder was used for vacuum evaporation on optically flat glass substrate. The dark green doped (Fe, Al) polyaniline thin films were prepared by vacuum evaporation technique (10^?4 torr). Deposited waveguide thin films have been characterized structurally, using X‐ray diffraction (XRD), optically etc. Effective refractive index of the thin film waveguide was also calculated theoretically and experimentally. Waveguide parameters, namely refractive index, propagation loss and depth of vacuum deposited polyaniline thin films optical waveguide have been determined. The optical spectra and structure and waveguide parameters of vacuum deposited polyaniline thin films are strongly affected by the type of doping. It is possible to reduce the losses by addition of Fe to the vacuum deposited polyanine thin film and modify the effective refractive index (O_eff) according to particular requirements. Results are compared with the results in the literature. Copyright © 2002 John Wiley & Sons, Ltd.     

Fabrication of a gas sensor using pentacene thin films as a detector

Highly sensitive gas sensors for both acidic and basic gases were fabricated based on conducting thin films of polyacene compounds. Gas sensors formed with pentacene thin films deposited on various kinds of substrates were found to exhibit high sensitivity in detecting subppm concentrations of NO₂ or Cl₂ by monitoring the conductivity of the thin film. Improvements in the conductance and duration period for detection were achieved by changing the shape of electrodes and substrate. The sensors with PEN thin films initially doped with iodine could detect ppm concentrations of ammonia gas, since iodine molecules were dedoped upon exposure to ammonia, causing the reduction of the conductivity.     

Fast fabrication of superabsorbent polyampholytic nanocomposite hydrogels via plasma‐ignited frontal polymerization

We report the facile synthesis of poly(VI‐co‐MAA) superabsorbent polyampholytic hydrogels (VI = N‐vinylimidazole, MAA = methacrylic acid) via plasma‐ignited frontal polymerization (PIFP). On igniting the top surface of the reactants with air plasma, frontal polymerization occurred and poly(VI‐co‐MAA) hydrogels were obtained within minutes. The preparation parameters were investigated, along with swelling capacity, morphology, and chemical structures of poly(VI‐co‐MAA) hydrogels. Interestingly, the hydrogels are superabsorbent in water and show ampholytic characteristic toward pH. Moreover, the hydrogels are able to capture cationic dyes through electrostatic interaction, offering the potential for further development as dye adsorbents for water purification. In addition, nanocomposite hydrogels were obtained by embedding quantum dots (carbon dots or CdS nanocrystals) into the polymer matrix, which endows the nanocomposite hydrogels with favorable fluorescence and potential applications in bioimaging and biosensing. The results indicate that FP can be applied as an alternative means for facile synthesis of multifunctional hydrogels with additional efficiency and energy‐saving. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 912–920     

Synthesis,characterization, and thin‐film properties of 6‐oxoverdazyl polymers prepared by ring‐opening metathesis polymerization

Redox‐active 6‐oxoverdazyl polymers were synthesized via ring‐opening metathesis polymerization (ROMP) and their solution, bulk, and thin‐film properties investigated. Detailed studies of the ROMP method employed confirmed that stable radical polymers with controlled molecular weights and narrow molecular weight distributions (Ð < 1.2) were produced. Thermal gravimetric analysis of a representative example of the title polymers demonstrated stability up to 190 °C, while differential scanning calorimetry studies revealed a glass transition temperature of 152 °C. Comparison of the spectra of 6‐oxoverdazyl monomer 12 and polymer 13 , including FT‐IR, UV‐vis absorption, and electron paramagnetic resonance spectroscopy, was used to confirm the tolerance of the ROMP mechanism for the 6‐oxoverdazyl radical both qualitatively and quantitatively. Cyclic voltammetry studies demonstrated the ambipolar redox properties of polymer 13 (E_1/2,ox = 0.25 and E_1/2,red = ?1.35 V relative to ferrocene/ferrocenium), which were consistent with those of monomer 12 . The charge transport properties of thin films of polymer 13 were studied before and after a potential of 5 V was applied, revealing a drastic drop in the resistivity from 10⁶?10¹⁰ Ω m or more to 1.7 × 10⁴ Ω m and suggesting the potential usefulness of polymer 13 in bistable electronics. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1803–1813     

Rapid synthesis of poly(HPA‐co‐VeoVa 10) amphiphilic gels toward removal of toxic solvents via plasma‐ignited frontal polymerization

Atmospheric air plasma was created and applied in the frontal polymerization (FP) of fabricating poly(HPA‐co‐VeoVa 10) amphiphilic gels (HPA = 2‐hydroxypropyl acrylate, VeoVa 10 = vinyl versatate) with enhanced physicochemical properties. In plasma‐ignited frontal polymerization (PIFP), once ignited by air plasma, no further energy or treatment was required for the following polymerization. In this system, the comparison between PIFP and thermal frontal polymerization (TFP) was conducted and observed that PIFP and TFP differ considerably in terms of swelling capacity, morphology and component distribution of the products. This finding is of great importance that the simultaneous generation of active radicals in the initial stage can spread throughout reactant and anchor on the synthetic polymer with the assistance of FP. More interestingly, the PIFP‐synthesized copolymer possesses remarkable selective absorption towards organic solvents, which can be facilely manipulated by varying the weight ratios of HPA/VeoVa 10. Obviously, these polymer products could serve as an “organic solvent scavenger” in the field of industrial wastewater treatment. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Electrochemical sensor for acetaminophen based on an imprinted TiO2 thin film prepared by liquid phase deposition

An electrochemical sensor based on a molecularly imprinted TiO₂ thin film is proposed for the determination of acetaminophen. The imprinted TiO₂ films were obtained by liquid phase deposition (LPD) in the presence of acetaminophen, the functional monomer and the aqueous solution of (NH₄)₂TiF₆ and H₃BO₃. The results show that acetaminophen is embedded into the imprinted film in the presence of p-tert-butylcalix[6]arene as a functional monomer, and can be removed completely by washing with ethanol. The surface morphology, spectral properties and electrochemical characterizations of the imprinted sensor were investigated in detail. The combination of molecularly imprinted and LPD technique was shown to be a general strategy for constructing a molecular recognition system.     

In situ doping polymerization of polyaniline microtubules in the presence of β‐naphthalenesulfonic acid

Conducting microtubules of Polyaniline (PANI) were synthesized for the first time by the “in situ doping polymerization” method in the presence of β‐naphthal‐ enesulfonic acid (NSA) as dopant. Different doping methods, such as “immerse doping” and “grind doping,” and different synthetic conditions, such as molar ratio of aniline (An) to NSA (An/NSA), concentration of NSA in the polymerization media, reaction temperature, and time were investigated to understand the formation of microtubules. It was found that the PANI–NSA microtubules can be formed only by the “in situ doping polymerization” method, and the above synthetic conditions strongly affect the formation of the PANI–NSA microtubules, especially the molar ratio of An to NSA. An optimal condition was found under which tubules with 1–3 μm in diameter and 10–50 μm in length were obtained. The morphology of PANI–NSA tubules was proved by SEM and TEM, and their backbone structure was characterized by FTIR, UV‐VIS, XPS, and X‐ray diffraction. Results of these measurements showed that the molecular structures of the resulted PANI–NSA microtubules were identical to that of PANI–HCl synthesized by conventional method. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 151–157, 1999     

Gas transport properties of asymmetric polyimide membranes prepared by plasma‐based ion implantation

In this study, we report the gas permeance and selectivity of the asymmetric polyimide membrane prepared by plasma‐based ion implantation (PBII). The asymmetric polyimide membranes were prepared using a dry–wet phase inversion process, and the surface skin layer on the membrane was implantated by He ions at 2.5 keV. The asymmetric membranes treated by PBII were measured using a high vacuum apparatus with a Baratron absolute pressure gauge at 76 cmHg and 35°C. The (O₂/N₂) and (CO₂/CH₄) selectivities in the He⁺‐implanted asymmetric membrane at 60 sec resulted in 1.5 and 1.8 time increases, respectively, when compared to those of the asymmetric membrane before PBII. On the other hand, the O₂ and CO₂ permeances in the asymmetric membrane after PBII decreased with an increase in the He⁺ treatment time. In this paper, we addressed, for the first time, the gas permeation behavior of the asymmetric polyimide membranes prepared by PBII. Copyright © 2009 John Wiley & Sons, Ltd.