Styrene Sulfonic Acid Sodium Salt Research Articles

Monitoring the salt stability and solvent swelling behavior of PAH‐based polyelectrolyte multilayers by quartz crystal microbalance with dissipation

AbstractThis contribution is aimed to examine the layer stability and solvent swelling behavior of polyelectrolyte multilayers (PEMs) obtained from poly(allylamine hydrochloride) (PAH), poly(styrene sulfonic acid sodium salt) (PSS), and poly(acrylic acid) against different salt solutions using Quartz Crystal Microbalance with Dissipation in terms of the solution concentration, charge type of the top layer, and PEM structure. In general, all multilayers remain stable against MgCl2 and NaCl, phosphate buffer saline, ionic liquid, and solvents, namely methanol and heptane, while 4.5‐bilayered PAH‐PSS film displays partial layer decomposition against 1 M NaOCl. Additionally, it is found that the stability of Layer‐by‐Layer (LbL) films remains unaffected by the surface charge type, although variations in the adsorbed and desorbed amounts, as well as the viscoelastic properties, occur during the salt passage and rinsing steps. Along the salt exposure, changes in dissipation (ΔD) significantly increase because of the fast diffusion of ions through the multilayers but return to their initial value after washing. Especially high and reversible ΔD values of the PEMs against methanol are evaluated as swelling in methanol without chemical disintegration. This behavior can be attractive for solvent‐induced release behavior for the LbL‐assembled films or microcapsules.Highlights Multilayer stability and solvent swelling of PEMs are discussed using QCM‐D. PAH‐PSS films have the highest stability against salt solutions. PAH‐PAA films exhibited significant changes in dissipation values. PEMs did not show multilayer stability against NaOCl solution. (PAH‐PSS)5 film was stable and had swelling/de‐swelling capability against methanol.

Influence of the formed interface during preparation of poly(vinylidene fluoride) blend cation exchange membrane on the electro-chemical properties and performance

Cation exchange membrane containing low fraction of charge moiety is beneficial as it minimizes the water swelling and back diffusion of ions, increases the mechanical property and lowers the cost. However, moderate to high extent of ion conducting group in a membrane is necessary for the effective ion exchange and good electrodialysis performance. To address this issue, we report a non-solvent (water) induced phase separation process where solid-water interface is generated and helps to migrate the ionic moieties on the surface and transport of ions, while a solid-air interface is formed in the solvent evaporation process which partially hinders the migration of the ionic moieties (high surface energy) on the membrane surface and ion transport property. Cation exchange membranes of the blend of poly(vinylidene fluoride) and poly(methyl methacrylate)-co-poly(styrene sulfonic acid sodium salt) have been prepared by both non-solvent induced phase separation and solvent evaporation process. Membrane containing about 5% (w/w) anionic polymer and prepared by non-solvent induced phase separation process exhibits high transport number (t+ = 0.93), good water desalination performance with power consumption of 1.15 KWhKg−1 and current efficiency of 90% than that of the membrane prepared by solvent evaporation process (power consumption = 1.58 KWhKg−1 and current efficiency = 58%).

The Blocking Properties of Styrene-Styrene Sulfonic Acid Sodium Salt Copolymer as a Nanodispersing Agent in Water-Based Drilling Fluids

Nanoplugging materials are used in drilling fluid systems to seal nanopores and cracks in the shale formation, which is a focus for developing shale gas. In this work, nanoparticles of the St-NaSS copolymer were synthesized by emulsion polymerization of styrene and styrene sulfonic acid sodium salt as monomers. The St-NaSS copolymer was characterized by FT-IR, TGA, and light scanning phase analysis. The results show that the grain size of the St-NaSS copolymer nanoparticles ranges from 37 to 50 nm, and the average diameter is about 43.2 nm. The decomposition temperature of the St-NaSS copolymer is 410.7°C, indicating that the material has good temperature resistance. The St-NaSS nanoparticles have little effect on the rheological properties of the water-based drilling fluid. The plugging performance of the St-NaSS nanoparticles was evaluated by the mud cake simulation method. The permeability of the mud cake is 3.32×10-5 μm2 which is close in value to that of the shale. When the drilling fluid contains 0.5 wt.% of St-NaSS nanoparticles, the plugging rate is 88.93%. The plugging rate of the mud cake increases with increase in the concentration of the St-NaSS nanoparticles. When the amount of rho St-NaSS nanoparticles is 1.0% the plugging effect of the drilling fluid is excellent. Therefore, St-NaSS copolymer nanoparticles can be successfully applied as a plugging agent to provide borehole stability in the shale formation.

Low-Voltage, Flexible IGZO Transistors Gated by PSSNa Electrolyte

A carving, cutting, and flip-chip bonding process is proposed for the fabrication of flexible electric double layer transistors (EDLTs) with low cost. Solution processed poly(styrenesulfonic acid sodium salt) is used as a gate dielectric. The large EDL-specific capacitance ( $4.5~\mu \text{F}$ /cm2 at 20 Hz) can induce very high charge carrier density in the InGaZnO (IGZO) channel layer, enabling the EDLTs to operate at a single-battery-drivable low voltage of 1.0 V with a high on-current of 10−4A. The effect of IGZO layer thickness on the performance of EDLTs was investigated. The flexible EDLT with optimized IGZO thickness of 100 nm has achieved a high on/off ratio of $1.4 \times 10^{7}$ , a low threshold voltage of 0.51 V, a saturated field-effect mobility of 1.14 cm2/Vs, and high positive gate bias stress stability. Furthermore, the achieved subthreshold swing, 76 mV/dec, is very close to the theoretical ideal minimum value.

Preparation, characterization and properties of polymer electrolyte nanocomposite membranes containing silica nanoparticles modified via surface-initiated atom transfer radical polymerization

Hydrophilic sulfonated monomers including styrene sulfonic acid sodium salt (SSA) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) were grafted onto a brominated silica nanoparticle (BSN) as a macroinitiator via surface-initiated atom transfer radical polymerization (SI-ATRP) at pH of about 10 in the presence of CuBr/bipyridine as a catalyst/ligand system and water/methanol (3/1 v/v) mixture as a solvent at 25 °C for 24 h. To synthesize BSN macroinitiator, silica nanoparticle (SN) was fist modified with 3-aminopropyltriethoxy silane and then brominated via reacting with 2-bromopropionyl bromide in the triethylamine/THF solution. Modified SNs were characterized by FTIR spectroscopy and thermogravimetric analysis (TGA). Grafting percentage of the monomers onto the SNs was calculated from TGA thermograms to be 30.6%, 47.6% (for the initial AMPS concentration of 0.8 and 2.0 M, respectively) for PAMPS and 28.1% (for the initial SSA concentration of 1.2 M) for PSSA. The PVA-based nanocomposite membranes containing various amounts of the pristine and modified SNs were prepared by solution casting and then cross-linked at 40 °C for 15 min in an acetone solution containing 0.5 M glutaraldehyde and 0.12 vol% HCl. SEM photograph and X-ray mapping of the cross-sectional view of the membranes showed that pristine and modified SNs have homogeneously dispersed at a nanometric scale in the PVA matrix. It was found that ion exchange capacity, water uptake (WU) and proton conductivity of the PVA-based membranes increase by increasing the SN, especially sulfonated polymer-modified SN, loading up to 10 wt%. It was found that proton conductivity of the nanocomposite membranes increases by increasing the grafting percentage of the sulfonated monomer onto SNs. Moreover, for similar grafting percentage of the monomers onto SNs, higher WU and proton conductivity was observed for a membrane containing SN modified with the PAMPS chains. Results showed that both hydrophilic nature and grafting efficiency of the sulfonated hydrophilic monomers can play an important role in the proton conductivity of the PVA-based membranes. Tensile modulus and tensile strength of the PVA-based membranes enhanced by adding modified SNs to the PVA matrix. Methanol uptake and permeability of the PVA-based polymer electrolyte membranes were also decreased by adding SNs to the PVA matrix.

Redox‐Responsive Macroscopic Gel Assembly Based on Discrete Dual Interactions

The macroscopic self-assembly of polymeric hydrogels modified with β-cyclodextrin (βCD gel), ferrocene (Fc gel), and styrenesulfonic acid sodium salt (SSNa gel) was investigated. Under reductive conditions, the Fc gel selectively adhered to the βCD gel through a host-guest interaction. On the other hand, the oxidized ferrocenium (Fc(+)) gel selectively adhered to the SSNa gel through an ionic interaction under oxidative conditions. The adhesion strength was estimated by a tensile test. We finally succeeded in forming an ABC-type macroscopic assembly of all three gels through two discrete noncovalent interactions.

Redox‐Responsive Macroscopic Gel Assembly Based on Discrete Dual Interactions

AbstractThe macroscopic self‐assembly of polymeric hydrogels modified with β‐cyclodextrin (βCD gel), ferrocene (Fc gel), and styrenesulfonic acid sodium salt (SSNa gel) was investigated. Under reductive conditions, the Fc gel selectively adhered to the βCD gel through a host–guest interaction. On the other hand, the oxidized ferrocenium (Fc+) gel selectively adhered to the SSNa gel through an ionic interaction under oxidative conditions. The adhesion strength was estimated by a tensile test. We finally succeeded in forming an ABC‐type macroscopic assembly of all three gels through two discrete noncovalent interactions.

Grafting of hydrophilic monomers onto aminopropyl-functionalized sodium montmorillonite via surface-initiated redox polymerization

Hydrophilic polymer/sodium montmorillonite (Na-MMT) hybrid nanomaterials were prepared via surface-initiated redox polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS-g-MMT), acrylamide (PAAm-g-MMT) and styrenesulfonic acid sodium salt (PSSA-g-MMT) from surface of aminopropyl-functionalized sodium montmorillonite (AMMT) dispersed in an aqueous medium. Cerium(IV) ammonium nitrate/nitric acid and aminopropyl groups on the surface of AMMT were used as oxidant and reducing groups, respectively. AMMT was prepared by covalently attaching 3-aminopropyltriethoxysilane onto the surface of Na-MMT. Hydrophilic monomers (AMPS, AAm and SSA) were then grafted onto AMMT dispersed in water via redox initiation at 40 °C. Structure, morphology and thermal properties of the AMMT, PAMPS-g-MMT, PAAm-g-MMT and PSSA-g-MMT hybrid materials were characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD) and thermogravimetric (TGA) analyses, respectively. FTIR results indicated that hydrophilic monomers were successfully grafted onto the surface of MMT. Grafting amounts of the hydrophilic polymers were estimated from TGA thermograms to be 28.8, 118.8 and 14.4% for PAMPS, PAAm and PSSA, respectively. XRD patterns showed an exfoliated morphology for PAMPS- and PAAm-grafted MMT hybrid nanomaterials and an intercalated/exfoliated morphology for the PSSA-grafted MMT one. The effect of the nature of hydrophilic monomer on the grafting efficiency is discussed in detail. © 2013 Society of Chemical Industry

High Flux Nanofiltration Membranes Prepared by Dynamic Self-Assembly of PSS-<i>co</i>-MA and PAH for CuCl<sub>2 </sub>Removal

A series of nanofiltration membranes with high flux at low operating pressure were prepared by dynamic self-assembly of poly (styrenesulfonic acid sodium salt) (PSS), poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (PSS-co-MA) and poly (allylamine hydrochloride) (PAH) on the modified polyacrylonitrile (PAN) membrane. Fourier transform infrared spectroscopy (FTIR-ATR) testified that the polyelectrolyte could successfully deposit on the surface of the modified polyacrylonitrile ultrafiltration membrane. The effects of substrates, assemble bilayer number and the capping PAH solution concentration, operating pressure and CuCl2 concentration on CuCl2 removal were investigated. The [PAH/PSS] 1 PAH/PSS-co-MA/PAHc NF membrane composed of only 2.5 bi-layers displayed 88.9% CuCl2 rejection and the permeate flux was 25.1 L/ m2.h when the operating pressure was 0.2 MPa. The CuCl2 rejection was still above 86.3% when the operation pressure increased to 0.8 MPa, meanwhile, the permeate flux increased greatly to 85.8 L/ m2.h.

Grafting of water‐soluble sulfonated monomers onto functionalized fumed silica nanoparticles via surface‐initiated redox polymerization in aqueous medium

AbstractSulfonated polymer/fumed silica hybrid nanoparticles were prepared via surface‐initiated free radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (PAMPS‐g‐FSN), styrene sulfonic acid sodium salt (PSSA‐g‐FSN) and vinyl sulfonic acid sodium salt (PVSA‐g‐FSN) from the surface of aminopropyl‐functionalized fumed silica nanoparticles (AFSNs) dispersed in aqueous medium. Cerium(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer respectively. AFSNs were prepared by covalently attaching 3‐aminopropyltriethoxysilane onto the surface of fumed silica nanoparticles. Sulfonated monomers (AMPS, SSA or VSA) were then grafted onto the AFSNs ultrasonically dispersed in water via redox initiation at 40 °C. Structure, thermal properties, particle size and morphology of the AFSNs and PAMPS‐g‐FSN, PSSA‐g‐FSN and PVSA‐g‐FSN hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, TGA, SEM, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results indicated that the sulfonated monomers were successfully grafted onto the fumed silica nanoparticles. Grafting amounts of the sulfonated polymers onto the fumed silica nanoparticle surface were estimated from TGA thermograms to be 59%, 13% and 29% for the PAMPS, PSSA and PVSA, respectively. From SEM, TEM and DLS analysis, polymer‐grafted fumed silica nanoparticles with an average diameter smaller than 70 nm and a (semi‐) spherical shape were observed. A significant bimodal particle size distribution was observed only for the PAMPS‐g‐FSN with average diameters of 39.6 nm (84.1% per number) and 106 nm (15.9% per number). The hydrophilic sulfonated polymer/grafted fumed silica obtained from the redox graft polymerization gave a stable colloidal dispersion in acidic aqueous medium. Copyright © 2012 Society of Chemical Industry

Water and Dye Uptake Studies of Acrylamide/4‐Styrenesulfonic Acid Sodium Salt Copolymers and Semi‐Interpenetrating Polymer Networks Composed of Gelatin and/or PVA

AbstractGelatin (GEL) and poly(vinyl alcohol) (PVA) based semi‐interpenetrating polymer network (semi‐IPN) hydrogels were prepared as a water adsorbent for cationic dye (methyl violet, MV) sorption. For this case, chemically cross‐linked copolymer of an acrylamide/4‐styrenesulfonic acid sodium salt (AAm/SSS) copolymer with PVA and/or GEL was prepared by polymerization of aqueous solution of acrylamide (AAm) and 4‐styrenesulfonic acid sodium salt (SSS) using ammonium persulfate/N,N,N',N'‐ tetramethylethylenediamine as a redox initiating pair in the presence of poly(ethylene glycol)diacrylate as a cross‐linker. FT‐IR analysis was used to identify the presence of different repeating units in the semi‐IPNs. Surface morphology was characterized by using a scanning electron microscopy technique. Some swelling and diffusion characteristics were calculated for different semi‐IPNs and hydrogels prepared under various formulations. Water uptake and dye sorption properties of the cross‐linked polymeric systems, such as AAm/SSS, AAm/GEL/SSS, AAm/PVA/SSS, and AAm/GEL/PVA/SSS hydrogel systems, were investigated as a function of chemical composition of the hydrogels. MV is used in sorption studies. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E531–E544, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21299

Modification of silica nanoparticles with hydrophilic sulfonated polymers by using surface-initiated redox polymerization

Sulfonated polymer/silica hybrid nanoparticles were prepared by free radical polymerization of 2-acrylamido-2-methyl-1-propane sulfonic acid (PAMPS-g-SN) and styrene sulfonic acid sodium salt (PSSA-g-SN), initiated on the surfaces of aminopropyl-functionalized silica nanoparticles (ASN). Ce(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer, respectively. ASN Nanoparticles were synthesized by a covalently attached 3-aminopropyltriethoxysilane onto the surface of silica nanoparticles. Sulfonated monomers (AMPS or SSA) were then grafted onto the ASN nanoparticles, ultrasonically dispersed in water, using redox initiator system at 40 °C. ASN, PAMPS-g-SN and PSSA-g-SN nanoparticles were characterized by Fourier transform infrared (FTIR), thermogravimetry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. FTIR and TGA results indicated that both AMPS and SSA monomers were successfully grafted onto the silica nanoparticles. The grafted amounts of sulfonated polymers onto the silica nanoparticles were estimated from TGA thermograms to be 46 and 22 % for PAMPS and PSSA, respectively. From SEM and TEM micrographs, the average-diameters of the polymer-grafted silica nanoparticles were measured to be <50 nm with a (semi)spherical morphology, in which several silica nanoparticles were able to form a core with PAMPS or PSSA existing around the silica nanoparticles.

Collapse of thermosensitive polyelectrolyte semi-interpenetrating networks

Thermosensitive ionic semi-interpenetrating polymer networks (semi-IPNs) based on poly(N-isopropylacrylamide) (PNIPAAm) and poly(styrene sulfonic acid sodium salt) (PSS) were synthesized, and their properties, such as conversion, swelling ratio and swelling/shrinking kinetics, were studied at different PSS fractions and molecular weight (MW). It is shown that studied semi-IPN hydrogels undergo shrinking under temperature increase. Swelling behavior and volume transition temperature of the semi-IPNs is controlled by the polyelectrolyte fraction. The increase of PSS MW allows obtaining of stable semi-IPN hydrogels. A novel phenomenon of collapse irreversibility in PNIPAAm-PSS semi-IPNs is reported. In contrast to PNIPAAm hydrogels, semi-IPNs of PNIPAAm with immobilized polyelectrolyte do not restore their volume when they reswell after shrinking. The magnitude of this effect is connected to the charged polyelectrolyte fraction.

Hydrogels as template nanoreactors for silver nanoparticles formation and their antimicrobial activities

Silver nanoparticles were synthesized and stabilized using the hydrogel template method. The synthesized hydrogels were composed of acrylamide and styrene sulfonic acid sodium salt monomers with different molar ratios. The copolymer with the highest ionic monomer content was interpenetrated with different chitosan concentrations. The main goal of this study was to evaluate the antimicrobial activity of the prepared hydrogels. The formation of silver nanoparticles within the swollen hydrogel was mainly due to an ion exchange process via the sulfonate and amino groups of the hydrogels. The surface morphology showed a uniform distribution of silver nanoparticles throughout the hydrogel structure. These nanoparticles had face-centered-cubic unit cell structure and dimensions less than 70 nm, as determined by X-ray and UV-visible spectroscopy, respectively. To investigate the antimicrobial activities of the prepared composites, their inhibitory effect was evaluated against bacteria, fungi, and yeasts. Increasing the ionic monomer and chitosan content enhanced both the swelling properties and the antimicrobial activities of these composites. The results clarified that the most sensitive strain was Bacillus subtilis.

Acid hybrid catalysts from poly(styrenesulfonic acid) grafted onto ultra-large-pore SBA-15 silica using atom transfer radical polymerization

Poly(styrenesulfonic acid)-functionalized materials based on poly(styrenesulfonic acid sodium salt) incorporated via aqueous atom transfer radical polymerization (ATRP) initiated from the surface of large-pore mesoporous SBA-15 silica support have been synthesized. The inorganic–organic nature of these hybrid materials makes them particularly desirable for acid-catalyzed reactions that require extended and hydrophobic surface areas with a narrow pore diameter distribution in the mesoporous range. Acidic hybrid materials were prepared by grafting the ATRP-initiator (3-(chlorodimethylsilyl)propyl bromoisobutyrate) on the silica surface, subsequent polymerization of the styrenesulfonic acid sodium salt monomer, and final sodium ion exchange by acid activation. Conventional and ultra-large-pore SBA-15 silica supports with nominal (BJH) pore diameter ranging from 8 to 32 nm were used for the incorporation of different polymer loadings at different polymerization times. The silylation of ATRP-initiator-functionalized SBA-15 supports has allowed a better control of the ATRP within the mesoporous structure. The use of ultra-large-pore SBA-15 supports provides a remarkable increase of the porosity which allowed us to properly allocate the polymer. The hybrid poly(styrenesulfonic acid)-modified materials showed good catalytic activities in the esterification of oleic acid with n-butanol, particularly in terms of intrinsic activity per acid site.

Electrochemical study on oxidation of ofloxacin at nano-ZnS/poly (Styrene sulfonic acid sodium salt) modified electrode and its interaction with calf thymus DNA

A PSS/nano-ZnS thin film modified electrode has been fabricated on the surface of glassy carbon electrode (GCE). In pH 5.0 phosphate buffer solution (PBS), Ofloxacin (OFX) appeared as an anodic peak with the peak potential of 1.28 V at PSS/nano-ZnS film modified electrode. In comparison with a bare GCE or a nano-ZnS modified electrode, the PSS/nano-ZnS film modified electrode exhibited an enhanced effectiveness for the oxidation of OFX. Cyclic voltammetry (CV) coupled with fluorescence and UV-vis absorbance spectra techniques were used to study the interaction of OFX with Calf thymus DNA (ctDNA). The interaction of OFX and ctDNA could result in a considerable decrease in the peak currents and positively shift in the peak potential, as well as changes of fluorescence, UV-Vis adsorption spectra. All acquired data showed that the new adduct between OFX and ctDNA was formed.

Polyelectrolyte membranes prepared by dynamic self-assembly of poly (4-styrenesulfonic acid- co-maleic acid) sodium salt (PSSMA) for nanofiltration (I)

In recent years, the layer-by-layer (LBL) self-assembly of polyelectrolyte has attracted much attention for the preparation of nanofiltration (NF) membranes. However, most researchers focused on the homopolymers, few studied on the copolymers for the preparation of NF membranes. In the present work, a series of nanofiltration membranes were prepared by dynamic self-assembly of a copolymer polyelectrolyte containing both weakly and strongly ionized groups, poly (4-styrenesulfonic acid- co-maleic acid) sodium salt (PSSMA), with poly (allylamine hydrochloride) (PAH) and poly (styrenesulfonic acid sodium salt) (PSS) on the modified polyacrylonitrile (PAN) ultra-filtration membranes. The effects of substrate, deposition pH, SS/MA ratio in PSSMA, concentration of the PSSMA and bilayer number on the properties of the NF membranes were investigated. The results indicated that the performances of the NF membranes prepared by dynamic self-assembly process were superior to those prepared by the static self-assembly process. The membranes terminated with PSSMA were negatively charged. Due to the changes of charge density and conformation of PSSMA in different pH conditions, the [PAH/PSS] 1PAH/PSSMA membrane prepared at pH 2.5 showed higher Na 2SO 4 rejection and larger flux than those of the membrane prepared at pH 5.7. The NF membrane [PAH/PSS] 1PAH/PSSMA composed of only two bilayers exhibited 91.4% Na 2SO 4 rejection and allowed solution flux of 28.6 L/m 2 h at 0.2 MPa. The solution flux increased to 106.6 L/m 2 h at 0.8 MPa, meanwhile, no obvious decrease in Na 2SO 4 rejection was observed.

Preparation of Poly(phenylene oxide-gstyrenesulfonic acid) and their Characterization for DMFC Membrane

Well-defined poly(2,6-dimethyl-4,4′-phenylene oxide)-g-poly(styrenesulfonic acid) (PPO-g-PSSA) graft copolymer was synthesized via living radical polymerization. For the graft copolymer, poly(2,6-dimethylphenylene oxide) (PPO) was brominated first, and the brominated PPO (PPO-Br) was used as a macroinitiator in the atom transfer radical polymerization (ATRP) of styrenesulfonic acid sodium salt. The number of grafts per PPO chain and the molecular weight of the graft were controlled by adjusting the degree of bromination, and conversion in ATRP, respectively. The graft copolymers obtained were transformed into proton exchange membranes for direct methanol fuel cell (DMFC) application. The performance of the membranes was measured in terms of water uptake, proton conductivity, methanol permeability, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with PSSA block content. Very low methanol permeability and good proton conductivity were observed by adjusting grafting frequency and PSSA block content.

Thermally induced surface graft copolymerization with concurrent lamination of polyaniline films under atmospheric conditions

Simultaneous lamination of emeraldine base (EB) films of polyaniline (PANI) was achieved during thermally induced surface graft copolymerization with various monomers, such as N,N′-dimethyl(methacryloylethyl)ammonium propanesulfonate (DMAPS), sodium salt of styrenesulfonic acid (NaSS), 1-vinyl imidazole (VIDz) and acrylic acid (AAc). The simultaneous thermal grafting and lamination process can be carried out under atmospheric conditions, and in the complete absence of an added polymerization initiator and surface preactivation of the EB substrates. The structure and chemical composition of the graft copolymerized surfaces from the self-delaminated junction in water were investigated by X-ray photoelectron spectroscopy (XPS). The effects of monomer concentration, thermal grafting/lamination temperature, and the physicochemical attributes of the various monomers on the observed lamination strength were studied. The efficiency of surface graft copolymerization and the lamination strength were found to increase with increasing temperature in the temperature range of 80–120°C. Maximum lap shear adhesion strengths of greater than 350 N/cm 2 and exceeding the yield strength of the substrate EB film could be readily achieved for grafting/lamination carried out in the presence of DMAPS, VIDz and AAc monomer.

Chemical modification and photograft polymerization upon expanded poly(tetrafluoroethylene)

Poly(tetrafluoroethylene) (PTFE) films were surface-modified by employing a reaction solution of benzophenone and sodium hydride in anhydrous dimethylformamide at a temperature of 150°C for 12 h. Electron spectroscopy for chemical analysis (ESCA) showed defluorination, oxygen incorporation, and extensive unsaturation within the treated PTFE surfaces. The suitability of these reduced PTFE films as substrates for graft polymerization was initially assessed via photograft polymerization of the sodium salt of styrenesulfonic acid (SS-Na), which permitted unequivocal surface analysis by the introduction of a new atom, as well as poly(ethylene glycol) monoacrylate (PEG-Ac). All photograft polymerization was performed employing ultraviolet irradiation with 2,2-dimethoxy-2-phenylacetophenone as an initiator. Photograft polymerization of SS-Na was verified by further reduction of fluorine atomic content and the appearance of new sulfur and sodium atomic peaks on ESCA survey spectra, and that of PEG-Ac was verified by further reduction of fluorine atomic content and increase of atomic percent ratio of O/C from ESCA survey spectra as well as appearance of a new ester peak on high resolution ESCA C Is spectra. Dynamic water contact angles on reduced and PEG-Ac photograft polymerized films were measured and showed that the PTFE film surface became more hydrophilic after reduction (from 120 to 89 deg) and the reduced film became more hydrophilic after photograft polymerization with PEG-Ac (from 89 to 36 deg). Modification of the complete surface of expanded PTFE (ePTFE), i.e. of the lumenal, outside and pore surfaces, was performed by employing the reaction described above, except at 105°C for 1 day, followed by photograft polymerization of PEG-Ac. ESCA was performed on the superficial surfaces (i.e. the lumen and exterior) as well as on cross-sections of the ePTFE to permit analysis of the pore surfaces. This analysis showed that both the initial surface reduction and the subsequent photograft polymerization were successful as indicated from F/C and O/C atomic percent ratios from ESCA survey spectra, from overall peak shapes of high resolution ESCA C1s spectra and from generation of new ester peaks on high resolution ESCA C Is spectra of ePTFE graft polymerized with PEG-Ac, which demonstrated an O/C atomic percent ratio close to that of PEG-Ac homopolymer. Low voltage scanning electron microscopy confirmed minimal morphological damage to the ePTFE microstructure after reduction and graft polymerization. The approach explored thus provides a means for modulation of biological interactions at ePTFE