Positive working photoresists sensitive to visible light,II: poly{2-arylpropyl-2 and bis(p-methoxyphenyl)methyl methacrylates}

Acid-labile polymers of methacrylates of 2-(p-substituted phenyl)propanol-2 and bis(p-methoxyphenyl)methanol were evaluated as visible light sensitive positive-type resists. The chemistry to form images is based on the cleavage of esters catalysed by an acid generated by photodecomposition of diphenyliodonium hexafluorophosphate sensitized by 2-benzoyl-3-(p-dimethylaminophenyl)-2-propenenitrile. A copolymer of bis(p-methoxyphenyl)methyl methacrylate-phenyl methacrylate exhibited a high photospeed upon exposure to 488 nm light when coupled with the iodonium salt and the dye, and was applicable to relief holography.     

Synthesis, characterization and hydrolytic stability of poly (amic acid) ammonium salt

A series of new poly (amic acid) ammonium salt (PAAS) precursors were prepared by incorporating different amounts of triethylamine (TEA) into terpolymer polyamic acid (PAA), which was synthesized by pyromellitic dianhydride (PMDA), 4,4’-oxydianiline (ODA) and p-phenylenediamine (PDA) in dimethylacetamide (DMAc). Then, the PAAS films were made by casting their solutions onto glass plates followed by the evaporation of the solvent. The chemical structure of PAAS films was confirmed by ¹H NMR and FTIR spectroscopy. Mechanical properties, intrinsic viscosities and solubility of PAAS precursors were examined, respectively. It was found that the intrinsic viscosity of PAA solution obviously decreased with storage time during 30 days, while no distinct changes were observed in the intrinsic viscosity of the PAAS (the mole ratio of TEA/repeating unit of PAA = 2/1) solution after 90 days. The results suggested that hydrolytic stability of the PAAS films was significantly improved as compared with that of PAA film due to the polyelectrolyte structure of PAAS. Moreover, the thermal and mechanical properties of polyimide (PI) films prepared from PAAS precursors were also investigated, respectively.     

Kinetics and mechanism of sensitized photooxidation of tetramethylammonium salt of 2-(phenylthio)acetic acid in solution: Steady-state and flash photolysis studies

The mechanism for the photo-induced oxidation of the tetramethylammonium salt of 2-(phenylthio)acetic acid was elucidated. The photosensitizer was the benzophenone triplet in acetonitrile solutions. Time-resolved absorption spectra and kinetics were used to follow the intermediates which included the triplet of benzophenone, the ketyl radical of benzophenone, and an ion pair consisting of a radical anion of benzophenone and a tetramethylammonium cation. Rate constants for the growth and decay of the transients were determined along with the quantum yields of the transients. The intermediacy of other radicals was inferred by the products observed following steady-state photolysis. Quantum yields were also determined for photoproducts resulting from the steady-state irradiation. The mechanism was proposed that rationalized the quantitative observations. Of particular note was how the nature of the counter ion effected the secondary reactions of the radicals and the radical ions.     

Design of anhydrous electrorheological (ER) suspensions based on I2-doped poly(pyridinium salt)

A rigid-rod aromatic poly(pyridinium salt) was synthesized and doped with iodine (I₂) for making anhydrous electrorheological (ER) fluids. The I₂-doped particles were further processed into ones having insulating skins. Dielectric properties and current densities of the suspensions containing these particles were studied to elucidate the roles of conductivity of the dispersed phase in the ER suspension. © 1994 John Wiley & Sons, Inc.     

pH-effects in the complex formation of polymers I. Interaction of poly(acrylic acid) with poly(acrylamide)

The effects of polymer concentration, molecular weight of poly(acrylic acid) (PAA), addition of sodium, potassium, ammonium and copper (II) chlorides on the complex formation ability of the system PAA-poly(acrylamide) (PAAM) have been studied in aqueous solutions. The critical pH values of the complexation were determined in different conditions. The complex formation ability of PAAM is compared with other non-ionic polymers. It was shown that an increase in polymers concentration, molecular weight of PAA and ionic strength favours the complexation and shifts the critical pH values to the higher pH region. An addition of CuCl₂ to the mixture of two polymers enhances the complexation drastically due to the formation of triple complexes.     

The grafting of acrylamide onto poly(ε‐caprolactone) and poly(1,5‐dioxepan‐2‐one) using electron beam preirradiation. I. Influence of dose and Mohr's salt for the grafting onto poly(ε‐caprolactone)

Poly(ε‐caprolactone) films (TONE® 787) were irradiated by electron beam in air prior to grafting in aqueous solutions of acrylamide. The grafting kinetics and molecular weight of the grafted poly(acrylamide) chains were studied with irradiation doses between 2.5 and 20 Mrad and in the Mohr's salt concentration range of 0.0025–1 wt %. The grafting rate and yield were strongly dependent on the Mohr's salt concentration. By molecular weight analysis of grafted poly(acrylamide) chains, it was shown that the molecular weight is approximately proportional to the mass of the grafted PAAm. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1643–1649, 1999     

IR laser ablative modification of poly(ethylene-co-acrylic acid) zinc salt

IR laser-induced ablative degradation of poly(ethylene-co-acrylic acid) zinc salt (PEAZn) leads to cleavage of both polyethylene backbone and CO₂H group. It yields carbon oxides and volatile hydrocarbons (ethene as a major product) and affords ablative deposition of solid ionomeric films in which the initial ratio -CO₂H/-CO₂Zn is decreased due to higher thermal stability of the -CO₂Zn group. The laser-induced process differs remarkably from conventional degradation of similar polyethylene chain-based metal methacrylate ionomers that are known to yield cold ring fraction containing only -CO₂H group. The cleavage of the polyethylene backbone in the laser-induced degradation becomes more important at higher fluences. The presence of sodium metasilicate is shown to accelerate the decomposition of the CO₂H group.     

Preparation of poly(bis(trialkylammonium) 4,4′-oxydiphenylenepyromellitamate) films: A useful polyimide precursor film

A poly[bis(trialkylammonium) 4,4′-oxydiphenylenepyromellitamate] film not containing residual solvents was prepared first as a polyimide precursor film. The preparative method is composed of three process steps involving (1) polymerization of pyromellitic dianhydride with 4,4′-oxydianiline in a mixed solvent of tetrahydrofuran/methanol, (2) addition of a mixture of methanol/trialkylamine to the resulting poly(4,4′-oxydiphenylenepyromellitamic acid) solution, and (3) casting onto glass plates and drying. The salt formation between the poly(amic acid) and trialkylamines was confirmed first by spectroscopic methods. The dried salt film is thermally cured to produce the polyimide film with a reduced coefficient of thermal expansion (CTE). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2493–2499, 1997     

Miscibility of poly(ϵ-caprolactone) and of poly(styrene-co-acrylonitrile) with poly(styrene-co-acrylic acid)

The miscibility of poly (?-caprolactone) (PCL) with poly (styrene-co-acrylic acid) (SAA) and of poly (styrene-co-acrylonitrile) (SAN) with SAA was examined as a function of the comonomer composition in the copolymers. For PCL/SAA blends it was found that PCL is miscible with SAA within a specific range of copolymer compositions. Segmental interaction energy densities were evaluated by analysis of the equilibrium melting point depression and application of a binary interaction model. The results suggest that the intramolecular repulsion in SAA copolymer plays an important role in inducing the miscibility. Additionally, the critical AA content in SAA for the blend to be homogeneous was predicted by correlating the segmental interaction energy densities with the binary interaction model. For SAN/SAA blends, it was also found that SAA is miscible with SAN within a specific range of copolymer compositions. From the binary interaction model, segmental interaction energy denisties between different monomer units were estimated from the miscibility map and were found to be positive for all pairs, indicating that the miscibility of the blends is due to the strong repulsion in the SAA copolymers.     

Hydrogen bonded layer-by-layer assembly of poly(2-vinylpyridine) and poly(acrylic acid): Influence of molecular weight on the formation of microporous film by post-base treatment

This article describes the buildup of hydrogen bonded multilayer film of poly(2-vinylpyridine) (P2VP) and poly(acrylic acid) (PAA), and the influence of polymer molecular weight on the formation of microporous film by post-base treatment. The formation of a microporous film involved a two-step mechanism: the release of PAA from P2VP/PAA multilayer, and the reorganization of the remaining P2VP on the substrate. Fourier transform infrared spectroscopy (FT-IR) indicated that the release of PAA from hydrogen bonded multilayer was a rapid process, which was almost independent of the molecular weight of PAA. Furthermore, the molecular weight of P2VP had a great effect on micropore formation by immersing the P2VP/PAA multilayer in basic solution. The rate of micropore formation increased with increasing molecular weight. We anticipate that a comparative study on P2VP/PAA films containing high or low molecular weight polymer provides a way to control the surface morphology, and will be helpful and constructive for the forthcoming discussion about the formation of the microporous film.     

Modification of polybenzimidazole: Synthesis and thermal stability of poly(N1-methylbenzimidazole) and poly(N1,N3-dimethylbenzimidazolium) salt

Poly(N₁,N₃-dimethylbenzimidazolium) (PDMBI) salt and poly(N₁-methylbenzimidazole) (PMMBI) were synthesized by methylation of commercial polybenzimidazole [poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole (PBI)]. First, the N-lithium salt of polybenzimidazole was formed by treating polybenzimidazole solution of 1-methyl-2-pyrolidinone (NMP) with lithium hydride at 80°C for 18 h. Ninety percent substitution of PMMBI was obtained by treating the N-lithium salt of PBI with equimolar ratio of iodomethane at room temperature. Upon addition of excess iodomethane to the lithium salt of PBI at 80°C, a polymer was formed that showed 100% substitution on the N₁ nitrogen and about 30% substitution of the methyl group on the N₃ nitrogen in the form of N₁,N₃-dimethylbenzimidazolium iodide salt [PDMBI (30%)]. The content of the benzimidazolium iodide salt was increased to about 90% by dissolving PDMBI (30%) in dimethyl sulfoxide (DMSO) and re-treating with excess iodomethane at 80°C overnight. The modified PBI polymers were characterized by NMR and FTIR. The modified PBI differed in solubility from PBI. PMMBI could be easily dissolved in NMP and PDMBI in DMSO at room temperature. The solution of PDMBI could be mixed with water in all proportions without precipitation. PDMBI could be also dissolved directly in a mixture of DMSO and water (1 : 1). Typical polyelectrolyte behavior of viscosity was found in solution of PDMBI (30%) and PDMBI (90%) when DMSO and a mixture of DMSO and water were used as solvents. A salt effect on viscosity was also found in the mixed solvent solution. Thermogravimetric analysis (TGA) showed that the methyl group on the imidazole ring was unstable above 180°C under nitrogen. When PDMBI was heated under nitrogen, one of the methyl groups was lost with the counterion to result in a neutral PMMBI. © 1993 John Wiley & Sons, Inc.     

Polycaprolactone–poly(ethylene glycol) block copolymer,I: synthesis and degradability in vitro

A new type of biodegradable polymer material, poly(caprolactone)–poly(ethylene glycol) block copolymer (PCL-b-PEG), was synthesized by means of direct copolycondensation of ε-caprolactone with poly(ethylene glycol) in the presence of a Ti(OBu)₄ catalyst. The degradability of the polycaprolactone was improved by introducing a PEG component into it. The degradation of PCL-b-PEG copolymer increase with a decreasing crystallinity of the copolymer, and can be controlled by adjusting the component ratio of the copolymer.     

Long-term performance of poly(vinyl chloride) cables, Part 2: Migration of plasticizer

Cable samples with plasticized poly(vinyl chloride) insulations were aged in air at temperatures between 80 and 155 °C. The concentrations of the plasticizer (di-(2-ethylhexyl) phthalate, DEHP) in the insulations of the aged cables were determined by extraction of samples in tetrahydrofuran followed by analysis of the extract by liquid chromatography. The plasticizer concentration data for different ageing times were analysed by numerical methods, fitting Fick's second law with a concentration-dependent diffusivity. The analysis showed that the transport of the plasticizer to the surrounding air phase was controlled by diffusion at 120 and 155 °C with an activation energy of 89 kJ mol⁻¹. The evaporation of the plasticizer from the outer boundary was rate controlling at lower temperatures (≤100 °C). The rate of evaporation was initially constant and independent of the plasticizer concentration at both 80 and 100 °C. The activation energy for the initial DEHP loss rate from PVC at these temperatures was the same as that obtained for evaporation of pure DEHP on a glass plate at 60-100 °C measured by thermogravimetry, 98 ± 2 kJ mol⁻¹. Furthermore, the evaporation rate of pure DEHP on a glass plate was also of the same order of magnitude as the rate of plasticizer loss from the cable insulation. Extrapolation of the plasticizer loss rate data (from the cable at 80 °C and from pure liquid DEHP at temperatures between 60 and 100 °C) to 25 °C predicted a maximum loss of plasticizer of 1% over 25 years. This is in accordance with earlier presented data and with the data presented in this report.     

Double‐layer poly(vinyl alcohol)‐coated capillary for highly sensitive and stable capillary electrophoresis and capillary electrophoresis with mass spectrometry glycan analysis

Glycosylation plays an important role in protein conformations and functions as well as many biological activities. Capillary electrophoresis combined with various detection methods provided remarkable developments for high‐sensitivity glycan profiling. The coating of the capillary is needed for highly polar molecules from complex biosamples. A poly(vinyl alcohol)‐coated capillary is commonly utilized in the capillary electrophoresis separation of saccharides sample due to the high‐hydrophilicity properties. A modified facile coating workflow was carried out to acquire a novel multiple‐layer poly(vinyl alcohol)‐coated capillary for highly sensitive and stable analysis of glycans. The migration time fluctuation was used as index in the optimization of layers and a double layer was finally chosen, considering both the effects and simplicity in fabrication. With migration time relative standard deviation less than 1% and theoretical plates kept stable during 100 consecutive separations, the method was presented to be suitable for the analysis of glycosylation with wide linear dynamic range and good reproducibility. The glycan profiling of enzymatically released N‐glycans from human serum was obtained by the presented capillary electrophoresis method combined with mass spectrometry detection with acceptable results.     

Surface charge modulation of poly(ethylene glycol)–poly( , -lactide) block copolymer micelles: conjugation of charged peptides

Block copolymer micelles with aldehyde functionality were prepared in aqueous medium by dialyzing the N,N-dimethylacetamide solution of α-acetoxy-poly(ethylene glycol)-poly( , -lactide) block copolymer (acetal-PEG–PDLLA) against water, followed by mild acid treatment to convert the acetal moiety of the micelle to the aldehyde group. Peptidyl ligands (phenylalanine (Phe) and tyrosyl–glutamic acid (Tyr–Glu)) were then chemically conjugated to the micelle through Schiff base formation and successive reductive amination using NaBH₃CN. Micelles with peptidyl ligands thus prepared have a size of approximately 40 nm with extremely narrow distribution (μ₂/ ²<0.1) based on cumulant analysis of dynamic light scattering. A maximum 53% of the PEG-chain end of the micelle could be converted into peptidyl groups. Zeta potential values of Tyr–Glu derivatized micelles were well correlated with the amount of conjugated ligands, controllable over the range of 0 to−9 mV in sodium phosphate buffer (pH 7.4, 10 mM). These micelles with peptidyl ligands may have a utility for exploring the effect of the surface charge on the pharmacokinetic behavior of particulate systems as well as for modulated drug delivery where cellular peptidyl receptors play a substantial role.     

Adsorption of lysozyme and α-lactalbumin on poly(styrenesulphonate) latices 2. Proton titrations

A study on the titration behaviour of hen's egg lysozyme (LSZ) and milk α-lactalbumin (LAC) is presented. Titration curves for the proteins in their native state, after exposure to denaturing agents, and adsorbed on poly(styrenesulphonate) (PSS) latices are compared. Titrations of the proteins in the presence of guanidinium hydrochloride and sodium dodecyl sulphate (SDS) show that electrostatic interactions, more than alterations in the chemical environment, affect the dissociation of the charged groups on the protein molecule. The titration of adsorbed (apo)-LAC is similar to that of the SDS-denatured state, independent of the surface coverage. The titration of LSZ depends on the degree of coverage, suggesting different modes of adsorption. The two conformers of LAC, i.e. apo-LAC and Ca-LAC, are compared to test the influence of the structural stability of the protein on the titration behaviour. In solution, the two conformers of LAC titrate differently, but after adsorption on to a PSS latex surface the titration behaviour is practically the same. This points to a similar adsorbed state, with expulsion of the Ca²⁺ ion from the Ca-containing form.     

Preparation and characterization of poly(2‐methacryloyloxyethyl phosphorylcholine)‐block‐poly(D,L‐lactide) polymer nanoparticles

A poly(D,L ‐lactide)–bromine macroinitiator was synthesized for use in the preparation of a novel biocompatible polymer. This amphiphilic diblock copolymer consisted of biodegradable poly(D,L ‐lactide) and 2‐methacryloyloxyethyl phosphorylcholine and was formed by atom transfer radical polymerization. Polymeric nanoparticles were prepared by a dialysis process in a select solvent. The shape and structure of the polymeric nanoparticles were determined by ¹H NMR, atomic force microscopy, and ζ‐potential measurements. The results of cytotoxicity tests showed the good cytocompatibility of the lipid‐like diblock copolymer poly(2‐methacryloyloxyethyl phosphorylcholine)‐block‐poly(D,L ‐lactide). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 688–698, 2007     

Modified cotton fabrics with poly (3-(furan-2-carboamido) propionic acid) and poly (3-(furan-2-carboamido) propionic acid)/gelatin hydrogel for UV protection,antibacterial and electrical properties

This research aimed to prepare smart cotton fabrics with multi functions for antibacterial activity, UV protection and electrical conductivity via in situ coating with conductive polymer and conductive hydrogel. Therefore, 3-(furan-2-carboamido) propionic acid was synthesized followed by polymerization using ceric ammonium nitrate. In addition, cotton fabrics coated with 3-(furan-2-carboamido) propionic acid via in situ polymerization and by the hydrogel that based on poly (3-(furan-2-carboamido) propionic acid) and gelatin which have been performed via in situ gelation process. The chemical structure and morphology of the 3-(furan-2-carboamido) propionic acid (monomer) and the synthesized polymer (PFu) were investigated by H¹NMR, IR, SEM, TGA and DSC. Where, the treated fabrics (PFu-T and PFu-G-T) are characterized by SEM, FTIR and contact angle. Furthermore, the AC electrical conductivity and dielectric properties of PFu, PFu-T, PFu-G-T and blank were investigated over the frequency range of 20 Hz–10 MHz at room temperature using impedance spectroscopy where the electric conductivity values are 1.74 × 10^-5, 7.5 × 10^-8, 4 × 10^-7, 8.24 × 10^-11 (S·cm)^-1, respectively. In addition, the anti-bacterial activity of PFu-T, PFu-G-T and blank was assessed versus gram-positive and gram-negative bacteria where, PFu-G-T shows activity against Escherichia coli and Staphylococcus aureus. Moreover, PFu-T, PFu-G-T showed high UV protection especially for PFu-G-T.     

Study on the reaction of triple helix poly(A:2I) with Cu~(2+)

The effect of Cu2+ on the triple-stranded helical structure of poly(A:2I) was studied by means of circular dichroism spectral method with the help of ultraviolet spectral and ethidium bromide fluorescence probe methods. It was found that Cu2+ destabilizes the structure of the triple helix poly(A:2I) and induces its structural transformations, meanwhile, the transformations can be partially reversed by a higher NaCl concentration. The structural transformations may be expressed by the following scheme: poly(A:2I) - poly(A:I) + poly(I)- poly(A) + 2poly(I)     

A first methodical approach to salts with unsymmetrical fluorophenyl(pentafluorophenyl)difluoroiodonium(V) cations [Rf(RF)IF2] (Rf=x-FC6H4, x=2, 3, 4; RF=C6F5)

A promising approach to the unknown type of [Ar′(Ar)IF₂]X salts is offered. x-FC₆H₄IF₄ (x=2, 3, 4) reacts with C₆F₅BF₂ in CH₂Cl₂ and forms [x-FC₆H₄(C₆F₅)IF₂][BF₄] salts in good yields. For [4-FC₆H₄(C₆F₅)IF₂][BF₄] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C₆F₅)₃ (E=P, As, Sb, Bi) and ArI (Ar=4-FC₆H₄, C₆F₅). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC₆H₄)₂IF₂][BF₄], an example with two identical aryl groups in the difluoroiodonium(V) moiety.