Glow discharge polymerization of tetramethylsilane by capacitive coupling of 20 kHz frequency and surface hardening of polyethylene sheet

Glow discharge polymerizations of tetramethylsilane (TMS) were performed by the capacitive coupling of a 20 kHz frequency in comparison with those by the inductive coupling of a 13.56 MHz frequency. The polymers prepared by the former coupling were poorer in carbon and hydrogen, but richer in silicon than those prepared by the latter coupling. These two polymers showing similar infrared spectra contained CH₃, CH₂, CH, Si? O? C, Si? O? Si, Si? CH₃, and Si? CH₂? CH₂? Si groups. Some physical properties involving surface energy, thermal stability, and absorption spectra in the regions of the UV and visible light were determined. This coating procedure was applied for surface hardening of a polyethylene sheet. The surface hardness of the polyethylene sheet was enhanced by a coating of plasma films prepared from TMS or the TMS/O₂ mixtures. Surface hardness was determined by the pencil method and hardness was enhanced from 2B to 2H. The adhesion between these plasma films and polyethylene sheet was good even when immersed in 0.9% NaCl solution at 40°C for 10 days.     

New fluorinated polysiloxanes containing an ester function in the spacer—II. Surface tension studies

The surface tensions of fluorinated polysiloxanes prepared by hydrosilylation of unsaturated perfluoroalkyl esters derived from undecylenic acid [CH₂?CH? (CH₂)₈? COO? CH₂? CH₂? R_F, with R_F = C₆F₁₃, C₈F₁₇, and C₈F₁₇? (CH₂)₁₀COO? CH₂? CH₂? CH?CH₂] by methylhydrodimethylsiloxane copolymers of various Si? H contents have been measured. The critical surface tensions, γ_c, and the solid surface tensions, γ^D_s, were deduced from n-alkane and water contact angle data. They decrease as the perfluoroalkyl graft content of the copolymers increases. Some of them, which are in the range of the lowest surface tension fluoro polymers known, are observed when the fluorinated segments are self-organized at the interface, i.e. when the polymers are mesomorphous or crystalline at room temperature.     

Thermomechanical behavior of poly(carborane–siloxane)s containing ?CB5H5C? cages

The thermomechanical spectra of two new carborane–siloxane polymers containing five-boron carborane cages in the backbones are reported and discussed. The polymers are the homopolymer, HO? [Si(CH₃)₂? CB₅H₅C? Si(CH₃)₂? O? ]_nH, and the random copolymer with 20 mole-% of the ten-boron meta-carborane analogue, ? [Si(CH₃)₂? CB₁₀H₁₀C? Si(CH₃)₂? O? ]. The mechanical spectra (～1 cps) were determined from ?180° → +625° → ?180°C (ΔT/Δl = 3.6°C/min for T > 25°C and 2°C/min for T < 25°C) using the semimicro thermomechanical technique, torsional braid analysis. In nitrogen, both polymers displayed secondary transitions at ?140°C. The glass transition (T_g) for the homopolymer was ?60°C and for the copolymer was ?52°C. The homopolymer had a melting point of +70°C. The copolymer was amorphous. The high-temperature stability in nitrogen of both polymers appeared to be identical; thermal stiffening commenced at 400°C, continued to 625°C, and resulted in materials that were typical of highly crosslinked resins. In air, the homopolymer began to stiffen catastrophically near 270°C, while the copolymer began to stiffen similarly nearly 50°C higher. The intrinsic elastomeric nature together with the thermomechanical results prompted further study of the copolymer. Thermomechanical cycling studies in nitrogen and air are reported for the copolymer. Some correlating TGA and DTA are also discussed.     

Polymerisation von Vinylchlorid bei Atmosphärendruck. 2. Chemische und spektroskopische Methoden zur Charakterisierung von U-PVC

PVC, which was polymerized at atmospheric pressure (so called U-PVC) contains relatively high concentrations of defects contrary to normal PVC. The number of chain scissions in U-PVC determined by ozonolytic cleavage resulted in values between 0.026 and 0.058 per 100 monomer units (100 VC). The determination of allylic and tertiary chlorine was done by selective reaction of U-PVC with phenol and NMR-spectroscopic investigations of the phenolized polymers. The average ‘labile chlorine’ content amounts to 0.65/100 VC. Hydroxyl radicals formed during the decomposition of the initiator (K₂S₂O₈) resulted in alcoholic endgroups in U-PVC, which were detectable in the IR-spectrum at 3580 cm^?1. The termination with hydroxyradicals also led to structures at the chain ends changing into ß-chloraldehyde groups accompanied by HCl-elimination. The corresponding signal in the IR-spectrum appeared at 1720 cm^?1. U-PVC raw material contained about two branch points per 100 VC. The CCl₄ extracts of the same polymers revealed the ten-fold content of branching. The olefinic structures ? CH?CH? CHCl? and ? CHCl? CH?CH₂ were determined by NMR-spectroscopy. The concentrations of each ranged from 0.25 to 0.3/100 VC. A typical double bond for U-PVC at the chain ends represented the structure ? CH?CH? CH₂Cl, which was preferably present in the low molecular weight material.     

Sulfonic acid group-containing thin films prepared by plasma polymerization

Plasam polymerization of hydrocarbon/sulfure dioxide mixtures, C₂H/SO₂, C₂H₄/SO₂, and CH₄/SO₂ mixtures, was investigated to obtain thin films containing sulfonic acid groups. Plasma polymerization of C₂H₂/SO₂ and C₂H₂/SO₂ mixtures gave filmlike products but that of the CH₄/SO₂ mixtures did not. The plasma polymers possessed much amount of sulfur and oxygen moieties with hydrocarbon chains. The sulfur moieties involved thio, sulfite, and sulfonic acid groups. This groups was a main product and reached 70–80 mol % of the total sulfur moieties. The remains (20–30 mol %) were sulfonic acid and sulfite groups. The oxygen moieties were hydroxyl and carbonyl groups with small amount of carbonxyl groups. The plasma polymers showed and hydrophilicity (the surface energy was 54–56mN/m) and good antithrombogenity.     

Effects of amines on the polymerization of isoprene with sec-butyllithium catalyst

Polymerization of isoprene (IP) with alkyllithium (RLi) catalysts in the presence of amines such as triethylamine (TEA), 1,2-dipiperidinoethane (DPPE) and N,N,N′,N′-tetramethyldiaminoalkanes [(CH₃)₂N(CH₂)_nN(CH₃)₂ where n=1, 2, 3, 4 and 6 (TMDAA)] has been studied. By adding the amines, the polymerization rate of IP was accelerated, and the contents of 3,4- and 1,2-units in the resulting polymers increased. The effects of methylene chain length of the TMDAA on the polymerization were examined. It was found that both the polymerization rates and the microstructure of the polymers depend on the methylene length of the TMDAA. The amines having 2 and 3 methylenes in (CH₃)₂N(CH₂)_nN(CH₃)₂ favoured production of the polymer consisting of predominantly 1,2- and 3,4-units. It was proposed that two types of active sites for the polymerization of IP were produced depending on the number n of the TMDAA. Two types of active species were confirmed to be produced with sec-BuLi in the presence of N,N,N′,N′-tetramethylethylenediamine (TMEDA) depending on the TMEDA/sec-BuLi mole ratios. © 1998 SCI.     

Permeation of simple gases through plasma polymerized films from fluorine-containing monomers

The permeation of several different permanent gases through plasma polymer membranes was studied. The plasma polymers were produced by a microwave discharge of various fluorine-containing monomers. Plasma polymers made from fluorine-rich monomers (F/C ≈ 1) yield films with the highest selectivities; those made from low fluorine content monomers show very little selectivity among the various gases. CO₂ solubility is very high in the fluorine-rich plasma polymers and gives rise to large CO₂ to CH₂ selectivities. © 1995 John Wiley & Sons, Inc.     

Decomposition of ethoxyethane in the cold plasma environment

A radio frequency (RF) plasma system was used to decompose the ethoxyethane (EOE) contained gas. The reactants and final products were analyzed by using an FTIR (Fourier Transform Infrared) spectrometer. The effects of plasma operational parameters, including input power wattage (W), equivalence ratios (Φ), feeding concentration (C) of EOE and total gas flow rate (Q) for EOE decomposition were evaluated. In addition, the possible reaction pathways for EOE decomposition and the formation of final products were built up and are discussed in this paper. The mole fraction profiles of C₂H₅OC₂H₅, CH₃CHO, CH₄, C₂H₆, C₂H₄, C₂H₂, CO₂ and CO were detected and are also presented in this paper. At lower input power wattages, the creation of glow discharge is strongly dependent on the plasma production index ( PPI ). When input power wattages are smaller than 30 W, the minimum values of PPI to create glow discharge ranged between 18.2 and 19.0. The results of this study revealed that, in the RF plasma reactor, the decomposition fraction of EOE could reach 100% under most operational conditions. © 2000 Society of Chemical Industry     

Introduction of carboxylic groups on ethylene-co-tetra fluoroethylene (ETFE) film surfaces by CO2 plasma

ETFE film surfaces were modified by CO₂, O₂ and Ar plasmas in order to form carboxylic groups on their surfaces, and the possibility that carboxylic groups could be predominantly introduced into the CH₂–CH₂ component rather than the CF₂–CF₂ component in the ETFE polymer chains was investigated from the viewpoint of chemical composition analyzed by XPS. The CO₂ plasma modification was more effective in the selectivity of the CH₂CH₂ component for the introduction of carboxylic groups, as well as in the concentration of the carboxylic groups formed on the film surfaces than O₂ plasma modification. The concentration of carboxylic groups formed on the ETFE film surfaces by the CO₂ plasma modification was 1.40–1.50 groups per 100 carbons. Topographical changes on the ETFE film surfaces by the plasma modification were also investigated by scanning probe microscopy.     

Plasma polymerization of perfluoro-2-butyltetrahydrofuran/methane and perfluorobezene/tetrafluoromethane mixtures and gas permeation properties of the plasma polymers

Plasma polymer films prepared from perfluoro-2-butyltetrahydrofuran (PFBTHF) and perfluorobenzene (PFB) were investigated by elemental analysis, infrared spectroscopy, and ESCA. The gas separation properties were also investigated to seek plasma polymer films with good permselectivity. Plasma polymer films from PFBTHF and PFB were composed of polymer chains with fluorinated moieties such as C –CF_n, C F, C F–CF_n, C F₂, and C F₃ groups. Changes in the afcurrent as an operating condition for plasma polymerization showed less influence on the distribution of the fluorinated moieties but more influence on the permselectivity of the plasma polymer films formed. The permselectivity was improved by plasma polymerization in the PFBTHF/CH₄ or PFB/CF₄ mixture systems. The P_O2/P_N2 ratio for the plasma polymer films prepared from PFBTHF/CH₄ and PFB/CF₄ mixtures increased from 3.1 at 0 mol % CH₄ to 4.0 at 50 mol % CH₄ addition, and from 4.1 at 0 mol % CF₄ to 5.0 at 25 mol % CF₄ addition, respectively. The permselectivity of the plasma polymer films may be related to the crosslinkage and aggregation of polymer chains rather than the elemental composition.     

Self-Organizing Cyclolinear Organosilicon Polymers in Bulk and on the Surface of Water ?

Cyclolinear organocarbosiloxane polymers with varying content and location of (CH₂)_n groups in the monomer unit were synthesized by reactions of heterofunctional polycondensation and polyaddition of difunctional organocyclosiloxanes and organocyclocarbosiloxanes. Their bulk properties were studied by differential scanning calorimetry and X-ray structural analysis. It was shown that on introduction of CH₂ groups into the methylcyclohexasiloxane unit, the polymer retains the ability to self-organize with formation of a mesomorphic state in a wide temperature range, while on introduction of (CH₂)₂ fragments in a cyclotetrasiloxane unit or in a bridge connecting two methylcyclotetra(hexa)siloxane units it does not. Comparison of the X-ray data of dihydroxy derivatives of decamethylcyclohexasiloxane and decamethyl-5-carbocyclohexasiloxane with packing of cyclolinear organosilicon polymers in bulk shows that the polymer inherits the layered type of crystalline structure typical for monomers. Langmuir films of cyclolinear polymethylcarbosiloxanes with different design of monomer units were studied as well. It was revealed that all polymers form monomolecular films at the air/water interface, excluding those having longer hydrophobic fragment than hydrophilic ones. The ability to form multilayers depends on the surroundings of Si atom in the bridge between the cycles.     

Surface coating protective against oxidative plasma etching of polypropylene

Polypropylene (PP) sheets were coated with the ultrathin polymer layers by plasma polymerization of hexamethyldisiloxane and two other Si-containing monomers, and the protection effects from oxidative plasma etching were investigated. Etching was evaluated by the weight loss of PP sheets after the exposure to an oxidative plasma of O₂ or air. The effects of plasma polymer coating on the etching resistance were investigated with respect to the type of plasma polymer, thickness of a coating layer, oxidative plasma etching conditions, etc. Weight of the coated PP sheets was less changed and the substrates remained stable after a certain period of oxidative plasma treatments, during which time the original PP film had prominently lost weight. The importance of the crosslinked network with —Si— MPO components in plasma polymers on the etching resistance was suggested from the results. Infrared spectra were taken and analyzed with the plasma polymers after O₂-plasma treatments, and the increase in the Si—O structure was indicated by the increase in the peak intensity at 1023 cm⁻¹. Stabilization against oxidative etching was attributed to the crosslinked Si—O structure on the surface layer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1049–1057, 1997     

Characterization of amorphous carbon films deposited by surface wave plasma CVD

Many dangling bonds in hydrogenated amorphous carbon (a-C:H) films are usually generated by bombardments of high-energy ion precursors in typical chemical vapor deposition (CVD). To generate low dangling bonds, a-C:H films should be deposited from low-energy radical species. Surface wave plasma (SWP) generates low-energy and high-density radicals. We prepare a-C:H films using SWP and investigate the relationship between the plasma characteristics and structures of a-C:H films. The microwave of the TM01 mode was introduced through the dielectric window and SWP generate under the dielectric window. An Ar and C₂H₂ plasma mixture mainly consists of neutral radical species, and the electron temperature is as low as 1 eV. Electron density significantly decreases with increasing distance from the dielectric window. The a-C:H films are prepared from these hydrocarbon and carbon low-energy radicals as main precursors. The sp² bonded network cluster size in a-C:H films increase with electron density in SWP. This structure change is the influence of the termination structure of clusters changing to CH from CH₃ and CH₂.     

Plasma polymerization of organosilicon compounds

Plasma polymerizations in five silicon compounds having chemical formula of (CH₃)₃Si? X? Si(CH₃)₃, X = none, CH₂, NH, O, and S atoms, were investigated by elemental analysis, infrared spectroscopy, and ESCA. The chemical composition of polymers plasma-polymerized was influenced by the X groups in (CH₃)₃Si? X? Si(CH₃)₃. Polymers, when X was S atoms, possessed no sulfur; and X was CH₂ groups polymers rich in carbon and hydrogen atoms were formed. Details in chemical composition were discussed by IR and ESCA. Such differences in chemical composition reflected on gas permeability of the plasma films.     

Ionic polymers with expanded π‐conjugation systems derived from through‐space interaction in piperazinium and homopiperazinium rings

Reactions of N‐(2,4‐dinitrophenyl)‐4‐arylpyridinium chlorides (aryl (Ar) = phenyl and 4‐biphenyl) with piperazine or homopiperazine caused opening of the pyridinium ring and yielded polymers that consisted of 5‐piperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂)₂N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) or 5‐homopiperazinium‐3‐arylpenta‐2,4‐dienylideneammonium chloride (? N(CH₂CH₂CH₂)(CH₂CH₂)N⁺ (Cl^?)?CH? CH?C(Ar)? CH?CH? ) units. ¹H NMR spectral analysis suggested that the π‐electrons of the penta‐2,4‐dienylideneammonium group of the polymers were delocalized. UV‐visible spectral measurements revealed that the π‐conjugation system expanded along the polymer chains because of the orbital interaction between electrons of the two nitrogen atoms of the piperazinium and homopiperazinium rings. However, the π‐conjugation length depended on the distance between the two nitrogen atoms; that is, the polymers containing the piperazinium ring had a longer π‐conjugation length than those containing the homopiperazinium ring. Conversion of the piperazinium and homopiperazinium rings from the boat to the chair form led to a decrease in the π‐conjugation length. The surface of pellets that were molded from the polymers exhibited metallic luster, and these polymers underwent electrochemical oxidation in solution. Copyright © 2010 Society of Chemical Industry     

CO2‐facilitated transport through poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate)/polysulfone composite membranes

Poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate) (VSA–SA)/polysulfone (PS) composite membranes were prepared for the separation of CO₂. VSA–SA contained secondary amines and carboxylate ions that could act as carriers for CO₂. At 20°C and 1.06 atm of feed pressure, a VSA–SA/PS composite membrane displayed a pure CO₂ permeation rate of 6.12 × 10^?6 cm³(STP)/cm² s cmHg and a CO₂/CH₄ ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO₂ and 50 vol % CH₄, at 20°C and 1.04 atm of feed pressure, the CO₂ permeation rate was 9.2 × 10^?6 cm³ (STP)/cm² s cmHg, and the selectivity of CO₂/CH₄ was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO₂ over CH₄ and the CO₂ permeation rate had a maximum against the carrier concentration. The high CO₂ permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 275–282, 2006     

Oxygen and water vapor gas barrier poly(ethylene naphthalate) films by deposition of SiOx plasma polymers from mixture of tetramethoxysilane and oxygen

SiO_x films were deposited from a mixture of tetramethoxysilane (TMOS) and oxygen on poly(ethylene 2,6‐naphthalate) film using ion‐assisted plasma polymerization technique (Method II) and conventional plasma polymerization technique (Method I), and were compared in chemical composition and gas barrier properties. Methods I and II were different in electrical circuit between electrodes (anode and cathode) and electric power supply. In Method I, the anode electrode was grounded, and the cathode electrode was coupled to the discharge power supply. In Method II, the anode electrode was connected with the discharge power supply, and the cathode electrode was grounded. There was not large difference in SiO_x deposition rate between the plasma polymerizations by Methods I and II. Plasma polymers deposited from TMOS/O₂ mixtures by Method II possessed smaller C/Si and O/Si atomic ratios than those deposited by Method I and showed advantage in gas barrier properties. The oxygen and water vapor permeation rates were 0.08–0.13 cm³ m^?2 day^?1 atm^?1 at 30°C at 90% RH and 0.244–0.276 g m^?2 day^?1 at 40°C at 90% RH, respectively. From these results, it can be concluded that the ion‐assisted plasma polymerization is a useful technique for deposition of gas barrier SiO_x thin films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 915–925, 2007     

Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.     

Preparation of ion exchange membranes by plasma polymerization. I

Plasma polymerizations of three kinds of amines, γ-aminopropylethoxydimethylsilane (APEMS), allylamine (AA), and pyrole (PY), were investigated by IR and XPS analysis. Plasma-polymerized films were deposited on porous substrates, and ion exchange abilities of the composite membranes were measured. When APEMS were used as the monomer, the polymer retained the chemical structure of the monomer, amino groups. However, when AA and PY were used as the monomers, the plasma polymers contained a larger amount of amido structures than did the polymer of APEMS. Each membrane had ion exchange ability. In particular, the membrane prepared from APEMS showed superior ion exchange ability, anion permselectivity and conductivity, in acidic solutions. This property was attributed to the chemical structure of the polymer from APEMS retenting amino groups. The ion exchange properties of the membranes depended on the pH of the solution. In particular, the membrane of APEMS showed high membrane potential and low electric resistance only in a narrow pH region due to the weak basicity of amines and the hydrophobic property of the polymer.     

Affinity of amine-functionalized plasma polymers with ionic solutions similar to those in the human body

This work presents a study on the synthesis and on the interaction of allylamine, pyrrole and ethylenglycol polymerized by plasma with solutions of ionic composition similar to those in the nervous system. These polymers are attractive substrates to interact with the ionic pulses of the spinal cord due to their electrical and biocompatible characteristics. The ionic solutions were prepared with aqueous combinations of NaCl, MgSO₄, KH₂PO₄, KCl, CaCl₂, and NHCO₃. The polymers were prepared as thin films on glass substrates. The results indicated that some of the most important physical characteristics in the hydrophilicity of the polymers, roughness, porosity and functional groups, can be controlled with the energy of polymerization. The interaction between polymers and solutions was studied measuring the contact angle at the solid–liquid interface and the electrical conductivity of the polymers wet with these solutions. The contact angles were between 8° and 38°, and the electrical conductivity was in the 10^?8 to 10^?9 S/cm interval. The general tendencies indicate that the amine-functionalized polymers of this work are good materials to interact with the spinal cord system.