Role of Plasma Parameters on the Conjugated Structure Retention in Polyaniline Thin Film

The role of plasma parameters on the film characteristics is investigated on polyaniline thin film deposited by radio frequency (RF) plasma polymerization. A series of un-doped and iodine doped polyaniline thin films are prepared by RF discharge operating at 13.56?MHz with different discharge powers and pressure variation from 0.1 to 0.05?mbar and variation in deposition time from 20 to 40?min. A good thin film is found with a power ranging from 9?W (?28?V self bias) to 20?W (?65?V self bias) at 0.1?mbar pressure which is confirmed by fourier transform infra-red spectroscopy showing the retention of aromatic rings. In addition, iodine doping is carried out with 9?W power and 0.1?mbar pressure. The characterization of process plasma is done using Langmuir probe diagnostics and optical emission spectroscopy. A correlation has been established between film characteristics and plasma properties investigated using optical emission spectroscopy and Langmuir probe analysis. Emphasis has been given on the study of the influence of plasma parameters, particularly of the electron energy distribution function on the quality of conjugated plasma polymerized aniline film.     

Polymérisation de monomères organiques dans des plasmas froids—I. Polymérisation de monomères acryliques déposés en couches minces

One of the applications of cold plasmas in macromolecular chemistry is the polymerization of high molecular weight acrylates in the solid or liquid phase. The reaction is controlled by several parameters (monomer functionality, power of irradiation, nature of the gas used to generate the plasma). The polymerization speed decreases with increasing monomer functionality. The strength of the electric discharge controls the creation of active species and consequently the striking speed. Polymerization speed increases with power but with a maximum depending on the type of the monomer and the nature of the ambient gas. The kinetics are affected by the gas nature (oxygen and carbon dioxide inhibit polymerization). The film surface can be degraded with incorporation of gas atoms. For instance, an argon plasma creates surface sites favourable to later oxidation. In freon 14 plasmas, the formation of C-F bonds can be observed.     

Design of experiment for optimization of plasma-polymerized octafluorocyclobutane coating on very high aspect ratio silicon molds

As-fabricated deep reactive ion etched (DRIE) silicon mold with very high aspect ratio (>10) feature patterns is unsuitable for poly(dimethylsiloxane) (PDMS) replication because of the strong interaction between the Si surface and the replica and the corrugated mold sidewalls. The silicon mold can be conveniently passivated via plasma polymerization of octafluorocyclobutane (C4F8), which is also employed in the DRIE process itself, to enable the mold to be used repeatedly. To optimize the passivation conditions, we have undertaken a Box-Behnken experimental design on the basis of three passivation process parameters (plasma power, C4F8 flow rate, and deposition time). The measured responses were fluorinated film thickness, demolding status/success, demolding force, and fluorine/carbon ratio on the fifth replica surface. The optimal passivation process conditions were predicted to be an input power of 195 W, a C4F8 flow rate of 57 sccm, and a deposition time of 364 s; these were verified experimentally to have high accuracy. Demolding success requires medium-deposited film thickness (66-91 nm), and the thickness of the deposited films correlated strongly with deposition time. At moderate to high ranges, increased plasma power or gas flow rate promoted polymerization over reactive etching of the film. It was also found that small quantities of the fluorinated surface were transferred from the Si mold to the PDMS at each replication, entailing progressive wear of the fluorinated layer.     

A STUDY ON THE STRUCTURE AND PROPERTIES OF POLYBUTYLALDEHYDE FORMED IN LOW TEMPERATURE PLASMA

The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition. The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm, in which the dispersion force contribution is the majority. The electron diffraction proved that some crystal substance, even the single crystals were present in the polymer. X-ray diffraction also proved the presence of crystal and showed about 15% crystaUinity fraction.     

Industrial-Scale Process Control by Means of Electrostatics Probes

We performed a series of measurements by means of the triple probe technique during plasma deposition of polymer films on large volume plastic containers. Based on the measured data, the process stability and process homogeneity were determined. The process stability was better than 5% and process reproducibility was about 6%. An inhomogeneity of the plasma density correlated to the barrier efficiency of the film deposited at different positions on the container. An increase in the power losses were found after changes in the electrical configuration of the deposition set-up. The quotient of electron density n_e and product of molar mass of the working gas M and its flow F is proposed as invariant instead the Yasuda's parameter W/MF for characterization of large-scale industrial plasma polymerization process.     

Immobilization of Ciliary Neurotrophic Factor on Model Biomaterials by Plasma Graft Polymerization

Acrylic acid was grafted on the surface of polypropylene (PP) film via plasma‐induced technology. It was shown by FT‐IR that there were carboxyl groups on the surface of the modified PP film. The grafting ratio was analyzed quantitatively through a dyeing process. The effects of the technology parameters of the plasma‐treatment and graft polymerization on the grafting ratio, such as power, discharge time, concentration of monomer and active species density, reaction temperature and time, were characterized. Moreover, the content of ciliary neurotrophic factor (CNTF) that was anchored on the surface of the modified PP film was measured through enzyme‐linked immunosorbent assay (ELISA). The results show that the amount of CNTF immobilized on the surface of the modified PP film increase with increasing content of carboxyl groups, showing that the existence of carboxyl groups on the surface of the PP film is beneficial to the immobilization of CNTF.     

醛类的等离子体聚合Ⅰ.丁醛等离子体聚合及聚合物结构与性能

应用外部电容耦合式等离子体聚合方法,首次得到了丁醛聚合物,研究了其聚合规律,找到了较好的聚合条件。通过元素分析和红外光谱分析,证实丁醛等离子体聚合物为交联结构;电子衍射分析和X-射线衍射分析发现聚合物中存在部分结晶,而且部分以单晶形式存在;表面能测定表明丁醛等离子体聚合物为疏水性。并初步探讨了反应机理。     

Pulsed-plasma polymerization of 1-vinyl-2-pyrrolidone: Synthesis of a linear polymer

The RF plasma induced polymerization of 1-vinyl-2-pyrrolidone was examined under variable duty-cycle pulsed-plasma conditions. Large-scale progressive changes in the composition of the resultant polymeric films were observed with sequential changes in the plasma duty cycle employed during polymerization, all other plasma variables held constant. The film compositional changes obtained are in the direction of increased retention of the lactam ring of the monomer in the resultant polymers as the duty cycles employed (i.e., the ratio of plasma on to plasma off times) were decreased. Particularly significant are the relatively linear polymeric structures obtained under the exceptionally low-average power deposition conditions made accessible with the pulsed plasma technique. XPS and FTIR spectroscopic examination of these latter films reveal compositions that are similar to those obtained by conventional (i.e., nonplasma) synthesis of the linear polymer. The film chemistry controllability demonstrated in the present study is achieved while maintaining the many advantages of the plasma polymerization approach for surface modifications. This work provides additional support for use of the pulsed operational mode as an effective means of film chemistry control, in particular extending the plasma polymerization technique to include synthesis of linear polymers, in lieu of the more highly crosslinked structures typically produced in conventional continuous-wave plasma polymerization processes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3121–3129, 1998     

A novel method of preparing of glass capillary columns: Low-temperature plasma etching and polymerization

A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC²). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.     

Functionalization of Poly[Ethylene Terephthalate) by Means of Glow-Discharge-Initiated Polymerization of Acrylic Acid

Glow-discharge-initiated polymerization of acrylic acid incorporated in poly(ethylene terephthalate) (PET) films was investigated. An increase in polymerization yield with plasma treatment duration and power was found. Polymerization was not confined to the film surface. At high power and long treatment time, polymerization in the bulk of the PET also took place. Water regain and contact angle of the PET-treated films were affected by the presence of poly(acrylic acid) (PAA). The carboxyl groups of the PAA chains incorporated in the PET matrix were utilized for further chemical modification of the PET film. Poly(ethylene glycol) (PEG) was grafted onto PAA by esterification. DSC studies showed the presence of both PAA and PEG in the PET matrix and shed light on the morphology of the multicomponent polymeric system. Free isocyanate groups were introduced into the PET matrix by reacting PAA carboxyl groups with hexamethylene diisocyanate.     

Solution-based assembly of conductive gold film on flexible polymer substrates

Conductive films of gold were assembled on flexible polymer substrates such as Kapton and polyethylene using a solution-based process. The polymer substrates were modified by using argon plasma and subsequent coupling of silanes with amino- or mercapto- terminal groups. These modified surfaces were examined by X-ray photoelectron spectroscopy and contact angle measurements. Colloidal gold was assembled onto the silane-modified surface from solution. The gold particles are attached to the surface by covalent interactions with the thiol or amine group. Formation of a conductive film is achieved by increasing the coverage of gold by using a "seeding" method to increase the size of the attached gold particles. Field emission scanning electron microscopy was used to follow the growth of the film. The surface resistance of the films, measured using a four-point probe, was about 1 Omega/sq.     

Preparation and characterization of plasma-polymerized styrene thin films

Plasma-polymerized styrene (PPS) thin films (several hundred to several thousand Å thick) have been prepared under a variety of discharge conditions in a tubular reactor inductively coupled to a radio frequency (13.56 MHz) power supply. Studies have focussed on the correlation of deposited polymer structure, evidenced both at the film surface (via XPS analysis) and in the bulk polymer (via transmission FT–IR analysis) with controllable plasma parameters (coupled rf power, monomer flow rate, monomer pressure). It has been determined that the relative number of phenyl rings incorporated into the film intact is an inverse function of the power per styrene molecule ratio. Polymer deposition rate was found to be a strong function of styrene flow rate and substrate temperature. Plausible elements of the styrene plasma polymerization mechanism will be considered.     

Surface Performance and Cytocompatibility Evaluation of Acrylic Acid-Mediated Carboxymethyl Chitosan Coating on Poly(tetrafluoroethylene-co-hexafluoropropylene)

To improve the biocompatibility of poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film, a technique based on Ar plasma pretreatment and UV-induced grafting polymerization was used to immobilize carboxymethyl chitosan (CMCS) on the FEP film surfaces. Initially Ar plasma was used to treat FEP film. Then, plasma treated FEP film was modified via UV-induced grafting polymerization with hydrophilic acrylic acid (AAc) monomer. The following immobilization of CMCS on the FEP-pAAc surface was carried out via an amidation reaction. The change of chemical composition and surface morphology of FEP film were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM) and atomic force microscopy (AFM). Results of water contact angles measurement showed that the hydrophilicity of the surface has improved significantly after surface modification. Furthermore, methyl thiazolyl tetrazolium (MTT) assay and cell morphology analysis confirmed that mouse fibroblasts (L929 cells) attachment and proliferation were improved remarkably on the modified FEP surface. These results suggest that CMCS were successfully employed to surface engineering FEP film, and enhanced its cell biocompatibility. The approach presented here may be exploited for surface modification of biomaterials.     

Stability of an ultrathin plasma polymerized film in aqueous solution: in situ detection by surface plasmon resonance

Recently, surface plasmon resonance (SPR) has been successfully implemented to characterize the film stability in real time: a radio frequency (RF) plasma polymerized film was monitored by swelling or extracting behaviors in aqueous solution. The high-resolution SPR revealed that film stability strongly depended on the monomers, plasma mode, and substrate locations as well as plasma polymerization conditions: incident power and working pressure. By Fourier transform infrared (FTIR), the possible reasons of film stabilization affected by plasma conditions and sample locations are explained. It is recommended that as an adhesive layer for future applications the plasma polymerized polymer shall be prepared in low working pressure pulsed plasma.     

金表面聚合物刷及图案化微结构的制备

采用表面引发室温原子转移自由基聚合(ATRP)方法在金基底上原位制备了接枝聚合物刷,其制备过程用厚度测量,ATR-FTIR,XPS等进行了表征,初始时聚合物刷的厚度随着聚合时间的增加线性增加,表现为活性聚合的特征．XPS表征证明表面引发聚合后聚合物刷末端仍然存在ATRP反应的引发剂．紫外光刻图案化的聚合物刷作为电沉积的模板,经电沉积、后紫外处理、湿化学刻蚀步骤后得到了分离的导电聚合物微阵列结构,通过浇注／粘附处理将导电聚合物微阵列转移至硅油弹性体片,由于导电聚合物在湿化学刻蚀中对基底金具有良好的保护作用,因此在导电聚合物阵列被转移后,基底表面得到金微阵列。     

基于等离子体聚合膜固定酶的H2O2生物传感器

以玻碳电极为基础电极,用微波等离子体技术聚合沉积聚乙二胺等离子体膜,使之形成带氨基功能团的表面,再通过戊二醛交联共价固定辣根过氧化物酶,制得H2O2生物传感器.探讨了等离子体聚合膜的形成条件(如放电功率、单体流速、单体气压和聚合时间),讨论了工作电位、介体浓度和pH值对传感器响应的影响.此外,用红外光谱对等离子体聚合膜进行了表征.该传感器在5×10-7～1.1×10-3mol/LH2O2浓度范围内有线性响应,最低检测限为0.3μmol/L.将此传感器用于实际试样回收率的测定,结果良好.     

Polymérisation de monomères organiques dans des plasmas froids—V. Polymérisation de monomères acryliques en présence d'amorceurs et de coamorceurs

The polymerization of high molecular weight acrylic monomers depends on low temperature plasma parameters (power, chemical structure of gas carrier etc.) but also on the initiator incorporated in the monomer film. The plasma initiator has a specific efficiency depending on plasma parameters. This paper deals with a new plasma initiator system: initiator with coinitiator such as tertiary amines (e.g. the dimethylparatoluidine). The poly(trimethylolpropane triacrylate) rate is higher when a system such as 2-chloro thioxanthone/dimethylparatoluidine or benzoïn/dimethylparatoluidine is added to the monomer film which is in the helium plasma.     

血液相容材料的合成研究Ⅷ.磺铵两性离子单体在聚醚氨酯表面的臭氧活化接枝

生物相容性 ,特别是血液相容性是生物医用材料极其重要的性能[1] .提高不凝血性一直是生物材料研究与发展 (Ｒ Ｄ)的主要内容之一 ,半个多世纪来 ,不凝血材料的Ｒ Ｄ已取得了很大的发展[2 ] .但还不能满足心血管植入物 (Ｃａｒｄｉｏｖａｓｃｕｌａｒｉｍｐｌａｎｔｓ)及心血管医物 (Ｃａｒｄｉｏｖａｓｃｕｌａｒｄｅｖｉｃｅｓ)对不凝血性的需要 .Ｒａｔｎｅｒ[3 ] 在最近一次的血液相容性问题研讨会上再次强调了不凝血材料研究的紧迫性 .会议的报告也反映了该领域的研究现状 ,并提出了今后要研究的问题等 .目前不凝血性较好的材料仅有聚…     

Radio-Frequency Hexamethyldisiloxane Plasma Deposition: A Comparison of Plasma- and Deposit-Chemistry

This study reports on the effect of input power to hexamethyldisiloxane (HMDSO) plasmas. The power dependence of the plasma-phase species and of the surface chemistry (of the deposits) has been investigated. Neutral and positive molecular species were detected within the plasma using mass spectrometry (MS). Secondary ion mass spectrometry (SIMS) was used to probe the molecular structure of the deposits. The elemental composition of the surface was determined by XPS and the deposition rate was monitored using a vibrating quartz crystal microbalance. Neutral and cationic molecules of mass greater than HMDSO were detected in the plasma. Their formation through ion-molecule reactions is proposed. Changes in the relative concentration of plasma-phase species follow those seen in molecular species detected at the deposit surface. Thus, we believe that the molecular structure of the deposits can be related to the species present in the plasma. While traditionally the dominant mechanism in deposit formation is assumed to be free radical combinations, we propose other possibilities involving cations with the aim of putting forward a new perspective on plasma polymerization mechanisms and thereby stimulating discussion.     

Effect of oxygen plasma treatment and gold sputtering on morphological and local mechanical properties of copolyimide/gold micropatterned structures

Atomic force microscopy (AFM) was used to analyze rectangular 3‐dimensional patterned microstructures with different functionalities induced on copolyimide containing alicyclic sequences film surfaces by means of oxygen plasma treatment. The plasma power was ranged to be big enough to accelerate the plasma species towards the copolyimide surface, and the exposure time was not very small to generate a roughness that still can be monitored by AFM. To create the rectangular pattern, transmission electron microscopy grid masks were placed on the samples before treatment. Plasma‐induced micropatterning with alternating hydrophilic and hydrophobic surface chemistries was evaluated by measuring the adhesion forces between the gold‐covered AFM tip and the copolyimide surfaces. To fabricate 3‐dimensional metallic microstructures arranged in well‐defined areas, thin metal layers were sputtered on these pretreated copolyimide films. The AFM morphological aspects of the obtained metallic structures were correlated with the surface modifications induced by plasma treatment conditions. Functional indexes and functional volume parameters were also calculate to characterize the functional behavior of the surface, such as wear, lubrication, and contact. The AFM data were compared with those obtained using the small‐angle X‐ray scattering measurements.