Plasma polymerization of fluoromethanes

Methane and fluoromethanes (CH_nF_4−n, 1 ≤ n ≤ 3) were subjected to an rf glow discharge plasma. All the fluoromethanes (including methane) polymerized in the plasma and formed thin films. The deposition rate of the fluoromethanes depended on their monomer structure: CH₂F₂, of which the F/H ratio is unity, showed the greatest deposition rate. The elimination of H and F atoms as H—F was found to be a key factor for the polymerization of fluoromethanes. The chemical composition of the polymerized film, measured with X-ray photoelectron spectroscopy and glow discharge emission spectroscopy, was also found to be strongly dependent on monomer structure. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2043–2050, 1998     

Zone-resolved mass spectroscopic study on RF plasma polymerization of styrene

The radiofrequency (rf) glow discharge plasma of styrene was investigated by direct sampling mass spectroscopy. Measurements were taken in three regions of the discharge: the plasma column and two dark zones before the electrodes. The plasma-polymerized styrene (PPS) thin films were analyzed by infrared spectroscopy (IR). The effects of monomer pressure and rf power on the ratios of mass peak heights C₄H/C₄H, C₆H/C₆H₅()CH in the three discharge regions, the polymer deposition rate, and the polymeric structure of the PPS films were studied. It was found that in the different discharge regions and under various discharge conditions, a variety of reactive species were formed by electron impact on monomer molecules. The polymer deposition rate was mainly dependent on the total number of the reactive species produced in the discharge. The concentration of phenyl groups in PPS films was proportional to the relative concentration of phenyl ring-containing reactive species in the gas phase plasma. © 1996 John Wiley & Sons, Inc.     

Dusty Plasma in Inhomogeneous Magnetic Fields in a Stratified Glow Discharge

We study the dynamics of dust particles in a stratified glow discharge in inhomogeneous magnetic fields. Dust structures are formed in standing striations, in which traps for dust particles arise. When a magnetic field is applied, these structures begin to rotate. The observations were carried out in striations near the end of the solenoid, where the region of an inhomogeneous magnetic field begins. With an increase in the magnetic field, the dusty structure can be deformed. The rotation of a dusty structure in an inhomogeneous magnetic field has been studied in detail; it has its own peculiarities in comparison with rotation in a uniform field. We have considered the mechanisms of such rotation and estimated its velocity.     

Glow characterization in direct current plasma polymerization of trimethylsilane

Plasma polymerization of trimethylsilane (TMS) was carried out in a direct current (dc) glow discharge and was investigated by optical photography and plasma diagnostic techniques including optical emission spectroscopy and residual gas analysis. The nature of the glow formed in TMS discharge, which deposited plasma polymers, was significantly different from that of a simple gas such as Ar. In an Ar discharge, the dominant glow was the well known negative glow, which developed at a distinctive distance from the cathode, whereas the cathode surface remained in the dark space. In strong contrast to this situation, in TMS dc discharge the dominant or primary glow was the cathode glow, which appeared at the cathode surface. At a similar location where the Ar negative glow appeared, a very feeble glow as a secondary glow was also observed in TMS glow discharge. The deposition results and plasma diagnosis data evidently indicated that in TMS glow discharge, the cathode glow resulted from the low‐energy electron‐impact dissociation of TMS molecules that creates polymerizable species, but the negative glow was related to nonpolymerizable species such as hydrogen atoms and molecules. In this article, the cathode glow formed in glow discharges of organic compounds was designated as the dissociation glow according to its underlying plasma reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1042–1052, 2004     

Polymer-supported titanium catalysts for syndiotactic polymerization of styrene

Poly(styrene-co-acrylamide)(PSAm)-titanium complexes (PSAm · Ti) were prepared and characterized. It is found that the coordination number of acrylamide (Am) to Ti in the complexes is strongly dependent on Am content in PSAm, but not on [Am]/[Ti] ratio in the feed. The infrared and x-ray photoelectron spectra suggest that the polymer-supported complexes possess the structure The catalytic behavior of the complexes in styrene polymerization is described. The catalytic activity is markedly affected by [Al]/[Ti] ratio in the complexes. ¹³C NMR, IR, and DSC data indicate that the polystyrene obtained with PSAm · Ti/MAO (MAO = methylaluminoxane) is highly syndiotactic. Use of Et₃Al and i-Bu₃Al in place of MAO gives atactic polystyrene. The activities of the various aluminum compounds used as the cocatalysts decrease in the order: MAO > Et₃Al > i-Bu₃Al. The polymer-supported complexes show relatively high activity even after the complexes had been exposed to air for 19 h or higher polymerization temperature. © 1996 John Wiley & Sons, Inc.     

Diagnostic analysis of styrene plasma polymerization

For studying plasma polymerization of styrene, two in situ diagnostic methods, optical spectroscopy and mass spectroscopy, were used to measure chemical components formed in the discharge volume and their concentrations in plasma column and two sheaths. The synergetic influence of power (W), pressure (p), and monomer flow rate (F) on plasma polymerization was expressed with a composite parameter, W/pF, which is proportional to the energy transferred to styrene monomer molecule. In a certain range of W/pF, the population of C₂H₂ and H₂ produced in the discharge decreased with W/pF, while the concentration of C₈ and C₆ fragments increased, which indicates that different chemical reactions may occur in different intervals of W/pF value. The similarity in change tendency between the deposition rate, the emission intensity of CH and C₄H and mass peak vs. W/pF implies that the polymerization is controlled by the reaction in the gas phase plasma, and supports the view that initial reactive species are produced in plasma, and polymerization is performed on the substrate surface. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 325–330, 1999     

Controlled free radical polymerization of styrene initiated from the alkoxyamine-functionalized silicon surface

Manipulation of surface properties of wafer is im- portant in technologies of biotechnology and advanced microelectronics[1,2]. A number of methods have been developed to modify the surface properties[3]. Among them, polymer brush is a well recognized met…     

Plasma polymerization using pulsed microwave power

Pulsed microwave power was used to polymerize a variety of monomers containing different functional groups. We examined the effects of pulse frequency and duty cycle on the deposition rates and the composition of the polymers. For monomers that do not contain oxygen we find that there is an increase in deposition rate with increasing pulse frequency and that the pulsed deposition rate is always less than the continuous power deposition rate. For monomers that contain oxygen, or for co-depositions of hydrocarbon monomers with O₂ or CO, we find that there is a decrease in deposition rate with increasing frequency, however the deposition rate using pulsed power is greater than the rate using continuous power. This result is shown to be related to the amount of etching that takes place during the deposition process. Infrared studies reveal that pulsed power can alter the composition of plasma polymers of some oxygen-containing monomers. The presence or absence of vinyl unsaturation, nitrile groups, or a cyclic structure have no effect on the polymerization process.     

Living/controlled radical polymerization of styrene with a new initiating system: DCDPS/FeCl3/PPh3

The living/controlled radical polymerization of styrene was investigated with a new initiating system, DCDPS/FeCl₃/PPh₃, in which diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS) was a hexa‐substituted ethane thermal iniferter. The polymerization mechanism belonged to a reverse atom transfer radical polymerization (ATRP) process. The polymerization was controlled closely in bulk (at 100 °C) or in solution (at 110 °C) with a high molecular weight and quite narrow polydispersity (M_w/M_n = 1.18 ∼ 1.28). End‐group analysis results by ¹H NMR spectroscopy showed that the polymer was ω‐functionalized by a chlorine atom, which also was confirmed by the result of a chain‐extension reaction in the presence of a FeCl₂/PPh₃ or CuCl/bipy (2,2′‐bipyridine) catalyst via a conventional ATRP process. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 101–107, 2000     

微波等离子体增强辉光放电光源激发温度的研究

研究了一种改进型的微波等离子体增强辉光放电光源在光谱分析中的应用，对其重要的参数指标－激发温度进行了较为较细的考察。结果表明引入微波等离子体后辉光放电的激发温度明显高于单纯辉光放电时的激发温度。     

Nanostructured latexes made by a sequential multistage emulsion polymerization

A series of linear and lightly crosslinked nanostructured latices was prepared by a sequential multistage semicontinuous emulsion polymerization process alternating styrene (S) and n‐butyl acrylate (BA) monomer feeds five times, that is ten stages, and vice versa, along with several control latices. Transmission electron micrographs of the RuO₄‐stained cross sections of nanostructured and copolymer latex particles and films showed that their particle morphologies were not very different from each other, but the nanostructured latex particles were transformed into a nanocomposite film containing both polystyrene (PS) and poly(n‐butyl acrylate) (PBA) nanodomains interconnected by their diffuse polymer mixtures (i.e. interlayers). The thermal mechanical behaviors of the nanostructured latex films showed broad but single T_gs slightly higher than those of their counterpart copolymer films. These single T_gs indicated that their major component phases were the diffuse interlayers and that they behaved like pseudopolymer alloys. The minimum film formation temperatures of nanostructured latices capped with PBA and PS, respectively, were 15 °C lower than and equal to those of their counterpart copolymer latices, but their T_gs were about 10 °C higher. Consequently, nanostructured latices enabled us to combine good film formation with high strengths for adhesives and coatings applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2826–2836, 2006     

Synthesis of poly(chloromethylstyrene‐b‐styrene) block copolymers by controlled free‐radical polymerization

The controlled free‐radical polymerization of styrene and chloromethylstyrene monomers in the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl (TEMPO) has been studied with the aim of synthesizing block copolymers with well‐defined structures. First, TEMPO‐capped poly(chloromethylstyrene) was prepared. Among several initiating systems [self‐initiation, dicumyl peroxide, and 2,2′‐azobis(isobutyronitrile)], the last offered the best compromise for obtaining a good control of the polymerization and a fast polymerization rate. The rate of the TEMPO‐mediated polymerization of chloromethylstyrene was independent of the initial concentration of TEMPO but unexpectedly higher than the rate of the thermal self‐initiated polymerization of chloromethylstyrene. Transfer reactions to the chloromethyl groups were thought to play an important role in the polymerization kinetics and the polydispersity index of the resulting poly(chloromethylstyrene). Second, this first block was used as a macroinitiator in the polymerization of styrene to obtain the desired poly(chloromethylstyrene‐b‐styrene) block copolymer. The kinetic modeling of the block copolymerization was in good agreement with experimental data. The block copolymers obtained in this work exhibited a low polydispersity index (weight‐average molecular weight/number‐average molecular weight < 1.5) and could be chemically modified with nucleophilic substitution reactions on the benzylic site, opening the way to a great variety of architectures. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3845–3854, 2000     

Plasma polymerization of cyano compounds

Plasma polymerizations of three cyano compounds—acrylonitrile (AN), 1,2-dicyanoethylene (FN), and tetracyanoethylene (TCE)—were investigated by FT IR and XPS, and the transforamtion of cyano groups during the plasma polymerization was discussed. The results pointed out an aspect of the preparation of plasma films with cyano groups. Plasma polymerizations of AN, FN, and TCE deposited brown or dark brown films that contained carbon, nitrogen, and oxygen. The elemental composition of the plasma films, especially N/C atomic ratio, showed a monomer dependence but no rf power dependence. The plasma films contained amide and amino groups, and ketene-imine and conjugated — C = N — structures as well as cyano groups as nitrogen functionalities, and carbonyl and carboxyl groups as oxygen functionalities. For the preparation of plasma films with cyano groups, compounds with more than two cyano groups themselves are not suitable as monomers. The operation of plasma polymerization under mild plasma conditions at low rf power and in no oxygen atmosphere is favorable for the preparation of plasma films with cyano groups. © 1992 John Wiley & Sons, Inc.     

微型辉光放电等离子体用于质谱成像分析的初步研究

本实验利用实验室自主研发的微型辉光放电等离子体(MFGDP)作为离子源解吸样品,使之离子化,得到样品的特征质谱图,经特定软件的转化即可得到对应的图像,图像表明,MFGDP用于质谱成像具有可行性.本方法具有装置简单、操作简易、等离子体羽低温、分析时间短(＜20 min)等优点,可同时定位样品中不同物质的空间分布.本研究探讨了影响质谱成像图清晰度的因素,优化了实验条件,在最优条件下,本方法的空间分辨率约300μm,对加有尿素的不同字迹进行初步质谱分析,并对冬枣切片中硬脂酸和槲皮素衍生物的空间分布做了影像探索.此技术可以根据化学物质的指纹图谱区分不同的字迹,也能够很好地获取样品中不同营养物质的分布状况,因此,为字画研究、艺术品鉴定、营养物质分布图的获取提供了一种新的方法.     

Miniemulsion polymerization of styrene with a block copolymer surfactant

A series of miniemulsion systems based on styrene/azobisisobutyronitrile in the presence of poly(methyl methacrylate‐b‐2‐(dimethylamino)ethyl methacrylate) as a surfactant and hexadecane (HD) as a cosurfactant were developed. For comparison, a series of pseudoconventional emulsions also were carried out with the same procedure used for the aforementioned series but without the cosurfactant (HD). Both the droplet size and shelf life were also measured. Experimental results indicate that it is possible to slow the effect of Ostwald ripening and thereby produce a stable miniemulsion with the block copolymer as the surfactant and HD as the cosurfactant. In addition, the extent to which varying the surfactant concentration and copolymer composition could affect both the polymer particle size during the polymerization and the polymerization rate was examined. Variation in the polymer particle sizes during polymerization indicates that droplet and aqueous (micellar or both homogeneous) nucleation occurs in the miniemulsion polymerization. With the same concentration of the surfactant used in the miniemulsion polymerization, the polymerization rates of systems with M₁₂B₃₆ are faster than those of systems with M₁₂B₁₂. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1818–1827, 2000     

On the evolution of the rate of polymerization,number and size distribution of particles in styrene emulsion polymerization above CMC

This work is an extension of a communication reported by two of the authors [Carro and Herrera‐Ordoñez, Macromol Rapid Commun 2006, 27, 274], where bimodal particle size distributions (PSD), obtained by asymmetric flow‐field flow fractionation (AFFF, AF⁴), were taken as evidence of certain degree of stability of primary particles. Now, emulsion polymerizations of styrene were performed under conditions employed before by other researchers, intending to examine if the behavior observed is general. The number of particles (N) and PSD were studied by means of dynamic light scattering and AF⁴. By the later, bimodal PSDs were detected in all cases, where the population corresponding to primary particles (diameter <20 nm) depends on reaction conditions. Regarding N, AF⁴ results show that it is constant during interval II, in contrast to DLS results. Primary particle coagulation was evidenced as minimums in N evolution and the rate of polymerization curves, monitored by calorimetry and gravimetry, which are enhanced when higher particle number is generated and/or the ionic strength is increased. These results suggest that particle coagulation is not as extensive as it would be expected according to the coagulative theory. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3152–3160, 2010     

苯硫酚等离子体聚会及其结构与性能

应用外部电容耦合式等离子体聚合装置．研究了苯硫酚等离子体聚合规律，找到了最佳聚合条件，通过热失重、红外光谱、X－射线衍射、电子衍射、GC－MS和接触角测定等研究了聚合物结构与性能。电导率测定表明等离子体聚苯硫酚具有半导体性质。     

Comparison Between Air Filamentary and Helium Glow Dielectric Barrier Discharges for the Polypropylene Surface Treatment

Recently, a glow like dielectric controlled barrier discharge (GDBD) working at atmospheric pressure has been observed. Such a discharge could replace a filamentary dielectric controlled barrier discharge (FDBD) used in corona treatment systems to improve the wettability or the adhesion of polymers. So it is of interest to compare these two types of discharges and their respective effect on a polymer surface. This is the aim of an extensive study we have undertaken. The first step presented here is the comparison of a filamentary discharge in air with a glow discharge in helium. Helium is the most appropriate gas to realize a glow discharge at atmospheric pressure. Air is the usual atmosphere for a corona treatment. The plasma was characterized by emission spectroscopy and current measurements. The surface transformations were indicated by the water contact angle, the leakage current measurement and the X-ray photoelectron spectroscopy. Results show that the helium GDBD is better than air FDBD to increase polypropylene wettability without decreasing the bulk electrical properties below a certain level. Contact angle scattering as well as leakage current measurements confirm that the GDBD clearly results in more reproducible and homogeneous treatment than the FDBD.     

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

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