Plasma copolymer membranes of acrylic acid and the adsorption of lysozyme on the surface

Plasma copolymerization was carried out from the monomer mixtures of acrylic acid with hexamethylxdisilozane and hexametydisillazane, and the membranes composed of the Si-C and/or Si-O networks sustaining carboxylic acid group were fabricated. The carboxylic acid contents were dependent on the discharge power conditions as well as the monomer ratio, and carboxylic acid was introduced at the more density in the polymerization by plasmas under the moderate power conditions. The plasma polymer coatings were effective for the adsorption of lysozyme especially on the plasma copolymer films of acrylic acid.     

Preparation of gas separation membranes by plasma polymerization with fluoro compounds

Plasma polymerization coatings were applied for the preparation of gas separation membranes. Mainly fluoro compounds were used as coating materials. The membranes showed good separation characteristics with high flux for gaseous systems. The plasma polymerization composite parameter given by W/FM plays an important role in obtaining excellent separation characteristics. The correlation between the conversion rate DR/FM, where DR is the deposition rate of plasma polymer, and W/FM is useful to consider the plasma polymer character under the different plasma polymerization conditions (discharge power W and monomer flow rate F). The proper conditions for membrane preparation lie in the intermediate region between the region in which the monomer flow rate is deficient and that in which the discharge power is deficient. Furthermore, the plasma polymerization coatings with the higher molecular weight monomer gave the higher separation characteristics. Plasma polymer composite membranes in this study showed superiority for the molecular sieve type of separation over the solution-diffusion type of separation.     

Study of the effect of process parameters for n-heptylamine plasma polymerization on final layer properties

Plasma polymerization processes are widely used to chemically functionalize surfaces, which properties can be tuned by different operating variables. In this study, thin amine-containing polymer layers were produced on solid substrates in a custom-made cylindrical plasma polymerization reactor by radio frequency glow discharges of n-heptylamine vapours. Carefully planned experiments were conducted to evaluate the importance of four different process parameters on the chemical composition and thickness of the resulting films. The parameters investigated were: 1) deposition time, 2) power of the glow discharge, 3) distance between the electrodes, and 4) monomer pressure. Possible interactions between these variables were investigated through the use of statistical analyses (i.e., factorial design). This study reveals that n-heptylamine plasma polymer (HApp) layer thickness is influenced by the power of the glow discharge and the deposition time, as assessed by surface plasmon resonance and atomic force microscopy step height measurements. Also, the atomic ratio of nitrogen to carbon atoms on the treated surfaces is mainly influenced by the power of the glow discharge, as revealed by X-ray photoelectron spectroscopy. Quartz crystal microbalance analysis also confirmed that HApp layers are stable when immersed in aqueous solution.     

Plasma modification of polyacrylonitrile ultrafiltration membrane

Polyacrylonitrile (PAN) ultrafiltration (UF) membranes were modified by plasma treatments and plasma polymerization. Influences of plasma modifications on membrane characteristics were investigated. The obtained results indicated that plasma treatments using non-polymer-forming plasma gases such as Ar, He and O₂ led to the increase of membrane surface hydrophilicity and membrane permeability. By using O₂ plasma treatment, UF property of PAN membranes could be improved with the enhancement of membrane flux meanwhile its albumin rejection was almost maintained. The experimental results also showed that plasma polymerization using acrylic acid vapor as monomer and PAN UF membrane as a substrate led to the formation of reverse osmosis membrane due to the deposition of plasma polymer layer onto substrate membrane surfaces. Plasma techniques can control membrane pore size and have a potential to improve the membrane characteristics by using their advantages.     

等离子体聚合工艺对聚合沉积速率的影响

利用等离子体聚合的方法对两种有机单体(正丙醇和丙烯醇)进行了等离子体聚合,成功地在Si基体上沉积了高分子薄膜.利用XPS研究了薄膜的结构和不同工艺对沉积速度的影响.研究表明,随着功率的增加或工作气压的增加,沉积速率增加;偏压的增加使等离子体聚合的沉积速率减小.研究还发现,丙烯醇含有双键结构,其沉积速率比正丙醇大.     

Synthesis and characterization of plasma-polymerized tert-butylacrylate films

Plasma polymerized tert-butylacrylate (pp-t-BA) film was prepared using tert-butylacrylate monomer under 100 Pa of vapor pressure with varying RF power of 10-250 W and continuous wave RF power of 13.56 MHz. The deposition rates of pp-t-BA films were determined using quartz crystal microbalance (QCM) method. The chemical structure of pp-t-BA films was characterized using FT-IR, contact angle and XPS techniques. The gas sorption properties of pp-t-BA were measured using a QCM sensor array. Results showed that deposition rates of pp-t-BA film were proportional to the polymerization time at 100 Pa of monomer pressure under the same RF power. The deposition amount of pp-t-BA films increased gradually with increasing RF power of 30-150 W. Increasing the RF power on plasma polymerization decreased the amount of ester group in pp-t-BA films. Sensitivity of gas sorption on pp-t-BA films is related to the RF power of polymerization.     

Plasma polymerization of tetramethyldisiloxane by a magnetron glow discharge

Plasma polymerization of tetramethyldisiloxane by a magnetron glow discharge was studied. The glow discharge was created between parallel electrodes with a 10 kHz electric power source with a superimposed magnetic field using permanent bar magnets. Polymers were deposited onto moving substrates placed on the surface of a rotating disc located in between the electrodes. The deposition rates were determined with a quartz crystal thickness monitor placed on the plane of the rotating disc and just outside the edge of the disc. The current-voltage relationship observed for plasma polymerization of the monomer depends on the monomer feed rate and the conditioning of the electrodes or the establishment of a steady state surface in the polymer-forming plasma, which also depends mainly on the monomer feed rate. Consequently, plasma polymerization cannot be correlated to single operational parameters such as the discharge current, the power or the monomer feed rate in a simple manner. However, when the deposition rate was expressed as R_p/FM, where R_p is the polymer deposition rate, F is the monomer feed rate and M is the molecular weight (FM is thus the monomer mass feed rate), it was found that R_p/FM is uniquely related to the parameter W/FM where W is the discharge power in Watts. It was shown that many polymer properties were also determined mainly by the same composite parameter. It was also found that the presence of O₂ gas in the monomer feed reduced the carbon content in the polymer and made the surface more hydrophobic while O₂ plasma treatment of the plasma polymer rendered the surface more hydrophilic.     

Preparation of plasma poly(1-isoquinolinecarbonitrile) thin film and its ultrafast nonlinear optical property

How to get a uniform, defect-free, and reproducible conjugated polymer thin films is now becoming the main fabrication problem for the practical application of these materials as the fast switches and modulators in opto-electronic devices. In this research, a novel plasma-polymerized 1-isoquinolinecarbonitrile (PPIQCN) thin film was prepared by plasma polymerization under different glow discharge conditions. The effect of the discharge power on the chemical structure and surface compositions of the deposited PPIQCN films was investigated by Fourier transform infrared (FTIR), UV-Visible absorption spectra and X-ray photoelectron spectroscopy (XPS). The results show that a high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 10 W was used during film formation. In the case of higher discharge power of 30 W, more severe monomer molecular fragmentation can be observed, which results in a decrease in the effective conjugation length of PPIQCN film. The morphology characterized by atomic force microscopy (AFM) indicates that a fine, homogenous PPIQCN film could be obtained under a relatively low discharge power. A femtosecond time-resolved optical Kerr effect technique at a wavelength of 820 nm has been applied to investigate the third-order nonlinearity of the plasma PPIQCN film. For the first time, a non-resonant optical Kerr effect and ultrafast response of the PPIQCN film was observed.     

Properties of tin/plasma polymer nanocomposites

Thin composite layers (tin in plasma polymer matrix) were prepared in a stainless steel vacuum chamber. An RF powered magnetron with tin target was used to excite the discharge and to activate the monomer species (n-hexane). The gas mixture introduced comprised Ar and n-hexane vapours. The properties of the films and chemical composition were characterized by AFM (surface morphology), TEM and Electron tomography (bulk structure characterization), XPS and FTIR spectroscopy (chemical composition analyses). Current-voltage characteristics were measured to examine the electrical properties of the layers and their dependence on the deposition parameters.     

Experimental investigations of semi-crystalline plasma polymerized poly(3-octyl thiophene)

Plasma polymerized thin film of conducting poly(3-octylthiophene) was deposited at room temperature by plasma enhanced chemical vapor deposition method using (3-octylthiophene) monomer as precursor. The radio frequency (RF: 13.56 MHz, power supply: 30 W) was applied at constant argon gas pressure for the formation of plasma. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), X-ray diffractometry (XRD) and high resolution transmission electron microscopy (HRTEM) have been done for the as grown films. As reported in literature polythiophenes prepared by rf plasma polymerization are highly crosslinked and amorphous. However, in present investigations, well defined crystalline regions have been observed by HRTEM investigations and have been correlated with X-ray diffraction data. The observed crystallinity is attributed to controlling the parameters of the synthesis.     

Preparation and characterization of hypercrosslinked resins with bimodal pore size distribution and controllable microporosity

Hypercrosslinked polystyrene resins with bimodal pore size distribution and controllable microporosity were prepared by combining traditional suspension polymerization and post crosslinking technique. The volume ratio of divinylbenzene (DVB) in monomer mixtures was kept at 20%, while vinylbenzyl chloride (VBC) concentration was progressively reduced to investigate effect of post crosslinking degree on the pore structure of the hypercrosslinked species. The results indicated that higher VBC concentration in monomer mixtures led to greater surface area, smaller average pore size and higher microporosity. Moreover, bimodal distribution of pore size could be observed for the final resins. The mesopore fraction should be derived from the pores originally present in precursor resins, while the micropore fraction was originated from the post crosslinking.     

Comparative study of chemically synthesized and plasma polymerized pyrrole and thiophene thin films

Pyrrole and thiophene polymers prepared via chemical means or plasma polymerization at different radio frequency (RF) power input on different substrates were compared using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy and UV-visible absorption spectroscopy. These polymers were deposited as thin films on either low-density polyethylene (LDPE) or LDPE surface graft copolymerized with acrylic acid (AAc). The results indicate that the structures of plasma polymerized pyrrole and thiophene are rather different from those of polymers synthesized by conventional chemical methods, due to a higher degree of crosslinking and branching reactions in plasma polymerization. A higher and more stable conductivity can be obtained with chemically synthesized polypyrrole and polythiophene, but the thin films generated from the plasma polymerization process are much smoother and more uniform. The lack of stability in the plasma polymerized samples’ conductivity may be due to the unstable nature of the charge transfer complex with the dopant (iodine) resulting in a greater ease of diffusion of the iodine from the film. Under the conditions tested, the thickness of plasma polymerized pyrrole and thiophene thin layers increases almost linearly with the RF power. The modification of the LDPE substrates using AAc-graft copolymerization can enhance the growth and adhesion of the thin film and its conductivity.     

Surface modification of nanoporous alumina membranes by plasma polymerization

The deposition of plasma polymer coatings onto porous alumina (PA) membranes was investigated with the aim of adjusting the surface chemistry and the pore size of the membranes. PA membranes from commercial sources with a range of pore diameters (20, 100 and 200?nm) were used and modified by plasma polymerization using n-heptylamine (HA) monomer, which resulted in a chemically reactive polymer surface with amino groups. Heptylamine plasma polymer (HAPP) layers with a thickness less than the pore diameter do not span the pores but reduce their diameter. Accordingly, by adjusting the deposition time and thus the thickness of the plasma polymer coating, it is feasible to produce any desired pore diameter. The structural and chemical properties of modified membranes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray electron spectroscopy (XPS). The resultant PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing, drug delivery, and engineering complex composite membranes.     

等离子体诱导接枝聚合修饰碳纳米管及其环氧树脂复合材料

以马来酸酐(MAH)为有机单体,通过等离子体诱导接枝聚合法修饰碳纳米管(CNTs),借助红外光谱、扫描电镜分析手段,对所得表面为聚合物膜修饰碳纳米管(p-CNTs)进行表征。将上述p-CNTs应用于环氧树脂(EP)固化体系,制备出p-CNT/EP纳米复合材料,研究了其对EP性能的影响。结果表明:等离子体可诱导马来酸酐在CNTs表面接枝聚合成膜。利用包覆于CNTs表面的聚马来酸酐(PMAH)薄膜功能化修饰CNTs。合适含量的p-CNTs可显著提高环氧树脂的强度和韧性,使其高度强韧化。     

可编程的多波形脉冲低温等离子电源

高压脉冲已经运用于许多领域,其中一个就是可以用来产生等离子体电源。脉冲输出参数是脉冲波形、脉冲电压幅度、脉冲频率以及脉冲持续时间等。本文应用现代电力电子技术提出了一种脉冲电路的拓扑结构,通过一定的控制算法可以产生不同的脉冲波形且脉冲幅度可以成倍增加以输出高压脉冲,并开发出了一套可编程的脉冲输出设备以用于生物组织或者材料等的改性加工。电路拓扑采用电容、二极管及开关管配合的方式工作,控制算法由复杂可编程逻辑器件FPGA来实现,通过导通或者关闭开关管来控制电容的充电或者放电以形成脉冲波形。电路拓扑通过Saber仿真软件和实测波形图证实了其可行性。通过单脉冲和多波形脉冲在生物组织上的实验对比,反应了多波形脉冲能够更好的对生物组织进行消融处理。     

低温等离子体液相接枝NVP改性PAN膜

采用液相等离子体接枝技术改性聚丙烯腈(PAN)膜,在PAN膜表面引入亲水性单体氮乙烯吡咯烷酮(NVP).通过傅立叶红外光谱、DSC、XPS对PAN改性膜进行了表征,研究了单体浓度、温度、接枝时间对PAN改性膜纯水通量的影响,考察了在不同单体接枝温度下,PAN改性膜对NaCl、MgSO4混合盐体系的分离性能.     

Surface modifications of polymethylmetacrylate films using atmospheric pressure air dielectric barrier discharge plasma

In this paper, polymethylmetacrylate (PMMA) films are modified using an atmospheric pressure non-thermal plasma generated by a dielectric barrier discharge (DBD) in air. The DBD is generated in a plane-parallel reactor, which is driven by a μs pulse power supply with amplitude of up to 25 kV and repetition rate of 1 kHz, and the plasma generated shows homogeneous mode discharge characteristics verified by electrical measurements and light emission images with 0.5 ms exposure time. The treatment time ranging from 0 to 60 s and the discharge power density ranging from 11.62 to 30.83 W/m² are used to study the effects of discharge parameters on the surface treatment, and the surface properties of PMMA films are studied using contact angle and surface energy measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), fourier transformed infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The study shows that, after the plasma treatment, the surface of PMMA film is etched, and oxygen-containing polar groups are introduced into the surface. These two processes can induce a remarkable decrease in water contact and a remarkable increase in surface energy, and the surface properties of PMMA films is improved accordingly. It is shown that the improvement of hydrophobicity depends on the discharge power density and treatment time, and there is a saturation treatment time at each discharge power density. Increasing discharge power density can induce more effective treatment of PMMA films, and less treatment time is needed to achieve the same level of surface treatment by increasing the discharge power density. Because more oxygen-containing polar groups are created and more obvious etching is occurred on the PMMA surface at higher discharge power density.     

HMDSO plasma polymerization and thin film optical properties

Thin films were deposited from hexamethyldisiloxane (HMDSO) in a glow discharge supplied with radiofrequency (rf) power. Actino-metric optical emission spectroscopy was used to follow trends in the plasma concentrations of the species SiH (414.2 nm), CH (431.4 nm), CO (520.0 nm), and H (656.3 nm) as a function of the applied rf power (range 5 to 35 W). Transmission infrared spectroscopy (IRS) was employed to characterize the molecular structure of the polymer, showing the presence of Si-H, Si-O-Si, Si-O-C and C-H groups. The deposition rate, determined by optical interferometry, ranged from 60 to 130 nm/min. Optical properties were determined from transmission ultra violet-visible spectroscopy (UVS) data. The absorption coefficient , the refractive index n, and the optical gap E₀₄ of the polymer films were calculated as a function of the applied power. The refractive index at a photon energy of 1 eV varied from 1.45 to 1.55, depending on the rf power used for the deposition. The absorption coefficient showed an absorption edge similar to other non-crystalline materials, amorphous hydrogenated carbon, and semiconductors. For our samples, we define as an optical gap, the photon energy E₀₄ corresponding to the energy at an absorption of 10⁴ cm⁻¹. The values of E₀₄ decreased from 5.3 to 4.6 as the rf power was increased from 5 to 35 W.     

大气压辉光放电液相沉积装置在表面改性中的应用

用高频高压电源、介质阻挡放电装置及惰性气体氦(He)产生大气压辉光放电等离子体,超声喷嘴喷射雾状液滴直接送入等离子体区域,喷洒在处理物表面上,进行等离子体接枝聚合.应用这套装置对PE纤维进行处理,选择甲基丙烯酸十二氟庚酯DFMA(C11H8F12O2)作为液相单体,对不同处理参数下PE纤维表面的接触角和接枝率变化进行了规律性和原理分析,用IR、SEM和EDS分析了处理前后PE纤维表面的变化.实验结果表明,在PE纤维表面成功引入了疏水性基团,提高了其疏水性.     

阳离子无皂含氟核壳苯丙乳液的制备及成核机理

在水溶性阳离子单体甲基丙烯酰氧基乙基三甲基氯化铵(DMC)存在下,以乙醇为助溶剂,通过种子半连续核壳乳液聚合法制备阳离子无皂含氟核壳苯丙乳液。考察了水溶性阳离子单体DMC和乙醇用量对乳液聚合过程的影响;用透射电镜(TEM)和X射线光电子能谱(XPS)对聚合物乳液乳胶粒形貌及涂膜化学组成进行表征,并讨论了无皂乳液聚合的成核机理和聚合过程。结果表明,采用种子半连续乳液聚合法,当DMC的质量分数为6.0%,乙醇的质量分数为7.5%(釜液)时,可以得到稳定的阳离子核壳结构含氟乳液,无皂乳液聚合的成核机理是先以均相成核方式后继续以低聚物成核方式进行,最终形成核壳结构。