聚丙烯片基不同气氛下等离子体改性及DNA原位合成研究

分别采用氮气／氢气、氨气和氧气三种不同气氛的等离子体处理了聚丙烯片基,先使其表面接枝功能性基团,然后分别进行寡核苷酸原位合成．光电子能谱(XPS)证实了在其表面分别接枝了大量氨基和其它含氮基团．荧光扫描分析并比较了在三种方法处理的聚丙烯片基上合成的寡核苷酸与靶序列杂交后的荧光强度．结果表明：三种方法处理的聚丙烯片基都可用于DNA原位合成,但从处理工艺和荧光分析结果来看,以氮气／氢气等离子体处理的聚丙烯片基最佳。     

Comparison of the surface characteristics of polypropylene films treated by Ar and mixed gas (Ar/O2) atmospheric pressure plasma

In an attempt to modify the hydrophobic surface properties of polypropylene (PP) films, this study examined the optimum process parameters of atmospheric pressure plasma (APP) using Ar gas. Under optimized conditions, the effects of a mixed gas (Ar/O2) plasma treatment on the surface-free energy of a PP film were investigated as a function of the O2 content. The polar contribution of the surface-free energy of the PP film increased with increasing O2 content in the gas mixture. However, slightly more oxygen-containing polar functional groups such as CO, CO, and COO were introduced on the PP film surface by the Ar gas only rather than by the Ar/O2 gas mixture. In addition, AFM analysis showed that the Ar plasma treatment of the PP film produced the smoothest surface as a result of the relatively homogeneous etching process.     

丁醛等离子体处理云母粉对其表面特性及与聚合物界面特性的影响

用电容耦合式等离子体聚合方法对云母粉进行丁醛等离子体处理,通过测定各种液体对密堆积云母粉的渗透速度,确定了液体在云母粉表面的接触角,估算了云母粉的表面张力及与典型线形聚合物的界面张力。结果表明,极性液体在云母粉表面的浸润性因处理而削弱,非极性液体的浸润性基本来变;云母粉表面张力由处理前的41.34(N·m~(-1)·10~(-3))下降到处理5min时的31.51和处理30min时的25.59(N·m~(-1)·10~(-3));处理对云母粉与线形聚合物界面张力的影响因聚合物而不同,但该界面张力的极性分量均因处理而减小。     

Treatment of a Polyethylene Powder Using a Remote Nitrogen Plasma Reactor Coupled with a Fluidized Bed: Influence on Wettability and Flowability

A Far Cold Remote Nitrogen Plasma is used both to fluidize and to treat a polyethylene powder in order to increase its hydrophilic character. The evolution of the wettability of the powder as well as the one of its physical (density, particles size distribution, average diameter, shape factor, and BET surface area) and flow properties (angle of repose, angle of slide, and Hausner index) are determined versus various experimental conditions. It is shown that the plasma treatment efficiency is strongly dependant on the oxygen content of the nitrogen flow and on the velocity of fluidizing gas. Best wettability is obtained by the addition of 0.75% of O₂ in the nitrogen plasma gas and with a high gas velocity. It is also evidenced that the flowability of the powder is slightly altered by the plasma treatment.     

Surface and electrochemical properties of polypropylene track membrane modified by plasma of non-polymerizing gases

The surface and electrochemical properties of polypropylene track membrane treated by plasma of nitrogen, air, and oxygen are studied. The effect of the plasma-forming gas composition on the surface morphology is considered. The membrane surface microrelief formed during the gas-discharge etching is found to change. Moreover, the non-polymerizing gas plasma treatment induces oxidation of the membrane surface layer and generates oxygen-containing functional groups, mostly carbonyl and carboxyl. The higher membrane roughness and its hydrophilization is shown to lead to its better wettability. In addition, the presence of polar groups in the membrane surface layer modifies its hydrodynamic and electrochemical properties so that water permeability and conductivity of modified membranes increase.     

Surface characteristic of poly(p‐phenylene terephthalamide) fibers with oxygen plasma treatment

Oxygen plasma is widely employed for modification of polymer surfaces. Plasma treatment process is a convenient procedure that is also environmentally friendly. This study reports the effects of oxygen plasma treatment on the surface properties of poly(p‐phenylene terephthalamide) (PPTA) fibers. The surface characteristics before and after oxygen plasma treatment were analyzed by XPS, atomic force microscopy (AFM) and dynamic contact angle analysis (DCAA). It was found that oxygen plasma treatment introduced some new polar groups (O? C?O) on the fiber surface, increased the fiber surface roughness and changed the surface morphologies obviously by plasma etching and oxidative reactions. It is also shown that the fiber surface wettability was improved significantly by oxygen plasma treatment. Copyright © 2008 John Wiley & Sons, Ltd.     

Surface Behavior of Polyamide 6 Modified by Barrier Plasma in Oxygen and Nitrogen

Polyamide (PA) 6 was modified by diffuse coplanar surface barrier discharge (DCSBD) plasma in an atmosphere of nitrogen and oxygen. The surface roughness decrease of PA 6 was detected by AFM and nano-indentation after modification in DCSBD plasma. A significant increase in O/C and N/C ratios of plasma-modified PA 6 using XPS analysis was found. The results show the importance of introducing oxygenic polar functional groups on the polymeric surface in order to increase its surface energy during a short time of plasma activation. The modification of PA 6 by DCSBD oxygen plasma was more efficient than by nitrogen plasma.     

Polymer matrix of polyethylene porous films functionalized by electrical discharge plasma

The polyethylene porous films were treated by dielectric surface barrier discharge (DSBD) plasma at atmospheric pressure in oxygen (O₂) or nitrogen (N₂), and by radio-frequency discharge (RFD) plasma in air at reduced pressure 46 Pa. The surface energy of films was carried out by direct measurements of contact angles of six testing liquids. The strength of adhesive joints in the system modified polyethylene porous films - polyacrylate was measured by peeling of the joints under the angle of 90°. The significant increase of the surface energy and its polar component of polyethylene porous films modified by all types of plasma were observed. The higher strengths of adhesive joints were found for modification of polyethylene porous films by radio-frequency discharge plasma in comparison with modification of the films by barrier discharge plasma.     

Analytical investigation of plasma-treated carbon fibres

As-grown and heat-treated vapour grown carbon fibres (VGCF) in the as-prepared state, washed in HCl/H(2)O, and treated in O(2) plasma for different periods have been investigated by means of XPS and scanning electron microscopy (SEM). The surface energy of the carbon fibres before and after plasma treatment was determined from the wetting contact angle. Washing introduced hydroxyl, carbonyl and carboxyl groups onto the fibre surfaces and oxygen plasma treatment increases the total atomic concentration of oxygen up to 17%. This is in good agreement with the value of the polar component of the surface energy. Plasma treatment also enhanced the fibre surface porosity (by etching).     

Study of the wettability properties of polypropylene nonwoven mats by low‐pressure oxygen plasma treatment

Surface modification by plasma treatment is widely used for textiles and polymeric materials. Plasma processes are environmentally friendly and reduce chemicals and energy consumption. This study reports the effect of cold, low‐pressure oxygen plasma on the wettability properties of polypropylene (PP) nonwoven mats. The wetting properties were examined using contact angle, surface energy, and diameters of the drop after 20 s of treatment. It was found that plasma treatment had a significant effect on the wettability of PP fibers. The ageing for 90 days had no significant effect on the wettability. It was also shown that the morphology of the fibers was not affected by the plasma treatment. Copyright © 2007 John Wiley & Sons, Ltd.     

Tuning the Surface Properties of Oxygen-Rich and Nitrogen-Rich Plasma Polymers: Functional Groups and Surface Charge

Controlling the concentration and nature of functional groups in plasma polymer films by adjusting the flow ratio of constituent precursor gases can be exploited to tune the surface charge of the resulting coating. Plasma polymer films containing various concentrations of nitrogen and oxygen functional groups were deposited in a low-pressure capacitively-coupled glow discharge reactor by plasma polymerization of binary gas mixtures of a hydrocarbon (ethylene or butadiene) and a heteroatom source gas (ammonia and/or carbon dioxide). Increasing the flow ratio of heteroatom to hydrocarbon gases increased the concentration of bonded nitrogen or oxygen, including that of primary amine or carboxylic groups as determined by X-ray photoelectron spectroscopy and chemical derivatization procedures. The zeta potential of samples was measured using an electro-kinetic analyser in a diluted sodium chloride solution. The deposition parameters controlled the composition of the coatings, allowing to tune the surface charge to either positive (ammonia based films)—or negatively (carbon dioxide base films) values at physiological pH.     

THE SURFACE PROPERTIES OF A HYDROPHOBIC TRANSPOSON (Tn-5) MUTANT OF RHIZOBIUM ETLI

The physicochemical surface characteristics of a Tn-5 induced hydrophobic mutant (CE3003) of Rhizobium etli CE3 were investigated. The wild type CE3 was very hydrophilic with low contact angles for polar liquids, while the Tn-5 induced mutant had a surface that was moderately hydrophobic, with polar liquid contact angles in the 50–60° range. As a result, the polar surface free energy components (γ ⁺ and γ ^-) that constitute the acid-base component (γ ^AB) of surface tension, were greatly reduced on THE surface of the hydrophobic mutant. This decreased electron donicity of the mutant' surface caused an almost five fold increase in the magnitude of the acid-base component of the interfacial interaction free energy between the mutant and hexadecane. The increased adhesion to hexadecane reported earlier is probably attributable to this interaction free energy change and not to any alteration in zeta potential, which was similar for CE3 and CE3003 at pH 7. X-ray photoelectron spectroscopy showed CE3OO3 to have less surface carbon and nitrogen and more surface oxygen than CE3 with alterations in the (C-C,H) and (C-O,N) components being observed.     

Surface roughness and hydrophilicity enhancement of polyolefin‐based membranes by three kinds of plasma methods

The introduction of antibacterial property, conductivity, wettability and antithrombogenicity into polyolefin‐based membranes has evoked much attention, which can be achieved by coating hydrophilic polymers. Therefore, it is necessary to modify the roughness and hydrophilicity of polyolefin‐based membranes to enhance the coating ability. In this paper, three kinds of plasma methods, including inductively coupled (ICP) plasma, radio frequency low pressure (RFP) plasma and atmospheric dielectric barrier discharge (DBD) plasma, were used to modify the surface of the polyethylene (PE), polypropylene (PP) and polyester‐polypropylene (PET–PP) membranes. The surface roughness of the plasma‐modified PE, PP and PET–PP films was investigated by scanning electron microscopy (SEM) and atomic force microscope (AFM). The polar functional groups of films were observed by energy dispersive spectrometer (EDX) and X‐ray photoelectron spectroscopy (XPS). Besides, the hydrophilicity of the plasma‐modified PE, PP and PET–PP films was evaluated by water contact angle measurement. It was found that the surface roughness and hydrophilicity of plasma‐modified PE, PP and PET–PP films increased with the generation of oxygen‐containing functional groups (i.e. C―O, and C?O). The PET–PP membranes were treated by RFP plasma at different processing powers and times. These results indicated that plasma is an effective way to modify films, and the treatment time and power of plasma had a certain accumulation effect on the membranes' hydrophilicity. As for the roughness and hydrophilicity, the DBD plasma modifies the PE film, which is the optimum way to get the ideal roughness and hydrophilicity. Copyright © 2015 John Wiley & Sons, Ltd.     

等离子体处理云母粉对其表面特性及对其与聚合物界面特性的影响

In this work mica powder was treated with n-butyl aldehyde plasma of radio frequency. Then the apparent contact angle of different liquids on the powder was determined by measuring the penetration rate of the liquid through the packed powder. The surface tension of mica powder and interface tension between the powder and typical linear macromolecules were calculated from the data of contact angle obtained under Fowkes' assumption. Rationalized conclusions were as follows: (i) For polar liquids, wetting of treated mica is more difficult than the untreated one and for nonpolar liquids, no difference has been observed. (ii) The surface tension of mica powder drops from 41.34 (N·m~(-1)·10~(-3)) to 31.51 after 5 min plasma treatment and to 25.59 (N·m~(-1)·10~(-3)) after 30 min plasma treatment. (iii) The polar component of interface tension between the mica powder and any linear macromolecule monotonically decreases with the time of plasma treating. However, the whole interface tension changes after plasma treatment, depending on the polymer used.     

Reactions and wetting properties of 1:1 perfluoroalkyl allyl and methallyl ether–maleic anhydride copolymers

Polymers with fluoroalkyl side-groups on three of every four carbon atoms along the polymer main chain were made by treating 1 : 1 copolymers of perfluoroallyl (or methallyl)ethers and maleic anhydride with SF₄, and then esterifying the resulting acid fluoride groups with 1H, 1H-pentadecafluorooctanol. Surface wettability of these polymers by polar and non-polar liquids was studied. The critical surface tension (γ_c) was found by Zisman's method. The dispersion force component of polymer surface energy (γ_s^D) and the polar component of surface energy (γ_s^p) were calculated by the respective methods of Fowkes and Owens. The γ_c values for several of the highly fluorinated polymers were lower than previously reported for any fluoropolymer but not so low as has been observed for the surface of an oriented perfluoroacid monolayer. In the range 11.4–18.5 dyne/cm, γ_c approximates γ_s^D for the fluorinated surfaces; however at lower γ_c values, considerable difference between γ_c and γ_s^D was noted.     

Analysis of functional groups on the surface of plasma-treated carbon nanofibers

Plasma chemically modified carbon nanofibers were characterized by X-ray photoelectron spectroscopy with regard to the content of carbon, oxygen, and nitrogen and the contribution of carboxylic groups or ester, carbonyl and hydroxylic groups or ether on the surface. Unfortunately, X-ray photoelectron spectroscopy only provides an average value of the first 10 to 15 molecular layers. For comparison, depth profiles were measured and wet chemical methods were applied to estimate the thickness of the functionalized layer and the distribution of oxygen-containing functional groups within the near-surface layers. The results indicate that the fiber surface is covered by a monomolecular oxygen-containing layer and that plasma treatment allows a complete oxygen functionalization of the uppermost surface layer. The best conditions for plasma treatment found within the set of parameters applied to generate complete functionalization are: plasma gas O(2)/Ar ratio 1:1, gas pressure 1-1.5 hPa, plasma power 80 W, treatment time >or= 5 min. Additionally, three quick and easy methods are presented to estimate the efficiency of plasma treatment with regard to surface functionalization: pyrolysis, contact angle measurements, and light permeability measurements of aqueous carbon nanofiber suspensions.     

Gasification of Municipal Solid Wastes in Plasma Arc Medium

Many thermal processes have been developed in order to eliminate the municipal solid wastes or produce energy from them. These processes include a wide range of applications from the simplest burning system to plasma gasification. Plasma gasification is based on re-forming of molecules after all molecules convert to smaller molecules or atoms at high temperatures. In this work, the production of fuel gas is aimed by plasma gasification of municipal solid wastes in high temperatures. Because of this, a plasma reactor of the capacity of 10 kg h^?1 was designed which can gasify municipal solid wastes. Plasma gasification with and without steam and oxygen was performed in temperatures of 600, 800, 1000, 1200, 1400 and 1600 °C in the reactor. A gas mixture containing methane, ethane, hydrogen, carbon dioxide and monoxide, whose content varies with temperature, was obtained. It was found that plasma gasification (or plasma pyrolysis, PG), plasma gasification with oxygen (PGO) and plasma gasification with steam (PGS) were more prone to CO formation. A gas product which was consisted of 95% CO between 1200 and 1400 °C was produced. It was observed that a gas with high energy capacity may be produced by feeding oxygen and steam into the entrance of the high temperature region of the reactor.

     

Oxygen/nitrogen separation by plasma chlorinated polybutadiene/polycarbonate composite membrane

The surface of a polybutadiene (PB)/polycarbonate (PC) composite membrane was plasma-modified by CHCl₃ to enhance its oxygen/nitrogen selectivity. The selectivity of the composite membrane was significantly improved after plasma chlorination. The degree of chlorination on the surface of this composite membrane surface was controlled by the supplied power for plasma and the plasma treating time. The chlorination was verified by infrared spectroscopy (FTIR-ATR) and ESCA analysis. The CHCl₃ plasma treated membrane had an oxygen/nitrogen selectivity of 7.5 and a gas permeation flux of 0.3 GPU. The selectivity enhancement was attributed mostly to the alteration of the physical structure on the membrane surface rather than the chemical effect introduced by chlorine. It was found that the surface hydrophilicity of the plasma treated membrane increased after long period of storage. Surface swelling by water vapor may be the reason for the selectivity degeneration.     

Laser-induced breakdown spectroscopy at a water/gas interface: A study of bath gas-dependent molecular species

Single-pulse laser-induced breakdown spectroscopy has been performed on the surface of a bulk water sample in an air, argon, and nitrogen gas environment to investigate emissions from hydrogen-containing molecules. A microplasma was formed at the gas/liquid interface by focusing a Nd:YAG laser beam operating at 1064 nm onto the surface of an ultra-pure water sample. A broadband Echelle spectrometer with a time-gated intensified charge-coupled device was used to analyze the plasma at various delay times (1.0–40.0 μs) and for incident laser pulse energies ranging from 20–200 mJ. In this configuration, the dominant atomic spectral features at short delay times are the hydrogen H-alpha and H-beta emission lines at 656 and 486 nm, respectively, as well as emissions from atomic oxygen liberated from the water and air and nitrogen emission lines from the air bath gas. For delay times exceeding approximately 8 μs the emission from molecular species (particularly OH and NH) created after the ablation process dominates the spectrum. Molecular emissions are found to be much less sensitive to variations in pulse energy and exhibit a temporal decay an order of magnitude slower than the atomic emission. The dependence of both atomic hydrogen and OH emission on the bath gas above the surface of the water was studied by performing the experiment at standard pressure in an atmospheric purge box. Electron densities calculated from the Stark broadening of the H-beta and H-gamma lines and plasma excitation temperatures calculated from the ratio of H-beta to H-gamma emission were measured for ablation in the three bath gases.     

Surface properties of polypropylene following a novel industrial surface‐treatment process

Polypropylene (PP) is used in many automotive applications where good paint adhesion is of primary importance. PP is widely known for its low surface energy which impacts negatively on its adhesion strength. PP surfaces were modified using a new industrial surface‐treatment process known as the Accelerated Thermo‐molecular adhesion Process (ATmaP). ATmaP grafts functional groups to the polymer surface derived from an atomised and vapourised nitrogen‐containing coupling agent. The surface properties and adhesion performance of PP samples treated using the ATmaP process and two different flame processes were compared using XPS, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and mechanical testing (pull‐up tests). The latter showed that ATmaP improved adhesion strength significantly in comparison with conventional flame treatments. XPS showed an increase in oxygen and nitrogen concentration on the surface of ATmaP‐treated samples compared with untreated and flame‐treated samples. Principal components analysis (PCA) of the ToF‐SIMS data revealed the major phenomena occurring during the surface treatment of PP samples. Early stage events, including the chain scission of the PP backbone chain and the subsequent reaction of these chains with the surrounding air, are captured by the first principal component (PC1). The increase in the concentration of NO surface functional groups resulting from ATmaP treatment is captured by the second principal component (PC2). Copyright © 2008 John Wiley & Sons, Ltd.