PDMS氧等离子体长效活性表面处理及与Si的键合

为了实现室温、常压下聚二甲基硅氧烷(PDMS)与硅的键合,本文利用氧等离子体分别对PDMS、硅进行表面改性处理.考察了等离子体射频电源功率、处理时间、氧气流量对PDMS-硅键合强度的影响.通过优化工艺适当降低PDMS表面被氧化的程度,可使PDMS活性表面的持续时间延长至45分钟,实现了PDMS-硅在室温常压下的永久性键合.通过X-射线光电子能谱(XPS)对改性后PDMS表面化学组分变化的分析,可推断出PDMS表面Si-OH的稳定性是影响键合强度的主要因素.     

液滴微流控中空气/CF4等离子体表面改性环烯烃共聚物

环烯烃共聚物(COC)是一种新型的微流控材料,其疏水性虽然可以保证油包水微滴生成,却极大降低了芯片的键合强度。采用空气/CF_4射频放电低温等离子体对COC进行表面改性,成功制备了高亲水性到高疏水性的COC表面,并利用接触角测量、X射线光电子能谱、扫描电子显微镜和傅里叶变换红外光谱对处理后的表面进行了分析和表征。通过微滴生成实验与剥离实验研究了等离子体表面改性对COC芯片微滴生成、流动行为和键合强度的影响,并监测了改性表面的时效性。结果表明,空气等离子体处理后芯片黏接性能与润湿性能显著提高,但此时生成水包油微滴。经过空气等离子体活化后再经过CF_4等离子体处理的芯片疏水性恢复并超越本征,油包水微滴再度生成。因此,低温等离子体改性可以成为在不影响芯片功能的前提下实现芯片结构强化的有效方法,另外改性后芯片的生物应用值得进一步探索。     

低温空气等离子体改性PDMS的研究

为了改善聚二甲基硅氧烷（PDMS）的亲水性和稳定其电渗性能,采用空气微波等离子体在低温条件下对其表面进行改性。利用原子力显微镜（AFM）、X射线光电子能谱（XPS）及静态接触角对处理前后的PDMS进行分析。经空气微波等离子体处理3min后,PDMS的亲水性得到极大的改善,水在其表面的接触角接近零度。XPS结果表明：处理后PDMS表面形成SiOx薄层;AFM显示空气等离子体处理对PDMS的表面没有损伤。与文献报道的高、中真空氧等离子体处理方法相比,亲水效果基本一致,却大幅度降低了对设备真空系统的要求,并缩短了操作时间,节约了成本。最佳处理条件为：微波为100W,腔体内气压为1.0kPa,空气的流量为20sccm（1sccm=1cm3·min^-1）,时间3min。     

PBO纤维的合成及表面改性研究进展

本文介绍了聚对苯撑苯并双啄唑（PBO）纤维的合成方法和目前常见的PBO纤维的表面改性方法,如化学试剂处理、偶联剂处理、等离子体处理、辐射处理、电晕处理、酶处理等表面改性技术的研究进展。     

聚四氟乙烯薄膜等离子体表面改性的研究

利用等离子体表面处理和化学接枝的方法对聚四氟乙烯（ＰＴＦＥ）薄膜表面进行了化学改性。利用ＸＰＳ研究了改性后的ＰＴＦＥ薄膜的表面结构和价键状态，并通过接触角的测定研究了表面改性对薄膜亲水性的影响。研究结果发现ＰＴＦＥ薄膜经等离子体处理后，薄膜表面的Ｃ－Ｆ键发生了断裂，形成了Ｃ－Ｃ键、Ｃ－Ｈ键及Ｃ－Ｏ键；等离子体处理后的薄膜再经丙烯酸化学处理，强亲水性的丙烯酸基被接枝到ＰＴＦＥ表面，使得ＰＴＦＥ薄膜获     

物理方法对纤维素纤维的表面处理及其应用研究进展

综述了近几年等离子体、激光、γ射线、电晕和真空紫外辐射等物理方法在纤维素纤维的表面处理领域中的研究进展,着重分析了这些物理改性方法对纺织品、复合材料以及纸制品表面性能的影响,并展望了未来的发展趋势。     

微结构PDMS压电俘能器设计与特性研究

设计了一种具有三明治结构的微结构驻极体膜,采用旋涂、"软刻蚀"等工艺,结合氧等离子体键合、恒压电晕放电技术,以铜网作为电极,摸索出完整的工艺流程,制作了基于微结构PDMS驻极体的柔性压电俘能器。测量了驻极体膜的压电系数以及力-电特性。结果显示,微结构PDMS压电俘能器的压电系数(d33)为25pC/N;在5N周期性压力下,最大能够产生1.98Vpp的开路电压;驻极体膜的谐振频率为32Hz,且产生的电压与受到的压力呈线性关系。     

Cu/Sn等温凝固芯片键合工艺研究

研究了Cu/Sn等温凝固芯片键合工艺,对等离子体处理、键合气氛、压力以及Sn层厚度等因素对焊层的键合强度的影响进行了分析和优化。实验表明,等离子体处理过程的引入是保证键合质量的重要因素,在功率500W、时间200s的处理条件下,得到了最大的键合强度;而键合气氛对键合质量有显著的影响,在真空环境下,能得到最佳的键合质量;压力对键合质量的影响较小,施加较小的压力(0.05MPa)即能得到较大的剪切强度;而Sn层厚度对键合质量的影响极小,而较薄的厚度能够缩短键合时间。在最优化条件下,得到的键合强度值全部达到了美军标规定的6.25MPa的强度要求(对于2mm×2mm芯片)。     

碳纤维/环氧复合材料界面改性的不均匀性EI北大核心CSCD

研究了等离子体表面改性和等离子体接枝改性碳纤维/环氧树脂基复合材料界面的不均匀性。层间剪切强度(ILSS)测量及其偏差评估的结果表明,在相同等离子体条件下,等离子体表面改性对ILSS的提升率只有8.6%,而等离子体接枝改性的提升率高达37%;但是,接枝改性ILSS的离散程度比较高。扫描电镜、金相显微镜和红外光谱分析的结果进一步表明,接枝改性可通过取代反应将较多的活性基团键接在碳纤维表面从而更容易实现界面提升,但是接枝层的不均匀及其产生的纤维粘连使ILSS的离散程度提高。     

PBO纤维表面空气冷等离子体改性

采用等离子体处理方法对PBO(聚对苯撑苯并二 口 恶 唑)纤维表面进行改性。用XPS和AFM测试分析等离子处理时间对PBO纤维表面组成和表面形貌的影响规律;首次采用浸润性测试和IR测试分析等离子体处理前后纤维浸润性和表面官能团的变化。用Microbond测试方法表征了纤维与树脂基体的界面剪切强度,并用SEM观察微复合材料破坏形貌。结果表明:等离子体处理后纤维浸润性得到改善,纤维表面苯环上引入了很多羟基。等离子体处理最佳条件下(170 W,10 min),纤维表面粗糙度最大,纤维表面O元素含量最大, O/C比率提高了50.5 %, IFSS值提高了64.7 %。     

Chemical-assisted bonding of thermoplastics/elastomer for fabricating microfluidic valves

Thermoplastics such as cyclic olefin copolymer (COC) and polymethylmethacrylate (PMMA) have been increasingly used in fabricating microfluidic devices. However, the state-of-the-art microvalve technology is a polydimethylsiloxane (PDMS)-based three-layer structure. In order to integrate such a valve with a thermoplastics-based microfluidic device, a bonding method for thermoplastics/PDMS must be developed. We report here a method to bond COC with PDMS through surface activation by corona discharge, surface modification using 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), and thermal annealing. The method is also applicable to PMMA. The bonding strength between thermoplastics and PDMS was represented by the peeling force, which was measured using a method established by the International Organization for Standardization (ISO). The bonding strength measurement offered an objective and quantitative indicator for protocol optimization, as well as comparison with other PDMS-associated bonding methods. Using optimized bonding conditions, two valve arrays were fabricated in a COC/PDMS/COC device and cyclic operations of valve closing/opening were successfully demonstrated. The valve-containing devices withstood 100 psi (～689 KPa) without delamination. Further, we integrated such valve arrays in a device for protein separation and demonstrated isoelectric focusing in the presence of valves.     

Magnetic microparticle-polydimethylsiloxane composite for reversible microchannel bonding

In this study, an iron oxide magnetic microparticles and poly(dimethylsiloxane) (MMPs-PDMS) composite material was employed to demonstrate a simple high-strength reversible magnetic bonding method. This paper presents the casting of opaque-view (where optical inspection through the microchannels was impossible) and clear-view (where optical inspection through the microchannel was possible) MMPs-PDMS. The influence of the microchannel geometries on the casting of the opaque-view casting was limited, which is similar to standard PDMS casting. Clear-view casting performance was highly associated with the microchannel geometries. The effects of the microchannel layout and the gap between the PDMS cover layer and the micromold substrate were thoroughly investigated. Compared with the native PDMS bonding strength of 31 kPa, the MMPs-PDMS magnetic bonding experiments showed that the thin PDMS film with an MMPs-PDMS layer effectively reduced the surface roughness and enhanced MMPs-PDMS reversible magnetic bonding strength. A thin PDMS film-coated opaque-view MMPs-PDMS device exhibited the greatest bonding strength of 110 kPa, and a clear-view MMPs-PDMS device with a thin PDMS film attained a magnetic bonding strength of 81 kPa.     

Poly(dimethylsiloxane) surface modification by plasma treatment for DNA hybridization applications

In this work, the surface modification of poly(dimethylsiloxane) (PDMS) was carried out by using a 2-step plasma modification with Ar followed by acrylic acid (AAc). The optimal conditions were found to be 0.5 min with Ar at 0.7 mbar; and 5 min with AAc at 0.2 mbar. The water contact angle (WCA) of the native PDMS decreased from 110 degrees to 30 degrees after modification, then stabilized to values between 50 degrees to 60 degrees after 1 day exposure to air. The stability of the modified PDMS was further improved by Soxhlet-extracting the PDMS with hexane prior to plasma treatment. Atomic force microscopy (AFM) showed significant changes in surface morphology after the 2-step plasma modification. X-ray photoelectron (XPS) spectroscopy further confirmed the successful modification of the PDMS surface with PAAc, by exhibiting C1s peaks at 285.9 eV, 287.4 eV and 289.9 eV, originating from C-O, C=O and O-C=O moieties, respectively. Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy of the poly(acrylic acid) (PAAc) modified PDMS surface showed a distinctive peak at 1715 cm(-1), attributed to the presence of COOH groups from the PAAc. The carboxyl peak on the spectra of the PAAc modified PDMS was quite stable even after storage at room temperature in phosphate buffer saline (PBS) and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffer for 17 h. 5'-amino-terminated oligonucleotides were covalently attached to the PAAc modified PDMS surface via carbodiimide coupling. Subsequently, fluorescently tagged complementary oligonucleotides were successfully hybridized to this surface, as determined by fluorescence microscopy.     

Optimum dispersion conditions and interfacial modification of carbon fiber and CNT–phenolic composites by atmospheric pressure plasma treatment

Electric resistance measurements were used to determine the optimal dispersion conditions for carbon nanotubes (CNTs) in phenolic resins. Plasma treatment is frequently used to modify carbon fiber surfaces to improve adhesion of the fibers to matrices. Such treatment might also influence carbon fiber tensile strength. In order to determine the effect of atmospheric pressure plasma treatment on carbon fiber tensile strength and interfacial bonding strength, change in tensile strength of the fiber was studied at different gage lengths before and after the plasma treatment. The wettability of carbon fibers was improved significantly after only 10 s of plasma treatment. Such plasma treatment resulted in a decrease in the advancing contact angle from 65° to 28°. Surface energies of carbon fiber and CNT–phenolic composites were measured using the Wilhelmy plate technique, indicating that the work of adhesion between plasma treated carbon fibers and CNT–phenolic composites was higher than it before plasma modification. The interfacial shear strength (IFSS) and apparent modulus were also increased by plasma treatment of the carbon fibers.     

Determination of antioxidant activity of surface‐treated PET films coated with rosemary and clove extracts

Commercial PET films were surface treated and subsequently coated with either rosemary (RME) or clove (CE) extracts. Surface treatments involved (1) corona treatment, (2) chemical modification, and (3) plasma treatment. Radical scavenging activity (RSA) of both pure plant extracts and coated film extracts were determined using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) method. RME‐coated films showed a % RSA of 25.6%, 22.4%, and 24.1% for plasma, chemical modification, and corona treatment, respectively, at an extract concentration of 1402 ppm, respectively, while pure RME showed a %RSA of 16.0%. Respective %RSA values for CE were 25.0% for plasma, 25.2% for chemically modified, and 25.2% for corona‐treated films at 1402 ppm, while pure CE showed a %RSA of 47.6%. Thiobarbituric acid (TBA) test, performed on ground fish muscle wrapped in all types of employed films, showed a remarkable decrease in the degree of fish oxidation ranging between 50.0 and 80.0% after 6 days of storage. Contact angle measurements confirmed that surface chemically modified films had the highest adhesion strength followed by corona and plasma‐treated films. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS) data also supported contact angle measurements. Finally, the oxygen permeability of surface‐treated films did not differ from untreated films indicating that surface treatment did not affect film barrier properties.     

Analysis of solids, liquids, and biological tissues using solids probe introduction at atmospheric pressure on commercial LC/MS instruments

Direct analysis of samples using atmospheric pressure ionization (API) provides a more rapid method for analysis of volatile and semivolatile compounds than vacuum solids probe methods and can be accomplished on commercial API mass spectrometers. With only a simple modification to either an electrospray (ESI) or atmospheric pressure chemical ionization (APCI) source, solid as well as liquid samples can be analyzed in seconds. The method acts as a fast solids/liquid probe introduction as well as an alternative to the new direct analysis in real time (DART) and desorption electrospray ionization (DESI) methods for many compound types. Vaporization of materials occurs in the hot nitrogen gas stream flowing from an ESI or APCI probe. Ionization of the thermally induced vapors occurs by corona discharge under standard APCI conditions. Accurate mass and mass-selected fragmentation are demonstrated as is the ability to obtain ions from biological tissue, currency, and other objects placed in the path of the hot nitrogen stream.     

Ca-deficient hydroxyapatite/polylactide nanocomposites with chemically modified interfaces by high pressure consolidation at room temperature

Hydroxyapatite (HAP) is a close synthetic analog of the bone mineral and is often considered as a material for bone graft substitutes and tissue engineering scaffolds. Despite its attractive bioactive properties low-fracture toughness limits the use of HAP ceramics to a number of non-load-bearing applications. To obtain a more adequate mechanical behavior, HAP is often combined with polymers based on lactic and glycolic acids or polycaprolactone using hot pressing. In such composite materials, the compatibility and bonding strength of HAP–polymer interfaces are critical parameters that must be controlled and improved. This may be achieved, for example, by covalent immobilization of organic moieties on the ceramic particles surface. In this work, the surface of calcium-deficient hydroxyapatite (CDHAP) was modified by reaction with hexamethylene diisocyanate (HDI) in a non-aqueous suspension. Composites of CDHAP–HDI with polylactide (PLA) were high pressure consolidated at room temperature at 2.5 GPa yielding up to 90% theoretical density. The effects of total organic fraction and modification extent on compression strength were studied. Materials with high extent of modification and high organic content exhibited compressive strength of ~295 MPa, much higher than reported in other studies. These materials are suitable candidates for load bearing orthopedic applications.     

空气中大气压下低温等离子体对聚四氟乙烯进行表面改性的研究

建立了空气中产生大气压下辉光放电 (APGD)和介质阻挡放电 (DBD)的装置 ,通过放电的电气特性和发光特性测量 ,界定了APGD和DBD的放电特点。研究了空气中APGD和DBD对聚四氟乙烯 (PTFE)表面进行改性的效果 ,用扫描电子显微镜 (SEM)观察、接触角测量和X射线光电子能谱分析 (XPS)等手段 ,研究APGD和DBD处理后PTFE的表面特性 ,并解释了两种放电形式处理效果不同的原因。结果表明 :APGD的处理效果要优于DBD ,即APGD可以对PTFE表面进行均匀处理 ,在其表面引入更多的O元素 ,使其接触角下降到更低值。     

Direct bonding of CMP-Cu films by surface activated bonding (SAB) method

The chemical mechanical polishing (CMP) process is indispensable to the fabrication of Cu wiring layers in the large-scale integration (LSI). Recently, a direct bonding method with low bonding temperature is required for the CMP-Cu surface in order to obtain a narrow bonding pitch. In this study, we realized a direct bonding between CMP-Cu films by means of the surface activated bonding (SAB) method at room temperature. The critical vacuum pressure to obtain large bonding strength was estimated at about 4×10⁻³ Pa from the growth rate of oxide on an active surface measured by the X-ray photoelectron spectroscope (XPS). The films were bonded successfully at the vacuum pressure better than around 3×10⁻³ Pa with the shear strength larger than 50 MPa. The transmission electron microscope (TEM) observation showed that the polycrystalline films with the mean surface roughness of 0.3 nm were bonded directly between Cu grains in atomic level. Moreover, the adhesion between the films was improved due to the stress relaxation at the interface during the thermal aging test conducted at 200 and 300^∘C in the vacuum condition.     

Superplastic diffusion bonding of γ-TiAl-based alloy

With laser surface melting and conventional heat treatment, superplastic diffusion bonding of TiAl alloy samples was carried out. Three different microstructure, i.e. fully lamellar structure, fine dendritic structure and refined equiaxed structure are used and their effects on bonding quality were investigated, and the bond quality was assessed by shear test at room temperature. Sound bonds could be achieved at 900 °C by laser surface modification or by laser surface modification and pre-bond heat treatment at 1000 °C for 60 min, which is lower than conventional diffusion bonding temperature. The bonds were also post-bond heat treated at 1200 °C for 30 min, which improved the bond quality in all cases. The best shear strength of the bonds is greater than 80% of that of base metal.