Effect of reactive oxygen species generated with ultraviolet lamp and plasma on polyimide surface modification

Understanding the effect of reactive oxygen species (ROS), such as singlet oxygen molecule and atomic oxygen, on polyimide (PI) film properties, such as wettability, morphology, and chemical bonding state, is essential for further development of PI‐based surfaces. We investigated the effect of different ROS generated during ultraviolet (UV) and plasma treatment in oxygen gas on surface modification of Kapton PI. Different surface modification techniques, UV and plasma treatment, are known to generate different ROS. In this work, we demonstrate the effect of different ROS on PI surface modification. From the diagnostics of ROS by means of electron spin resonance and optical emission spectroscopy, we confirmed that during UV treatment, excited singlet oxygen molecules are the main ROS, while plasma treatment mainly generated atomic oxygen. The wettability of PI surface treated by UV and plasma resulted in hydrophilic PI surfaces. XPS results show that the wettability of PI samples is mainly determined by their surface O/C ratio. However, chemical bonding states were different: while UV treatment tended to generate C=O bonds, while plasma treatment tended to generate both C―O and C=O bonds. Singlet oxygen molecules are concluded to be the main oxidant during UV treatment, and their main reaction with PI was concluded to be of the addition type, leading to an increase of C=O groups on the surface of PI film. Meanwhile, atomic oxygen species were the main oxidant during plasma treatment, reacting with the PI surface through both etching and addition reaction, resulting in a wider variety of bonds, including both C―O and C=O groups.     

Dielectric properties of UV-irradiated ultrathin polysulfone films revealed by surface plasmon resonance method

The surface plasmon resonance research of manufactured highly homogeneous ultrathin polysulfone films was performed, which were exposed to the short-wave (254?nm) UV irradiation of various durations. Surprisingly, the resonance incident angle and dielectric constant increase after short-term UV irradiation before the ordinary decrease caused by usual polymer degradation. The experimental results are ascribed to the formation of polar groups leading to orientation of chain fragments of intermediate length followed by their breaking and formation of mobile short fragments under longer times of irradiation.     

The effects of surface layers on third harmonic generation from solutions of a nematogenic polymer

Third harmonic generation (THG) is used to study the third-order nonlinear optical properties of nematic and isotropic solutions of poly(1,4-phenylene-2,6-benzobisthiazole) and related small-molecule model compounds. Maker fringe patterns (MFP) obtained using both plane slab and wedge-shaped cells for fundamental wavelengths of 1.542 and 1.907 μm are analyzed in terms of postulated surface layers in the isotropic preparations. The layers are postulated to comprise regions with concentration smaller than for the bulk sample, in which the rod-like chains tend to have their axes parallel to the plane of the surface, creating a negatively birefringent uniaxial nematic layer. The THG with the nematic solution exhibits intensity with polarization components unexpected for the uniaxial nematic symmetry attributed from linear optical properties, along with other unexpected features in the MFP. This behavior is attributed to the effects of surface layers, postulated to exhibit biaxial nematic symmetry, in which the uniaxial nematic symmetry is broken in regions on the scale of a wavelength. This provides for averaging that does not cause departure from the linear optical behavior expected for a uniaxial nematic, but does produce effects on nonlinear optical properties. © 1996 John Wiley & Sons, Inc.     

Interest of NH3 and N2 plasmas for polymer surface treatment before “electroless” metallization

The electroless metallization of polymers needs an activation of their surface which consists of palladium chemisorption. In this study, the effect of surface treatments of polystyrene and polyamide substrates by reactive gas plasmas (O₂, NH₃, N₂) has been followed by XPS analysis. According to the functional groups grafted on the surface, specific chemisorption reactions can occur. The latter have been highlighted through a comparative investigation of two activation processes, viz. a conventional way using successively SnCl₂ and PdCl₂ solutions and a new procedure, developed by the authors, using only a PdCl₂ solution. This work shows that this simplified process can be extended to any polymer whose surface is grafted with nitrogenated functions.     

钼、钨系过氧化物在Sharpless烯烃环氧化反应中的应用*

钼、钨系过氧化物是非常重要的Sharpless烯烃环氧化催化剂,有着非常广泛的工业发展前景。本文综述了钼、钨系过氧化物的种类,结构,合成方法及催化活性,分析了各种钼、钨系过氧化物的特点以及在催化环氧化领域的发展现状。同时,本文还讨论了钼、钨系过氧化物催化烯烃环氧化反应的机理。评述了在催化环氧化领域中两种主要理论——Mimoun机理与Sharpless机理的争论焦点及发展现状,以及计算化学对两种理论中间过渡态的研究进展,并且重点分析了Sharpless机理的过渡态结构。此外,本文还综述了影响钼、钨系过氧化物催化剂反应活性的各种因素以及质子所产生的副反应。最后,本文对应用于催化环氧化领域的钼、钨系过氧化物未来的研究方向提出了建议。     

Microwave-assisted synthesis of highly functionalized guanidines on soluble polymer support

An efficient method for the N,N′-di(Boc)-protected guanidines containing piperazine and homopiperazine scaffolds has been developed under multi-step microwave irradiation. Followed by alkylation of carbamate-protected guanidines with various alkyl halides is also explored. This protocol proceeds via deprotonation of the acidic N-carbamate hydrogen of the guanidine by sodium hydride on soluble polymer support. In this manner, highly functionalized guanidines were obtained after cleavage from the support. The reaction is tolerant of a wide range of functional groups on both the alkyl halide and guanidine components. In addition, the reaction is sufficiently simple workup by precipitation in each step to yield the substituted guanidines in high purity. In conjunction with microwave irradiation and soluble polymer support, this method provides an efficient route to access highly functionalized guanidines.     

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.     

Influence of functional nanoparticles on the photostability of polymer materials: Recent progress and further applications

The photochemical behaviour of polymer–nanoparticles/nanocomposites has been studied depending on the geometry of the nanofiller and an overview of the studies reported in the last decade is tentatively given. Depending on their functionality, nanoparticles can impact the durability of the nanocomposite materials under light irradiation. The behaviour to UV-light exposure in presence of oxygen of various types of nanocomposites with clays, LDH and carbon nanotubes has been investigated and recent progress on the influence of functional nanoparticles on the polymer photodegradation is reported. The influence of photocatalytic (ZnO and TiO₂) nanoparticles and phosphors on the photooxidation of the polymeric matrix and the durability of the material properties are characterized. From a general point of view, the stabilization strategy of polymer nanocomposites must be adapted depending on the nanofiller.     

等离子体改性聚合物表面动力学的动态接触角法研究

不同聚合物经CF~4/CH~4等离子体处理后,在浸水过程中表面动力学衰减常数对温度通过Arrhenius关系作图,对于所研究的聚合物都有一个明显的转折点。转折点处的温度称作表面构型转变温度(T~s),大约为15℃,与表面邻近水的Drost-Hansen温度一致。T~s以上及以下的活化能数值较小,说明表面构型变化的本质可看作是由于基团的翻转运动,而不需要整个大分子或链段的迁移运动。在浸水过程中,接触角滞后Δθ在表面构型转变温度T~s附近有转变,并有极小值,此后随着温度的升高出现极大值,继续升高温度接触角滞后Δθ又反而下降。     

Ozone-induced graft polymerization onto polymer surface

Ozone-induced graft polymerization was carried out to improve polymer surfaces. The polymers were exposed to ozone and the surface density of peroxides formed was determined by three methods; iodide, DPPH, and peroxidase method. The peroxide production could be readily controlled by the ozone concentration and the ozone exposure time. In addition, it was dependent on the kind of polymer. Further, it seemed probable that the ozone oxidation introduced peroxides not only on the outermost surface but also into a layer deeper from the outermost surface. Such polymeric peroxides were capable of initiating graft polymerization onto PU. All the physical and biological measurements on the grafted surface indicated that ozone-induced graft polymerization has effectively made the PU surface covered with the grafted water-soluble chains, their location being restricted to the film surface region. The interaction of the PU surface with blood components could be greatly reduced by the surface graft polymerization. © 1993 John Wiley & Sons, Inc.     

Retention of poly(N-isopropylacrylamide) thin films on polycarbonate via polymer interdiffusion

This study explored the possibility of polymer interdiffusion for retaining thermoresponsive poly(N-isopropylacrylamide) (pNIPAAm) on polycarbonate (PC). It was hypothesized that interdiffusion could be facilitated either by increasing the annealing temperature or by treating PC using air plasma (AP) and ultra-violet ozone (UVO). The results showed that increasing annealing temperature only moderately improved pNIPAAm retention. Treating PC with AP led to an increase in surface-active groups and a greatly enhanced retention of pNIPAAm. UVO treatment, however, severely damaged the PC layer with no noticeable enhancement on pNIPAAm retention. The retained pNIPAAm films on PC exhibited thermoresponsive behavior as evidenced by water contact angle and desired cell attachment/detachment behaviors. These results illustrate the simplicity of using polymer interdiffusion to successfully retain pNIPAAm films on a polymer, and the resulting substrates would be less expensive and more versatile than those retained on brittle supports (e.g., glass) for applications that require resilient thermoresponsive substrates.     

UV curing polymer materials for making laser glass

Epoxy acrylate was synthesized by reacting epoxy resin with acrylic acid in the presence of quaternary ammonium salt. The effects of photoinitiators on the curing rate have been studied. UV curing polymer materials for making laser glass have been selected. The laser glass thus manufactured is a new decorative building material. Copyright © 1999 John Wiley & Sons, Ltd.     

Hydrogen Peroxide Electrosynthesis on Nonplatinum Materials

A combination of electrochemical and physicochemical methods is used to investigate electrocatalytic and corrosion properties of nonplatinum materials in a direct hydrogen peroxide electrosynthesis by the oxygen ionization. A modifying action of ozone and hydroquinone added in solution is established. Surface properties of the electrocatalysts are studied. Presumably, the electrosynthesis occurs via a mixed path, which includes direct oxygen electroreduction catalyzed by redox processes involving surface groups and chemical oxidation processes.     

Assembly and decomposition of building blocks to analyze polymer NEXAFS spectra

The poly(ethylene-terephthalate) and poly(bisphenol-A-carbonate) compounds are used to illustrate the possibilities and limitations of building-block analysis of polymer near-edge X-ray absorption spectra. Experimental spectra obtained for thin polymer films are analyzed using theoretical static exchange calculations of C_1s and O_1s excitation spectra on model molecules selected as possible building blocks. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 749–765, 1997     

Preparation and Its Application of Novel Graphene/Gold/Functional Conducting Polymer/Hydrogen Peroxide Biosensor

石墨烯材料和酶的固定对石墨烯基生物传感器性能及应用至关重要.金电极依次放入氧化石墨（0.05 mg/mL）和氯金酸（0.05 mmol/L）溶液中进行控制电位电解,循环以上操作20次后,转移至2,5-二（2-噻吩）-1-对苯甲酸吡咯单体溶液采用循环伏安法进行电聚合形成含有羧基的导电高分子膜,然后以1-（3-二甲氨基丙基）-3-乙基碳二亚胺盐酸盐（EDC）/N-羟基琥珀酰亚胺（NHS）为活化剂将辣根过氧化物酶共价键合在修饰电极表面制备过氧化氢生物传感器.研究表明,交替电沉积得到的石墨烯/金纳米复合材料分散性好,所制备的生物传感器对过氧化氢的氧化还原过程有显著的催化作用.过氧化氢浓度在2～200 nmol/L之间传感器的电流响应与浓度呈线性关系,相关系数（R2）为0.9996,方法的检测限是0.67 nmol/L（S/N=3）,灵敏度明显优于现有文献报道.此外,共价键合方式固定酶使传感器的稳定性和方法的重现性大大提高.5 nmol/L的过氧化氢溶液测定20次,相对标准偏差为1.2%.在4℃下储藏3个月传感器电化学响应变化值少于3%.该方法已成功应用于牛奶样品中痕量过氧化氢的测定.     

Acrylation of polyvinylsilazane with allyl bromide for an UV photosensitive inorganic polymer

A novel inorganic polymer resin with high photosensitivity was prepared by grafting acrylate functional groups onto the backbone of polyvinylsilazane through a reaction with methyl-2-(bromo-methyl)acrylate via the highly efficient electrophilic substitution of allyl bromide. The as-modified polymer was characterized by ¹H NMR and 2D-¹H-¹H NMR (COSY) methods to determine the reaction mechanism. Differential photocalorimetry, FT-IR spectroscopy and TGA were used to examine its properties. The modified polyvinylsilazane is a promising inorganic polymer photoresist with a high UV sensitivity and a 55% ceramic yield, which is useful for fabricating non-oxide ceramic microstructures using mold free photocuring shaping processes.     

Second harmonic generation and optical anisotropy of a spin-cast polymer film

The nonlinear susceptibilities (χ⁽²⁾₃₃, χ⁽²⁾₃₁), and the refractive index anisotropy, of a main chain accordion polymer, BCSC (see the text for the complete chemical formula), have been measured by the techniques of second harmonic generation (SHG) and waveguiding. A large birefringence, which is induced in the BCSC film by the spin-coating process, is almost removed by electric field poling. Our results demonstrate the fundamental difference between the birefringence associated with quadrupolar orientational order and the dipolar order associated with SHG. © 1993 John Wiley & Sons, Inc.     

Synthesis of a new polymer surface bearing grafted azo polymer chains

Azobenzene, a photosensitive chromophore that undergoes photoinduced and thermal cis–trans isomerization, can be applied in a nonlinear optical field. {4′‐[(Hydroxy)ethyl]amino}‐4‐nitroazobenzene (disperse red 1) corresponds to one of these azo compounds, which can be grafted to a polymer chain as a part of the main chain, as a dangling group, or onto the polymer surface. In the last case, disperse red 1 is transformed into an acrylic monomer and then grafted onto a polypropylene surface modified with a cold carbon dioxide‐plasma treatment. A method is proposed for quantifying the radicals formed during the plasma treatment and, consequently, for optimizing the grafting reaction. The best conditions (the nature of the solvent, temperature, monomer concentration, and duration) are given. Both IR and Raman spectroscopies were used as efficient techniques for grafting characterization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3052–3061, 2001