基于近红外光谱的柔性基底紫外臭氧改性效果表征研究

近年来,随着纳米科技、聚合物材料和先进制造技术的发展,以柔性传感器为代表的新兴柔性电子器件在可穿戴、健康医疗、物联网终端等领域发挥着越来越重要的作用。作为柔性电子器件的载体,柔性基底对传感器的机械可靠性和电学传感性能等方面有着重要的意义。但由于其表面非极性键造成的高疏水性限制了功能性材料在其表面的沉积,常常造成柔性基底层与电极层/敏感层之间不稳定的界面结合。因此,利用紫外臭氧处理对柔性基底表面改性受到了广泛的关注。利用近红外光谱技术对柔性基底的紫外臭氧处理效果进行快速精准评估,旨在从基团分子层面探究其改性效果,在实际应用中是对传统依靠接触角测量评估方法的有效补充。具体而言,对四种常见的柔性基底材料聚二甲基硅氧烷(PDMS)、聚萘二甲酸乙二醇酯（PEN）、聚对苯二甲酸乙二醇酯（PET）和聚酰亚胺（PI）进行了1/2/5/10 min不同时长的紫外臭氧（UVO）改性处理,并利用近红外光谱对其改性效果进行表征研究,最后利用接触角测量方法对上述的表征结果进行了验证分析。近红外光谱分析表明：对于柔性PDMS基底,紫外光能量不足以切断其中的甲基（—CH₃）官能团和（—C—Si—）等化学键,无法引入羟基、羧基等亲水性基团。对于柔性PEN和PET基底而言,紫外臭氧处理的效果要优于柔性PDMS基底,且对柔性PET基底的处理效果要优于柔性PEN基底,其原因可能是PEN基底材料中萘环的双环结构具有很强的紫外光吸收能力,阻隔了380 nm以下的大部分紫外线能量。对于柔性PI基底,紫外臭氧处理可以有效引入羟基（—OH）和羧基（—COOH）等活性基团,且这些官能团的强度和数量随着处理时间的增加而增加,从而在短时间内使得PI基底表面能增大、接触角减小、湿润性提高。接触角测试结果验证：紫外臭氧处理对于柔性PDMS基底处理效果不明显（接触角下降幅度为8.4%）;对柔性PET基底处理的效果（接触角下降幅度为39.6%）要优于柔性PEN基底的处理效果（接触角下降幅度为9.4%）;紫外臭氧处理的效果对柔性PI基底处理效果最佳,接触角下降幅度达到了62.7%。     

臭氧化法表面改性聚苯乙烯薄膜

 为增强聚苯乙烯(PS)与聚乙烯醇(PVA)之间的结合力,进而提高PS-VA双层空心微球存活率。利用臭氧化改性法在酸性介质中对聚苯乙烯薄膜进行表面改性,用红外光谱对处理后的表面进行了半定量的分析。结果表明：改性过后聚苯乙烯表面产生羟基、羰基等极性基团;接触角测试证明,处理后的表面由憎水变为亲水,并通过纳米压痕划痕法得到了处理前后PS与PVA薄膜之间的相互作用强度,臭氧化改性后PS与PVA膜间作用强度增大了40%。     

交流和纳秒脉冲Ar/H2O介质阻挡放电聚丙烯材料表面亲水改性对比研究

为了提高等离子体对聚合物材料表面处理的应用效果,优化亲水处理的条件,研究了交流和纳秒脉冲氩气介质阻挡放电（DBD）中添加适量H₂O,对聚丙烯（PP）亲水改性的处理效果。利用电学和光学诊断方法,系统地对比了交流DBD和纳秒脉冲DBD的放电特性,结果表明,纳秒电源驱动DBD具有更高的放电瞬时功率,更好的放电均匀性和更高的能量效率。通过测量不同水蒸气含量下DBD的OH发射光谱强度,确定了PP材料亲水性处理中H₂O添加的最优含量。利用交流和纳秒脉冲电源驱动DBD分别对PP材料进行亲水改性的处理,测量了不同条件下改性处理后的表面水接触角,并利用原子力显微镜（AFM）和傅里叶红外光谱（FTIR）分别对处理前后PP材料的表面物理形貌和表面化学成分进行分析。结果发现,经DBD处理后PP材料的水接触角明显降低,表面粗糙度明显增大,表面的亲水性含氧基团,羟基（?OH）和羰基（C=O）的数量大幅增加。相比交流电源,纳秒脉冲DBD处理的改性效果更好,其处理后的材料表面水接触角,比交流DBD处理的低5°左右,表面粗糙度也有所提升。而水蒸气的加入可使PP材料的表面水接触角进一步减小4°左右,表面粗糙度明显提升。研究结果为优化DBD聚合物材料表面改性实验条件及处理的效果提供了重要的参考依据。     

不同物料和炭化方式制备生物炭结构性质的FTIR研究

红外光谱是了解生物炭结构性质特征的重要手段。通过采用傅里叶红外光谱技术(FTIR)对不同物料和制备方式的生物炭结构性质特征进行表征。结果表明：不同的物料制备的生物炭均具有羟基、芳香基及一些含氧基团的吸收峰,与活性碳有共同特征;但其他吸收峰,有着显著差异。高温炭化可以使玉米秸秆中—OH,—CH₃,—CH₂—,CO间发生缔合或消除,促进了芳香基团的形成。在不同炭化方式下,加热和微波炭化,对生物炭形成有着机理上差别,加热炭化可致使醇、酚中的—OH彼此结合或者消除,形成苯环类基团,而微波法能使得芳香基团钝化阻止其参与反应,使得苯环类物质得以更多形成。综上表明,红外光谱可较好反映生物炭的结构特征,揭示了生物炭主要含有—OH、芳香基团等活性基团。     

利用氟硅烷提高溶胶-凝胶SiO2增透膜的疏水性

 以正硅酸乙酯为前驱体，氨水为催化剂，采用溶胶 凝胶法制备了二氧化硅增透膜；通过自组装技术，用氟硅烷对膜层进行表面修饰，制得了疏水增透膜，克服了常规增透膜亲水的缺点。采用红外光谱、分光光度计、扫描探针显微镜和静滴接触角测量仪等测试手段分析了薄膜的特性。结果表明：疏水增透膜的峰值透光率为99.7％，疏水角为110°；氟硅烷自组装改性不影响二氧化硅增透膜的光学性能。     

银/二氧化硅复合材料对硝酸钠红外吸收光谱特性影响

对海洋营养盐进行快速检测是海洋污染监控中的一项重要任务。测量了硝酸钠溶液蒸发过程中的红外光谱,发现表面增强红外光谱法在营养盐的快速检测中有重要的应用价值。采用Stober方法制备了二氧化硅纳米颗粒,然后采用银氨溶液与二氧化硅溶液混合的方法制备银/二氧化硅(Ag/SiO₂)复合材料,并利用扫描电镜(SEM)、X射线衍射(XRD)以及紫外-可见(UV-Visible)吸收光谱对其进行表征。研究了硝酸钠水溶液干燥过程中Ag/SiO₂复合材料对硝酸钠红外吸收光谱的影响,结果表明硝酸根反对称伸缩振动吸收峰的吸收强度得到增强,这可能来自Ag/SiO₂薄膜材料的界面效应。     

聚合硫酸铁钛混凝剂的制备及红外、紫外-可见光谱分析

复合混凝剂由于其具有优异的混凝性能而受到越来越广泛的关注,但与钛离子络合的铁基复合混凝剂的制备和表征还鲜有报道。研究以Ti(SO₄)₂为配合物,PO3-₄为稳定剂和络合剂制备了聚合硫酸铁复合混凝剂钛(PFTS)。主要利用红外光谱(FTIR)、紫外-可见光谱(UV/VIS)表征分析了PFTS在不同Ti/Fe,P/Fe,OH/Fe物料配比下对化学基团,分子结构变化的影响。结果表明,Ti4+和PO3-₄的加入,不是以单一离子形态存在,而是生成了诸如Ti—O,—Fe—P—Fe—和—Ti—P—Ti—等有助于增大聚合物分子量的基团键,而一定比例的Ti/Fe和P/Fe配比有助于物料单体相互络合生成诸如—Fe—P—Ti—的基团键和Fe₆(OH)6+₁₂,[Fe_x(OH)_y]₂H₂PO(6x-2y-1)+₄等类型的中聚体结构,此比例在P/Fe为0.2—0.3,Ti/Fe为1∶8比较恰当。过高的P/Fe比,Ti/Fe比和OH/Fe会生成TiO₂,Ti₃(PO₄)₄和FePO₄沉淀或高聚体络合物,不利于混凝性能的发挥。     

三硼酸钾的合成、表征及其振动光谱的研究

借助自行设计的沸腾反应器,采用碳酸钾和硼酸通过控制适宜的原料配比、反应温度和脱水温度合成出三硼酸钾。通过化学分析确定合成物分子式为一水三硼酸钾(KB₃O₅·H₂O),通过粉末X射线衍射光谱(XRD)、傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman)和热重分析(TG)等手段对其进行了表征,由粉末X射线衍射光谱分析确定合成物物质形态为无定形态,由傅里叶变换红外光谱和拉曼光谱分析确定合成物分子中存在三配位硼氧键B₍₃₎—O、四配位硼氧键B₍₄₎—O、羟基及三硼酸根离子,由热重分析确定合成物分子中存在能够失去一分子水的基团,并推出合成物三硼酸钾的结构式为K[B₃O₄(OH)₂]。研究了合成物的振动光谱,包括红外光谱和拉曼光谱,考察了其中硼原子的主要存在形式三配位硼氧键B₍₃₎—O和四配位硼氧键B₍₄₎—O以及其他基团的振动情况,对振动频率进行了归属。     

紫外臭氧处理聚-a-甲基苯乙烯微球表面化学镀镍

通过对微球表面进行紫外臭氧的处理,改善了镍层在微球表面的沉积性,经紫外臭氧处理的聚-a-甲基苯乙烯微球通过红外图谱和红外图像表征,用扫描电镜测量处理前后的镀镍微球表面形貌.结果表明:经过紫外臭氧联合处理后,微球表面被氧化,同时接人了氨基,且处理过的微球镀镍后的结合力和表面形貌得到了明显改善.从而得出用紫外臭氧表面改性的方法可以提高塑料微球和金属壳的结合力.     

紫外光引发阳离子聚丙烯酰胺的红外光谱研究

以丙烯酰胺(AM)、 丙烯酰氧基乙基三甲基氯化铵(DAC)、 丙烯酸丁酯(BA)为单体,采用紫外光引发聚合制备阳离子聚丙烯酰胺P(AM-DAC-BA)。 采用紫外光谱和红外光谱研究其结构特征;分析AM,DAC,BA,P(AM-DAC-BA)的红外光谱中的典型红外振动频率的归属。 通过与单体红外光谱比较得出：由于聚合产物的对称性增加,聚合产物红外光谱更加简单。 P(AM-DAC-BA)的特性粘度随着光强、 BA含量、 光引发剂浓度、 光照时间的增加而增加。 选取AM,DAC,BA中的—CONH₂,—COOCH₂(CO), —COOCH₂—(C—O—C),—CH₂—N+(CH₃)₃基团吸收峰为特征吸收峰,随着光强、 BA含量的增加,特征峰面积增加;随着光引发剂浓度增加特征峰面积却呈现减少趋势;随着光照时间增加,峰面积是先减小后增加。 但不同P(AM-DAC-BA)在红外光谱上对应的特征吸收峰的峰型类似,特征峰位置基本一致。     

Hydrophobic recovery of UV/ozone treated poly(dimethylsiloxane): adhesion studies by contact mechanics and mechanism of surface modification

Silicone elastomers (Sylgard 184 and 170), based on poly(dimethylsiloxane) (PDMS), were surface treated by a combined exposure to UV and ozone. The effects of the treatments were analyzed as a function of time elapsed after stopping the treatments using different standard surface characterization techniques, such as water contact angle measurements, XPS and atomic force microscopy (AFM). However, the primary focus of this study was to apply the Johnson–Kendall–Roberts (JKR) contact mechanics approach to investigate PDMS samples prior to and following UV/ozone surface treatment. A gradual formation of a hydrophilic, silica-like surface layer with increasing modulus was observed with increasing UV/ozone exposure. A subsequent hydrophobic recovery after UV/ozone exposure was observed, as indicated by increasing contact angles. This supports the hypothesis that the hydrophobic recovery is mainly caused by the gradual coverage of a permanent silica-like structure with free siloxanes and/or reorientation of polar groups. PDMS containing a homogenously dispersed filler (Sylgard 184), exhibited a decreasing surface roughness (by AFM) when the oxidized surface region “collapsed” into a smooth SiO_x layer (final surface roughness <2 nm). PDMS containing heterogeneously distributed, aggregated filler particles (Sylgard 170), exhibited an increasing surface roughness with treatment dose, which was attributed to the “collapse” of the oxidized surface region thus exposing the contours of the underlying filler aggregates (final surface roughness ∼140 nm). A dedicated device was designed and built to study the contact mechanics behavior of PDMS prior to, and following surface treatment. The value of the combined elastic modulus obtained for PDMS lens and semi-infinite flat surface system showed an increase in full agreement with the formation of a silica-like layer exhibiting a high elastic modulus (compared with untreated PDMS). The work of adhesion observed in JKR experiments exhibited an increasing trend as a function of treatment done in agreement with contact angle data. JKR experiments showed hydrophobic recovery behavior as anticipated from contact angle measurements. Single pull-off force measurements by JKR and numerical analysis of full-approach JKR curves were in quantitative agreement regarding practical work of adhesion values.     

Long term hydrophilic coating on poly(dimethylsiloxane) substrates for microfluidic applications

Poly(dimethylsiloxane) (PDMS) has been used extensively for microfluidic components and as substrates for biological applications. Since the native nature of PDMS is hydrophobic it requires a functionalization step for use in conjunction with aqueous media. Commonly, oxygen plasma treatment is used for the formation of hydrophilic groups on the surface. However, the hydrophilic nature of these surfaces is short lived and the surfaces quickly revert back to their original hydrophobic state. In this work, branched-polyethylenimine (b-PEI) was used for long term modification of plasma treated PDMS surface. Contact angle, X-ray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM) were used for characterization of the modified surfaces and their stability with time was studied. The results obtained demonstrate that comparatively higher stability, hydrophilic, positively charged surfaces can be obtained after b-PEI treatment. These b-PEI treated PDMS surfaces can be used as fluidic channels for the separation of molecules as well as a substrate for the adherence of bio-molecules or biological cells.     

Patterning and modification of PDMS surface through laser micromachining of silicon masters and molding

We describe preparation of micro patterned PDMS sample surfaces and their chemical modification for the purposes of increased hydrophobicity. The process includes ablation of micrometer sized patterns on a silicon master by pulsed radiation from a Nd:YAG laser, transfer of the patterns to PDMS through molding, and chemical modification of the topmost surface layers of the polymer sample by further laser irradiation and UV/ozone treatment. The samples were characterized by XPS, FTIR, contact angle measurements, optical microscopy and SEM. The study shows the feasibility of the method to manufacture regular patterns with micron-sized cylindrical pillars and to control surface composition. In the absence of chemical modification of the surfaces due to preparation, we compare the effect of increased roughness on the contact angle with theoretically predicted values. Samples with patterned and chemically modified surfaces due to UV/ozone treatment show reduced hydrophobicity. PACS 52.38.Mf; 81.65.Cf; 81.05.Lg     

A new approach to immobilize poly(vinyl alcohol) on poly(dimethylsiloxane) resulting in low protein adsorption

The hydrophobic characteristics of PDMS and non-specific protein adsorption are major drawbacks for its application in biosensing. Here we have combined surface oxidation by plasma and chemical binding of polyvinyl alcohol (PVA) to obtain long-term stability of hydrophilic PDMS surfaces. Mercaptopropyltrimethoxisilane and aminopropyltrimethoxisilane were used as adhesives between the plasma-oxidized PDMS surface and the PVA, immobilized at room temperature. This approach has allowed for fast, uniform, and very stable modification of the PDMS surface, which maintained a hydrophilic character for as long as 30 days. In addition, the modified hydrophilic surface presented minimized protein adsorption when compared to pristine PDMS. The results obtained in this work are important contributions to the growing field of integrated microfluidic biosensors.     

三甲基硅烷化改性二氧化硅气凝胶

 采用六甲基二硅氮烷对二氧化硅凝胶进行疏水处理,得到了疏水性的二氧化硅气凝胶。用红外光谱和热分析表征处理前后二氧化硅气凝胶的性质,用测量显微镜跟踪处理前后气凝胶柱在空气中直径变化。结果表明,处理后气凝胶的表面羟基明显减少,在空气中的吸潮性大大降低,圆柱体在空气中的径向收缩率从30%降至3%。     

Investigation of the hydrophobic recovery of various polymeric biomaterials after 172 nm UV treatment using contact angle, surface free energy and XPS measurements

Surface modification as a route to improving the performance of polymeric biomaterials is an area of much topical interest. Ultraviolet (UV) light treatment has received much attention, but polymers so treated revert to their original surface condition over a period of time—an effect known as hydrophobic recovery. It is important to develop an understanding of the underlying processes contributing to the effect, since it has an impact on the applicability of UV treatment. In this work a number of polymeric biomaterials were surface-modified using 172 nm UV light from an excimer lamp. The modified polymers were characterised using contact angle, surface free energy (SFE) measurements and X-Ray Photoelectron Spectroscopy (XPS) techniques. The wettability, variation in surface free energy and chemical functionality changes were analysed on the surfaces immediately after UV treatment and subsequently over a period of 28 days. It was noted that hydrophobic recovery proceeds at a different rate for each polymer, is generally a two-phase process and that surfaces are still more hydrophilic after 28 days than the original untreated state. XPS analysis reveals that particular chemical configurations move from the surface at a faster rate than others which may contribute to the two-phase nature of the process.     

Topographic control on silicone surface using chemical oxidization method

The paper describes a wet process for modifying the surface of polydimethylsiloxane (PDMS) using H₂SO₄/HNO₃ solutions. The oxidation on the surface of PDMS was confirmed by the examinations of Fourier transform infrared spectrometry (FTIR), contact angle of water drop and X-ray photoelectron spectroscopy (XPS). The hydrophobic surface of pristine PDMS was not only changed to hydrophilic, but also formed wrinkles on it after chemical modification. Bilayer systems, stiff oxidized PDMS layers were capped on soft PDMS foundations, would generate easily compressive stresses due to the large difference in volumetric contraction rates and led to form wrinkles on the surface. Experimental results demonstrated the periodicity of wrinkles was controllable by controlling the duration of oxidation. Therefore, wrinkles could be arranged orderly by the guidance of external forces before oxidization. The potential technology for generating and ordering wrinkles on the PDMS surface is valuable in the applications of pressure sensors, biology, micro-optics and nano-/micro-fabrication in the future.     

Surface modification of polyester to produce a bacterial cellulose-based vascular prosthetic device

The surface of medical grade polyesters was modified to impart hydrophilic character for attachment to bacterial synthesized cellulose to produce a vascular prosthetic device. The polyesters were treated with UV/ozone, air plasma, and nitrogen plasma for various lengths of time. The unmodified and modified surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and advancing contact angle measurements. The surfaces were then coated with bacterial produced cellulose to study adhesion properties through tensile testing (peel testing). UV/ozone and plasma treatment XPS results indicated an increase in the oxygen concentration in the form of CO(H) on the treated polyester surfaces. The treatment time to reach steady state in the case of air and nitrogen plasmas took the order of seconds, while 7 min and longer were required for UV/ozone treatment. Peel strength tests to measure adhesion of modified polyester to cellulose reached their maximum values when the CO(H) concentrations were at the highest level. It was also at this level that the contact angle measurements showed no further decrease.