臭氧改性及搅拌桨结构对大直径双层球制备的影响

随着高功率激光器的飞速发展,ICF物理实验对聚苯乙烯（PS）-聚乙烯醇（PVA）双层空心微球的规格要求逐渐提高,直径要求将达到700～900 m。针对该直径范围的PS-PVA双层空心微球,通过采用PS球臭氧化表面改性技术和搅拌桨叶轮结构优化技术,对传统乳液微封装法制备双层空心微球工艺进行了改进,臭氧化表面改性后PS固体核心发生憎水-亲水转变,提高了PS与PVA之间的作用强度;搅拌桨叶轮结构优化,改善了体系容器内溶液流场均匀性,使得微球在整个体系中的运动相对平稳,从而初步制得了直径范围在700～900 m的双层空心微球。     

非离子型表面活性剂Tween 20对大尺寸双层空心微球制备的影响

为了改善臭氧处理聚苯乙烯(PS)单层球与聚乙烯醇(PVA)溶液生成的双层乳粒在油相中的分散性,提高大尺寸双层球的成活率,在双层球制备过程中采用了非离子型表面活性剂Tween 20(T-20)来改性该种PS单层球。结果表明经表面活性剂T-20改性后显著降低了PS薄膜的亲水接触角,提高了PS与PVA间的相互作用,同时也大幅度提高了PS薄膜对PVA的吸附速率。红外光谱和紫外-可见分光光度计的测试结果证明:在PVA固化过程中,由于PVA与T-20的相比太大,PS表面吸附的表面活性剂T-20部分会被PVA置换、迁移至PVA溶液中。T-20的迁移提高了制备双层球过程中水相与外油相的粘度比且显著降低PVA溶液表面张力,从而有利于实现双重乳粒在油相中的单分散。因此,T-20是制备大尺寸PS-PVA双层空心微球有效的表面活性剂。     

离子型表面活性剂对双重乳粒分散性能的影响

为了改善臭氧处理PS单层球与PVA溶液生成的双重乳粒在油相中的分散性,采用了低分子量阴离子型表面活性剂十二烷基硫酸钠(SDS)和十二烷基苯磺酸钠(SDBS)及高分子量混合型表面活性剂十八烷基胺聚氧乙烯醚双季铵盐(PAVDA)来改性该种PS单层球,测试并分析了不同表面活性剂对相应薄膜亲水接触角及其对PVA吸附速率的影响,同时也考察并对比了静电排斥作用和空间位阻作用对双重乳粒分散性的影响。实验结果表明这三种表面活性剂均能不同程度的改善双重乳粒在油相中的分散性。其中,经SDS和SDBS处理后,双重乳粒在油相中固化时会发生絮凝作用而无法以较高成活率制得大尺寸双层球;经PAVDA处理PS单层球后,实现了以较高的成活率制得700~900μm的PS-PVA双层空心微球。同时,也表明在改善PS单层球的分散性方面,空间位阻稳定作用较静电排斥作用更为有效。     

Al纳米颗粒表面等离激元对ZnO光致发光增强的研究

基于聚苯乙烯球自组装法,在P型氮化镓(P-GaN)衬底上制备了有序致密的掩模板;采用热蒸发法在该模板上沉积金属Al薄膜,通过甲苯溶液去除聚苯乙烯球,得到了金属Al纳米颗粒阵列;采用原子层沉积法,在Al纳米颗粒阵列表面依次沉积氧化铝(Al_2O_3)和氧化锌(ZnO).通过测试Al纳米颗粒阵列的消光谱以及ZnO薄膜的光致发光谱,研究了Al纳米颗粒表面等离激元与ZnO薄膜激子之间的耦合效应.实验结果表明:引入Al纳米颗粒后,在约380 nm位置附近的ZnO近带边发光峰积分强度增强了1.91倍.对Al纳米颗粒表面等离激元增强ZnO光致发光的机理进行探讨.     

多层塑料微球的研制

2004年研究了PVA溶液的浓度对PS微球成活率的影响；并且通过O3处理，提高了PS微球球壳强度；并且还进行了内表面掺硫的多层塑料微球的研制；同时完成了二氧化硅气凝胶的增强和疏水改性研究。     

紫外/臭氧法PDMS表面亲水改性机理研究

紫外/臭氧改性法是一种操作简单、成本低廉的PDMS表面亲水改性方法。采用该方法对PDMS表面进行亲水改性,利用接触角测量仪对改性效果进行评价,并与PDMS无臭氧紫外法进行了比较。测试表明PDMS表面经紫外/臭氧法处理12小时后,表面接触角达到60°左右,在空气中放置两周后仍保持较好的亲水性。其改性机理可以通过多种表征手段进行分析。红外光谱测试可以看出,PDMS在经过紫外/臭氧改性后,其表面官能团变化明显,随改性时间延长,疏水基团—CH₃逐渐减少,亲水基团Si—OH和—OH逐步增加,二氧化硅典型红外光谱峰也同时出现。通过扫描电镜和能谱测试可以看出,PDMS表面经过改性产生了二氧化硅为主的硅的氧化物。综合上述结果,紫外/臭氧处理法能够使PDMS表面亲水基团增多,同时生成类玻璃态SiO_x薄层,既改善了PDMS表面的亲水性,又阻止了PDMS表面疏水性的完全恢复,亲水性可以长时间保持。     

表面增强拉曼光谱研究高分子共混物薄膜相结构

采用拉曼光谱法研究了由聚苯乙烯(PS)/聚甲基丙烯酸甲酯(PMMA)的四氢呋喃(THF)溶液在玻璃基板上旋转涂膜得到的共混物薄膜。应用显微共焦拉曼光谱,根据PS在1604,1585cm-1处苯环的伸缩振动峰和PMMA在1728cm-1处羰基的伸缩振动峰,可以确定薄膜(厚度约为800nm)表面海岛状相结构的组分分布信息。另外,还对210℃下PS/PMMA(30/70)共混物薄膜退火过程中表面的变化进行了分析。采用表面增强拉曼散射效应对高聚物的增强作用得到了薄膜(厚度约为400nm)的Raman光谱,并且成功地对其组成进行了分析。     

电容器薄膜等离子体表面改性实验研究

 建立了一套辉光放电等离子体对电容器薄膜进行表面处理的装置。采用N₂，O₂及Ar三种气体对聚丙烯、聚酯和聚苯硫醚膜进行了表面处理。红外光谱分析表明:薄膜表面的生成物与薄膜种类、气体种类和处理强度密切相关。场扫描电镜显示了薄膜表面的刻蚀现象明显。处理过的薄膜，非晶相被去除，球晶暴露。能谱分析说明了薄膜中C元素下降，N，O元素增加，但总体改变量很小。处理前后薄膜的直流击穿电压没有明显改变，但刻蚀过程造成的薄膜表面粗化可帮助电容器的浸渍过程更充分，从而可提高电容器的使用场强与储能密度。     

采用溶胶凝胶协同自组装方法制备SiO2反蛋白石结构薄膜及其光学性质研究

研究了溶胶凝胶协同自组装制备大面积高质量SiO₂反蛋白石结构薄膜的方法. 向单分散的聚苯乙烯(PS)胶体溶液中添加SiO₂前驱物溶液,用垂直自组装法一步得到微球空隙中均匀填充有凝胶的 复合PS胶体晶体薄膜,在空气中烧结去除PS后得到SiO₂反蛋白石结构薄膜.通过对添加前驱物溶液比例、 自组装温度以及烧结温度等参数的研究,用不同粒径的PS微球制备了不同孔径的高质量SiO₂反蛋白石结构薄膜. 用扫描电子显微镜和X射线能量色散谱仪对制备得到的薄膜样品进行显微形貌和成分表征,并测试了其透射光谱. 结果表明:溶胶凝胶协同自组装法制备的SiO₂反蛋白石结构薄膜大面积高度有序,孔径可以控制且选择范围宽; 薄膜的透射光谱带隙明显,带隙中心波长与理论计算结果相符.     

纳秒脉冲放电对聚对苯二甲酸乙二酯憎水改性

基于自主研制的ns脉冲电源(上升沿约70ns,脉宽约100ns)激励介质阻挡放电产生大气压低温等离子体,在CF4气氛下对聚对苯二甲酸乙二酯(PET)表面进行了憎水改性处理,测量了改性前后的薄膜表面的水接触角,给出了CF4气流量、放电电压、处理时间和CF4比例等参数对改性效果的影响规律。结果表明,大气压ns脉冲DBD表面处理能够实现PET材料的憎水性,改性后的PET表面水接触角由66°提高到最大100°。     

多孔硅的表面碳膜钝化

报道对多孔硅（ＰＳ）进行碳膜（ＣＦ）钝化处理的结果。红外吸收光谱表明,经钝化处理样品的表面由Ｓｉ－Ｃ、Ｓｉ－Ｎ和Ｓｉ－Ｏ键所覆盖;荧光我谱表明,经钝化处理的样品较未处理的样品发光强度提高４￣４．５倍,且发光峰位明显蓝移;存放实验显示,经钝化处理的样品发光强度稳定、发光峰位不变。这些结果表明正丁胺可以在多孔硅表面形成优良的钝化碳膜,是一种十分有效的多孔硅后处理途径。     

Spectroscopic and antimicrobial studies of polystyrene films under air plasma and He-Ne laser treatment

Polystyrene (PS) films are used in packaging and biomedical applications because of their transparency and good environmental properties. The present investigation is centered on the antifungal and antibacterial activities involved in the film surface. Subsequently, microbial formations were immobilized on the modified PS films. Living microorganisms such as bacteria and yeast were used. Untreated PS films show very fast rate of growth of bacteria within few hours. The study involves developments of polymer surfaces with bacterial growth and further studies after giving antibacterial treatment such as plasma treatment. Major emphasis has been given to study the effect of various parameters which can affect the performance of the improved material. Films were prepared by two methods: plasma treatment under vacuum and under ongoing He-Ne laser source. The parameters such as (1) surface area by contact angle measurements, (2) quality of material before and after treatment by SEM and FTIR spectra and (3) material characterization by UV-vis spectra were studied. It was observed that plasma treatment of the PS material for different processing time improved the surface properties of PS films.      

Effect of the surface-modifying macromolecules on the duration of the surface functionalization

Functionalization of polystyrene films by the preferential surface enrichment of surface-modifying macromolecules (SMM) to achieve a hydrophilic surface with long effective duration is described. The comb-like amphiphilic copolymers (PKG-g-PS) based on styrene-maleic anhydride copolynier (SMA) backbone was synthesized by esterification of SMA with poly(ethylene glycol) (PEG). When PEG-g-PS was melt blended with polystyrene, the preferential surface enrichment of PEG-g-PS was much evident resulting in the large increase of the surface polarity. The effective duration of the surface functionalizatoin was also hugely extended as SMMs were added into the blends. Furthermore, more polyether chain segments on PEG-g-PS could selectively migrate to the surface by the inducement of polar solvent. Compared with the PEG-g-PS/PS and PEG/PEG-g-PS/PS blends, the surface polarity and the effective duration of surface modification both increased greatly when PEG-g-PS was used as the compatibilizer of PEG/PS blends. It was an effective solution to balance the conflict between the duration and efficiency of the surface-modifying additives.     

Retardation of enzymatic degradation of microbial polyesters using surface chemistry: effect of addition of non-degradable polymers

The effects of addition of non-degradable polymers on the rate of enzymatic erosion for the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] have been studied at 37 °C and pH 7.4 in the aqueous solution of an extracellular PHB depolymerase from Alcaligenes facalis. Polystyrene (PS) or poly(methyl methacrylate) (PMMA) was selected as a minor component (5 wt%) in a blend because of their non-enzymatic activity. Enzymatic degradation behaviors of the “as-cast” and “annealed” blend films were investigated using atomic force microscopy and weight loss measurements. Although the spherulites of P(3HB-co-3HV) cover all blend film surfaces throughout, the retardation of biodegradation in the P(3HB-co-3HV)/PS blend films was detected from morphological observation and weight loss measurement for both as-cast and annealed blend films while there was little difference between the P(3HB-co-3HV)/PMMA blend and pure P(3HB-co-3HV). Since the enzymatic degradation of P(3HB-co-3HV) initially occurs by a surface erosion process, these degradation behaviors were explained by the surface structure of blend films measured by X-ray photoelectron spectroscopy. The surface of P(3HB-co-3HV)/PS blend films revealed an excess of PS, whereas the surface of P(3HB-co-3HV)/PMMA blend films was nearly covered by P(3HB-co-3HV). It was concluded, therefore, that the PS, which exists within P(3HB-co-3HV) spherulites at surface acts as a retardant of enzymatic attack to the surface of the blend film.     

Surface free energy of films of alkali-treated cellulose microfibrils from banana rachis

Cellulose microfibrils extracted by various alkaline treatments of vascular bundles from banana rachis were used to elaborate films. The films were comparatively studied to determine changes in polarity induced by various treatments. Atomic force microscopy was used to characterize the surface morphology of the films and transmission electron microscopy was employed to characterize the microfibrils used to elaborate the films. Contact angles were measured to determine surface free energy (SFE) and thermogravimetric analyses were carried out to determine changes in composition of the films. The results showed that the films of cellulose microfibrils prepared by the peroxide alkaline (PA) and peroxide alkaline-hydrochloric acid (PA-HCl) treatments had lower content of non-cellulosic constituents like xylose and had lower SFE than films of microfibrils treated with KOH-5. Furthermore, specimens treated with the most concentrated KOH solution (18 wt%) and sodium chloride presented the highest SFE and polar component.     

Characterization of fluoroalkylsilane monolayer on polystyrene sphere arrays after plasma treatment

Polystyrene (PS) colloidal crystal films with well-ordered arrays of PS spheres treated with argon plasma and coated with fluoroalkylsilane (FAS) were characterized by means of spectroscopy ellipsometry, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). The XPS analysis indicated that the FAS film on the plasma treated PS surface was a monolayer with an orderly packed CF₃ group pointing outwards from the surface. The chemical composition of the PS surface changed immediately after a very short period of argon plasma treatment, while the subsequent coating of FAS on the plasma treated PS surface further modified the surface chemistry. The untreated PS surface exhibited poor interaction with FAS molecules. XPS and ToF-SIMS analyses showed the plasma treatment involved the oxidation of PS surface, where oxygen functional groups -O and O were generated, promoting FAS deposition on the plasma treated surface with strong secondary ion fragments originating from the FAS. The overall results indicated that plasma treatment was beneficial to the deposition of the FAS monolayer.     

Improving nucleation in the fabrication of high-quality 3D macro-porous copper film through the surface-modification of a polystyrene colloid-assembled template

A new approach is developed to the fabrication of high-quality three-dimensional macro-porous copper films. A highly-ordered macroporous copper film is successfully produced on a polystyrene sphere (PS) template that has been modified by sodium dodecyl sulfate (SDS). It is shown that this procedure can change a hydrophobic surface of PS template into a hydrophilic surface. The present study is devoted to the influence of the electrolyte solution transport on the nucleation process. It is demonstrated that the permeability of the electrolyte solution in the nanochannels of the PS template plays an important role in the chemical electrodeposition of high-quality macroporous copper film. The permeability is drastically enhanced in our experiment through the surface modification of the PS templates. The method could be used to homogeneously produce a large number of nucleations on a substrate, which is a key factor for the fabrication of the high-quality macroporous copper film.     

IR spectroscopic study of the effect of polymer nanofilm thickness on its surface density

The effect of the thickness (in the range 50–10,000 nm) of free-standing (separated from substrate) polystyrene (PS) films on their surface density was investigated by FTIR spectroscopy. For this, an approach has been employed for the first time than consists of analyzing the distortions of the IR band shape caused by anomalous dispersion of the refractive index in the vicinities of these bands. It was found that the surface density of PS films is halved as the film thickness changes from 1500 to 150 nm. The fact that the density starts to decrease in the micron range of film thickness rather than in the submicron range may suggest that there are important factors not taken into account by existing theoretical models for thin and ultrathin polymer films. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 63–67, January–February, 2008.     

Preparation and Surface Properties of Fluorinated Acrylates Copolymers

Copolymerization of acrylates and styrene (St) with perfluorooctylacyloxyethyl methacrylate (FA) monomer, prepared from the reaction of perfluorooctanoic acid and hydroxymethyl methacrylate, was carried out by solution polymerization. The fluorinated acrylate and St copolymers (PFA) were examined by GPC, FT-IR, and ¹H NMR. The surface tension of the PFA solution in N-methyl pyrrolidone was tested by the drop volume method. The results showed that the surface tension of the PFA solution decreased in exponential decay with increase of the PFA concentration, and the surface tension of the solution also decreased with increased addition of the FA monomer in the copolymer at the same concentration. Meanwhile, the adsorption of the PFA macromolecules in the air–solution interface increased and enrichment of the fluorinated segments on the solution surface occurred. The studies of the surface free energy, polarity, fluorine content, and morphology of the PFA films illustrated that the surface free energy and polarity of the PFA films were decreased with the augment of the FA monomer in the copolymers, and that the fluorine content and the surface roughness were increased. The surface free energy of the PFA film was as small as 16.6 mN·m^?1. The surface properties of the PFA copolymers obtained by one shot feed during polymerization were superior to those obtained by continuing feed procedure. More fluorine segregation occurred and induced the formation of a fluorine-enriched surface if the PFA copolymer was postheated. The posttreatment was thus beneficial to the improvement of the surface properties of the PFA film.