无皂阳离子MMA/HEMA胶乳粒子的制备及表征

讨论了微波辐照下带正电荷的自由基引发剂偶氮二异丁基脒盐酸盐 (AIBA)引发甲基丙烯酸甲酯(MMA)和甲基丙烯酸 2 羟乙酯 (HEMA)共聚 ,用透射电子显微镜、红外光谱仪、差热分析仪等对聚合产物进行表征 .结果表明 :两种单体发生了共聚反应 ,制得均分散、表面洁净的无皂阳离子胶乳粒子 ;粒子的粒径随着单体HEMA浓度的增加先减小后增加 .在微波辐照下共聚反应的速率非常快 ,几乎所有的反应在 2 0min之内就能完成 .随着单体HEMA浓度的增加 ,乳液抗电解质稳定性提高     

微模塑法制备PMMA/SiO2二氧化硅杂化材料微结构

以摩尔比为 1∶1的甲基丙烯酸甲酯 (MMA)、甲基丙烯酸 (3 三乙氧基硅烷基 )丙酯 (ESMA)单体、0 .2 %(单体总量的质量分数 )的偶氮二异丁腈AIBN引发剂和四氢呋喃 (THF)溶剂 ,及 2 0 % (总质量分数 )的正硅酸乙酯TEOS合成出PMMA/SiO2 有机 无机杂化的杂化溶胶 .将溶胶在洗净的普通光学玻璃基片表面甩膜 .利用软刻蚀中的微模塑法 ,把有机硅弹性印章复制有精细图纹一面轻放在杂化溶胶膜上进行微模塑 ,外加 1N压力于12 0℃下处理 2h使溶胶凝胶化 .印章剥离后在基片表面就形成了PMMA/SiO2 有机 无机杂化材料的微图纹结构 .从微图纹的光学显微镜照片可以看出微模塑方法制备杂化材料复制的图纹精细度高 ,操作简单易行 ,是一类比较理想的微细图纹结构加工的方法 .     

13C NMR方法研究聚甲基丙烯酸羟乙酯的立构序列分布

用C_o^oγ-射线辐照聚合方法,在20%(V/V)的乙醇溶液中成功地制备出了线性聚甲基丙烯酸羟乙酯。从在20MHz和35℃条件下获得的¹³CNMR光谱中,观察到该聚合物的二单元组、三单元组和五单元组单体序列分布。将所观察到的各类型碳的强度分布与通过柏努利统计模型所计算出的值进行比较,对各峰进行归了属。其结果表明,该聚合过程符合柏努利过程。用这种方法制备的聚甲基丙烯酸羟乙酯的三单元组规整度分别为:间规立构70.2%;杂规立构27.2%等规立构2.6%。     

多孔PMP聚合物薄膜微结构控制

将二氧化硅(SiO2)微球为模板材料分散在聚-4-甲基-1-戊烯(PMP)溶液中,通过对流自组装方法将其涂覆于基片上,经过热致相分离(TIPS)过程形成含SiO2微球模板的PMP薄膜,然后通过氢氟酸(HF)溶液腐蚀除去SiO2微球,获得了具有规则多孔结构的PMP聚合物薄膜。采用扫描电子显微镜(SEM)对含SiO2微球的PMP薄膜以及除去SiO2微球后的PMP多孔薄膜的微结构进行了表征。研究结果表明:SiO2微球在聚合物中呈有序排列,腐蚀除去SiO2微球后PMP薄膜有效复制了SiO2微球形成的有序结构,形成了有序多孔PMP薄膜。     

稀土/高分子杂化发光材料的研究

用SiO2为无机组份和以与SiO2具有相似折射率和优良力学性能的丙烯酸类如甲基丙烯酸甲酯（MMA）和甲基丙烯酸羟乙酯（HEMA），在交联剂3－（三甲氧基硅）丙基甲基丙烯酸酯（MSMA）存在下，快速制备了两种杂化基质材料SiO2/P(MMA-MSMA)和SiO2/P(HEMA-MSMA)。分别以盐酸和六次甲基四胺作为酸性催化剂和碱性催化剂，建立了快速制备透明凝胶的两步溶胶－凝胶法，大大缩短了溶胶的成胶时间，所得杂化材料具有良好的光学透明性，利用此方法制备了掺杂稀土配合物的多种发光杂化材料。采用组装的方法，得到了稀土配合物与层次化合物α－磷酸氢锆（α－ZrP)及中孔分子筛材料MCM－41的组装体，并对所制备的杂化材料进行了表征。另外，将稀土配合物通过共价键嫁接于无机SiO2基质中，得到了含有稀土配合物的分子杂化材料。     

聚甲基丙烯酸甲酯光子晶体的生长和结构分析

金属/半导体基光子晶体有重大的国防应用价值,其生长技术的核心是设计合适的方法将聚甲基丙烯酯甲酯(PMMA)微球组装成光子晶体。在目前垂直沉积法的基础上,通过控制甲基丙烯酸甲酯(MMA)和偶氮引发剂的反应,使用等温蒸发工艺开发了光子晶体的可控垂直沉积(CVD)技术。实验合成了高度单分散的PMMA微球,并将PMMA微球组装成了光子晶体;对试样进行扫描电镜研究发现,晶体内部排列有序度很高,表面层很完美平整,在3μm×5μm的有序区内仅有两个点缺陷;使用直径分别为294nm和345nm的PMMA微球,沉积出具有规则的周期性密堆积结构的光子晶体,试样的完美有序区范围在20μm以上。实验发现,在可控垂直沉积法的晶体生长过程中,光子晶体的生长方式为连续生长,生长界面为粗造界面。     

微乳液法SiO2/罗丹明B荧光杂化纳米微球的制备与表征

在甲苯存在下的反相微乳液体系中,将γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)与罗丹明B进行预反应;再与正硅酸乙酯( TEOS)经原位溶胶-凝胶反应,制备SiO2/罗丹明B荧光杂化纳米微球.通过FTIR、UV-Vis、TEM、TG和光致发光谱对杂化纳米微球进行了表征.结果表明:罗丹明B与KH560间通过酯基形成化学键...     

乳化剂组成与压力对中空聚合物微球的影响

 在高温高压下,以单分散的P(St-MAA)为种子微球,采用碱/冷却法制备了P(St-MAA)中空聚合物微球。研究了乳化剂 (Tween-80和Span-80) 组成对P(St-MAA)种子微球的影响和压力对其形成中空结构的影响。扫描电子显微镜、透射电子显微镜等测试分析表明,乳化剂组成对种子微球的分散性影响明显：P（St-MAA)粒子的单分散性随着Tween-80含量的增加而逐渐变好。当单体St与MAA质量比一定时,乳化剂Tween-80与Span-80的质量比为3∶1时,可得到制备中空微球必需的单分散P(St-MAA)种子微球;种子微球经高温高压处理后,可形成平均壁厚为50 nm的单分散中空聚合物微球。     

甲基丙烯酸甲酯-丙烯酸乙酯辐射共聚物的NMR研究

用¹H NMR,¹³C NMR,DEPT,gHMBC 和gHSQC 等一维、二维谱研究了γ 射线辐射引发聚合的甲基丙烯酸甲酯(MMA)与丙烯酸乙酯(EA)共聚物的微观化学结构并作了归属．结果表明二种单体的聚合转化率都较高,共聚物中MMA含量略多一些．由羰基碳的共振信号测得的共聚物中单体链节的三元组含量表明,在共聚物主链结构以嵌段分布为主,这是由于MMA与EA的竟聚率差异所致．     

红外光谱法测定固相微萃取新型吸附质中单体的摩尔比

以丙烯酸丁酯和苯乙烯为单体 ,过氧化苯甲酰为引发剂 (用量为wt 0 3% ) ,醋酸丁酯和甲苯作混合溶剂 ,溶剂用量与单体混合物的体积相同 ,采用溶液聚合的方法合成了一种新型固相微萃取吸附质 (苯乙烯 丙烯酸丁酯共聚物 )。以朗伯 比耳定律为依据 ,通过一系列的推导过程 ,得出了共聚物中两种官能团的吸收值比与共聚物中两种单体摩尔比的线性关系式A1 /A2 =kn1 /n2 。采用红外光谱法测定聚合物中两种官能团的吸收值比 ,再通过外标曲线法确定了共聚物中两种官能团的吸收值比 (y)与共聚物中两种单体的摩尔比 (x)的线性回归方程 y =0 136 2 0 0 84 1x。方法的精密度RSD(% ) =2 4 6 4 ,方法的回收率为 92 89%～10 3 94 %。红外光谱法测定作为固相微萃取新型吸附质的苯乙烯与丙烯酸丁酯共聚物中单体的摩尔比是一种快速准确的分析方法     

Opto-acoustic study of tinuvin-P and rhodamine 6G in solid polymeric matrices

Laser-induced opto-acoustic calorimetry has been used to examine the thermo-elastic properties of two polymer matrices doped with tinuvin-P and the radiation-less decay processes of rhodamine 6G (Rh6G) in them. The matrices assayed were methyl methacrylate (MMA) homopolymers P(MMA), and methyl methacrylate and 2-hydroxyethyl methacrylate (HEMA) copolymers P(MMA:HEMA). A slight difference in the thermo-elastic properties of the polymers, namely their adiabatic expansion coefficients, has been detected and found to correlate with the long-term stability of the laser material. This suggests a key role of the heat-dissipation processes in the photostability of these polymeric materials. On the other hand, the fluorescence quantum yield of Rh6G is shown to vary with the polymer-matrix composition in a way consistent with its lasing efficiency. The Rh6G absorption and fluorescence quantum yield also change dramatically upon increasing its concentration, which suggests the co-existence of different Rh6G forms with different photophysical properties. Received: 10 February 2000 / Revised version: 12 June 2000 / Published online: 10 January 2001     

Highly efficient and photostable solid-state dye lasers based on modified copolymers doped with PM567

Solid-state dye samples based on modified copolymers of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) with methanol doped with PM567 were first prepared. The volume proportions of methanol have great effects on the laser's characteristics including spectra, lasing output and thermal properties. The highest slope efficiency of 64.25% was achieved in the sample MP (MMA:HEMA = 85:15 + 10% methanol). Pumping the samples at a repetition rate of 5 Hz with a pulse energy as high as 100 mJ (the fluence was 0.26 J/cm²), the maximum lifetime of 278,000 shots was obtained in the sample MP (MMA:HEMA = 85:15 + 15% methanol), and the corresponding normalized photostability reached 180.7 GJ/mol. The obtained ten-shots damage thresholds were as high as 6.7 J/cm². The results indicate that the laser properties of solid-state dyes can be greatly enhanced by using modified copolymers of MMA and HEMA with methanol as solid hosts.     

Photophysical characterization of pyrromethene 597 laser dye in silicon-containing organic matrices

Samples of dipyrromethene-BF₂ dye PM597 incorporated in copolymers of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) with methyl methacrylate (MMA) and 2-hydroxyethylmethacrylate (HEMA), and in terpolymers of MMA, HEMA and TMSPMA are characterized. The absorption cross-section spectra, stimulated emission cross-section spectra, and the excited-state absorption cross-section at 527 nm are determined. The fluorescence quantum distributions and fluorescence lifetimes are measured. The photo-degradation is studied under cw laser excitation conditions and quantum yields of photo-degradation are extracted. PM597 solid state samples are compared with PM597 in liquid ethyl acetate solution. The fluorescence quantum yield of PM597 is higher in doped samples (around 70%) compared to PM597 in ethyl acetate (43%). The excited-state absorption cross-section was found to be negligibly small. The photo-stability is considerably larger in the polymeric samples compared to the liquid solutions. PACS 42.55.-f; 78.45.+h; 78.55.-m; 78.40.Me     

Laser Performance of Some Oxazole Laser Dyes in Restricted Matrices

This article reports the optical properties such as absorption profile, molar absorptivity, fluorescence profile and photo-physical parameters such as dipole moment, oscillator strength, fluorescence quantum yields, fluorescence lifetimes, laser performance and finally photostability of 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBOT),1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOB), 5-diphenyel-oxazole (PPO) laser dyes in different restricted hosts. (BBOT), (POPOB) and (PPO) are embedded in transparent silica-based nanoporous sol-gel glass and copolymer matrix of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). The absorption and fluorescence properties of these laser dyes in sol-gel glass matrices are compared with their respective properties in copolymer host. In case of sol-gel matrix, all dyes had higher quantum yields as well as lasing wavelength maxima. The laser performances as well as the photostability of these laser dyes in sol-gel glass displayed senior behavior compared with (MMA/ HEMA) copolymer samples upon using nitrogen laser (337.1 nm) as pumping energy.     

Time-resolved thermal lens study on the heat dissipation effects in solid polymeric matrices used as laser dyes

A dual-beam pulsed-laser time-resolved thermal lens (TRTL) has been used to study the heat dissipation effects in solid polymers employed as laser dyes. The laser-dye samples studied are polymer solutions of rhodamine 6G (Rh6G), namely homopolymers of methyl methacrylate (MMA) and copolymers of methyl methacrylate and 2-hydroxyethyl methacrylate (HEMA) with MMA:HEMA compositions 1:1 and 7:3 vol./vol., where the dye is either dissolved or modified and copolymerized with methacrylate monomers. The long-term stability of the laser material is independent of the thermal diffusivity of the samples, as determined by the TRTL technique. This suggests that the rate of heat dissipation does not play a major role in the photostability of the samples. In contrast, the TRTL experiments have revealed permanent changes in the optical properties of the polymers when subjected to a large number of laser pulses. This is explained in terms of permanent plastic deformation of the matrices. Received: 19 June 2002 / Revised version: 1 August 2002 / Published online: 15 November 2002 RID="*" ID="*"Dedicated to Prof. S.E. Braslavsky on the occasion of her 60th birthday. This work was presented at the V Congreso de Fotoquímica, Torremolinos, Spain, 2001 RID="**" ID="**"Corresponding author. Fax: +34-93/205-6266, E-mail: s.nonell@iqs.es     

The Effect of Cross‐Linking on the Actuation of an Electroactive IPMC Prepared with a Fluorinated Acrylic Copolymer

The hydroxyl group of HEMA was cross‐linked with 1,3‐diethoxy‐1,1,3,3‐tetramethyldisiloxane in order to enhance the actuation force of the ionic polymer‐metal composite (IPMC) made from the acrylic ter‐polymer of fluoroalkyl methacrylate, 2‐acylamido‐2‐methyl‐1‐propanesulfonic acid, and 2‐hydroxyethyl methacrylate (HEMA). The water uptake was reduced and the mechanical strengths of the membrane were improved by the cross‐linkage. The actuation force of the IPMC was generally enhanced, although it was reduced somewhat at high levels of cross‐linking. The current and deformation responses of the IPMC were both decreased by cross‐linking.     

Spectroscopic properties and amplified spontaneous emission of a new derivative of fluorescein

The new laser dye, 2-(6-acryloyloxy-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester [AOXBE] has been synthesized. Its chemical structure was confirmed by ¹HNMR, IR, MS and elemental analysis. This new dye was covalently bonded with methyl methacrylate (MMA) and 2-hydroxy ethyl-methacrylate (HEMA) copolymer backbone. Its optical properties were experimentally investigated. Amplified spontaneous emission (ASE) and photostability were studied by pumping the dye polymeric sample with a 355 nm (8 ns) pulsed Nd:YAG laser. PACS 42.55.Mv; 42.70.Hj; 42.70.Jk; 42.55.Px     

Photo-physical properties and amplified spontaneous emission of a new derivative of fluorescein

The synthesis of new high-performance dyes and the implementation of new ways of incorporating the organic molecules into the solid host matrices have produced a great deal of activity in the field of solid-state dye lasers. In this article, the new laser dye, 2-(6-allyl-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester [AXBE] has been synthesized, and its chemical structure was confirmed by ¹H NMR, ¹³C NMR, IR and elemental analysis. This new dye was covalently bonded with methyl methacrylate (MMA) and 2-hydroxy ethyl methacrylate (HEMA) copolymer backbone and evaluated as the active medium of the solid-state laser dye. Its optical properties were experimentally investigated. Amplified spontaneous emission (ASE) and photostability were studied by pumping the dye sample with 355 nm (8 ns) pulsed Nd-YAG laser.     

Environment effects on the lasing photostability of Rhodamine 6G incorporated into organic-inorganic hybrid materials

The effect on the lasing photostability of Rhodamine 6G (Rh6G), and the rigidity of a hybrid inorganic-organic matrix by controlled addition of di-, tri- and tetrafunctionalized alkoxides has been evaluated. The dye was incorporated into hybrid matrices of (2-hydroxyethyl methacrylate) (HEMA) or vol/vol copolymers of methyl methacrylate (MMA) and HEMA with different weight proportions of polycondensated dimethyldiethoxysilane (DEOS), methyltriethoxysilane (TRIEOS), and tetraethoxysilane (TEOS). The laser samples were transversaly pumped at 534 nm at 5.5 mJ/pulse and up to a 10 Hz repetition rate. The dependence of the laser photostability on organic-inorganic composition, pH of the medium, and thermal treatment of the samples was studied. Good stability, with a drop of the initial laser output of only 13% after 10000 pump pulses at 10 Hz in a thermally postcured (HEMA-15 wt%TRIEOS) matrix was obtained. Careful control of the synthesis process is required to reach the necessary photostability for a solid-state dye laser based on hybrid matrices to become competitive with liquid dye lasers. PACS 81.05.Lg; 81.05.Zx; 81.20.Fw; 42.55.Mv; 42.55.Rz; 42.60.Lh; 42.62.b; 42.70a; 42.70-Hj; 42.70.Jk     

Equivalent cross-relaxation rate imaging in the synthetic copolymer gels and invasive ductal carcinomas of the breast

The values of equivalent cross-relaxation rate (ECR) correlated well with [i] water conditions in various copolymer gels and [ii] nature of malignant cells with regard to nuclear dysplasia and mitotic potential in breast carcinomas. The synthetic copolymer gels composed of any two or three monomers among 2-hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), N-vinyl-2-pyrrolidinone (N-VP), methyl methacrylate (MMA) and benzyl methacrylate (BMA). The ECR measurement was performed by using an off-resonance saturation pulse under conventional field-echo imaging at frequency within +/- 75 ppm apart from the water resonance frequency. The ECR values were readily to determine and non-time consuming parameter for cross relaxation rate. The ECR values at the frequency offset by 7-ppm (ECR-7) were divided the sample gels two classes, which must correspond to hydrophilic or hydrophobic ones.The sensitivity in the gels was nearly equivalent to the cross-relaxation rate itself. In the breast carcinomas, the ECR-7 correlates with the nature of malignant cells with regard to nuclear dysplasia and mitotic potential. The ECR-7 is better or more accurate than the STR-7 because the SDNRs between carcinoma and glandular tissue increased by approximately 50% on the ECR-7 compared with the STR-7. Thus the ECR values could be a new parameter for malignancy and cell proliferative activity of the breast carcinomas with non-invasive modalities by magnetic resonance imaging.