光学活性N-邻噁唑啉苯基甲基丙烯酰胺聚合物的合成及其手性光学性质

在三氟甲磺酸稀土盐(Ln(OTf)3,Ln=La,Nd,Sm,Y)的存在下,光学纯N-邻唑啉苯基甲基丙烯酰胺((S)-MeOPMAM)经自由基聚合反应得到相应的光学活性聚合物.考察了稀土盐种类、用量及溶剂性质等因素对聚合反应立体化学的影响.研究发现,以Y(OTf)3为调节剂、正丁醇为溶剂的体系能在一定程度上提高聚合反应的全同立体定向性.聚合物的手性光学性质明显依赖于立构规整度,随全同含量增大,聚合物的比旋光度和π-π*电子跃迁区域的Cotton效应强度呈下降趋势.利用1H-NMR技术研究了上述聚合物与1,1′-联-2-萘酚(BINOL)的对映选择性相互作用,结果表明,全同三元组含量较高的聚合物不仅使酚羟基质子峰向低场位移,而且导致信号分裂.     

DETECTION OF ACTIVE RADICALS FORMED DURING THE SONOLYSIS OF POLYMERS

Active radicals formed during the sonolysis of PVK (polyvinyl carbazole) and PMMA (polymethylmethacrylate) have been studied with the combination of spin thepping technique and ESR spectroscopy-The results show that: 1. For PVK, radicals CA and--CH_2--CH--are produced during the ultrasonic irradiationand only the later can be trapped by MNP. 2. For PMMA, radicals --C and --CH_2 are grnerated by sonolysis and both can be trappedby ND.     

氢化丁腈橡胶/聚甲基丙烯酸镁/有机蒙脱土纳米复合材料制备及其耐介质老化性能

采用原位聚合和混炼插层相结合技术制备了氢化丁腈橡胶/聚甲基丙烯酸镁/有机蒙脱土(HNBR/PMgMA/OMT)纳米复合材料,通过XRD,SEM和TEM等测试方法研究了HNBR/PMgMA/OMT纳米复合材料的结构、形态和性能.PMgMA离子簇与未反应完全的MgMA单体形成纳米-微米共存形态结构,PMgMA对HNBR有显著的增强效果,HNBR/PMgMA/OMT纳米复合材料具有良好的加工性能、物理机械性能和耐介质老化性能.TEM结果显示MgMA/OMT并用有助于OMT剥离分散,有机蒙脱土在硫化胶中形成以剥离和插层为主、反插层和未插层共存的微观结构;SEM显示当MgMA/OMT用量为20/10份时能明显改善复合材料的界面结合,此时纳米复合材料的拉伸强度、扯断伸长率和扯断永久变形分别为30.2 MPa,520%和30%;同时具有优异的耐热空气和耐油老化性能,耐热水性能也明显改善,在165℃的热空气、水和油中长期老化14天的老化系数分别达到0.61,0.63和0.84,其耐介质老化性能明显好于炭黑增强HNBR硫化胶及HNBR/PMgMA复合材料.良好的蒙脱土片层分散结构是提高HNBR/PMgMA/OMT纳米复合材料耐介质老化性能的主要原因.     

PHYTOCHROME INTERMEDIATES IN VIVO–II. CHARACTERISATION OF INTERMEDIATES BY DIFFERENCE SPECTROPHOTOMETRY

Abstract— In epicotyl tissue of Pisum , irradiation of P_r at – 196°C forms a stable product P₆₉₈, whereas P_fr forms a stable product P₆₅₀. On warming P₆₉₈, dark transformation to P_r predominates. On warming P₆₅₀ to – 70°C an intermediate P₆₉₀ is formed which bleaches on further warming to –10°C. When tissue is cooled to –196°C during actinic irradiation, difference spectra for subsequent warming to –10°C indicate that P_r, P_fr and an intermediate P₇₁₀ are formed from weakly absorbing intermediates. Complete photoconversion of P_r to P_fr is not possible at temperatures below –5°C. As the temperature is reduced, the amount of P_fr produced from P_r decreases, while P₇₁₀ increases. P₇₁₀ can be photoconverted at –20°C and above, ultimately forming P_r, but in contrast to P_fr it is not photoconvertible at –196°C.     

SYNTHESIS OF ACTIVE ACRYLIC ESTERS OF 8-HYDROXYQUINOLINE AND IMMOBILIZATION OF PROTEINS WITH THEIR POLYMERS

Active esters, 8-acryloyloxyquinoline (AQ) and 8--methacryloyloxyquinoline (MAQ) were synthe-sized and characterized. It was found that polymers of these two monomers can react with nucleophilicreagents such as amines or alcohols under mildcondition. The ammonolysis yield of P(AQ) for aliphaticamines were above 60% and the specific activity of the immobilized glucoamylase on P(AQ) andP(MAQ) was 5328 u/g and 4320 u/g, respectively.     

氯乙烯在高聚物中的溶解度

本文进行了氯乙烯在氯相/高聚物 (PVC,EVA,EVA-g-VC) 间相平衡的研究。实验数据用三种数学模型作了处理:Flory-Huggins 经典模型、Prigogine-Flory 自由容积模型和本文作者提出的线性模型。氯乙烯在高聚物中的溶解度按三种模型的计算值与实验结果都符合得很好。而且,结果表明,线性模型具有精确易用的优点,Prigogine-Flory 模型完全适用于 VC/PVC体系,VC在EVA-g-VC接枝共聚树脂中的溶解度服从加和性规律。     

PRIMARY INTERMEDIATES IN THE PULSED IRRADIATION OF RETINOIDS

Abstract Laser flash photolysis and pulse radiolysis have led to the characterisation of several shortlived intermediates formed after irradiation of retinoic acid and retinyl acetate in hexane or methanol. For retinoic acid, the triplet state, wavelength maximum 440 nm, extinction coefficient 7.3 × 10⁴ dm³ mol^?1 cm^?1, decay constant 6.2 × 10⁵ s^?1, is formed with a quantum yield of 0.012 for 347 nm excitation. The radical cation, absorption maximum 590 nm, extinction coefficient ～7 × 10⁴ dm³mol^?1 cm^?1, is formed in a biphotonic process. The radical anion, absorption maximum 510nm in hexane, 480 nm in methanol where its extinction coefficient is 1.2 × 10⁵ dm³mol^?1 cm^?1, appears to decay partially in methanol into another longer-lived neutral radical, wavelength maximum 420 nm, by loss of OH^?. For retinyl acetate, the triplet state, absorption maximum 395 nm, extinction coefficient 7.9 × 10⁴dm³mol^?1 cm^?1, decay constant 1.2 × 10⁶s^?1 is formed with a quantum yield of 0.025 for 347 nm excitation. Monophotonic photoelimination of OCOCH₃? in methanol produces the retinylic carbenium ion, wavelength maximum 590 nm, whose decay is enhanced by ammonia, k ～ 2 × 10⁶ dm³ mol^?1 s^?1 and retarded by water. The radical cation also has a wavelength maximum at 590 nm, its extinction coefficient being ～ 1.0 × 10⁵ dm³mol¹ cm^?1. The long-lived transient absorption with maximum at 385 nm, extinction coefficient 1.0 × 10⁵ dm³mol^?1 cm^?1, obtained from the reaction of the solvated electron with retinyl acetate in methanol may be due to either the radical anion itself or more likely the radical resulting from elimination of OCOCH₃? from this anion. These results suggest that skin photosensitivity caused by retinyl acetate might be greater than that due to retinoic acid.     

SYNTHESIS OF POLYMERS WITH AMINO END GROUPS BY ATOM TRANSFER RADICAL POLYMERIZATION

Atom Transfer Radical Polymerization (ATRP) is a controlled radical polymerization process that produces polymers with predictable molecular weights, narrow polydispersities, and well-defined halogen end groups. The key factor in the control of the polymerization process is the presence of a metal/ligand complex that provides a fast, reversible activation and deactivation of the growing polymer chains. The ligands, used to complex the metal are mostly tertiary amino compounds. However, amines can interact with the halogen end groups of the initiator molecules or of the growing chains. Our investigations concern-ing this issue indicate that under the experimental conditions used during the polymerization process, interactions of end groups with tertiary amines are negligible. Ammonia and primary amines, e.g., n-butylamine, however can react with the halogen end groups. Moreover, after the polymerization reaction they can be used as nucleophilic agents to replace the halogens by other functional end groups. The use of difunctional molecules such as ethanolamine leads to the incorporation of alcohol end groups at the chain ends.     

END GROUP TRANSFORMATION OF POLYMERS PREPARED BY ATRP,SUBSTITUTION TO AZIDES

Polystyrenes, polyacrylates and poly(methyl methacrylate) prepared by atom transfer radical polymerization (ATRP) have predictable molecular weights, low polydispersities and well-defined halogen end groups. The halogen end groups have been substituted by other functionalities such as azides and amines. In order to predict the feasibility and selectivity of nucleophilic substitution reactions, the reactivities of the end groups of the different polymers were studied. First, model studies with benzyl halide (BzX), 1-phenylethyl halide (1-PEX), methyl 2-halopropionate (MXP), ethyl 2-bromoisobutyrate (EBiB) and 2-halopropionitrile (2-XPN) were performed. The models compounds were dissolved in DMF and after adding sodium azide (1.1 eq.), the reaction mixtures were stirred at 25°C. The relative magnitude of the rate constants for the reactions with the chlorinated substrates were found to be BzCl > MClP > 1-PECl ≈ 2-ClPN:22 > 6 > 1. Increased substitution at the carbon center decreased the rate of reaction, benzyl chloride reacted 22 times faster than 1-phenylethyl chloride. The brominated substrates reacted very fast. The rate constant of 1-PEBr, determined by competition experiments, was 4.5 times higher than the rate constant of benzyl chloride. Based on these results, the bromine end groups of different polymers were substituted under reaction conditions simular to those used for the model reactions. The end-functionalized polymers were characterized by ¹H-NMR, IR and MALDI-TOFMS.     

SYNTHESIS AND CHARACTERIZATIONS OF NEAR INFRARED ABSORBING POLYMERS

A series of near infrared (NIR) absorbing dinuclear ruthenium dicarbonylhydrazine complexes (DCH-Ru),[{Ru(bpy)_2)_2μ-DCH]~(n ) (where bpy = 2,2'-bipyridinc and n = 2, 3 or 4), were prepared. The DCH-Ru complexes areelectrochromic in the NIR region with a high absorption coefficient at 1550-1600 nm typically over 10000 M~(-1)cm~(-1). DCH-Ru complex polymers with good NIR electrochromic properties were also obtained and processed to make a device foroptical attenuation at a wavelength of 1550 nm. The potential of these DCH-Ru polymers for use in a variable opticalattenuator has been demonstrated with an attenuating power at the 1550-nm telecommunication wavelength over 7.0 dB permicron of polymer film thickness. Other classes of NIR active materials are the pentacenediquinones and the correspondingpoly(ether pentacenediquinone)s. These polymers can be electrochemically reduced to the corresponding semiquinone(radical anion) having NIR absorption within a telecom window (e. g., 1310 nm).     

ROLE OF SYNTHETIC ANTIOXIDANTS ON THE AGING PROPERTY OF ELECTRON BEAM IRRADIATED NATURAL RUBBER

The aging property of radiation vulcanized natural rubber was studied using various kinds of antioxidants. Aging test was done at 100℃ for various lengths of time. It was found that some antioxidants are excellent in preventing the oxidative degradation of the irradiated rubber. DAH (2,5-di-tert-amylhydroquinone) CBP (2,2‘-dihydroxy-3,3‘-di(-methylcyclohexyl)-5,5‘-dimethyl diphenyl methane) P16 (tris(2,4-di-tert-butylphenyl)phosphate) in a proportion of (1:0.5:0.5) was found to be the best combination to achieve 100% retention of tensile strength.     

光致变色液晶聚合物的光致再取向性能研究进展

光致变色分子经掺杂或键合作用嵌在液晶聚合物中可形成光致变色液晶聚合物,在线性偏振光或非偏振光的照射下,此物质中光致变色分子的构型变化会引起整个液晶分子的二维或三维光致再取向的形成,本文综述了光致变色液晶聚合物的光致再取向的近期研究进展.     

吩噻嗪和吩噁嗪氧化中间体的共振喇曼光谱研究

本文对吩噻嗪和吩噁嗪的单电子氧化产生的两种氧化态的亚稳态正离子进行了共振喇曼光谱研究。随着吩噻嗪的p电子逐步失去,结构变形振动δ_(CNC)和δ_(CSC)的喇曼频移显著地增大,环C=C伸缩振动区域的喇曼峰数目明显变多。由此推断,随着吩噻嗪正离子氧化态的增高,正离子转变成平面共轭结构。     

COMPLEXATION OF METAL IONS WITH 3,5-DI-TERT-BUTYL-1,2-BENZOQUINONE-1-MONOOXIME,ESR STUDIES OF RADICAL INTERMEDIATES

Abstract

The possibility of chelate formation of 3,5-di-terf-butyl-o-benzoquinone-1-monooxime with Cu(II), Co(II), Ni(II), Mn(II), Pd(II) metal ions under N₂ and in air have been investigated. It was found that complexation of metals except Cu(II) and Mn(II) was accompanied by formation of various stable radical species under air. The complexation of Co(II) even under N₂ unlike other metal ions, results in the formation of very stable radical species, which are assigned to phenazinyl type radical. ESR examination of reduction of bis(3,5-di-tert-butyl-o-benzoquinone-1-monooximato)M(II) (M = Cu, Pd) with triarylphosphines P(C₆H₄ X)₃ (X = H, m-Cl, m-CH₃, p-Et₂N) reveal the formation of the N-(2′-hydroxy-3,5-di-tertbutylphenyl)-4′,6′-di-tertbutyl-o-benzosemiquinone iminate radical. Finally, ESR spectra of Cu(II), Ni(II), and Mn(II) complexes at 300 and 130 K, as well as reaction of bis(oximato)Ni(II) with PPh₃ have been studied.     

氧负离子聚合在超支化聚合物合成中的应用

近年来,氧负离子聚合得到较快发展,单体种类已经由酯基的β位上含有供电性杂原子的甲基丙烯酸酯类扩展到环氧类、甲基丙烯酸羟酯类单体.氧负离子引发这两类单体聚合,可以得到新型结构的超支化聚合物.对氧负离子引发合成超支化聚合物的机理及其应用进行了综述.     

SYNTHESIS OF POLYMERS WITH PHOSPHONIUM END GROUPS BY ATOM TRANSFER RADICAL POLYMERIZATION

The end groups of polymers prepared by atom transfer radical polymerization (ATRP), are well-defined and determined by the initiator used, at least one of them is a halogen end group. The halogen end groups can be transformed to other functionalities such as phosphonium salts as demonstrated in this paper. Kinetic studies with the compounds 1-phenylethyl bromide and methyl 2-bromopropionate, models for the polystyrene and polyacrylate chain ends respectively, indicated that bromine end groups were readily transformed to phosphonium end groups upon the addition of phosphines. Stability tests with the obtained phosphonium salts showed that 1-phenylethyl trialkylphosphonium bromide was stable, even at higher temperatures and in the presence of free phosphines. The stability of the propionate analogue was limited due to the presence of the ester group in the molecule. Polystyrene and poly(methyl acrylate) phosphonium salts were synthesized and the presence of the end groups was demonstrated by ¹H NMR and ESI-MS or MALDI-TOFMS.     

聚合物片晶中链折叠模型的对称性讨论

本文从对称的观点讨论了在聚合物片晶中链折叠的问题.提出只有当分子链在折向相反方向后对称性不改变时,近邻规整折叠才是可能的.它是近邻折叠的必要条件.根据折叠时“对称性不变”这一论点,可以预言分子链近邻规整折叠的可能性及可能的折叠方向.     

高聚物高压下的状态方程

本文从高分子体系内分子链间相互作用能出发,得到了一个描述高聚物高压下的等温状态方程 从实验中发现n、m为普适常数,n=6.14,m=1,16.在不存在转变的情况下,该方程对处于玻璃态、结晶态及液态高聚物体系均适用.     

APPLICATION OF TIME-RESOLVED DIFFUSE REFLECTANCE TECHNIQUES IN STUDIES OF REACTION INTERMEDIATES IN SUSPENSIONS OF BACILLUS SUBTILIS

Short lived reaction intermediates such as triplet states and free radicals can be detected in vivo using laser photolysis techniques with time-resolved diffuse reflectance detection. This novel approach is illustrated for bacterial suspensions of Bacillus subtilis.     

RADICAL INTERMEDIATES IN THE FLUORESCEIN-AND EOSIN-PHOTOSENSITIZED AUTOXIDATION OF l-TYROSINE*

Abstract The Primary reactions of the cosin-and fluorescein-photosensitized autoxidation of L-tyrosine were studied in aqueous media (pH = 8.6) by the flash-photolysis technique. The dye molecules were quantitatively converted to their triplet states in a single flash. The triplet dye molecules were found to react with tyrosine or oxygen. Ground state or radical dye molecules were formed in these reactions. Some 40 per cent of the triplet-tyrosine reactions yielded radicals, in triplet dye-oxygen reactions the corresponding yield was less than 10 per cent. The ground state dye was regenerated from the semireduced dye in reactions with oxygen and from the semioxidized dye in reactions with tyrosine. In the absence of oxygen the radicals formed in the photoinduced electron-transfer between the triplet dye and tyrosine recombined to a large extent.