丙烯酰胺与4-乙烯基吡啶共聚物的季胺化及其若干性能

将丙烯酰胺 (AM)与 4 乙烯基吡啶 (4VP)的共聚物 (P(AM co 4VP) )用硫酸二甲酯季铵化 ,制备了系列吡啶季铵盐型阳离子丙烯酰胺共聚物 ,用FTIR、1 H NMR和紫外分光光度法表征了其分子结构与组成 ,并重点研究了其絮凝与缓蚀性 ,考察了阳离子度与分子量对其各种功能的影响 .研究结果表明 ,吡啶季铵盐型阳离子丙烯酰胺共聚物具有优良的絮凝 缓蚀等功能 ,且阳离子度越高 ,性能越好 ,而分子量对其性能亦有显著的影响 .     

丙烯酰胺与4-乙烯基吡啶共聚合反应竞聚率

测定了丙烯酰胺与4－乙烯基吡啶共聚反应的竞聚率。用紫外分光光度法测定了不同浓度的4－乙烯基吡啶均聚物的吸光度，从而求出在低转化率不同初始单体组成的共聚物中4－乙烯基吡啶含量。用FR和KT两种作图法及YBR计算法对单体的竞聚率进行计算和比较。结果表明：KT法和YBR法计算法较为准确，4－乙烯基吡啶的竞聚率和丙烯酰胺的竞聚率分别为γrVP=0.636,γAM=0.379。     

谷维素的分析

本文报导了在谷维素提取过程中应用紫外分光光度法的测定结果,并确定了比色方法以适应生产需要。此外还利用薄层层析、气相层析、光谱分析等方法测试谷维素成品的质量,包括组分及所含杂质。试验结果表明,比色法和紫外分光光度法的测定结果接近,能反映提取过程中成品和中间品的含量。谷维素成品的主要组分为24—亚甲基环木波罗醇阿魏酸酯、环木波罗烯醇阿魏酸酯、菜油甾醇阿魏酸酯等。成品中含有少量糠腊和无机物。     

蛇床子不同炮制品中的总黄酮含量测定

采用超声波提取法提取蛇床子不同炮制品中总黄酮,以芦丁为对照品,紫外分光光度法测定总黄酮的含量,标准曲线在2.1～11.0μg/mL范围内,吸光度与浓度的线性关系良好(R~2=0.999 7),实验的精密性和稳定性RSD分别为1.13%和2.15%,平均回收率为105.81%,RSD为2.98%。结果表明紫外分光光度法测定蛇床子不同炮制品中的总黄酮含量操作简便、结果准确、重现性好,实验方法切实可行。     

光度法测定压裂返排液中硼酸的含量

压裂施工完成后会产生大量的压裂返排液,将其简单处理后再次用于压裂液的配制,不仅可以节约处理废水的成本,还可以避免污染环境、浪费水资源。准确测定其中硼酸的含量,对消除返排液中硼酸的影响、成功重复利用返排液具有重要意义。实验探索了萃取-紫外分光光度法并筛选了关键的实验条件,其次还探索了姜黄素可见分光光度法。实验结果表明:两种方法都能够准确测定返排液中硼酸的含量,其中姜黄素可见分光光度法每次需配制新鲜的姜黄素-草酸溶液,需对水样除去钙镁且显色后还要离心处理;相比来说萃取-紫外分光光度法操作方法更简单,共存离子对测定结果的干扰更小。     

低吸光度差示分光光度法测定油品中的铁

将一新的低吸光度差示分光光度法用于油品中铁的测定并与普通分光光度法测定结果的精密度和准确度进行了比较。结果表明，对于低吸光度样品的测定，该法较普通分光光度法准确。同时，该法克服了以前低吸光度差示分光光度法中差示吸光度与样品含量不成线性关系的不足。     

虎杖中总蒽醌含量测定不确定度的评定

对紫外分光光度法测定总蒽醌含量的测量不确定度进行分析,以期找出影响不确定度的因素,为评价检测报告提供科学依据.用分光光度法测定虎杖中总蒽醌的含量,并根据<测量不确定度评定与表示>(JJF1059-1999)中有关规定评估其不确定度.本次实验的不确定度评估为0.0912%.     

褪黑素含量测定方法

褪黑素因对人体具有一定的保健功能而作为保健品的主要添加成分被广泛使用。测定褪黑素含量的方法有生化免疫方法、紫外分光光度法、色谱法及色谱-质谱联用法等。主要介绍用气相色谱-质谱联用法、紫外分光光度法和高效液相色谱法测定褪黑素的含量。     

人工神经网络在仪器分析实验数据处理中的应用

以紫外分光光度法为例,将人工神经网络方法引入到仪器分析实验数据处理中,实现了吗啉的紫外分光光度法测定并拓宽了仪器分析的应用。     

刺五加叶中黄酮类化合物的分析

利用电喷雾多级串联质谱 (ESI MSn)技术 ,分析了刺五加叶中黄酮类化合物 ,并根据黄酮类化合物的特征显色反应 ,采用紫外 可见分光光度法 ,对刺五加叶中总黄酮的含量进行了测定。分析结果表明 :刺五加叶含有槲皮素及其相关的黄酮甙类化合物 ,其含量达 37.2 5 %。     

Synthesis and Self-Association of Stimuli-Responsive Diblock Copolymers by Living Cationic Polymerization

The living cationic polymerization of several functional monomers in the presence of an added base is investigated as a possible preparation of a new series of water-soluble or stimuli-responsive copolymers. Under appropriate conditions, the polymerization allows the selective preparation of polymers with various shapes and different sequence distributions of monomer units, including stimuli-responsive block copolymers, gradient copolymers, poly(vinyl alcohol) graft copolymers, and star-shaped polymers. The stimuli-induced self-association of the diblock copolymers is also examined. An aqueous solution of the diblock copolymer with a thermo-sensitive segment undergoes rapid physical gelation upon warming to the critical temperature to give a transparent gel, and returns sensitively to the solution state upon cooling. The sharp transition of stimuli-responsive segments with highly controlled primary structure turns out to play an important role in the self-association. Small-angle neutron scattering, dynamic light scattering, and electron microscopy studies reveal that the physical gelation involves a thermosensitive micellization of diblock copolymers (core size: 18-20 nm) and subsequent micelle macrolattice formation (bcc symmetry). Based on the gelation mechanism, several stimuli-responsive gelation systems are achieved using other stimuli such as the addition of a selective solvent or compound, cooling, pH change, and irradiation with ultraviolet light.     

活性正离子聚合方法合成两亲性共聚物研究进展

综述由活性正离子聚合方法设计合成两亲性共聚物与两亲性聚合物网络的研究进展 ,并进一步介绍这些两亲性聚合物在生物材料领域的应用。     

Wavelength Flexibility in Photoinitiated Cationic Polymerization

The spectral sensitivity of onium salt photoinitiators in cationic polymerization can be tuned from the short wavelength region of the UV spectrum to wavelengths up to the visible region by using direct and indirect activation, respectively. Indirect activation is based on the electron transfer reactions between onium salts and free radical photoinitiators, appropriate sensitizers and compounds capable of forming charge transfer complexes. Bisacylphosphine oxides, dimanganese decacarbonyl in conjunction with alkyl halides and titanocene type photoinitiators such as Irgacure 784 were shown to be useful free radical promoters providing the possibility of performing cationic polymerization in the long wavelength and visible region. The synthetic routes to prepare block copolymers by using electron transfer photosensitization and free radical promoted cationic polymerization are also described.     

Photoinitiated Cationic Polymerization of Unconventional Monomers

Photoinitiated cationic polymerization of unconventional monomers namely, benzoxazines, monothiocarbonates and macromonomers of poly(ε-caprolactone) and poly(ethylene oxide) is described. Ring opening polymerization of benzoxazines and thiocarbonates by direct and sensitized photoinitiation using onium salts was studied. The structures of the resulting polybenzoxazine were complex and related to the ring opening process of the protanated monomer either at through oxygen or nitrogen atoms. In the case of monothiocarbonate, the polymerization was accompanied with isomerization of thiocarbonate group. The potential use of macromonomers in photoiniated cationic polymerization to design complex macromolecular structures such as graft copolymers, water-borne photoresist materials and networks with dangling chains was presented. Photoinduced oxidative polymerization of thiophene, precursor for conducting polymers, using onium salts was also demonstrated.     

Structure-Property Dependence of Copolymers Prepared by Cationic Polymerization

α-Methylstyrene/isobutene, α-methylstyrene/diisobutene, cyclopentadiene/isobutene, and cyclopentadiene/α-methylstyrene were copolymerized by cationic polymerization techniques. Several properties of the copolymers such as softening ranges and oxidation stability depend on their constitutional composition, and were controlled by variation of the conditions of their synthesis.     

Synthesis and Degradation of Vinyl Polymers with Evenly Distributed Thioacetal Bonds in Main Chains: Cationic DT Copolymerization of Vinyl Ethers and Cyclic Thioacetals

We report a novel method to synthesize degradable poly(vinyl ether)s with cleavable thioacetal bonds periodically arranged in the main chains using controlled cationic copolymerization of vinyl ethers with a 7-membered cyclic thioacetal ( 7-CTA ) via degenerative chain transfer (DT) to the internal thioacetal bonds. The thioacetal bonds, which are introduced into the main chain by cationic ring-opening copolymerization of 7-CTA with vinyl ethers, serve as in-chain dormant species to allow homogeneous propagation of vinyl ethers for all internal segments to afford copolymers with controlled overall and segmental molecular weights. The obtained polymers can be degraded into low- and controlled-molecular-weight polymers with narrow molecular weight distributions via hydrolysis. Various vinyl ethers with hydrophobic, hydrophilic, and functional pendants are available. Finally, one-pot synthesis of multiblock copolymers and their degradation into diblock copolymers are also achieved.     

聚(4-乙烯基吡啶季铵盐-丙烯酰胺)的抗菌性能与机理研究

季铵盐型阳离子聚合物具有絮凝、缓蚀与杀菌等多种功能,据此,我们通过分子设计,先将丙烯酰胺与4-乙烯基吡啶（4-VP）进行共聚合,然后使用季铵化试剂硫酸二甲酯使共聚物阳离子化,制备了吡啶季铵盐型阳离子聚丙烯酰胺（QPAV）,本文报道QPAV的抗菌性能,并探讨其抗菌机理,结果表明,吡啶季铵盐型阳离子聚丙烯酰胺具有很强的抗菌性能,且其抗菌机理是基于杀菌而不仅仅是抑菌。     

Mechanistic Transformations Involving Radical and Cationic Polymerizations

Mechanistic transformation approach has been widely applied in polymer synthesis due to its unique feature combining structurally different polymers prepared by different polymerization mechanisms.Reported methods for the formation of block and graft copolymers through mechanistic transformation involve almost all polymerizations modes.However,certain polymerization processes require extensive purification processes,which can be time-consuming and problematic.Recent developments on controlled/living polymerizations involving radical and cationic mechanisms with the ability to control molecular weight and functionality led to new pathways for mechanistic transformations.In this mini-review,we systematically discussed relevant advances in the field through three main titles namely(i)from radical to cationic mechanism,(ii)from cationic to radical mechanism,and(iii)application of specific catalyst systems for both radical and cationic polymerizations.     

Cationic Complexes of Monovalent Nickel as Catalysts for Styrene Polymerization

The interaction of the [Ni(PPh₃)₃]BF₄ complex with styrene and the products of styrene conversion in the polymerization reaction were studied by EPR and ¹³C NMR spectroscopy. The structure of the σ-carbocationic complex of Ni(I) formed by the interaction of styrene with the [Ni(PPh₃)₃]BF₄ cationic phosphine complex of Ni(I) was characterized in detail. It was found that the reaction of styrene polymerization occurred with the participation of the coordination center of the σ-carbocationic complex (coordination catalysis), whereas the reaction of telomerization occurred with the participation of the cationic center of this complex (ionic catalysis). The resulting polymer contained active terminal double bonds; it is a promising macromonomer for the synthesis of grafted copolymers. The discovered capacity of alcohols to undergo nucleophilic addition to a growing polymer chain offers strong possibilities for preparing functional polymers and block copolymers.     

Synthesis of Block Copolymers by Combination of Atom Transfer Radical Polymerization and Visible Light‐Induced Free Radical Promoted Cationic Polymerization

A new synthetic approach for the preparation of block copolymers by mechanistic transformation from atom transfer radical polymerization (ATRP) to visible light‐induced free radical promoted cationic polymerization is described. A series of halide end‐functionalized polystyrenes with different molecular weights synthesized by ATRP were utilized as macro‐coinitiators in dimanganese decacarbonyl [Mn₂(CO)₁₀] mediated free radical promoted cationic photopolymerization of cyclohexene oxide or isobutyl vinyl ether. Precursor polymers and corresponding block copolymers were characterized by spectral, chromatographic, and thermal analyses.