Atom transfer radical polymerization initiated by N‐bromosuccinimide

N‐Bromosuccinimide (NBS) was used as the initiator in the atom transfer radical polymerizations of styrene (St) and methyl methacrylate (MMA). The NBS/CuBr/bipyridine (bpy) system shows good controllability for both polymerizations and yields polymers with polydispersity indexes ranging from 1.18 to 1.25 for St and 1.14 to 1.41 for MMA, depending on the conditions used. The end‐group analysis of poly(MMA) and polystyrene indicated the polymerization is initiated by the succinimidyl radicals formed from the redox reaction of NBS with CuBr/bpy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5811–5816, 2004     

ROMP based photoinitiator‐coinitiator systems with improved migration stability

Nowadays, migration stability is one of the key features for photoinitiators used in radiation curable formulations, especially when the material is in contact with food or the human body. Herein, the synthesis and characterization of statistical copolymers with covalently bound eosin and/or ethyl dimethylamino benzoate units by ring opening metathesis polymerization is presented. The prepared compounds were tested as macroinitiators for the photopolymerization of acrylates aiming at an initiator/coinitiator system which combines good polymerization activity with improved migration stability. An acrylate modified eosin derivative which is incorporated into the polymer network during the photopolymerization reaction and, therefore, less likely to leak from the polymer compound was used as reference. Photoinitiating activities of low and high molecular weight initiators and coinitiators were investigated by photo‐DSC. Moreover, leakage studies and viability tests with osteoblast‐like cells were performed to proof the suitability of this concept. The use of polymeric eosin in combination with a low molecular weight coinitiator was found to be a good compromise when aiming at a photoinitiating system with sound performance and improved migration stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3648–3661, 2008     

Toward self-assembling dendritic macromolecules from conventional monomers by a combination of living radical polymerization and irreversible terminator multifunctional initiator

TERMINI stands for irreversible terminator multifunctional initiator and represents a new concept elaborated in our laboratory for the design of novel macromolecules with complex architecture from a diversity of commercial monomers. TERMINI is a masked multifunctional initiator that quantitatively interrupts a living polymerization. After demasking, the TERMINI-derived repeat unit provides access to a quantitative reinitiation of the same living polymerization in more than one direction, thus becoming a branching point. In this article, with a combination of self-regulated metal-catalyzed living radical polymerization and TERMINI, we demonstrate a new method for the divergent synthesis of dendritic poly(methyl methacrylate) containing a bifunctional core at its focal point. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 505–513, 2004     

Initiator‐fragment incorporation radical polymerization of divinylbenzene in the presence of glyoxylic oxime ether: Formation of soluble hyperbranched polymer

The copolymerization of divinylbenzene (DVB) and ethylstyrene (EtSt) was carried out at 70 and 80 °C in benzene with dimethyl 2,2‐azobisisobutyrate (MAIB) at high concentrations as initiator in the presence of methyl benzyloxyiminoacetate (MBOIA), a glyoxylic oxime ether, as a retarder. The copolymerization system of DVB (0.25 mol/L), EtSt (0.25 mol/L), MBOIA (0.5 mol/L), and MAIB (0.5 mol/L) gave benzene‐soluble copolymers despite a considerably high concentration of DVB as an excellent crosslinker. The yield and molecular weight of the resulting copolymers increased with time both at 70 and 80 °C and then leveled off because of initiator consumption. The homogeneous polymerization system involved electron spin resonance (ESR), observable nitrogen‐centered polymer radicals (MBOIA·) under the actual polymerization conditions. The MBOIA· concentration increased with time despite a homogeneous polymerization system, suggesting the formation of rigid hyperbranched polymers. A benzene solution of isolated copolymer also showed an ESR signal. The copolymer was soluble in acetone, toluene, chloroform, ethyl acetate, tetrahydrofuran, and N,N‐dimethylformamide but insoluble in n‐hexane, methanol, and dimethyl sulfoxide. MAIB fragments as high as 30–40 mol % were incorporated into the copolymers through initiation and primary radical termination, on the basis of which this polymerization was named the initiator‐fragment incorporation radical polymerization. MBOIA (13–16 mol%) was also incorporated into the copolymers through an opening of the C?N bond. The intrinsic viscosity of the copolymers was very low (0.08 dL/g), and the reduced viscosity was almost independent of the polymer concentration, supporting a hyperbranched structure of them. Gel permeation chromatography and multi‐angle laser light scattering and transmission electron microscopy revealed that the copolymer was formed as a hyperbranched nanoparticle. The thermal behavior of the copolymer was examined by dynamic thermogravimetry and differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3038–3047, 2003     

基于试验熵的火工品可靠性评估理论与方法研究

为了降低可靠性评估试验样本量,避免计量法评估试验中由于刻度参数的估计偏差所带来的风险,研究了火工品可靠性验证试验中数据的统计分析方法,引入了熵,给出了试验熵等值方程,提出了结合产品的感度分布函数,通过计数和计量相结合评估火工品可靠性的试验熵等值方法,并结合某火工品的大小样本对比试验验证了该方法的正确性及可行性。研究结果表明,使用该方法可以用较少的试验样本量,实现对高可靠性指标要求的火工品进行可靠性评估。     

烯丙基氯化镁引发己二酸酐开环聚合

以烯丙基氯化镁引发己二酸酐开环聚合制备功能化的聚己二酸酐。考察了引发剂、温度、溶剂对聚合反应的影响.核磁端基分析表明开环聚合反应可能是通过酰氧键断裂,按“配位－插入”机理进行的。     

ε-己内酯负离子聚合过程烷氧基锂活性种的缔合

本文以粘度法研究在苯溶剂中,ε-己内酯负离子开环聚合过程,增长链活性种烷氧基锂(—O~-Li~+)的缔合,发现己内酯活性种的缔合和一般非极性单体不同,前者在聚合过程中(单体消耗完以前)并不发生缔合。在单体消耗完以后,聚己内酯活性种才确实以缔合体的形式存在。这是由于内酯本身贡献了强的溶剂化作用。     

含二苯酮基的大分子光敏引发剂的研究进展

简要介绍含二苯酮基的大分子光敏引发剂的合成制备、引发聚合机理及应用方面的研究进展情况。     

Determination of solubility parameters of cross-linked macromonomeric initiators based on polypropylene glycol

A new type macromonomeric azo initiators also named macroinimers, MIMs, based on polypropylene glycol, PPG, with molecular weight 400 and 2000, were synthesized. Self-condensing radical polymerization of the macroinimers gave cross-linked polypropylene glycols. The solubility parameters of the cross-linked polymers determined using swelling experiments in a series of solvents have been reported. Crosss-linked PPG-400 and cross-linked PPG-2000 indicated the same solubility parameter value. But their swelling ratios were different because of the differences of the chain lengths in between of the cross-points (Mc) of the gels. Therefore, while the largest swelling ratio exhibited by a cross-linked PPG-2000 in tetrahydrofurane was being 19.48, this ratio was 6.84 for the cross-linked PPG-400 in the same solvent. The solubility parameters and constant α for these cross-linked polymers were obtained as δ_{cross-linked PPG-400} = 9.56 (cal cm⁻³)^1/2, α = 0.123 cm³ cal⁻¹ and δ_{cross-linked PPG-2000} = 8.95 (cal cm⁻³)^1/2, α = 0.107 cm³ cal⁻¹ by using the least squares regression method.