二苯基碘鎓盐引发乙烯基醚热聚合研究

合成了一种液态聚氨酯乙烯基醚预聚物 (PUE)并对其进行了表征 .研究发现二苯基碘六氟磷酸盐(PI810 )能够引发PUE和三缩乙二醇二乙烯基醚 (DVE 3)进行阳离子热聚合 ,热聚合温度远低于PI810的纯态热分解温度 ,且聚合转化率较高 .热聚合的机理初步认为是电子转移机理 .研究了乙烯基醚化合物、环氧树脂、二苯基碘六氟磷酸盐混合体系的热聚合 .     

电子束辐射固化环氧树脂的反应过程分析

对双酚A型环氧树脂的电子束辐射固化反应过程进行了分析.考察了引发剂、稀释剂对树脂体系辐射反应的影响,以环氧丙烷作为模型化合物,研究了环氧丙烷-碘盐体系的电子束辐射反应机理,证实了在电子束辐射下,碘盐分解产生质子酸,引发环氧树脂阳离子开环聚合的反应过程.观测环氧树脂辐射固化区域发现,电子束穿过样品时发生强烈的散射,在辐射方向以及周围一定区域内引发固化反应,固化反应从活性中心开始向体系内部层层扩展,整个固化区域由很多的层状结构组成.     

一种可以正负互用的水型化学增幅抗蚀剂的研究

研究了一种由甲酚醛树脂、六甲氧基甲基三聚氰胺(HMMM)、六氟磷酸根二苯碘盐和光敏剂组成的水型紫外化学增幅抗蚀剂,发现二苯基碘盐不仅可以作为光敏产酸物,而且可以作为阻溶剂.用碘盐作为光敏产酸物,光解产生的酸可以在中烘时催化甲酚醛树脂与HMMM的交联反应;用氢氧化钠-乙醇水溶液显影可以得到负性光刻图形;采用碘盐作为阻溶剂,可阻止非曝光区的胶膜溶解在显影液中,用稀的氢氧化钠水溶液显影可以得到正性光刻图形.通过优化后的光刻工艺条件,采用不同的显影液和光刻工艺流程,实现了同一光致抗蚀剂的正负性反转,并分别得到负性和正性光刻图形.     

光氧化还原碘盐引发阳离子固化的研究

合成了二苯基碘六氟磷酸盐光引发剂。研究了染料的种类和浓度对碘盐引发阳离子光固化速度的影响，用光致电子转移（光氧化还原）理论解释了这些光敏染料的光敏机理。     

光氧化还原碘Wong盐引发阳离子固化的研究

合成了二苯基碘Ｗｏｎｇ六氟磷酸盐光引发剂。研究了染料的种类和学地磺Ｗｏｎｇ盐引发阳离子光固化速度的影响，用光致电子转移理论解释了这些光敏染料的光敏机理。     

分子内敏化鎓盐的合成及光敏性研究

二芳基碘鎓盐和三芳基硫鎓盐是阳离子聚合的光引发剂和光敏产酸物,但他们在300nm以上的光吸收很低,限制了对紫外光的利用效率。为解决此问题,本文合成了一些新的碘鎓盐和硫鎓盐,并用凝胶时间方法考察了它们的光引发效率。实验结果表明,2-苯硫基甲基,2′,4′-二甲基二苯碘鎓盐和9-蒽丙基,二苯基硫鎓盐具有特别高的光引发效率,这归之于光照时这些鎓盐发生了分子内电荷转移反应,即发生了分子内敏化。9-蒽丙基二苯硫鎓盐分子中的蒽基(An)是电子给体也是敏化基团,光照时可发生如下反应: .     

新型感可见光的光引发体系乙基曙红碘■盐的研究

合成并研究了新型感可见光的光引发体系乙基曙红碘盐。结果表明，该引发剂的物理化学性质和光敏引发效率受其结构、介质性质和浓度等诸多因素影响。在可见光照射下，发生由乙基曙红阴离子向二苯基碘阳离子的电子转移反应，产生具有引发活性的苯自由基和非活性的乙基曙红自由基。测定了光聚合的动力学方程以及聚合物的分子量和分子量分布。比较了曙红单碘盐和双碘盐的各种不同性质     

阳离子型UV光引发剂--三芳基硫鎓盐的合成

以硝基苯、浓硫酸、六氟磷酸钾和碘酸钾为原料,经氧化、取代、置换反应得到3,3′-二硝基二苯基碘六氟磷酸盐(2)。2与苯硫醚在苯甲酸铜的催化下合成了3-硝基苯基二苯基硫六氟磷酸盐(3)。3是一种新型的三芳基硫鎓盐阳离子UV光引发剂,其结构经UV,1H NMR,IR及MS确证。     

N-丁基-2-乙氧基硫代吖啶酮的光化学反应机理

采用荧光光谱研究了N-丁基-2-乙氧基硫代吖啶酮的光化学反应机理.结果表明:在Xe灯光照下,N-丁基-2-乙氧基硫代吖啶酮转变成了相应的吖啶酮,用紫外-可见光谱和质谱证实了吖啶酮的存在;生成的吖啶酮可被二苯基碘NFDA1 盐猝灭,它们之间的荧光猝灭遵循电子转移的反应机理.实验又证明了由硫代吖啶酮、二苯基碘NFDA1 盐和硫代水杨酸三者组成的光聚合引发体系的引发效果最好.     

氨基甲酸酯乙烯基醚类化合物光聚合性能研究

本文合成了一种双官能度的氨基甲酸酯乙烯基醚和一种三官能度的氨基甲酸酯乙烯基醚,并用实时傅立叶红外光谱分别监测了单官能度、双官能度和三官能度的乙烯基醚化合物在三芳基六氟锑酸锍鎓盐阳离子光引发剂(PAG-201)引发下的光聚合情况,对其光聚合动力学性能进行了比较,研究了引发剂PAG-201的浓度对双官能度单体光聚合的影响.结果表明,随着官能度的增加,乙烯基醚化合物的转化率和聚合速率降低.此外,对它们的聚合产物进行的热失重分析表明,随着官能度的增加,聚合产物的热稳定性增加.本文的结果对于研究开发基于氨基甲酸酯乙烯基醚单体的阳离子聚合体系具有较好的指导意义.     

Cationic RAFT Polymerization Using ppm Concentrations of Organic Acid

A metal‐free, cationic, reversible addition–fragmentation chain‐transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10⁵ and narrow molecular‐weight distributions (M_w/M_n<1.1). This “living” or controlled cationic polymerization is applicable to various electron‐rich monomers including vinyl ethers, p‐methoxystyrene, and even p‐hydroxystyrene that possesses an unprotected phenol group. A transformation from cationic to radical RAFT polymerization enables the synthesis of block copolymers between cationically and radically polymerizable monomers, such as vinyl ether and vinyl acetate or methyl acrylate.     

Cationic polymerization of vinyl monomers initiated by 10-methylphenothiazine cation radicals

A small quantity of 10-methylphenothiazine cation radical (MPT^.+), electrochemically prepared and stocked in acetonitrile solution, initiated cationic polymerizations of n-butyl, t-butyl, and 2-methoxyethyl vinyl ethers and p-methoxystyrene, while no initiation occurred for phenyl vinyl ether, styrene, methyl methacrylate, and phenyl glycidyl ether. ¹H-NMR studies of oligomers and low molecular weight compounds isolated from the reaction mixture for the polymerization of t-butyl vinyl ether in the presence of a small amount of D₂O indicated that electron transfer from the monomer to MPT^.+ was involved in the initiation step. ¹H- and ¹³C-NMR and MO calculation implied that monomers with higher electron densities on the vinyl groups and with lower ionization potentials were more susceptible to the initiation of MPT^.+. © 1994 John Wiley & Sons, Inc.     

The Role of Donor-Acceptor Complexes in the Initiation of Ionic Polymerization

Work carried out in the past few years aimed at elucidating the mechanism of initiation of vinyl polymerization when a donor and an acceptor molecule, one or both of which may be vinyl monomers, is summarized. The emphasis of our investigation has been on polymerizable ether donors and strong electron acceptors which do not undergo polymerization, or the acceptor vinylidene cyanide. Alkyl vinyl ethers were polymerized in the presence of tetracyanoquinodimethane (TCNQ) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in polar solvents. Observation of the ESR spectrum of the DDQ radical anion and the isolation of a 1:1 addition product of DDQ and alkyl vinyl ether when the two are mixed in a 1:1 ratio and quenched in alcohol support an initiation mechanism involving a coupling reaction of the donor monomer (radical cation) and the acceptor initiator (radical anion). The reaction of vinylidene cyanide (VC) with the vinyl ethers p-dioxene, dihydropyran, ethyl vinyl ether, isopropyl vinyl ether, and ketene diethylacetal in a variety of solvents at 25°C spontaneously afforded poly(vinylidene cyanide), the cycloaddition products 7,7-dicyano-2,5-dioxo-bicyclo[4.2.0] octane, 8,8-dicyano-2-oxo-bicyclo[4.2.0] octane, the 1,1-dicyano-2-alkoxycyclo-butanes, and 1,1-diethoxy-2,2,4,4-tetracyanohexane, respectively, and with the exception of p-dioxene, homopolymers of the vinyl ethers. In the presence of AIBN at 80°C, alternating copolymers were obtained in addition to the homopolymers and cycloaddition products, supporting the involvement of donor-acceptor complexes. The reaction of styrene with VC spontaneously formed an alternating copolymer in addition to the 1:2 head-to-head cycloaddition product, 1,1,3,3-tetracyano-4-phenylcyclohexane. Mixing VC with any one of the cyclic ethers tetrahydrofuran, oxetane, 2,2-dimethyloxirane, 2-chloromethyloxirane, and phenyloxirane resulted in the polymerization of both the VC and the cyclic ether to afford homopolymers of both. The cyclic ethers trioxane, 3,3-bis(chloromethyl)oxetane, and oxirane initiated the polymerization of VC, but did not undergo ring-opening polymerizations themselves. Other ethers such as 1,3-dioxolane, tetrahydropyran, and diethyl ether did not initiate the polymerization of VC. In these polymerizations, VC and the cyclic ethers polymerize via anionic and cationic propagation reactions, respectively.     

Near‐Infrared Free‐Radical and Free‐Radical‐Promoted Cationic Photopolymerizations by In‐Source Lighting Using Upconverting Glass

A method is presented for the initiation of free‐radical and free‐radical‐promoted cationic photopolymerizations by in‐source lighting in the near‐infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron‐transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate. To execute the corresponding free‐radical‐promoted cationic polymerization of cyclohexene oxide, isobutyl vinyl ether, and N ‐vinyl carbazole, it was necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer, coinitiator, and oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations. Thus, cationic polymerization with efficiency comparable to the conventional irradiation source was achieved.     

Some new developments in vinyl ether polymerization

Different combinations of acetals with trimethylsilyl iodide have been explored as new initiating systems for the vinyl ether polymerization. The resulting polymers are characterized by controlled molecular weights and narrow molecular weight distributions, confirming the living polymerization mechanism. Acetals can also be used as transfer agents in the polymerization of vinyl ethers. When using 1,1-diethoxyethane (DEE) as transfer agent and isobutyl vinyl ether (IBVE) as monomer, a transfer constant of 0.2 was obtained (at −40°C in toluene). This method, transposed to functional acetals, provides a new way to prepare polyvinyl ethers with one or two functional end groups. The cationic polymerization of isobutyl vinyl ether initiated with the combination triflic acid/thietane, where thietane acts as electron donating moderator, leads to star-shaped polyvinylether-polythietane block-copolymers (at −40°C in dichloromethane). The block-copolymer structure is obtained because the vinyl ether polymerization is stopped when the α-alkoxy thietanium ion (active species) is attacked by a thietane molecule, which is at the same time an initiation reaction for the thietane polymerization. The star-shaped structure of the block-polymer is the result of the intermolecular termination in the cationic polymerization of thietane. When using a bifunctional initiator system, a polymer network is obtained consisting of linear polyIBVE-segments interconnected by branched polythietane segments. These findings support the sulfonium ion structure of the active species in the cationic polymerization of vinyl ethers initiated by the acid-sulfide system.     

Polymerization of cyclic ethers in the presence of maleic anhydride. Part II. Investigation of the polymerization mechanism

In order to elucidate the reaction mechanism of both the radiation-induced and benzoyl peroxide-catalyzed polymerizations of cyclic ethers in the presence of maleic anhydride, the development of color during reaction and copolymerization of oxetane derivatives were investigated. Upon addition of a small amount of the γ-ray or ultraviolet-irradiated equimolar solution of a cyclic ether and maleic anhydride to isobutyl vinyl ether, a rapid polymerization took place, and the resulting polymer was confirmed to be a homopolymer of isobutyl vinyl ether. A heated solution of dioxane, maleic anhydride, and a small amount of benzoyl peroxide can initiate the polymerization of isobutyl vinyl ether in the same manner. The electrical conductivity of a 1:1 mixture of maleic anhydride and dioxane is increased by about a factor of ten after ultraviolet irradiation. These results indicate that some cationic species are actually formed in the system by irradiation or the decomposition of added benzoyl peroxide. The mechanism of formation of the cationic species responsible for the initiation may be explained as follows. A free radical of an ether is formed by abstraction of a hydrogen atom attached to the carbon adjacent to oxygen atom, followed by a one-electron transfer from the resulting radical to maleic anhydride, an electron acceptor, to yield the cationic species of the ether and the anion-radical of maleic anhydride, respectively. The resulting cationic species as well as the counteranion-radical are resonance-stabilized. Therefore, the present polymerization may be designated a radical-induced cationic polymerization.     

Copolymerization of butyl vinyl ether and methyl methacrylate by combination of radical and radical promoted cationic mechanisms

Butyl vinyl ether (BVE) and methyl methacrylate (MMA) mixtures were polymerized by using free radical initiators in conjunction with a cationic initiator such as diphenyl iodonium salt. Polymerization mechanism involves free radical polymerization of MMA which is switched to cationic polymerization of BVE by addition of growing poly(MMA) radicals to BVE and subsequent oxidation of electron donating polymeric radicals to the corresponding cations by iodonium ions. Two representative bifunctional monomers, ethylene glycol divinyl ether (EGDVE) and ethylene glycol dimethacrylate (EGDMA) were also used together with MMA and BVE, respectively, in photo and thermal crosslinking polymerizations. Vinyl ether and methacrylate type monomers can successfully be copolymerized by this double-mode polymerization under photochemical conditions.     

Front velocity dependence on vinyl ether and initiator concentration in radical-induced cationic frontal polymerization of epoxies

Formulations containing vinyl ethers and epoxy were successfully polymerized through a radical-induced cationic frontal polymerization mechanism, using an iodonium salt superacid generator with a peroxide thermal radical initiator and fumed silica as a filler. It was found that an increase of vinyl ether content resulted in higher front velocities for divinyl ethers in formulations with trimethylolpropane triglycidyl ether. However, increased hydroxymonovinyl ether either decreased the front velocity or suppressed frontal polymerization. The kinetic effects of the superacid generator and thermal radical initiator with varying vinyl ether content were also studied. It was observed that increasing concentrations of initiators increased the front velocity, with the system exhibiting higher sensitivity to the superacid generator concentration.     

Interaction of epoxy and vinyl ethers during photoinitiated cationic polymerization

A kinetic study of the independent and simultaneous photoinitiated cationic polymerization of a number of epoxide and vinyl (enol) ether monomer pairs was conducted. The results show that, although no appreciable copolymerization takes place, these monomers undergo complex interactions with one another. These interactions are highly dependent on the epoxide monomer employed. In all cases, the rate of epoxide ring-opening polymerization is accelerated, whereas that of the vinyl ether is depressed. When highly reactive cycloaliphatic epoxides are subjected to photoinitiated cationic polymerization in the presence of vinyl ethers, the two polymerizations proceed in a sequential fashion, with the vinyl ether polymerization taking place after the epoxide polymerization is essentially complete. A mechanism involving an equilibration between alkoxy-carbenium and oxonium ions has been proposed to explain the results. In addition, the free-radical-induced decomposition of the diaryliodonium salt photoinitiator also takes place, leading to a decrease in the induction period. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4007–4018, 1999