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Published in Eli Ruckenstein, Hangquan Li, Chong Cheng, Solution and Surface Polymerization, 2019
Eli Ruckenstein, Hongmin Zhang
Synthesis of the Block–Graft Copolymer by Cationic Graft Copolymerization of IBVE to the Block Macroinitiator. The living cationic polymerization of a number of vinyl monomers, such as alkyl vinyl ether, isobutylene, and styrene-type monomers, was carried out by a number of researchers.27–30 Higashimura et al.17–19 found that 1-(isobutoxy)ethyl acetate (IBEA) can be used as an initiator for the cationic polymerization of alkyl vinyl ether in the presence of a Lewis acid. The linkage between the acetoxy group and ethoxy group can be activated by the Lewis acid to generate a partly dissociated carbocation, which induces the cationic polymerization of alkyl vinyl ether. However, when a very strong Lewis acid, EtAlCl2, was used, the cationic polymerization could not be controlled. In the latter case, the molecular weight distribution of the obtained polymer was broad, because the counteranion (−OCOCH3⋯EtAlCl2) possesses a too weak nucleophilicity. However, when a weak Lewis base, such as THF, 1,4-dioxane, or ethyl acetate, was introduced into the above system, a living cationic polymerization could be achieved.17,18 In this case, the propagating site was suitably stabilized by the added Lewis base.
Elements of Polymer Science
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
Cationic polymerizations are started by reaction of electrophilic initiator cations with electron-donating monomer molecules. Catalysts are Lewis acids and Friedel-Crafts catalysts, such as aluminum trichloride AlCl3, and strong acids, such as sulfuric acid H2SO4. Monomer molecules able to undergo cationic polymerization include electron-rich olefins, such as vinyl aromatics and vinyl ethers, and ring compounds, such as ethylene oxide and tetrahydrofuran.
Analyzing Deformation of a Cationic Photopolymerized Epoxy Adhesive during the Curing Process in UV Irradiation and Dark Reaction based on Finite Element Method and Measurement
Published in The Journal of Adhesion, 2023
A. Takahashi, Y. Sekiguchi, N. Taki, M. Okamura, C. Sato
Several studies have reported models for the curing reaction of adhesives[5–16] and the changes in the physical properties during the curing process.[17–22] Most of these studies have focused on heat-curable resins and radical polymerization UV-curable resins. Cationic polymerization UV-curable adhesives are also often used for optical products because of their advantages over radical polymerization adhesives, such as a smaller curing shrinkage, no oxygen inhibition, and superior heat resistance. However, few studies have modeled the curing reaction for cationic polymerization UV-curable adhesives,[14–16] and few researchers have formulated the deformation associated with curing for these adhesives.
Advances in self-crosslinking of acrylic emulsion: what we know and what we would like to know
Published in Journal of Dispersion Science and Technology, 2019
Sumit Parvate, Prakash Mahanwar
The process of UV curing works on free radical or cationic polymerization mechanism and requires multifunctional acrylates and photoinitiator. Photoinitiator should be slightly miscible in water or should be an aqueous dispersion. In this process the coating is exposed to UV light of wavelength 240−450 nm at room temperature. The exposure of UV wavelength dissociates the photoinitiator into the free radicals. These free radical attacks on unsaturations in multifunctional acrylate which results in crosslinking between two mutual polymer chain.[168] Steps of self- crosslinking reactions of silanes have been illustrated in Figure 14.
Constitutive model for epoxy shape memory polymer with regulable phase transition temperature
Published in International Journal of Smart and Nano Materials, 2021
Fei Zhao, Xueyao Zheng, Shichen Zhou, Bo Zhou, Shifeng Xue, Yi Zhang
The cross-linked network of SMP will change when exposed to ultraviolet, which due to the free radical polymerization or cationic polymerization. The material parameters vary with the variation of the expose time, and the expression of the glassy transition temperature is obtained as