Cationic cyclopolymerization of 1,2‐bis(2‐vinyloxyethoxy)benzenes: Introduction of bulky substituents to increase cyclopolymerization tendency

Abstract

To suppress intermolecular propagation by steric hindrance of monomer substituents and increase cyclopolymerization tendency thereby, two bulky tert‐butyl groups are introduced to the benzene ring of 1,2‐bis(2‐vinyloxyethoxy)benzene (1), which is a representative monomer for cationic cyclopolymerization of divinyl ethers. Thus, 3,5‐di‐tert‐butyl‐1,2‐bis(2‐vinyloxyethoxy)benzene (2) was synthesized and polymerized with the HCl/ZnCl2 initiating system in CH2Cl2 at −15 °C ([Monomer]0 = 0.15 M) to produce completely soluble polymers quantitatively. The vinyl content of the polymer obtained in the early stage of the polymerization (17% monomer conversion) was 4.0 mol %; in other words, its degree of cyclization was 96%. The cyclopolymerization tendency of 2 was found to be higher than that of 1 (the degree of cyclization, 93%; under the same conditions).

Star-shaped cyclopolymers: A new category of star polymer with rigid cyclized arms prepared by controlled cationic cyclopolymerization and subsequent microgel formation of divinyl ethers

“…The broadening of polymer MWD in the course of cyclopolymerization of divinyl ethers comes from the occurrence of a minor extent of crosslinking and/or branching reactions to consume the pendant unreacted vinyl groups. 19,20,23,24 Figure 4 also shows the time-conversion plots (A), the M n (B), and M w /M n (C) of the product polymers vs. monomer conversion plots for the polymerization of 1 at 0 C. The polymerization proceeded smoothly and rather fast (conversion 5 100% at 10 min), and the M n s of the produced polymers increased in direct proportion to monomer conversion before and after the monomer addition with the polymer MWDs being narrow and were in good agreement with the calculated values assuming that one HCl molecule formed one polymer chain. The results of these plots in Figure 4 confirm living nature of the cyclopolymerization of 1 at 0 C. However, close inspection of the M n of the product polymers versus monomer conversion plots [ Fig.…”

“…In other words, the degree of cyclization for the poly(1) was over 97%, high value and similar to those of the reported cyclopolymers from other divinyl ethers. 19,20,23,24 To check living nature of the present cyclopolymerization systems, a fresh monomer feed (equivalent to the first stage) was added to the almost completely polymerized reaction mixture. The polymers obtained after the monomer addition were also soluble and the peak top of the MWD curves of the polymers clearly shifted toward high molecular weight region.…”

“…13,14 In contrast, cyclopolymerization of divinyl ethers is a polymerization route to produce so-called cyclopolymer, which is a linear polymer consisting of cyclized repeating monomeric units produced by propagation with intramolecular cyclization. [15][16][17][18][19][20] The incorporation of consecutive cyclic groups into the polymer backbones provides rigidity, and hence high thermal stability and high T g to the resulting polymers. [21][22][23] Our recent study showed that some of cyclopoly(divinyl ether)s possessed high T g (up to 200 C) and high thermal decomposition temperature (up to 300 C).…”

Cyclopolymerization of a bisacrylate through selective formation of a 19-membered ring

“…): 0.80-2.80 (14H, -CH 2 CH(COOR)-, -CH 2 (CH 2 ) 2 CH 2 -), 2.90-3.82 (4H, br, -COOCH 2 CH 2 NH-), 3.82-4.95 (6H, -COOCH 2 CH 2 NH-, -NHCOOCH-), 4.95-6.80 (2H, br, -NH-). 13 …”

“…However, the low concentration often limits the yields of polymers. 4,9 Effective strategies for improvement of the cyclization tendency involve conformational orientation of two polymerization groups with cyclic structures [10][11][12][13][14][15][16][17][18][19][20][21] or templates such as metal cations 22,23 and selective alternating copolymerization. 24,25 In the most common method, namely, the design of oriented monomers, additional constraints by steric hindrance 12,13,19 and hydrogen bonding 17 are effective in improving the cyclization tendency.…”