Cationic photopolymerization of cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane

Abstract

The spiro‐orthoester, cis‐2,3‐tetramethylene‐1,4,6‐trioxaspiro[4,4]nonane (cis‐TTN) (I), underwent rapid cationic photopolymerization when exposed to UV light using diphenyliodonium salts as a photoinitiator. The polymer, poly[(trans‐OCB)x′‐(cis‐OCB)x″‐(CHO)y] thus formed consisted of poly(trans‐2‐oxycyclohexyl butanoate) (trans‐OCB)x′ (II), poly(cis‐2‐oxycyclohexyl butanoate) (cis‐OCB)x″ (III), and poly‐ (1,2‐cyclohexene oxide) (CHO)y segments, and no expected pure poly(ether‐ester), that is, poly(2‐oxycyclohexyl butanoate), was isolated. The structure of the polymer was identified, and the mechanism of the reaction was deduced. The polymer thus formed exhibited expansion in volume during cationic photopolymerization when compared to that obtained by conventional cationic polymerization using a Lewis acid (e.g., BF3OEt2, CH3OSO2CF3, or SnCl4) as an initiator, which demonstrated volume shrinkage during polymerization. The volume expansion of the polymer during polymerization was due to (1) the lower content of the higher density (CHO)y segment in the polymer chain and, more importantly, (2) the higher and optimal mole ratio of (trans‐OCB)x′ and (cis‐OCB)x″ segments that led the polymer in a more disordered, less dense, and higher volumetric state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3680–3690, 2009

Characterization of a Low Shrinkage Dental Composite Containing Bismethylene Spiroorthocarbonate Expanding Monomer

“…Many efforts have been directed toward modifying Bis-GMA, such as substitution of a hydrogen atom, methyl or trimethicone for the hydroxyl group [ 12 ], and so on. Since a double ring-opening polymerization was reported in 1972 [ 13 ], various monomers based on spiroorthoester (SOE) [ 14 , 15 ], bicycloorthoester (BOE) [ 16 ], and spiroorthocarbonate (SOC) [ 17 – 19 ] have been developed that indeed exhibit volumetric expansion upon polymerization. Among these, spiroorthocarbonates (SOCs) have been the most widely investigated because they show the most significant volume expansions due to the compact nature of the bicyclic monomer and the relatively more flexible open-chain structure associated with the polymer.…”

Temperature triggered alternating copolymerization of epoxides and lactones via pre-sequenced spiroorthoester intermediates

“… 13 Namely, a wide range of spiroorthoesters (SOEs), a class of pre-sequenced monomer, can be synthesized through the coupling of epoxides and lactones ( Scheme 1A ). 14 However, Lewis-acid-catalyzed formation and polymerization 15 of spiroorthoesters to date have suffered from poor selectivity, resulting in the need for distillation, low monomer yields (<50%), low molecular weights, and high dispersities for the resulting polymers. 16 …”

Coating films prepared by photoreactions of the surface‐modified diamond powder and PET film with a binder agent

“…[18][19][20] Radical or cationic species are generated by the interaction of UV light with a suitable photoinitiator or photosensitizer. Onium salts initiate both the cationic and free radical curing processes by generating Brö nsted acids (or cations) and free radicals upon photodecomposition.…”

“…The UV-curing process is a polymerization technique in which radiation is used to induce a very high polymerization rate so that the reaction is completed, or the change in phase from liquid to solid takes place, within a few seconds or even within a fraction of a second. [18][19][20] Radical or cationic species are generated by the interaction of UV light with a suitable photoinitiator or photosensitizer. Onium salts initiate both the cationic and free radical curing processes by generating Brö nsted acids (or cations) and free radicals upon photodecomposition.…”