Thermally Induced Twin Polymerization of 4H‐1,3,2‐Benzodioxasilines

Abstract

The twin monomer 2,2'-spirobi[4H-1,3,2-benzodioxasiline] (1) can be polymerized to nanostructured SiO2/phenolic-resin composite material by thermally induced twin polymerization. Thermally induced twin polymerization represents a way to produce nanocomposites simply by thermal induction of twin monomers. Besides 1, the thermal reaction of several related salicylic (2-oxybenzylic) silicon molecules has been investigated. The thermal cleavage of the molecules is studied by using several trapping reagents (e.g., vinyl compounds). A significant occurrence of quinone methide adducts indicates that the thermal mechanism proceeds not only by a ring opening at the oxymethylene position, but also with the ortho-quinone methide as a central or alternative intermediate. This is supported by product analyses of thermally initialized reactions of 1 and its substituted analogues as well as by quantum chemical calculations.

B2O3/SiO2/Phenolic Resin Hybrid Materials Produced by Simultaneous Twin Polymerization of Spiromonomers

“…The spectra in Figure clearly show a high amount of o , o ′‐substitution in the reference sample (bottom spectrum). This result is in agreement with the literature . Thus, increasing content of 2 results in hybrid materials with increased amounts of o , p ′‐substitution, which can easily be monitored by the signals C″ and D″ in the 13 C solid state NMR spectra as already explained before.…”

“…These signals are assigned to a Diels–Alder type product, which may arise by the reaction of chinomethide intermediates with the alkene that is formed during thermal decomposition of the cation (Figure ). The existence of such chinomethide intermediates and their reactions with alkenes in the thermally induced TP is already proven by us and reported for monomer 1 …”

Chiral Spirocyclic Germanium Thiolates - An Evaluation of Their Suitability for Twin Polymerization based on A Combined Experimental and Theoretical Study

“…Resonance signals with chemical shifts centered at δ = 44 and 16 ppm, which are assigned to R 3 CH (R = alkyl) and ortho ‐CH 3 groups, respectively, were also detected. The presence of these signals is indicative for the formation of quinone methides and ortho ‐cresol that have been identified as reactive intermediates in the process of thermally induced TP for precursor A . Note that quinone methide formation was also observed upon heating of 6‐bromo‐2,2‐di‐ tert ‐butyl‐4 H ‐1,3,2‐benzo[ d ]dioxagermine, which is structurally related to compound 3 but contains only one salicyl alcoholate moiety .…”

Functional twin monomers and twin macro monomers as components for the synthesis of hierarchically nanostructured hybrid materials*

“…Principally, twin polymerization of the type 1 monomers can be induced by acid‐ or base‐catalysis or triggered by thermal treatment resulting in formation of interpenetrating networks of phenolic resin and silica (derivatives) as demonstrated in Scheme (2a, left side) . Preliminary investigations were carried out to check radical polymerizability of the monomers of type 2 .…”