Spiro monomer

The spiro monomers 57-59 are reported to give single ring-opening.27 5 27> Solution polymerization of 57m and 58 (R CH3, R C3H7) 4 provided soluble products. 

Reduction of Carbon-epoxy Spiro monomer 50 15 Izod impact... 

Cationic polymerization of spiroorthoesters is of interest because, in contrast to the vast majority of polymerization processes, conversion of spiro monomer into linear polymer is accompanied by expansion in volume. In the first report on the cationic polymerization of 1,4,6-trioxaspiro[4.4]-nonane ... 

Finally, the unsaturated spiro-ort -carbonate shown in reactions 12 and 13 undergoes double ring opening during free radical copolymerization so as to introduce carbonate groups into the backbone of an addition polymer. Therefore, telechelic polystyrene containing two primary hydroxy chain ends is obtained by hydrolysis of the copol5uner from styrene and the spiro monomer. 

An interesting modification involves expandable monomers. These materials, synthesized by Dr. William J. Bailey and coworkers at University of Maryland, are spiro monomers, double rings which open and expand on polymerization. They can be useful in adhesives which are based on polymer/monomer solution, such as structural acrylics, radiation-cured acrylates, etc. These monomers can counteract shrinkage on curing, which is detrimental to adhesion. 

Polymers obtained by homopolymerization of spiropho-sphoranes have higher molar mass than their analogues from zwitterionic copolymerization, probably because of higher purity of the spiro monomers and an Inherent stoichiometry. ... 

Details are given of the successful construction of a novel reversible system of network polymers between bifunctional monomers by utilising the equilibrium polymerisation system of a spiro orthoester. Molecular structures were determined by NMR and IR spectroscopy. 9 refs. 

Sulfur-containing spiro orthocarbonates, cationic polymerization of, 23 729 Sulfur-cured EPDM, 21 8041. See also Ethylene- propylene-diene monomer (EPDM) rubber Sulfur deposits... 

Apparently, the driving force for the ring opening is the relief of the strain in the spiro system and the formation of the stable carbonate double bond. The double ring opening is probably a concerted process from the initial radical addition product to the open-chain radical. Even though the spiro compound XI is an allyl monomer, it does copolymerize with a wide variety of comonomers. 

Fig. 7.25. Impacl fracture toughness (O) and interlaminar shear strength (ILSS, ) of unidirectional carbon fiber-epoxy matrix composites as a function of expanding monomer (spiro) content. After Lim...

Source-based nomenclature identifies the starting monomer(s) from which the doublestrand polymer is prepared with addition of an appropriate prefix "ladder- or "spiro- . Examples are ... 

Spiro orthoesters (92, R = Me, Ph, and H) show typical equilibrium polymerization behavior at or below ambient temperature. [92] The poly(cyclic orthoester)s derived from 92 depolymerize to the monomers, although they have sufficient strains to be able to undergo ring-opening polymerization. The polymerization enthalpies and entropies for these three monomers were evaluated from the temperature dependence of equilibrium monomer concentrations (Table 5). The enthalpy became less negative as the size of the substituent at the 2-position in 92 was increased H < Me < Ph. This behavior can be explained in terms of the polymer state being made less stable by steric repulsion between the bulky substituents and/or between the substituent and the polymer main chain. The entropy also changed in a similar manner with the size of the substituents. 

Cationic polymerization of norbomene spiro orthocarbonate (125) differs from that of other spiro orthocarbonates in that it gives a structurally complicated polymer. [102] When polymerized with boron trifluoride etherate at 100 °C in chlorobenzene for 24 h, the 1H NMR of a polymer of 125 showed very reduced olefinic proton signals (22% of the original monomer). The monomer was... 

Scheme 20 [103] shows that the polymerization of 131 proceeds via a stable tris(alkylthio)carbenium ion 135. This species can be attacked in three different ways by the second monomer, producing 134, 133, and 132 via paths a, a, and b, respectively. Kinetically, path a should dominate over the others. Path a is one of the possible pathways, but presumably it is of minor importance. Although the conversion of 134 to 132 cannot be ruled out, 132 is more likely to be formed via path b, as is the case with six-membered spiro orthocarbonates. At high... 

Endo, Suzuki, Sanda, and Takata [57] showed (Fig. 14b) that dithiol-linked bifunctional spiro orthoesters 48 can generate cross-linked polymers 49 in the bulk under acidic conditions (2 mol% CF3COOH). The increase of the temperature shifts the equilibrium in favor of the monomer. Conversely, the cross-linked polymers can be depolymerized from CH2C12 suspensions to form the initial monomers, also under acidic conditions (5 mol% CF3COOH). The yield of these processes is not quantitative. 

Spiro-ketal nitroxides have been prepared that are effective as regulators in nitroxide mediated polymerizations. These agents have high hydrocarbon and monomer solubility over existing nitroxides, particularly in styrene, and are also effective as regulators in vinyl acetate and acetonitrile polymerizations. 

TABLE 8.1 Spiro [pyrrolidine-2,3-oxindole] Discrete Library L5 Chemistry Assessment and Monomer Rehearsai... 

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