Poly thiourethane

Using poly(thiourethane) (PTU) as a polymer matrix for DHIs is a method for generating transparent polymers that may be used for different purposes, such as in ophthalmic lenses or information recording material. The compounds shown in the scheme (Scheme 23) were studied in such a PTU matrix. Typical fading or bleaching... 

Photochromic materials for information storage can be envisaged on the basis of the system shown in Figure 6.12. The dicyano DHI is a molecule that can be photochemically switched from the colorless form 7 to the colored form 9 and vice versa. So information could be stored with light of A.max = 400 nm and erased by light of A,max = 580 nm. Thus a dicyano-DHI/poly(thiourethane) matrix can be used to record information. In an initial study, the information was shown to last at least a week (Figure 6.12).58 59... 

A novel one-pot synthesis of sulfur-containing polymers including poly(monosulfide)s (polythioethers), poly(disulfide)s, polythioesters, and poly-thiourethanes from a five-membered cyclic dithiocarbonate (5-phenoxjunethyl-l,3-oxathiolane-2-thione) and diamines has been examined. Polythioethers with Mn = 2600-17,700 were obtained by condensation of in situ forming dithiol with o ,a -dibromo-p-xylene [623-24-5] (25). A synthesis by using a bifimctional five-membered cyclic dicarbonate and benzylamine [100-46-9] has also been reported (26). 

Scheme 2.4 Step-growth polymerization via the thiol-isocyanate reaction, yielding poly(thiourethane)s. (Reproduced with permission from AJ. Inglis and C. Bamer-Kowollik, Ultra rapid approaches to mild macromolecular conjugation, Macromolecular Rapid Communications, 2010, 31, 14, 1247-1266. Wiley-VCH Verlag GmbH Co. KGaA.)...

Klemm and Stockle in the convenient preparation of thiol- and isocyanate-terminated thiocarbamate prepolymers, as depicted in Scheme 2.4 (Klemm and Stockl, 1991). By varying the stoichiometry, either di-thiol or di-isocynate functional poly(thiourethane)s could be assembled within 1 h at ambient temperature. 

TABLE 2. Physical Properties of Poly(thiocarbonate-co-thiourethane) Step 2 Derivatives Prepared by Condensing 2,4-Tolylene Diisocyanate with Step 1 Polythiocarbonates Described in Table 1 Prepared According to the Current Invention... 

Interfacial aspects and adhesion of polysulfides have been studied extensively and reported by us [3,17]. The epoxy-modified poly sulfide has improved adhesion due to chemical reactions that increase electronic attraction forces. Water has been found to be the most potent debonding agent in cured polysulfides. Formation of thiourethane is responsible for excellent adhesion of polysulfide onto polyurethane coatings. 

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