Photolysis polystyrene copolymers

Polystyrene, its copolymers, and its alloys are used in a wide variety of applications where stability to both direct sunlight and filtered or artificial lighting is important. At wavelengths below 300 nm photolysis [12] of polystyrene can result in unacceptable color development (yellowing) along with reduction of physical prop-... 

Poly(styrene)s containing acylperoxide groups are thus obtained by selective photolysis of the azo moieties at 350 or 371 nm. These prepolymers are successively used as macronitiators for the free radical polymerization of vinyl chloride at 70 °C. Styrene/vinyl chloride block copolymers are thus produced [55] by the above two-step route, although relevant amounts (50-60%) of poly(styrene) and poly(vinyl chloride), due to both low peroxide content ( 0.6 groups per macromolecule of polystyrene) and chain transfer with solvent and monomer, are also pre t. 

In this report we examine the effects of several vinyl ketone monomers on the photodegradation of polystyrene in the solid phase. Previous work Sj has indicated that copolymers containing vinyl ketones undergo photolysis by the Norrish type I and type n primary reactions. Studies by Golemba and Gulllet and by Kato and Yone-shiga 0 have shown that these processes also occur in copolymers of styrene with meUiyl vinyl ketone and widi phenyl vinyl ketone. 

Figure 6. Photolysis of 4 1 blends of polystyrene with polystyrene 5% vinyl ketone copolymers...

Product III has not been identified. It has a weak, unstructured fluorescence maximum ca. 390 nm, with an excitation maximum at 332 nm. This product was fully extractable from a photolyzed film with methanol, suggesting that it may be a secondary photolysis product arising from Product II. If nonaltemating sequences exist within the copolymer, Product III might be thought to correspond to the diene observed in the photolysis of polystyrene. However, Product III formed more rapidly in vacuum than in air, the reverse of the manner in which diene appeared to form in polystyrene. 

The self-assembly induced by the photolysis was determined for a poly(4-tert-but05g styrene)- /oc -polystyrene diblock copolymer (PBSt- -PSt) [18] (Figure 2-1). In this photolysis-induced self-assembly, a diblock copolymer produced by the photolysis formed micelles. This new w of molecular self-assembly induced by photoirradiation has the potential to produce new plications for optical memory materials and optical devices using the photoirreversible reaction. 

E. Yoshida and S. Kuwayama, Micelle formation induced by photolysis of a poly(tert-butoxystyrene)-block-polystyrene diblock copolymer, Colloid and Polymer Science, vol. 285, no. 11, pp. 1287-1291, 2007. 

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