Photoinduced crosslinking

Introduction. It is the purpose of this article to report the present status of a research program which has as its goal photoinduced crosslinking of various industrial polymers. The results received for poly(vinyl butyral) and for unsaturated polyester resin in mentioned project, are dealt with. 

Assuming that the yield for gel fraction is proportional to the rate of crosslinking, it seemed that the observation on possibility of resolving the experimental results into terms proportional to I and Ia /2, points out the dual mechanism of photoinduced crosslinking of poly (vinyl butyral). The over all character of the equation (l) suggests that the main role in the discussed reaction plays the relation gel content connected possibly with direct coupling of... 

More recently, iodonium salts have been widely used as photoinitiators in the polymerization studies of various monomeric precursors, such as copolymerization of butyl vinyl ether and methyl methacrylate by combination of radical and radical promoted cationic mechanisms [22], thermal and photopolymerization of divinyl ethers [23], photopolymerization of vinyl ether networks using an iodonium initiator [24,25], dual photo- and thermally-initiated cationic polymerization of epoxy monomers [26], preparation and properties of elastomers based on a cycloaliphatic diepoxide and poly(tetrahydrofuran) [27], photoinduced crosslinking of divinyl ethers [28], cationic photopolymerization of l,2-epoxy-6-(9-carbazolyl)-4-oxahexane [29], preparation of interpenetrating polymer network hydrogels based on 2-hydroxyethyl methacrylate and N-vinyl-2-pyrrolidone [30], photopolymerization of unsaturated cyclic ethers [31] and many other works. 

Negative near-UV resists are derived mainly from photoinduced crosslinking of partially cyclized c/s-l,4-polyisoprene with bisazido sensitisers [15]. Cyclised cis 1,4-polyisoprene is obtained by heating 1,4-polyisoprene in the presence of a Lewis acid (Zn02, AICI3, SnCl4) (Figure 6.9). 

DIZ 13] Dizman C., Uyar T., Tasdelen M.A. et al, Synthesis and characterization of polysulfone/POSS hybrid networks by photoinduced crosslinking polymerization , Macromolecular Materials and Engineering, vol. 298, pp. 1117-1123, 2013. 

STR 03] Strehmel V., Epoxies structures, photoinduced crosslinking, network properties, and apphcations . Handbook of Photochemistry and Photobiology, in Nalwa H.S. (ed.), American Scientific Publishers, vol. 2, pp. 1-110, 2003. 

The photoinduced radical crosslinking of silicone containing pendant acrylate 1 and 3 or methacrylate groups 2 and 4 was investigated by swelling and calorimetric measurements. 

The photoinduced cationic crosslinking of a, co-terminated disiloxanes containing vinyl ether (VEl and VE2) and epoxy flmctional groups (Scheme 1) in dependence of the light intensity and the type of photosensitizers was investigated by means of ceal rime (nfraced (RTIR) spectroscopy and calorimetric measurements. 

Figure 4.28. Molecular structures and photoinduced reactions of common photoresists. Shown (top) is the positive tone resist containing the active diazonapthoquinone (DNQ) chromophore group. Chemical amplification (CAM) reactions are illustrated in (i)-(iii). Reaction (i) represents photoinduced acid generation step (ii) is an acid-catalyzed deprotection mechanism (positive tone resist) and step (iii) is an acid-catalyzed crosslinking mechanism (negative tone resist).

Ruthenium has been incorporated into ODNs, via an oxime conjugate,or through an amide linker. In the latter case, the ruthenium conjugate was used to photo-crosslink with a G residue on a complementary strand. Ruthenium and osmium have been incorporated into ODNs via a C5-phenanthroline dU amidite to study photoinduced energy transfer, and metallocarboranes have been used as redox labels by attachment to 04 of dT. Ferrocene has... 

Takase, H., Natansohn, A., Rochon, P. (2001). Effect of crosslinking on the photoinduced orientation of azo groups in thin polymer films. J. Polym. Sci. Part B Polym. Phys. 39, 1686-1696. 

Photocyclodimerization is now considered to be a major factor in mutagenesis in DNA and polynucleotides. The reaction involves the photoinduced dimerization of pyrimidine bases such as thymine. The crosslinking which results causes a defect in the coding sequence and can cause other cell damage. 

To increase the stability of photoinduced birefringence, we designed new copolymers to contain photocrosslinkable groups, and we analyzed the effect of crosslinking these materials in various conditions on the long-term stability of the photoinduced birefringence. ... 

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