Polymerization photoaddition reaction

Polymerization and Crosslinking by the Benzene-Bismaleimide Photoaddition Reaction... 

Direct excitation of the molecules M is performed with UV-light energies below the monomer absorption edge hv < hv (with wavelength 320 nm < K < 370 nm).. The photoaddition polymerization reaction obtained in this way at 10 K is shown for the optical absorptions of the AC-centres (b, c, d,...) in Fig. 15. After preparation of the b photoproduct (see the procedure of Fig. 6) the sequence of the AC centres b->c->d->e->f gis obtained upon 364 nm-irradiation. Simultaneously chain termination reactions leading to the stable oligomers 5 and e are observed. The same reactions are also observed with the diradicals in the ESR and optical spectra. After preparation of the dimer diradical and subsequent 364 nm-irradiation, very effective addition polymerization reactions are observed parallel with chain termination reactions leading to AC-molecules. The same effects are valid for the dicarbene DC species described below (Section 3.2). 

Photodimerization of acetylene to give vinylacetylene (butenyne) and formation of polymers in the photolysis of alkynes generally are examples of photoaddition to alkynes. Photopolymerization of di- and poly-ynes has been studied, and for both conjugated diynes or triynes the polymerization process is a 1,4-addition reaction (equation 34). The products are highly unsaturated, and they tend to contain a high proportion of oxygen after exposure to the atmosphere. 

Schlaad and coworkers " applied another click reaction for glycoconjugation - the thiol-ene reaction. They first synthesized a well-defined poly[2(-3-isobutenyl)-2-oxazoline] scaffold via cationic ring opening polymerization, which was then followed hy the addition of sugar thiols such as acetylated thioglucose via photoaddition to the polymeric vinyl groups (Figure 2.12). 

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