Photo-initial crosslinking polymerization

Zhuo and co-workers have synthesized PPE linkage-containing hydrogels based on PEG by photo-initial crosslinking polymerization of the... 

Jacobine AF, Glasser DM, Nakos ST. Photo-initiated crosslinking of norbomene resins with multifunctional thiols. In Hoyle CE, Kinstle JF, eds. Radiation Curing of Polymeric Materials. ACS Series 417. Washington DC American Chemical Society 1990 160—175. 

Photo-initiated polymerization of pendant vinyl ether groups attached to a polystyrene backbone has been used as a convenient method of crosslinking. However, the potential commerical importance of this is marred by the fact that a slow thermal initiation involving the acceptor is also possible and occurs, for example, during processing of the carrier polymer. ... 

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. 

Recently, semirigid-rod diacrylate compounds were investigated by Hikmet et al. in order to obtain densely crosslinked LC network materials [57] as well as loosely crosslinked anisotropic gel [58-60]. Copolymerization of an LC monoacrylate having a chiral group and LC diacrylate led to a ferroelectric LC network. In a series of papers by Broer et al. [48,49,61,62], highly crosslinked LC networks were prepared by the photopolymerization of diacrylate LC monomers. Photo-polymerization allowed control of the initiation of polymerization and, therefore, the temperature of polymerization. Orientation was induced using surface treatment technique as applied in liquid crystal display, such as a rubbed polyimide film. The resulting ordered networks showed anisotropic behavior in a number of physical properties, such as coefficient of thermal expansion, modulus of elasticity, and refractive index. 

Network properties. The UV-cured materials obtained by crosslinking polymerization of mixed donor-acceptor monomers or by crosslinking copolymerization of multifunctional allyl monomer with an acceptor comonomer in presence of 1 wt-% of TPO (diphenyl-(2,4,6)-tri-methylbenzoyl)phoshine oxide) as photo-initiator were placed between glass lids allowing for the formation of 1 mm-thick samples after... 

Mixed donor-acceptor monomers. The glass transition temperature of FAIR polymerized with 1 wt-% of TPO as photo-initiator gradually increases with irradiation time (Fig. 7) and conversion (Fig. 8). Furthermore, the glass transition broadens as the crosslinking proceeds due to increasing heterogeneity within the material. For a final conversion of... 

Another important molecule which is very largely used in several applications of hybrids is 3-methacryloxypropyltrimethoxy silane (MPTMS). This organically modified aUcoxide is characterized by a C=C double bond that can be opened to form an organic network the crosslinking reactions are generally thermally induced or catalyzed by a photo-initiator. FT-Raman can be used, in combination with FTIR, to follow the polymerization. The assignments of the most important modes in MPTMS are reported in Table 7-2. 

The chemistry of UPRs involves the synthesis of unsaturated polyesters (UPs) by polyesterification or step-by step ionic copolymerization. The thus synthesized UP is then dissolved in an unsaturated monomer and crosslinked applying the radical polymerization approach. Thus, the chemistry of UPRs involves the polycondensation or ionic polymerization methods and crosslinking by peroxide or photo chemically initiated radical polymerization. 

Photo-polymerization was conducted at 254 nm under a modified fluorescent microscope. Allyl-oligonucleotides were employed with methylene blue as the free radical initiator for crosslinking. In the case of proteins, acryloyl streptavidin was first immobilized so that biotinylated proteins could be applied to the gel pad (Vasiliskov et al., 1999). One of the major drawbacks with the gel pad approach was that separate pads had to be manufactured instead of coating the enhre slide with the gel and then printing down the microarray. 

Treatment of the monomer with an acidic catalyst leads initially to polymers of low molecular weight and ultimately to crosslinked, black, insoluble, heat-resistant resin (17). Despite their reportedly excellent properties, virtually no commercial use of such resins exists outside the Soviet Union. The structure and polymerization mechanism of these furfural-ketone polymers are described in a recent study (18). An excellent combustion-resistant resin has been reported (19) from the addition of dialkylphosphites to bis(2-furfurylidene) ketone (6). Furfural condensates with other aliphatic and aromatic ketones have been reported (20,21) to provide photo-crosslinkable resins and hypergol components. 

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