Poly irradiation with monomer

Monomer 44a was also found to electropolymerize on indium-tin-oxide (ITO) under potential-sweep conditions (Figure 33). The resulting film poly-44a) can be electrically doped by oxidation, as was demonstrated by UV/Vis spectroelectrochem-istry (oxidative dotation leads to a broad absorption band beyond 1000 nm). We found that on irradiation with a 500 W incandescent lamp the pristine film (at 0 mV vs. Ag/AgCl) gave rise to the formation of the VHF form poly-44b). Under thermal conditions, the DHA spectrum could be restored (Figure 34). 

Polymerization of Styrene Solutions of Volatile Hydrocarbons. Addition of Hydrocarbon before Polymerization. Bulk Polymerization. Expandable polystyrene was prepared inadvertently in 1945 in an attempt to bulk copolymerize 10% isobutylene with styrene. The product formed a low density foam when heated (96). An early method (1950) for rendering polystyrene expandable by petroleum ether was to dissolve 6 parts of petroleum ether in a 40% solution of polystyrene in benzoyl peroxide-catalyzed styrene and to hold the mass for 28 days at 32 °C. (124). In a recent version of this process, the monomer (chlorostyrene) and blowing agent (trichlorofluoromethane) in a poly (vinyl fluoride) bag were irradiated with y-rays (105). 

First, the authors prepared PEG with an anthracene group at one end of the polymer chain. Then, the modified polymer was treated with a-CD to formp5eudo-polyrotaxane. Finally, the p5eudo-polyrotaxane was capped with 9-anthracene carboxylic acid to obtain polyrotaxane (Scheme 10). The ratio of CD and monomer units was found to be 4 1 (ethylene glycol unit CD) by NMR. When a DMSO solution of a-CD-polyrotaxane was irradiated with visible fight (A > 340 nm) (500 W Xe lamp with UV cut filter) under argon, poly(Q -CD-polyrotaxane) was precipitated out. The NMR spectrum of the product showed broad resonance bands due to a-CD and PEG and the absence of the absorption bands due to monomeric 9-anthracene. Characteristic absorption and emission bands due to monomeric 9-anthracene have completely disappeared. 

When poly(BOMA-co-MMA)s are subjected to UV irradiation in benzene solution, in the absence of any monomer, extensive degradation takes place [55,75], thus confirming the occurrence of a photocleavage mechanism. Similar results have been found [55] by irradiation in monomer-free benzene solution of the copolymers of 1-phenyl-1,2-propanedione-2-0-methacryloyloxime with MMA [poly(POMA-co-MMA)], although a much higher efficiency of main chain degradation is obtained (Scheme 18 and Table 14). 

Polymer radicals, that have radical centers on the backbone chain to initiate grafting, can also be produced by irradiation of a polymer-monomer mixture with ionizing radiation. Most radiation graft polymerizations are carried out as heterogeneous reactions. The typical reaction system involves equilibration (swelling) of polymer with monomer followed by irradiation of the monomer-swollen polymer while immersed in excess monomer. For example, to produce poly(ethylene-gra/t-styrene),... 

Experimental details.1503 A mixture of the monomer 579 (1 3 mg) and a photoinitiator ( 3 wt%) in a sample (open-air) cell was irradiated with a high-pressure mercury discharge lamp (200 W) (Figure 3.11). In order to prevent evaporation of the monomer, the cell was covered with a thin poly(ethylene terephthalate) film. The extent of polymerization was evaluated by differential photocalorimetry. 

Materials for intervertebral disc replacement — Interpenetrating polymer networks based on crosslinked poly(vinyl alcohol) were prepared by impregnating the PVA matrix with hydrophilic and hydrophobic monomers and subsequently irradiating with gamma rays [22],... 

A widely studied commercially available polymer is poly(methylmethacrylate) (Fig. 14.2). It is a polymer that can be completely depolymerized by heating above the ceiling temperature (7c). It is possible only to achieve 100% monomer as product by laser irradiation with a C02 laser (2 9.6 or 10.6 pm) [71]. About 1% monomer can be detected in the ablation products after irradiation with 248 nm laser light, and about 18% monomer can be produced with 193 nm [71,72]. 

Ag-poly(butyl acrylate-co-styrene) nanocomposites were prepared by Yin et al. [410] where the silver nanoparticles were obtained from a microemulsion. An aqueous solution of AgN03 was added to a mixture of toluene, butylacrylate, styrene, sodium dodecyl sulfate and 2-hydroxy-a-methacrylate (HEMA). A transparent microemulsion formed after addition of Span 80 under stirring. This product was bubbled with N2 and irradiated with to y-ray source for 6h (the irradiation helped both polymerization of monomers and reduction of metal ions). Silver particles, collected after de-emulsification by acetone and water, had an average size of about 8.5 nm. 

An attempt to determine the quantitative characteristics of the ageing of PS and poly- -butylmethacrylate (PTBMA) under the action of NO has been undertaken by Huber [7]. Samples were exposed to a stream of air containing NO (2.5 x 10 to 3.7 X 10" mol/1) at 300 K and simultaneously irradiated with light (A,>290 nm). The number of chain scission per 10,000 monomer units a( ) can be described by the empirical equation ... 

In the next paper, the same method was applied for polymerization of vinyl monomers such as AA, acrylic anhydride, acrylonitrile, methyl acrylate, MMA, and methyl vinyl ketone, and, in all cases, stereoregular polymers were obtained. The molecular weight of the clathrate-synthesized polymers were similar to those of polymers prepared in the bulk phase. The overall experimental approach was as follows the monomer molecules were absorbed into the crystal framework of the pure host. Polymerization of the dathrated monomer was induced by y-irradiation at low temperature (-29 °C or -78 °C). After irradiation, unreacted monomer was removed in vacuo and any polymer external to the host crystals was removed by washing with solvent. Then, induded polymer was removed by extraction and purified. As a result, isotactic poly(acrylonitrile), poly(methyl acrylate), and poly (vinyl ketone) and syndiotactic PAA and PMMA were obtained. 

Figure 2 Simplified mechanism of free radical chain polymerization. On heating or by UV-irradiation, the initiator generates free radicals 1 whose reaction with methyl methacrylate 2 creates the active species 3. Further reaction with monomer molecules leads to poly(methyl methacrylate) PMMA 4. Applied to 2,3-epoxypropyl methacrylate 5 this process gives the linear aliphatic polymer 6 with pendent epoxy groups.

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