Divinyl oligomer

The waveguide is made by laser irradiation of a thin liquid layer, enclosed between two glass plates. The liquid is a divinyl oligomer containing uranyl perchlorate as a photoinitiator. After removal of the cover glass and the unexposed material, the... 

Deionized water (720 g), sodium lauryl sulfate (4.3 g), dioctanoyl peroxide (40 g), and acetone (133 g) were emulsified using an ultrasonic probe for 10 minutes. The step 1 polystyrene seed (48.0 g seed, 578 g latex) was added to the emulsion together with lauryl sulfate (0.8 g) and acetone (29.6 g). The mixture was transferred to a flask and left to agitate at approximately 25°C for 48 hours. Acetone was then removed and the solution added to a 5-liter double-walled glass reactor. The temperature was increased to 40°C while styrene (336 g) and divinyl benzene (0.88 g) were added drop-wise over approximately 60 minutes. After 4 hours the mixture was treated with deionized water (1200 g), potassium iodide (1.28 g), and polyvinyl pyrrolidone (18.48 g) with the temperature increased to 70°C. The polymerization continued for 6 hours at 70°C and 1 hour at 90°C. Styrene-based oligomer particles with a diameter of 1.7 pm and with a narrow size distribution were obtained. 

Acyclic diene metathesis (ADMET) polymerization of divinyl benzene, shown in Scheme 37, using an extremely reactive tungsten alkylidene catalyst (Schrock s catalyst) yielded PPV oligomers with DP of 8 [153]. In this example ethylene is formed as a side product of metathesis, and its removal by the use of high vacuum helps drive the polymerization in the forward direction. 

In this method mono- or dihydroxy-terminated polyoxyethylene oligomers are reacted in bulk with potassium metal at 120 °C, thus converting quantitatively the hydroxy groups into potassium alcoholate functions. Then, the medium is heated up to 180 °C and acetylene is added. This addition to the alcoholates quantitatively produces mono- or divinyl-terminated polyoxyethylenes, respectively ... 

On the other hand, divinyl-substituted organosilicon compounds in the presence of ruthenium and rhodium complexes containing or generating M-H and M-Si (M = Ru, Rh) bonds undergo competitive silylative coupling cyclization and polycondensation to give a mixture of oligomers and... 

The silylative coupling reaction of l,2-bis(dimethyIvinylsiloxy)ethane was effectively catalyzed by 1 mol% of ruthenium hydride catalyst, and the divinyl compound was completely consumed within 1 h at 80 °C. The reaction successfully proceeded without the solvent under air, but toluene could also be employed without affecting either the activity of the catalyst or the selectivity of this process. Application of this catalytic system for silylative coupling cyclization of l,2-bis(dimethyl-vinylsiloxy)ethane gave exclusively a cyclic product (Isolated yield 85%) with the exo-methylene bond between two silicon atoms in the molecule (2,2,4,4-tetramethyl-3-methylene-l,5-dioxa-2,4-dlsilacycloheptane) accompanied only by trace amounts of oligomers. 

Hydrosilylation of unsaturated organosilicon compounds has also found several applications in molecular and polymer organosilicon chemistry. In particular, the addition of polyfunctional silicon hydrides to poly(vinyl)organosiloxane, catalyzed exclusively by Pt compounds and providing an activated cure for silicon rubber [10], has been of great practical importance. Hydrosilylation of the vinyl group at silicon seems to be effective synthetic method for preparation of oligomers and polymers with a linear or cyclolinear stmcture (polyhydrosilylation), and can occur either via the addition of dihydro-carbosilanes and -siloxanes to divinyl-silanes and -siloxanes [25, 26] or by intermolecular hydrosilylation [4] (eq. (1)). 

Hyperbranched polymers were synthesized by direct free-radical polymerization of ethylene glycol dimethacrylate monomer in the presence of a CCT catalyst. The free-radical homopolymerization of divinyl monomers is thought to selectively yield trimer 96,32i 322 though previous work on oligomer distributions would indicate that this is unlikely. 

For use in plastics, this might require chain extension with diisocyanates, bisoxazolines, carbodiimides, bis(an-hydrides), and such. One use of the oligomers would be to form polyurethanes by reaction with isocyanates. The use of acid chlorides can be avoided if the polymers are made by ester exchange or made enzymatically, with compounds such as divinyl adipate. Poly(butylene sebacate) with a molecular weight of 46,400 has been made has been made from bis(2,2,2-trifluoroethyl)sebacate and 1,4-butane diol.150 One polyester with a molecular weight of 24,000 has been made by ester exchange from isosorbide and a... 

Other less reactive monomers were incorporated into chain ends of oligomers, including divinyl benzene for MMA [138] and maleic anhydride for styrene [139] (Scheme 21) and methacrylates [140]. The method for the synthesis of maleic anhydride terminated PS is based on the fact that maleic anhydride cannot be homopolymerized under normal conditions [141]. These maleic anhydride terminated PSs were used for the compatibilization of the nylon 6-PS binary system in the melt by reaction with NH2-terminated polyamide. 

Two types of methathesis polymerization have been used to make PAVs. Thorn-Csanyi and coworkers have used transition-metal-mediated metathesis of divinyl-benzenes to make alkyl- and alkoxy-substituted PPVs, but the products are primarily oligomers [53,54]. 

Keywords silylative coupling, divinyl silyl etiiCTs, l,l-bis(silyl)ethenes, siloxylene-alkylene-vinylene oligomers, ruthenium hydride catalyst... 

As has already been mentioned, divinyl silicon derivatives, similarly to monovinyl-substituted silicon compounds, are also completely inert to productive homometathesis, particularly as far as acyclic diene metathesis (ADMET) polymerization is concerned. However, we have shown in earlier reports that in the presence of ruthenium, rhodium and cobalt complexes containing or generating M-H and/or M-Si bonds, divinyl-substituted silicon compounds undergo de-ethenated (poly)condensation to yield a mixture of oligomers and cyclic unsaturated siloxanes, silazanes and caibosilanes, as shown in Scheme 2 [21-29]. 

Toy et al. [12] demonstrated that by replacing divinyl benzene with more flexible compounds usually increases their mechanical stability and allows them to absorb more solvent. In addition, when the cross-linked compounds contain oligomers of such materials as ethylene glycol, the compatibility with polar solvents increases. Subsequently, Janda and coworkers used polytetrahydrofuran in suspension polymerization of styrene to prepare general solid support resins for organic syntheses [13],... 

METATHESIS POLYCONDENSATION OF SUBSTITUTED p-DIVINYL-BENZENES A WAY TO EASILY PROCESSABLE /i-PHENYLENEVINYLENE (PV) OLIGOMERS WITH VALUABLE PROPERTIES... 

Rudewicz and Munson [45] used this technique for the direct determination of additives in PP. The technique has also been used to determine oligomers in polyacrylates, PEG, siloxanes and polycarbonates [87], polyglycols [88] and adhesion promoters, primers and additives in the surface of PET film [89], volatile antioxidants in styrene-butadiene rubbers [34, 50], mercaptobenzothiazole sulfenamide accelerator in rubber vulcanisates [90] and divinyl benzene in styrene-divinyl benzene copolymer [91]. 

Petro and co-workers [31] used a moulded monolithic rod of macro porous PS-divinyl benzene copolymer as a separation medium for the HPLC of styrene oligomers and copolymers, e.g., styrene-2-naphthyl-methacrylate. On column precipitation redissolution chromatography is an alternative to size-exclusion chromatography (SEC). The solvent gradient used comprises a poor solvent (water, methanol, acetonitrile) and increasing amounts of a good solvent such as tetrahydrofuran. 

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