Free Radical Initiator Modifiers

Title A-Alkoxv-4,4-Dioxy-Polyalkyl-Piperidine Compounds, Their Corresponding iV-Oxides, and Controlled Radical Polymerization Therewith 

Assignee Ciba Specialty Chemicals Corporation (Tarrytown, NY) 

Patent Application Material Patentability Anticipated Issuing Date  

Research Focus Synthesis of lV-alkoxy-4,4-dioxy-piperidine and A-oxide derivatives for use as controlling agents in free radical polymerization reactions. 

Application Free radical chain transfer agents 

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Free Radical Initiator Modifiers a. Piperidine N-oxide derivatives... 

Polymers ndResins. / fZ-Butyl peroxyneopentanoate and other peroxyesters of neopentanoic acid can be used as free-radical initiators for the polymeri2ation of vinyl chloride [75-01-4] (38) or of ethylene [74-85-1]. These peresters have also been used in the preparation of ethylene—vinyl acetate copolymers [24937-78-8] (39), modified polyester granules (40), graft polymers of arninoalkyl acrylates with vinyl chloride resins (41), and copolymers of A/-vinyl-pyrrohdinone [88-12-0] and vinyl acetate [108-05-4] (42). They can also be used as curing agents for unsaturated polyesters (43). 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

Hill and (letin (2000) modified the surfaces of wood veneers with methacrylic anhydride (Figure 6.6a) and formed lap joints using either styrene or methyl methacrylate in the presence of the free radical initiator azoisobutyronitrile. Significant improvements in bond strength were found when compared to unmodified wood. 

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. 

Commercial products based on copolymers of ethylene and TEE are made by free radical-initiated addition copolymerization.69 Small amounts (1 to 10 mol%) of modifying comonomers are added to eliminate a rapid embrittlement of the product at exposure to elevated temperatures. Examples of the modifying comonomers are perfluorobutyl ethylene, hexafluoropropylene, perfluorovinyl ether, and hexafluoro-isobutylene.70 ETFE copolymers are basically alternating copolymers,70 and in the molecular formula, they are isomeric with polyvinylidene fluoride (PVDF) with a head-to-head, tail-to-tail structure. However, in many important physical properties, the modified ETFE copolymers are superior to PVDF with the exception of the latter s remarkable piezoelectric and pyroelectric characteristics. 

The chlorination of alkyl aromatics by sulfuryl chloride promoted by free-radical initiators, which was originally discovered by Kharasch and Brown990, can be modified by incorporation of transition metal complexes. Matsumoto and coworkers have observed that, upon addition of Pd(PPh3)4, in place of a radical initiator, the side-chain monochlorination of toluene is substantially more selective991. Davis and his colleagues992 have extended this study and report that Pt(0) and Pd(0) are effective initiators for side-chain chlorination of toluene by sulfuryl chloride and dichlorine. Mn, Re, Mo and Fe complexes, on the other hand, behave more like Friedel-Crafts catalysts. Gas-phase chlorination of olefins to allyl chlorides is catalyzed by PdCl2 or by PtCl2993. 

Polyvinyl chloride-montmorillonite nanocomposites were prepared either by in-situ suspension polymerisation using initiator- and comonomer-modified montmorillonite in the presence of free-radical initiators, such as AIBN, and compared. It was found that monomer conversion was low when the nanocomposites were prepared using initiator-modified montmorillonite. Exfoliated nanocomposites... 

Recently, biodiesel has been used as a solvent in free radical-initiated polymerization reactions (Figure 5.8). It should be noted that in contrast to polymerization reactions in some other green solvents, including SCCO2, there is no need to modify the initiator for reactions in biodiesel. All the resulting polymers except poly(methyl methacrylate) were soluble in the biodiesel. Lower molecular weights were obtained compared with conventional polymerization... 

A two-step synthesis of modified 2 -C-nucleoside precursor, ethyl [2-(5-methyl-2,4-dioxo-3,4-dihydro-2i/-pyrimidin-l-yl)-4-hydroxyl-5-hydroxymethyltetra-hydrofuran-3-yl]fluoro-acetate 172, from protected glycal 170 and xanthate has been developed following the same idea, and a diastereomeric 1 1 mixture of 2,3-trans product 171 was obtained in 57% yield (O Scheme 46). The use of triethylborane as a free-radical initiator was less successful and a longer reaction time was also required. Interestingly, introducing th)miine at C-1 in the presence of silver triflate at 0°C was highly stereoselective, and only a C, C2-trans linked product was detected. 

Because the free radical initiated graft reaction can also lead to the cross-linking of polyethylene, copolymers of ethylene and with acrylic acid (184,185), glycidyl methacrylate (184,186), methacrylic acid and 10-undecenoic acid (187-189) were synthesized to compatibilize polyethylene/polyamide blends. The poly (ethylene-co-methacrylic acid) ionomers neutralized by sodium (184) and zinc (45,118,190-192) has also used as compatibilizers. High energy irradiation, used to modify the surface of fibers or films at beginning, was also used to compatibilize the polyethylene/polyamide blends (193-196). 

The reason that the designation resin-modified is preferred to light-cured (or light-curable ) is that these latter terms incorrectly imply that the characteristic acid-base reaction is initiated by irradiation with light. It should be noted, however, that unfortunately this term has been widely used for these materials, including in the first two scientific papers describing the properties of the first commercially successful formulation [3,4]. The option dual-cure is rendered inappropriate because of the possibility of tri-cure formulations, where the monomer is polymerized both by photo-initiators and two-component free radical initiators, both of which complement the acid-base cure process. Consequently, it is possible in principle to have a dual-cure material in which there is no acid-base reaction, and the system is not a giass-ionomer at all. 

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