Free radical polymerization graft polymers

N. Dissanayake and J. Summerscales, Fife cycle assessment for natural fiber composites, in Green Composites from Natural Resources, pp. 157-181, CRC Press, Boca Raton, FT (2013). V.K. Thakur, M.K. Thakur, and R.K. Gupta, Graft copolymers from natural polymers using free radical polymerization. Int. /. Polym. Anal. Charact. 18, 495-503 (2013). 

Lao HK, Renard E, Langlois V, VaUee-Rehel K, Linossier I. Surface functionalization of PHBV by HEMA grafting via LTV treatment comparison with thermal free radical polymerization. JAppl Polym Sci 2010 116 288-297. 

In 1966, a new class of polyols that were highly useful in enhancing the modulus of polyurethane foams and elastomers, while maintaining other desirable properties, was introduced to the marketplace (66, 67). These polyols had the unique feature of containing in situ, free-radical polymerized vinyl polymer particles that were grafted to the polyol. The final product, which was termed a polymer polypi, is a conventional or an ethylene oxide-capped poly(propylene oxide) polyol that contains a stable dispersion of the vinyl polymer that acts as a reinforcing filler. When monomers such as acrylonitrile and styrene/acry-... 

In the manufacture of highly resident flexible foams and thermoset RIM elastomers, graft or polymer polyols are used. Graft polyols are dispersions of free-radical-polymerized mixtures of acrylonitrile and styrene partially grafted to a polyol. Polymer polyols are available from BASF, Dow, and Union Carbide. In situ polyaddition reaction of isocyanates with amines in a polyol substrate produces PHD (polyhamstoff dispersion) polyols, which are marketed by Bayer (21). In addition, blending of polyether polyols with diethanolamine, followed by reaction with TDI, also affords a urethane/urea dispersion. The polymer or PHD-type polyols increase the load bearing properties and stiffness of flexible foams. Interreactive dispersion polyols are also used in RIM appHcations where elastomers of high modulus, low thermal coefficient of expansion, and improved paintabiUty are needed. 

Yin et al. [73,74] prepared new microgel star amphiphiles and stndied the compression behavior at the air-water interface. Particles were prepared in a two-step process. First, the gel core was synthesized by copolymerization of styrene and divinylbenzene in diox-ane using benzoylperoxide as initiator. Microgel particles 20 run in diameter were obtained. Second, the gel core was grafted with acrylic or methacryUc acid by free radical polymerization, resulting in amphiphilic polymer particles. These particles were spread from a dimethylformamide/chloroform (1 4) solution at the air-water interface. tt-A cnrves indicated low compressibility above lOmNm and collapse pressnres larger than 40 mNm With increase of the hydrophilic component, the molecnlar area of the polymer and the collapse pressure increased. 

Radical grafting, 10 206 Radical-induced decompositions, 14 280 of dialkyl peroxydicarbonates, 14 289 Radical ozone reactions, 17 774 Radical polymerization, 22 40. See also Free-radical polymerization controlling, 14 297 of methacrylic ester polymers, 16 279-290... 

Living free-radical polymerization has recently attracted considerable attention since it enables the preparation of polymers with well-controlled composition and molecular architecture previously the exclusive domain of ionic polymerizations, using very robust conditions akin to those of a simple radical polymerization [77 - 86]. In one of the implementations, the grafting is achieved by employing the terminal nitroxide moieties of a monolith prepared in the presence of a stable free radical such as 2,2,5,5-tetramethyl-l-pyperidinyloxy (TEMPO). In this way, the monolith is prepared first and its dormant free-... 

Dynamic formation of graft polymers was synthesized by means of the radical crossover reaction of alkoxyamines by using the complementarity between nitroxide radical and styryl radical (Fig. 8.13) [40]. Copolymer 48 having alkoxyamine units on its side chain was synthesized via atom transfer radical polymerization (ATRP) of TEMPO-based alkoxyamine monomer 47 and MMA at 50°C (Scheme 8.9). The TEMPO-based alkoxyamine-terminated polystyrene 49 was prepared through the conventional nitroxide-mediated free radical polymerization (NMP) procedure [5,41], The mixture of copolymers 48 and 49 was heated in anisole... 

SIP-driven polymer brush library fabrication leverages the fact that the polymerization initiation species are permanently bound to the substrate. Since the initiators are tethered, controlled delivery of monomer solution to different areas of the substrate results in a grafted polymer library. In NIST work, initiators bound via chlorosilane SAMs to silicon substrates were suitable for conducting controlled atom transfer radical polymerization (ATRP) [53] and traditional UV free radical polymerization [54, 55]. Suitable monomers are delivered in solution to the surface via microfluidic channels, which enables control over both the monomer solution composition and the time in which the solution is in contact with the initiating groups. After the polymerization is complete, the microchannel is removed from the substrate (or vice versa). This fabrication scheme, termed microchannel confined SIP ([t-SIP), is shown in Fig. 10. In these illustrations, and in the examples discussed below, the microchannels above the substrate are approximately 1 cm wide, 5 cm long, and 300-500 [tm high. 

Direct Radiation Grafting of Polymer in the Presence of Vinyl Monomer. This leads to the formation of free radicals on both polymer and monomer, resulting in graft polymerization and homopolymerization. The extent of homopolymerization depends on the sensitivity of the monomer used. 

One method is to measure chain-transfer coefficients with low-MW analogues of the polymer. Thus Gilchrist (140) measured the rate at which 14C labelled decane was incorporated into polyethylene in the free-radical polymerization, and hence obtained an estimate of the transfer coefficient with methylene groups this was in fair agreement with another estimate obtained from the effect of the addition of fractions of linear polyethylene on the Mn of the branched polyethylene, which could be separated from linear polymer plus grafted branched polymer by column extraction. Low MW polymer may be used as a transfer agent Schulz and co-workers (189) obtained chain-transfer coefficients in styrene polymerization from the effect of added low MW polymer on Mn. 

Free radical polymerization of styrene, of acrylate and of methacrylate monomers in solutions at 60° C in the presence of this preformed polymer produced graft copolymers in high efficiency, the chain transfer constants for these mercapto groups with styrene and methyl methacrylate being similar to those found with simple mercaptans (80, 85). 

A graft or block copolymer of cellulose is defined here as a combination of cellulose and polymer that is difficult to separate by solvent extraction without first degrading the cellulose. Furthermore, only proposed mechanisms and reaction methods of free-radical initiated graft and block polymerizations of vinyl monomers with cellulose are discussed. 

PEG molecules which are relatively nontoxic and capable of reducing the interaction between the blood components and man-made materials, can be also tethered to a polymer surface through surface grafting. This has been achieved by free-radical polymerization of methacrylate monomers carrying a pendant PEG chain [71-73]. For instance, the surface of a PU film was subjected to UY-induced graft polymerization of methoxy-PEG methacrylate monomers with numbers of ethylene glycol (EG) units of 4, 9, and 23 [74]. As shown in Fig. 14, the monomer with the shortest PEG length of only 4 EG... 

Organic peroxides are used to initiate free-radical polymerization of ethylene, butadiene, styrene, vinyl chloride, vinyl acetate, and methyl methacrylate. They are also used to cure unsaturated polyesters, occasionally to cross-link thermoplastics such as polyethylene and polyacrylates, and increasingly for grafting and compatibiliza-tion of polymer blends. A variety of organic peroxides offer useful reactivity over a temperature range from 0 to 130°C or more, for different polymers and different processes. 

Cellulose can also be modified by introducing long-chain polymer(s) onto its main chain. The preparation of a graft copolymer requires the formation of a reactive site on cellulose in the presence of a polymerizable monomer. The principal techniques frequently used are (1) grafting initiated by free radical polymerization, (2) grafting initiated by ionic polymerization (3)... 

It is important to pay attention to the potential role of peroxides created on the surface of plasma-treated, including plasma polymer-coated, TPOs in the formation of durable bonds between the substrate and primer. It has been known for decades that the peroxides formed on the irradiated polymers (by y-ray. X-ray, electron beams, etc.) can be utilized in graft copolymerization of various monomers. This method is known as the peroxide method of radiation copolymerization [27]. The trunk polymer is first irradiated by ionizing radiation in a vacuum or in an inert gas environment. The irradiated polymer is exposed to air or oxygen to convert free radicals to peroxides. Thus created peroxides-containing polymers were used as the initiator of the free radical polymerization of the second monomer. The polymer peroxides are decomposed by heat or by the use of reduction/oxidation accelerator, i.e., peroxides are converted to free radicals. 

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