Acrylonitrile Block Copolymer

Economically produced block copolymers containing acrylonitrile or methacrylo-nitrile as the principal component have been prepared that are heat resistant, weath-erable, and oil and flame resistant. These materials were prepared using reversible addition-fragmentation chain transfer polymerization. 

A reactor was charged with water (490 g), sodium dodecyl sulfate (0.56 g), acrylonitrile (8.8 g), and cumenyl thiobenzoic acid (1.09) and then heated to 80°C for 20 minutes. This solution was treated with 4,4 -azobis(4-cyanovaleric acid) (0.93 g) and additional water (25 g) and then stirred for 30 minutes. Thereafter additional acrylonitrile (45.0 g) was added dropwise over 1 hour, and the mixture heated for approximately 5 hours. A sample was taken that indicated thepolymer had aMwOf 13,700daltonsandM of 10,300daltons with a polydispersity index of 1.33. The mixture was then treated with n-butyl acrylate (20.0 g), 4,4 -azobis(4-cyanovaleric acid) (0.40 g), and water (10 g) and stirred 1 hour at 80°C. The mixture was further treated with n-butyl acrylate (80.0 g) over 2 hours and 

Preparation of Mercapto-Terminated Poly(Acrylonitrile-b-n-Butyl Acrylate) 

The Step 1 product (50 g) was dissolved in 200 ml of toluene and treated with ethylamine (15 g) and stirred 8 hours at 30°C. The toluene solution was washed with water and then poured into methanol to precipitate and the product isolated. H-NMR and FTIR analyzes confirmed that the end groups had been quantitatively converted into mercapto groups. 

Selected diblock polymers are provided in Table 1. Izod impact strength and flame retardancy testing are provided in Table 2. Flame retardancy was measured according to the UL-94 standard. 

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A number of methods such as ultrasonics (137), radiation (138), and chemical techniques (139—141), including the use of polymer radicals, polymer ions, and organometaUic initiators, have been used to prepare acrylonitrile block copolymers (142). Block comonomers include styrene, methyl acrylate, methyl methacrylate, vinyl chloride, vinyl acetate, 4-vinylpyridine, acryUc acid, and -butyl isocyanate. 

MOPVC Modified PVC CPVC Chlorinated PVC ASA Acylonitrile-styrene-acrylonitrile block copolymer PVDF Polyvinylidene fluoride ... 

In addition to graft copolymer attached to the mbber particle surface, the formation of styrene—acrylonitrile copolymer occluded within the mbber particle may occur. The mechanism and extent of occluded polymer formation depends on the manufacturing process. The factors affecting occlusion formation in bulk (77) and emulsion processes (78) have been described. The use of block copolymers of styrene and butadiene in bulk systems can control particle size and give rise to unusual particle morphologies (eg, coil, rod, capsule, cellular) (77). 

Block copolymers of vinyl acetate with methyl methacrylate, acryflc acid, acrylonitrile, and vinyl pyrrohdinone have been prepared by copolymeriza tion in viscous conditions, with solvents that are poor solvents for the vinyl acetate macroradical (123). Similarly, the copolymeriza tion of vinyl acetate with methyl methacrylate is enhanced by the solvents acetonitrile and acetone and is decreased by propanol (124). Copolymers of vinyl acetate containing cycHc functional groups in the polymer chain have been prepared by copolymeriza tion of vinyl acetate with A/,A/-diaIlylcyanamide and W,W-diaIl5lamine (125,126). 

The composition of block copolymers and, in particular, alternation of PAN and PEO blocks in the macromolecule of copolymers depends on the ratio between PEO and acrylonitrile in the reaction system. At low PEO concentrations in the reaction mixture a tri-block copolymer is probably formed with the following alternation of blocks ... 

Seymour and coworkers (27,28,29,30) actually used these composition gradients to prepare block copolymers by swelling particles containing occluded (i.e., living) macroradicals with a second monomer. Such block copolymers were prepared from occluded vinylacetate, methyl methacrylate, and acrylonitrile macroradicals, and the yield of block copolymers was studied as a function of the solubility and rate of diffusion of the swelling monomer in the particles. 

We commonly copolymerize styrene to produce random and block copolymers. The most common random copolymers are styrene-co-acrylonitrile and styrene-co-butadiene, which is a synthetic rubber. Block copolymerization yields tough or rubbery products. 

We have considerable latitude when it comes to choosing the chemical composition of rubber toughened polystyrene. Suitable unsaturated rubbers include styrene-butadiene copolymers, cis 1,4 polybutadiene, and ethylene-propylene-diene copolymers. Acrylonitrile-butadiene-styrene is a more complex type of block copolymer. It is made by swelling polybutadiene with styrene and acrylonitrile, then initiating copolymerization. This typically takes place in an emulsion polymerization process. 

Methyl methacrylate (MMA), 16 227 Alfrey-Price parameters, 7 617t azeotropic mixtures with, 16 236t block copolymer synthesis, 7 647t C-2 routes to, 16 252-254 C-3 routes to, 16 246—252 C-4 routes to, 16 254—257 carbon monoxide in production of, 5 6 chain-transfer constants for, 16 284t comonomer with acrylonitrile, 1 451t cumene as feedstock, 8 156 in flame-retardant resin formulation,... 

Uses Copolymerized with methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, or 1,1-dichloroethylene to produce acrylic and modacrylic fibers and high-strength fibers ABS (acrylonitrile-butadiene-styrene) and acrylonitrile-styrene copolymers nitrile rubber cyano-ethylation of cotton synthetic soil block (acrylonitrile polymerized in wood pulp) manufacture of adhesives organic synthesis grain fumigant pesticide monomer for a semi-conductive polymer that can be used similar to inorganic oxide catalysts in dehydrogenation of tert-butyl alcohol to isobutylene and water pharmaceuticals antioxidants dyes and surfactants. 

E4 polystyrene-Z)/ocA -[l,4-polybutadiene-grq/Z -poly(styrene-co-acrylonitrile)] (copolymer from styrene and acrylonitrile grafted to a 1,4-polybutadiene-polystyrene two-block copolymer at unspecified sites of some of the but-2-ene-... 

ABS Three-component copolymer of acrylonitrile, butadiene, and styrene, alloy Rubber-toughened materials in which the matrix can be a mixture of polymer tyrpes. alternation copolymer Ordered copolymer in which every other building is a different mer. azeotropic copolymer Copolymer in which the feet and composition of the copolymer are the same, blends Mixtures of different polymers on a molecular level may exist in one or two phases, block copolymer Copolymer that contains long sequences or runs of one mer or both mers. 

Draw representative structures for (a) homopolymers, (b) alternation copolymers, (c) random copolymers, (d) AB block copolymers, and (e) graft copolymers of styrene and acrylonitrile. 

Several polymers based on 1,3-dienes are used as elastomers. These include styrene-1,3-butadiene (SBR), styrene-1,3-butadiene terpolymer with an unsaturated carboxylic acid (carboxylated SBR), acrylonitrile-1,3-butadiene (NBR or nitrile rubber) (Secs. 6-8a, 6-8e), isobutylene-isoprene (butyl rubber) (Sec. 5-2i-l), and block copolymers of isoprene or... 

Acrylonitrile monomer when masticated in the presence of polymer leads to the formation of pseudocrosslinked block copolymers by mechanical scission of soluble block copolymers. The aggregation of the polyacrylonitrile chains of the block copolymer fraction results in the formation of swollen gels when the polymerization products are extracted with solvents from the initial polymer (78-80). 

Ceresa (78,79) studied in detail the system poly(methyl methacrylate)-acrylonitrile. Figure 25 shows the change in composition with mastication time. A study of gel formation by the block copolymers was made by subjecting the isolated fractions of block copolymers to further mastication. A wide range of block copolymers with varying composition and structure was obtained (Fig. 26). 

Fig. 25. Polymerization of acrylonitrile by poly(methyl methacrylate) mastication. Analysis of products at various extent of polymerization, i free poly(methyl methacrylate) 2 soluble block copolymer 3 chloroform-insoluble block copolymer gel (78)...

Fig. 26. Polymerization of acrylonitrile by polylmethyl methacrylate) mastication. Schematic representation of block copolymer formation and...

Ceresa (80) demonstrated the possibility of synthetizing block copolymer by subjecting a starch emulsion with free radical polymerizable monomers to repeated freezing at — 200° C and subsequent thawing to room temperature. He used acrylonitrile owing to the case of separating the insoluble block copolymer fraction, see Table 22. 

Ceresa synthetized also block copolymers of poly(methyl methacrylate) with acrylonitrile and styrene and of polyethylene with methyl methacrylate, styrene using this method (104). 

Homopolymers of polybutadiene can consist of three basic isomeric forms (czs-1,4, trans-1,4, and 1,2 vinyl), and these can be present in different sequential order. Copolymers may obtain a variety of co-monomers, such as styrene, acrylonitrile, etc. Depending on their distribution in the chain, random copolymers or block copolymers of different types and perfection can be produced. There are many synthetic elastomers based on butadiene available commercially. 

Abbreviations coiX-V] = copolymers of X and Y colX-b-Yl = block copolymers of poly X and poly Y ST = styrene MA = methyl acrylate MMA = methyl methacrylate AN = acrylonitrile BD = butadiene LR (liquid rubbers) = a, cj-polybutadiene-diols and -dicarboxylic acids Cell-Ac = cellulose acetate Cell-N02 = cellulose nitrate. 

Chemical processes are far more varied and may involve either the formation of radicals or ions along a polymeric backbone. Both cationic processes3 as well as radical processes have been widely used for graft copolymerization of vinyl monomers onto various polymers. Radical graft copolymerization has been reported for many polymers including styrene-butadiene block copolymers, and acrylonitrile-butadiene-styrene terpolymer, ABS.3 7 9... 

The vinyl monomers used in this study, methacrylic acid, methyl methacrylate, acrylic acid, methyl acrylate, and acrylonitrile, as well as the solvents, initiators, and polystyrene were supplied by the Aldrich Chemical Company. The styrene-butadiene block copolymer was supplied by Shell as Kraton D1102, known as SBS this contains approximately 75% butadiene and 25% styrene. 

Order-disorder transitions and spinodals were computed for linear multi block copolymers with differing sequence distributions by Fredrickson et al. (1992). This type of copolymer includes polyurethanes, styrene-butadiene rubber, high impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene (ABS) block copolymers. Thus the theory is applicable to a broad range of industrial thermoplastic elastomers and polyurethanes. The parameter... 

Table 4.10. Synthesis of block copolymers of l-vinyl-2-pyrrolidone/acrylonitrile by precipitation polymerization in terr-butylalcohol 5 g prepolymer, 5 g acrylonitrile, 45 g /erf-butylalcohol polym. temp. 60 °C polym. time 144 h monomer feed 0.1 ml/h...

Poly(VP) containing azo groups, prepared as described above, has been employed for preparing block copolymers with acrylonitrile using a precipitation polymerization technique in t-butyl alcohol (see Table 4.10). 

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