Copolymerization of styrene with

Pig. 14. Preparation of biodegradable PS by incorporating ester linkages into the backbone via ring-opening copolymerization of styrene with a cycHc ketene... 

Other miscellaneous compounds that have been used as inhibitors are sulfur and certain sulfur compounds (qv), picryUiydrazyl derivatives, carbon black, and a number of soluble transition-metal salts (151). Both inhibition and acceleration have been reported for styrene polymerized in the presence of oxygen. The complexity of this system has been clearly demonstrated (152). The key reaction is the alternating copolymerization of styrene with oxygen to produce a polyperoxide, which at above 100°C decomposes to initiating alkoxy radicals. Therefore, depending on the temperature, oxygen can inhibit or accelerate the rate of polymerization. 

Group of plastics whose resins are derived from the polymerization of styrene or the copolymerization of styrene with various unsaturated compounds. 

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Table 2 Copolymerization of Styrene with MMA [43] Initiated by Pyridinium Dicyanomethylylide ...

The data analyzed in this work were reported by Hill et al. ( ) for the copolymerization of styrene with acrylonitrile. They are shown in Table III in the form of triad fractions measured by C-NMR for copolymers produced at various feed compositions. One reason for choosing this particular dataset is that the authors did indicate the error structure of their measurement. 

C13-0110. Copolymerization of styrene with a small amount of divinylbenzene gives a cross-linked polymer that is hard and insoluble. Draw a picture of this polymer that shows at least tw o cross-links. 

Poly(azophenylene-o-carborane) (see 6) has been prepared from diphenyl-o-carborane by means of nitration, reduction, and acylation to initially give 1,2-bis(/ -nitroso-acetylaminophenyl)-o-carborane (NAFC). Rapid decomposition in solution affords phenylene amino phenyl carborane (PAFC) by recombination of phenylene and azophenylene radicals.40 These radicals have also been utilized to form copolymers of carborane-containing copolymers from monomers polymerizable via radical mechanisms. Thus, copolymers of polystyrene and poly(azophenylene) can be readily formed by means of emulsion copolymerization of styrene with NAFC decomposition products. 

For the first time attention to the highly important role played by the thermodynamic factors in the formation of macromolecules during copolymerization was drawn almost a quarter of a century ago [52], When investigating the copolymerization of styrene with methacrylic acid in a solution of CCI4 and in a solution of dioxane in the region of low conversions, the authors established that copolymers with the same composition had an identical microstructure regardless of the solvent type and of the monomer molar ratio... 

Another reason for copolymerization is to insert functional grouping in the polymer. A functional group is one that is easily reacted. For example, copolymerization of styrene with acrylonitrile, CH2=CH-CN, involves only the double bond, leaving the newly formed copolymer with the active functional group -CN, available for subsequent reaction. The copolymer might be reacted later with itself or another monomer to give a cross-linked thermoset. 

Copolymerization allows the synthesis of an almost unlimited number of different products by variations in the nature and relative amounts of the two monomer units in the copolymer product. A prime example of the versatility of the copolymerization process is the case of polystyrene. More than 11 billion pounds per year of polystyrene products are produced annually in the United States. Only about one-third of the total is styrene homopolymer. Polystyrene is a brittle plastic with low impact strength and low solvent resistance (Sec. 3-14b). Copolymerization as well as blending greatly increase the usefulness of polystyrene. Styrene copolymers and blends of copolymers are useful not only as plastics but also as elastomers. Thus copolymerization of styrene with acrylonitrile leads to increased impact and solvent resistance, while copolymerization with 1,3-butadiene leads to elastomeric properties. Combinations of styrene, acrylonitrile, and 1,3-butadiene improve all three properties simultaneously. This and other technological applications of copolymerization are discussed further in Sec. 6-8. 

The copolymerization of carbonyl monomes with alkenes has been even less studied than that between different carbonhyl monomers. The radiation-initiated copolymerization of styrene with formaldehyde proceeds by a cationic mechanism with a trend toward ideal behavior, r = 52 and r2 = 0 at —78°C [Castille and Stannett, 1966]. Hexafluoroacetone undergoes radiation-initiated copolymerization with ethylene, propene, and other a-olefins [Watanabe et al., 1979]. Anionic copolymerizations of aldehydes with isocyanates have also been reported [Odian and Hiraoka, 1972]. 

Most polystyrene products are not homopolystyrene since the latter is relatively brittle with low impact and solvent resistance (Secs. 3-14b, 6-la). Various combinations of copolymerization and blending are used to improve the properties of polystyrene [Moore, 1989]. Copolymerization of styrene with 1,3-butadiene imparts sufficient flexibility to yield elastomeric products [styrene-1,3-butadiene rubbers (SBR)]. Most SBR rubbers (trade names Buna, GR-S, Philprene) are about 25% styrene-75% 1,3-butadiene copolymer produced by emulsion polymerization some are produced by anionic polymerization. About 2 billion pounds per year are produced in the United States. SBR is similar to natural rubber in tensile strength, has somewhat better ozone resistance and weatherability but has poorer resilience and greater heat buildup. SBR can be blended with oil (referred to as oil-extended SBR) to lower raw material costs without excessive loss of physical properties. SBR is also blended with other polymers to combine properties. The major use for SBR is in tires. Other uses include belting, hose, molded and extruded goods, flooring, shoe soles, coated fabrics, and electrical insulation. 

Radical copolymerization of styrene with lCM-0% acrylonitrile yields styrene-acrylonitrile (SAN) polymers. Acrylonitrile, by increasing the intermolecular forces, imparts solvent resistance, improved tensile strength, and raises the upper use temperature of polystyrene although impact resistance is only slightly improved. SAN finds applications in houseware... 

Polystyrene is presently the overwhelming choice as the polymer support [Frechet and Farrall, 1977 Frechet et al., 1988 Messing, 1974]. The polystyrene used is a crosslinked polymer prepared by copolymerization of styrene with divinylbenzene (DVB). (The divinyl-benzene is usually the commercially available mixture containing the meta and para isomers... 

Copolymerization of Styrene with Methyl Methaaylate (Dependence on Type of Initiation)... 

Radical Copolymerization of Styrene with 4-Chlorostyrene (Determination of the Reactivity Ratios)... 

Template copolymerization seems to be applied to the synthesis of copolymers with unconventional sequences of units. As it was shown, by copolymerization of styrene with oligomers prepared from p-cresyl-formaldehyde resin esterified by methacrylic or acrylic acid - short ladder-type blocks can be introduced to the macromolecule. After hydrolysis, copolymer with blocks of acrylic or methacrylic acid groups can be obtained. Number of groups in the block corresponds to the number of units in oligomeric multimonomer. Such copolymers cannot be obtained by the conventional copolymerization. 

Effect of Alkali Metal Intiators and Solvents on Copolymerization of Styrene with Isoprene at 25°C... 

It has been emphasized in the copolymerization of styrene with butadiene or isoprene in hydrocarbon media, that the diene is preferentially incorporated. (7,9,10) The rate of copolymerization is initially slow, being comparable to the homopolymerization of the diene. After the diene is consumed, the rate increases to that of the homopolymerization of styrene. Analogously our current investigation of the copolymerization of butadiene with isoprene shows similar behavior. However, the... 

Sakurada, I., N. Isb, Y. Hayashi, and M. Nakao Cationic copolymerization of styrene with indene or a-methylstyrene catalyzed with boron trifluoride etherate under an electric field. Macromolecules 1, 265 (1968). 

Braun and Kern (25) believed that the production of isotactic polystyrene with alkalimetalalkyls takes place with the propagating anion on the carbon alpha to the aromatic ring. Smid and Szwarc (26) studied the copolymerization of styrene with various substituted styrenes... 

Waterman et al.7B described a method for the preparation of homogeneous copolymerization products of drying oils with styrene, according to which styrene vapours are brought into contact with the oils at temperatures of 220-28o°C. This method prevents the formation of high-molecular polystyrene and favours the chemical combination (copolymerization) of styrene with the oils79. 

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