Initiation copolymerization of styrene with

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]. 

Noninterfering anions covalently bound to polymers have been prepared by the AIBN-initiated copolymerization of styrene with trialkylammonium 4-styryltris(pentafluorophenyl)borate (Scheme 30). High-density polyethylene prepared from Cp2ZrCl2— Al(i-Bu)3 and this activator shows no signs of reactor fouling in a slurry polymerization. "... 

The alkyllithium-initiated copolymerizations of styrene with dienes, especially isoprene and butadiene, have been... 

Tapered Block Copolymers. The alkyllithium-initiated copolymerizations of styrene with dienes, especially isoprene and butadiene, have been extensively investigated and illustrate the important aspects of anionic copolymerization. As shown in Table 15, monomer reactivity ratios for dienes copolymerizing with styrene in hydrocarbon solution range from approximately 8 to 17, while the corresponding monomer reactivity ratios for styrene vary from 0.04 to 0.25. Thus, butadiene and isoprene are preferentially incorporated into the copolymer initially. This type of copolymer composition is described as either a tapered block copolymer or a graded block copolymer. The monomer sequence distribution can be described by the structures below ... 

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. 

In contrast to /3-PCPY, ICPY did not initiate copolymerization of MMA with styrene [39] and AN with styrene [40]. However, it accelerated radical polymerization by increasing the rate of initiation in the former case and decreasing the rate of termination in the latter case. The studies on photocopolymerization of MMA with styrene in the presence of ICPY has also been reported [41], /8-PCPY also initiated radical copolymerization of 4-vinylpyridine with methyl methacrylate [42]. However, the ylide retarded the polymerization of N-vinylpyrrolidone, initiated by AIBN at 60°C in benzene [44]. (See also Table 2.)... 

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

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. 

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

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... 

An elegant example of the analysis of colloid surfaces containing covalently attached hydrophilic species has been provided by Brindley et al who studied the surface chemistry of polystyrene colloids with surface grafted polyethylene glycol groups [39]. These colloids were prepared by surfactant-free copolymerization of styrene with PEG using potassium persulphate as an initiator. The XPS analysis of these microparticles is shown in Fig. 11. 

The radical model cannot be applied for ionic and coordination polymerizations. With a few exceptions, termination by mutual combination of active centres does not occur. The only possibility is to measure the rate of each copolymerization independently. The situation can be greatly simplified for copolymerizations in living systems. The constants ku and k22 can usually be measured easily in homopolymerizations. Also, the coaddition constants fc12 or k2] are often directly accessible when the M] and M2 active centres can be differentiated spectroscopically or when the rate of monomer M2 (M[) consumption at M] M 2 centres can be measured. Ionic equibria, association, polarity of medium and solvation must be respected, even when their quantitative effect is not known exactly. The unusual situations confronting macromolecular chemistry will be demonstrated by the example of the anionic copolymerization of styrene with butadiene initiated by lithium alkyls in hydrocarbon medium. 

Only in the lithium catalysed copolymerization of styrene with the dienes in hydrocarbons do the monomers show an unexpected order of reactivity, an anomaly which disappears for polar solvents. The preference for the diene in the copolymer vanishes even in hydrocarbon solvents if sodium is used as initiator [231]. With the dienes, however, an added complication exists which makes simple experiments on electron affinity measured in solvents such as dioxane—water a poor guide to reactivity. They can react in more than one way to give a 3,4 (or 1,2) structure or alternatively a 1,4 structure. There appears to be good correlation between the amount of styrene in the copolymer and the percentage of... 

A number of studies have attempted to model this process stage by stage and to determine the values of some kinetic constants. Thus, in112 the researchers investigated the initial stage of isothermal bulk copolymerization of styrene with polybutadiene in the presence of di-tert-butyl peroxide. 

Other related co-monomers were also studied. These included 7V-(hydroxy-methyl)acrylamide (HMA), methacrylamide, and iV,A/-dimethylacrylamide. The copolymerization of styrene with HMA led to less water-soluble polymer in the serum than in the case of copolymers of acrylamide and styrene. This may be attributable to differences in the hydrophilic-hydrophobic properties of acrylamide and HMA. Some monodisperse latices were prepared from styrene-HMA-water systems by procedures similar to Procedure 12-2. At a ratio of HMA to styrene of 0.2 to 1.0 the reported particle diameter was 0.3 /im with good size uniformity. It was projected that even better uniformity would be obtained when the ratio of HMA to styrene is 0.09 to 1.0. Either potassium persulfate or Af,A -azobisisopropylamidine hydrochloride has been used as initiators with similar results. Latices were generally purified by repetitive centrifiigation-decantation-redispersion cycles. 

Copolymerization of styrene with 33 The copolymerization was carried out in DMF, containing 0.46 mol L of each comonomer and 1.22 10 mol L of AIBN as initiator. Metal acrylate and AIBN were placed in a glass tube and evacuated. The monomer and the solvent were then frozen in the reactor tube... 

Copolymer SMC can be obtained by the copolymerization of styrene with 2-(methylsulfinyl)ethyl methacrylate at 70 C in toluene with azobisisobutyronitrile as initiator (4,5). 

The large inner surface area of microemulsions can be easily modified and functionalized by simple copolymerization reactions or by embedding reactions as recently shown by Antonietti et al. [6,86,87,89,96]. Microemulsion copolymerization of styrene with functional monomers acting as cosurfactants and in the presence of a cross-linker resulted in spherical microgels in which most of the functional groups are located at the particle surface [86,87]. The functional additives were shown to stabilize or destroy the initial microemulsions, depending on their nature. Successful additives were based on methacrylate derivatives such as dimethylaminoethyl methacrylate (DAMA). 

Copolymerizations of styrene with butadiene in hydrocarbon solvents using lithium alkyls initiators initially yield copolymers containing mainly butadiene. The amount of styrene in the copolymer increases considerably, however, in tetrahydrofuran solvent. 

The cure reaction in polyester gel coat systems makes them particularly useful model coatings materials since the cure kinetics can be studied by several analytical techniques. The initiation of cure in polyester gel coat resins begins with the decomposition of hydroperoxide (MEKP is predominately hydroperoxide) and the subsequent copolymerization of styrene with the unsaturated groups, either fumarate or maleate, incorporated into the resin backbone. ... 

When a miniemulsion polymerization initiated by Co y-rays was carried out to synthesize polystyrene particles [65], the dose rate and total dose were each found to aflect the size of the latex particles. Y-Hke branched surfactants were synthesized and used for y-ray miniemulsion polymerization at room temperature [66] moreover, 2wt% polyurethane used as a hydrophobe for the miniemulsion polymerization of styrene was suflBdent to ensure a shelf-Hfe of one year for the miniemulsion [67]. In both cases [66, 67], the particle size and distribution were preserved throughout the polymerization. The copolymerization of styrene with l-vinyl-2-pyrrolidone as a polar monomer in the presence of dodecane in the oil droplets, also led to the production of nanocapsules [68]. Subsequent H NMR spectroscopic analyses showed that graft copolymers had been obtained via radiation-induced polymerization, rather than random copolymers. Hence,... 

But such diagnoses must be very carefully made. The anionic copolymerization of styrene with isoprene in trimethyl aminine with lithium butyl as initiator gives almost the same copolymerization parameters (rs= 0.8,r, = 1.0) as the free radical copolymerization (r5 = 0.4, r, = 2.0), but very different anionic copolymerization parameters are found in other solvents (see also Table 22-17). 

Various mechanisms have been proposed to explain the initiation mechanism of self initiated copolymerizations of styrene (S) with electron acceptor monomers such as maleic anhydride (MA), acrylonitrile, vinyliden cyanide or dimethyl l,l-dicianoethane-2-2-dicarboxylate. They... 

This mechanism has been extended to the spontaneous copolymerizations of styrene with maleic anhydride and other electron-acceptor monomers (see Scheme 1, Several authors have studied the spontaneous polymerization of st5rene with acrylonitrile focusing on isolated trimers that are produced presumably as a result of the initiation step however, the trimer structures do not suffice to differentiate between the Mayo mechanism and the Flory diradical mechanism. 

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