Styrene, free-radical copolymerization

Styrene-butadiene rubber is prepared from the free-radical copolymerization of one part by weight of styrene and three parts by weight of 1,3-butadiene. The butadiene is incorporated by both 1,4-addition (80%) and 1,2-addition (20%). The configuration around the double bond of the 1,4-adduct is about 80% trans. The product is a random copolymer with these general features ... 

In all manufacturing processes, grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of an elastomer. Ungrafted styrene—acrylonitrile copolymer is formed during graft polymerization and/or added afterward. 

Free-Radical Gopolymerization. Examples of the types of copolymers formed by free-radical copolymerizations are shown ia equations 18—20, where S = styrene [100-42-5] B = butadiene [106-99-0] and AIBN = azobisisobutyronitrile [78-67-1] (see Initiators) (27—29). 

The electrophilic functions most commonly used in grafting onto processes are ester 141 144), benzylic halide 145,146) and oxirane, 47). Other functions such as nitrile or anhydride could be used as well. The backbone is a homopolymer (such as PMMA) or a copolymer containing both functionalized and unfunctionalized units. Such species can be obtained either by free radical copolymerization (e.g. styrene-acrylonitrile copolymer) or by partial chemical modification of a homopolymer (e.g. 

Free radical copolymerizations of the alkyl methacrylates were carried out in toluene at 60°C with 0.1 weight percent (based on monomer) AIBN initiator, while the styrenic systems were polymerized in cyclohexane. The solvent choices were primarily based on systems which would be homogeneous but also show low chain transfer constants. Methacrylate polymerizations were carried out at 20 weight percent solids... 

The DIS monomer, unlike its iron analogue, did not homopolymerize with SnCl initiator even on heating. A plausible reason for this result is that this monomer contains a lone pair of elec-trons available for donation to Lewis acids.JU Thus side reactions similar to those of the previous two monomers would prevent propagation. However, the DIS monomer also underwent a free radical copolymerization reaction with styrene and AIBN initiation. 

Free-radical copolymerization of trimethyl- or tributylvinyltin with styrene or methyl methacrylate results in low ( 10%) yield of copolymer. Moreover, both the reaction rate and viscosity decrease considerably with higher vinyltin content in the starting mixture 49). These findings imply that organotin monomers tend to inhibit free-radical copolymerization. 

Binary free-radical copolymerizations of organotin derivatives of unsaturated acids (tri-n-butylstannyl methacrylate, bis-triethylstannyl maleate (TESM) and P-phenyl-tri-n-butylstannyl methacrylate (PBSM)) with certain vinyl monomers such as styrene (St) 87) and vinyl chloride (VC) have been studied 24,25,92). 

A noticeable change in the TBSM activity as compared with that of its organic analog BMA (rBMA = 0.64 and rSt = 0.54)89) in the free-radical copolymerization with styrene may be ascribed to steric factors and the effect of intermolecular coordination. 

K Dusek, L Matejka, P Spacek, H Winter. Network formation in the free-radical copolymerization of a bismaleimide and styrene. Polymer 37 2233-2242, 1996. 

T. Cao, S.E. Webber, Free-radical copolymerization of fullerenes with styrene,... 

PolylStyrene co-n-Butyl Methacrylate) Fractionation. OC was developed with the particular idea of elucidating the kinetics of the free radical copolymerization of styrene n-butyl methacrylate. Thus, this polymer provided the main focus of the work. 

Synthesis of a styrene monomer containing a diiron hexacarbonyl moiety and its copolymer together with the metal atom of the preferred copolymers has been achieved [6]. (3) and (4) (Fig. 2) undergo free radical copolymerization with... 

Cyclopolymerization of bifunctional monomers is an effective method of chirality induction. Optically active vinyl homopolymers and copolymers have been synthesized by using optically active distyrenic monomers (41) based on a readily removable chiral template moiety. Free-radical copolymerization of 41a with styrene and removal of the chiral template moiety from the obtained copolymer led to polystyrene, which showed optical activity ([Oc]365 -0.5-3.5°) (Scheme 11.6) [84], The optical activity was explained in terms of chiral (S,S)-diad units generated in the polymer chain through cyclopolymerization of 41a [85], Several different bifunctional monomers have been synthesized and used for this type of copolymerization [86-90]. 

Storsberg, J. Glockner, P. Eigner, M. Schnoller, U. Ritter, H. Voit, B. and Nuyken, O. (2001) Cyclodextrins in polymer synthesis photocrosslinkable films via free radical copolymerization of methylated / -cyclodextrin-complexed styrene with sodium 4-(acrylamido)-phenyldiazosulfonate in aqueous medium, Designed Monomers and Polymers 4, 9-17. 

An alternative rationale for the unusual RLi (hydrocarbon) copolymerization of butadiene and styrene has been presented by O Driscoll and Kuntz (71). Rather than invoking selective solvation, these workers stated that classical copolymerization kinetics is sufficient to explain this copolymerization. They adapted the copolymer-composition equation, originally derived from steady-state assumptions for free-radical copolymerizations, to the anionic copolymerization of butadiene and styrene. Equation (20) describes the relationship between the instantaneous copolymer composition c/[M,]/rf[M2] with the concentrations of the two monomers in the feed, M, and M2, and the reactivity ratios, rt, r2, of the monomers. The rx and r2 values are measures of the preference of the growing chain ends for like or unlike monomers. 

Example 13.6 The following data were obtained using low-conversion batch experiments on the bulk (solvent-free), free-radical copolymerization of styrene (X) and acrylonitrile (Y). Determine the copolymer reactivity ratios for this polymerization. 

The attachment of preformed polyethereal dendrons (e. g., 70, see Scheme 5.17), which have been functionalized at the focal point by reaction with p-(chloromethyl)sty-rene, has been shown1501 to undergo free radical copolymerization with styrene giving rise to polystyrene with appended benzyl ether dendritic wedges. 

Kennedy 67,77 118) studied the ability of w-styryl-polyisobutene macromonomers to undergo free-radical copolymerization with either styrene or butyl or methyl methacrylate. Here, the macromonomers exhibited a relatively high molecular weight of 9000, and the reaction was stopped after roughly 20% of the comonomer had been converted. The radical reactivity ratios of styrene and methyl methacrylate with respect to macromonomer were found to be equal to 2 and to 0.5, respectively. From these results, Kennedy concluded that in the ra-styrylpolyisobutene/styrene system the reactivity of the macromonomer double bond is reduced whereas with methacrylate as the comonomer the polar effect is the main driving force, yielding reactivities similar to those observed in the classical system styrene/MMA. 

The p-DVB-piperazine adducts can also undergo self condensation whereby the macromonomers formed exhibit rather low molecular weights, and are insoluble in the reaction mixture (benzene or THF). They dissolve only upon the addition of an acid or in hot chloroform. Free-radical copolymerization of this macromonomer with styrene was carried out in benzene in the presence of some acetic acid (to obtain a homogeneous reaction mixture) to yields of about 20% M). Here again separation of the unreacted macromonomer is possible, and the polyamine content of the graft copolymer is very close to the amount contained in the reaction mixture. 

Coincidental with Ivin and Spensley, O Driscoll and Gasparro (12) studied the free radical copolymerization of styrene-methyl methacrylate but at 250°C. The latter workers varied monomer feed ratio over a wide... 

Predict the ratio of butadiene to styrene repeating units initially produced by free radical copolymerization of an equimolar mixture of the two monomers at 50°C. (Use Table 6-5 below.)... 

A number of years ago we asked one of our students (Dr. Yun Xu) to free radically copolymerize styrene with a (protected) vinyl phenol monomer. We needed to determine the reactivity ratios and Dr. Xu obtained the following data for monomer M, (which happened to be the vinyl phenol monomer). 

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