Polymerization of Substituted Styrenes

Influence of Structure on the Cationic Polymerization of Substituted Styrenes... 

The data in Table I are not directly comparable, since the viscosity of the 3-isomer was determined in benzene while the others were measured in DMSO. In addition, the first two polymers were prepared in bulk polymerizations, while the polymerization of methyl 3-vinylsalicylate was carried out with the monomer diluted 1 1 with benzene. Thus no certain conclusion can be drawn the data are, however, an indication of possible difficulty in radical polymerization of substituted styrenes bearing a phenol ortho to the vinyl group. 

Bevington has continued his studies of the initiation reaction and of the reactivities of monomers towards reference radicals (69—71). A study of the polymerization of substituted styrenes was recorded (72). In methyl methacrylate polymerization by ammonium trichloroacetate in the presence of copper derivatives, the complexities of the initiation and termination reactions were elegantly unravelled by Bamford and Robinson using two differently labelled trichloroacetates (73). Apparently cyclic processes involving alternate oxidation and reduction of copper may arise. 

The ion exchange resins can be obtained either from the polymerization of substituted styrene or by the chemical modification of the polymer. For example, styrene/divinylbenzene (SDVB) polymer can be modified by chloromethylation (using HCl and formaldehyde in the presence of ZnCb) followed by reaction with a tertiary amine. This derivatization leads to a strong anion exchange material. Sulfonation of SDVB leads to a strong cation exchanger. The idealized structure of SDVB and of the anion and cation exchangers obtained from this material are shown below ... 

While there is a considerable body of research on CCT polymerizations of styrene itself, there are no reports of CCT in polymerizations of substituted styrenes. In the case of styrene as well as in the case of other vinylic monomers bearing no methyl group adjacent to the propagating radical, CCT always provides oligomers with an exclusively trans configuration of the double bond.28 368 Because there is no abstractable methyl hydrogen atom, the only site for... 

Many other metal-containing groups have been attached to organic polymers. Polymers 51 containing Pd-G cr-bond linkages have been successfully prepared by the radical polymerization of / -substituted styrene derivatives (Equation... 

In Table I, the results of the polymerization of substituted styrenes with electron-withdrawing (p-Cl, p-Br, -CF3) as well as with electron-donating substituents (p-Me, p-t-Bu) are listed. All of these monomers were polymerized in diphenyl ether... 

The protonation of substituted styrenes generally leads to sequential oligomerization and polymerization reactions (3). Only when carefully... 

Polymerization of isobutylene, in contrast, is the most characteristic example of all acid-catalyzed hydrocarbon polymerizations. Despite its hindered double bond, isobutylene is extremely reactive under any acidic conditions, which makes it an ideal monomer for cationic polymerization. While other alkenes usually can polymerize by several different propagation mechanisms (cationic, anionic, free radical, coordination), polyisobutylene can be prepared only via cationic polymerization. Acid-catalyzed polymerization of isobutylene is, therefore, the most thoroughly studied case. Other suitable monomers undergoing cationic polymerization are substituted styrene derivatives and conjugated dienes. Superacid-catalyzed alkane selfcondensation (see Section 5.1.2) and polymerization of strained cycloalkanes are also possible.118... 

Another approach to the preparation of polymer-supported metal Lewis acids is based on polymerization of functional monomers. If synthesis of the functional monomer is not difficult, polymerization should afford structurally pure functional polymers, because the polymer formed requires no further complicated chemical modification. A variety of substituted styrene monomers are now commercially available styrene monomers with an appropriate ligand structure can be prepared from these. Several other interesting functional monomers such as glycidyl methacrylate, 2-hydr-oxyethyl methacrylate, and other acrylics have also been used extensively to prepare functional polymers. 

Soon after syndiospecific styrene polymerization, attention was directed to the homopolymerization of substituted styrenes as well as to their co-polymerization with styrene.956,957,964,1027-1029 Mono-Cp-based Ti systems are capable of homopolymerizing methyl-substituted styrenes and />-chlorostyrene, as well as co-polymerizing them with styrene. The general trend that emerged is that electron-withdrawing Cl substituents decrease the reactivity relative to styrene, whereas electron-releasing Me groups increase it. In both cases, syndiotactic co-polymers were obtained. 

Fig. 3.6 ATRP of substituted styrenes, a Kinetic plot and b polydispersities of polymerizations performed in diphenyl ether at 110 °C with an initial monomer concentration of [M]q = 4.37M and [MJo [1 — PEBrJo [CuBrJo [bipyjo = 100 1 1 3 (Reprinted with permission from Qui et til. [30]. Copyright 2013 American Chemical Society)...

Uses Chemical synthesis intermediates esterification/alkylation/ hydroisomerization/acylation catalyst reactant polymerization of epoxies, styrenes, and THF petroleum refining explosives dyes paints electrolytes formation of biaryls foods (catalyst in prod, of cocoa butter substitute from palm oiO catalyst for pharmaceuticals Reguiatoty FDA 21CFR 173.395... 

Proton transfer to monomer in the polymerization of a-methyl styrene can be suppressed by the presence of 2,6-di-t-butyl pyridine. This scavenges all the protons and effectively converts the reaction from a transfer to a termination reaction. The copolymerization of crmethyl styrene with isobutyl vinyl ether - has shown how the relative reactivities of carbenium and carboxonium ions affect conversion and molecular weights. Other interesting studies include the polymerization of substituted cs-methyl styrenes - and the stereospecific polymerization of anethole. ... 

We were able to demonstrate the mechanism of the carbocationic polymerization using substituted styrenes by copolymerization and showing that the reactivities of these monomers obeyed the classical Hammit free energy equation. In addition, we demonstrated steric factors involved in cationic polymerization through the copolymerization method. We demonstrated that 3-niethyl styrene would copolymerize whereas 3-ethyl styrene would not. 

A number of substituted styrenes of the type C F3CR CR R e.g. CaFe CH CHEt, C,F5-CH CMe2) have been synthesized by dehydration with phosphorus pentoxide of alcohols [CeFj CRXOHj-CHR R ] obtained by the action of pentafluorophenylmagnesium chloride on appropriate carbonyl compounds. The kinetics of the thermal and AZBN-initiated polymerization of 2,3,4,5,6-pentafluorostyrene have been studied, and nucleophilic attack on this monomer by sodium methoxide, methylamine, dimethylamine, and lithium anilide has been shown to cause preferential displacement of the fluorine para to the vinyl group. ... 

With the improvement of refining and purification techniques, many pure olefinic monomers are available for polymerization. Under Lewis acid polymerization, such as with boron trifluoride, very light colored resins are routinely produced. These resins are based on monomers such as styrene, a-methylstryene, and vinyltoluene (mixed meta- and i ra-methylstyrene). More recently, purified i ra-methylstyrene has become commercially available and is used in resin synthesis. Low molecular weight thermoplastic resins produced from pure styrene have been available since the mid-1940s resins obtained from substituted styrenes are more recent. 

Thermoplastic resins produced from pure monomers such as styrene, alkyl-substituted styrenes, and isobutylene are produced commercially. An advantage of these resins is the fact that they are typically lighter in color than Gardner 1 (water-white) without being hydrogenated. Among the earliest resins in this category were those made from styrene and sold as Piccolastic. Styrene and alkyl-substituted styrenes such as a-methylstyrene are very reactive toward Friedel-Crafts polymerization catalysts. 

The organic and aqueous phases are prepared in separate tanks before transferring to the reaction ketde. In the manufacture of a styrenic copolymer, predeterrnined amounts of styrene (1) and divinylbenzene (2) are mixed together in the organic phase tank. Styrene is the principal constituent, and is usually about 90—95 wt % of the formulation. The other 5—10% is DVB. It is required to link chains of linear polystyrene together as polymerization proceeds. DVB is referred to as a cross-linker. Without it, functionalized polystyrene would be much too soluble to perform as an ion-exchange resin. Ethylene—methacrylate [97-90-5] and to a lesser degree trivinylbenzene [1322-23-2] are occasionally used as substitutes for DVB. 

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