Styrene monomeric

Reaction Mechanism. The reaction mechanism of the anionic-solution polymerization of styrene monomer using n-butyllithium initiator has been the subject of considerable experimental and theoretical investigation (1-8). The polymerization process occurs as the alkyllithium attacks monomeric styrene to initiate active species, which, in turn, grow by a stepwise propagation reaction. This polymerization reaction is characterized by the production of straight chain active polymer molecules ("living" polymer) without termination, branching, or transfer reactions. 

Ability to analyze unreacted monomers was dependent on detector selectivity. The UV detector was operated at 254 nm for analysis of AN/S latex solutions. Styrene is a strong UV abosrber at this wavelength while acrylonitrile has no measurable absorbance at 254 nm. Thus, the UV detector was entirely selective to monomeric styrene. The refractometer detector was sensitive to both acrylonitrile and styrene when each was present in the desired copolymer proportions (70/30). However,... 

Traditionally, a polymer has been named by attaching the prefix poly to the name of the real or assumed monomer (the source ) from which it is derived. Thus, polystyrene is the name of the polymer made from styrene. When the name of the monomer comprises two or more words, parentheses should be used [1], as in poly(vinyl acetate), poly(methyl methacrylate), etc. Failure to use parentheses can lead to ambiguity. For example, polychlorostyrene could be the name of either a polychlorinated (monomeric) styrene or of a polymer derived from chlorostyrene similarly, polyethylene oxide could refer to the polymer 1, the polymer 2 or the macrocycle 3. 

The concept is similar to the grafting of plants in botany. To form a styrene-butadiene graft polymer, already polymerized butadiene is dissolved in monomeric styrene and an initiator is added. Because polybutadiene readily undergoes chain transfer at the allylic sites, polystyrene chains grow on the polybutadiene backbone. This forms high impact polystyrene, a low cost plastic that is otherwise too brittle without the grafting. 

Monomeric styrene is freed from phenolic inhibitors by shaking twice with 10% sodium hydroxide solution, washing three times with distilled water, drying over calcium chloride or silica gel and distilling into a receiver (see Sect.2.2.5.3) under reduced pressure of nitrogen (bp 82 °C/100 torr, 46 °C/20 torr). It is stored in a refrigerator until required. 

Monomeric styrene is destabilized (see Example 3-1) and distilled into a suitable receiver (see Sect. 2.2.S.3) under nitrogen. Butadiene from a cylinder is condensed under nitrogen atmosphere into a trap cooled in a methanol/dry ice bath. A 500-ml pressure bottle is evacuated and filled with nitrogen. A solution of 5 g of sodium oleate (or sodium... 

Monomeric styrene is destabilized as in Example 3-1 and pre-dried with calcium chlo-ride.The monomer is now allowed to stand over calcium hydride for 24 h and then distilled under reduced pressure of nitrogen into a previously flamed-out Schlenk tube. Pure 4-vinylpyridine is distilled twice over KOH pellets in vacuum.lt is then vacuum distilled under nitrogen through a column packed with Raschig rings into a previously flamed out Schlenk tube (bp 62 °C/12 torr).The closed Schlenk tubes containing the monomers are stored in a refrigerator until required.The preparation of the initiator solution (sodium naphthalene) is described in Example 3-19. 

POLYMERIZATION (Radical). In addition polymerization, polymer is the sole product of the reaction so that the monomer and polymer have essentially the same chemical composition—for example, monomeric styrene and polystyrene. In a polymerization of this type, polymer is formed by a stepwise reaction in which molecules of monomer are added one at a time, to a reactive, center the center grows in size while retaining its reactivity. 

Complete thermolysis of the azo groups in polyazoesters 56,61) in the presence of monomeric styrene leads to block copolymers of an (AB) -type, whereas, when the added monomer is one that tends to terminate via disproportionation (e.g. MMA), the block copolymer products are of an ABA- or an AB-type ... 

Monomeric styrene (95% purity) 17 500 tons Catalytic dehydrogenation of ethyl benzene. 

A liquid preparation with solid polystyrene (0.6 g) dissolved in liquid styrene monomer (1.5 mL) was cast against a mold. Polymerization was accomplished with UV irradiation (21°C, 18 h). Solid PS was included to reduce the degree of shrinkage that occurred when monomeric styrene was photopolymerized [85]. In a similar manner, PMMA dissolved in MMA was cast against a Si master. Upon UV polymerization (with BME as the photoinitiator), a PMMA chip is formed. Nearly 100 PMMA chips can be replicated using a single Si master [223]. 

Hallensleben andMoller ) prepared block copolymers of styrene and polyesters by mixing the latter with monomeric styrene in methylene chloride and adding BF3 Et20. The authors claimed that growing polystyrene chains transferred to the polyesters to give dialkoxycarbenium ions capable of initiating the polymerisation of styrene to give block copolymers. 

This behavior is an evidence of the small-scale mechanism of the molecular motion of polystyrene in the electric field each monomer unit of the polymer chain is oriented virtually independently of other units, just as in the monomeric styrene. Equation (99) shows that for high molecular weight polymers K is proportional to S, This accounts for the much higher values of K for rigid-chain polymers than for flexible-chain polymers (Table 13) since the corresponding values of S are of order of m nitudes 10—10 for flexible and approximately unity for i%id polymers in the electric field. 

In the ethylbenzene process the 1-methylbenzyl alcohol (MBA) co-product is dehydrated to monomeric styrene (SM). The theoretical SM/PO ratio is 1.8 1 and commercial plants operate in the range 2.2-2.7 l, indicating that the selectivity of ethylbenzene hydroperoxide (EBHP) formation is much higher than that of... 

Unsaturated rubber polymers are especially important grafting vehicles. Consider, for example, the polymerization of styrene in the presence of l,4-poly(l,3-butadiene). A method consists of dissolving the polybutadiene rubber (about 5 to 10%) in monomeric styrene containing benzoyl peroxide initiator and applying heat. Polymer radicals, formed by (a) chain transfer between the propagating radical and polymer or (b) addition (copolymerization) of the propagating radical to the -double bonds of the polymer. 

Tirrell and co-workers studied copolymerization of styrene (S) and acrylonitrile (A) using l,l -azobis(l-phenylethane)-a,q/-13C, which generates a monomeric styrene radical, 1-phenylethyl radical 87... 

Polyester resin coatings are synthesized with components that introduce unsaturation into the polymer chain (—C=C—). The paint is manufactured by mixing a dissolved polyester resin in styrene monomer with pigment and reaction inhibitor. Additional styrene and peroxide are packaged in a separate container and are mixed with the paint when applied using a dual-headed spray gun. Peroxide serves as a radical polymerization initiator for the polyester resin with monomeric styrene and cross-linking. Figure 13.5 shows the chemical structure of an isophthahc polyester resin. 

As a consequence, monomeric styrene polysulfides (from mass 168 up to m/z 328, Table 5.1) detected by DPMS, lose sulfur and yield the most... 

Monomeric styrene is destabilized as in Example 3.1 and pre-dried with calcium chloride. The monomer is now allowed to stand over calcium hydride for 24 h and then distilled under reduced pressure of nitrogen into a previously flamed out... 

X-ray studies also suggest the presence of order. Intensity maxima of 0.126, 0.223, 0.478, and 0.9-1 nm were obtained with amorphous polystyrene, for example. The value 0.126 nm corresponds to the normal distance between two neighboring carbon atoms in the chain. The value 0.223 nm is approximately the distance between one main-chain carbon atom and its next nearest neighbor. The value of 0.478 nm is also observed with monomeric styrene. It is displaced to higher values with increasing cross-linking and consequently must refer to an intermolecular distance. 

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