Styrene-DVB copolymer

Strong" Acid Cation Excha.ngers. AH strong acid-type resins are made from styrene—DVB copolymers, with the exception of a minor quantity of phenoHc resin. Batch sulfonation using commercial strength sulfuric acid [8014-95-1] is common. 

Styrene-divinylbenzene resins, 23 353 Styrene-DVB copolymers, 14 388 Styrene ionomers, 14 466, 481 properties of, 14 470-473 Styrene liquid, 23 347 Styrene-maleic anhydride (SMA) copolymers, 23 391 copolymer, 10 207 Styrene manufacture, 24 259 Styrene manufacturing, 23 326, 334-345 development of high selectivity catalyst for, 23 339... 

Weak Base Anion Exchangers. Both styrenic and acrylic copolymers can be converted to weak base anion-exchange resins, but different synthetic routes are necessary. Styrene—DVB copolymers are chloromethylated and aminated in a two-step process. Chloromethyl groups are attached to the aromatic rings (5) by reaction of chloromethyl methyl ether [107-30-2], CH3OCH2Cl, with the copolymer in the presence of a Friedel-Crafts catalyst such as aluminum chloride [7446-70-0], A1C13, iron(III) chloride [7705-08-0]9 FeCl3, or zinc chloride [7646-85-7], ZnC. ... 

The first attempt to imprint a metal complex with a reaction intermediate coordinated to the metal center was reported by Mosbach and coworkers [51], A Co monomer coordinated with dibenzoylmethane, which is as an intermediate for the aldol condensation of acetophenone and benzaldehyde, was tethered to a styrene-DVB copolymer matrix. After, the template, dibenzoylmethane was removed from the polymer, the resulting molecularly imprinted cavity had a shape similar to the template due to the interaction of the template with the polymerized styrene-DVB monomers through n-n stacking and van der Waals interactions. The rate of aldol condensation of adamantyl methyl ketone and 9-acetylanthracene was lower than the rate of condensation with acetophenone, indicating some degree of increased substrate selectivity. This is the first known formation of a C-C bond using a molecularly imprinted catalytic material. 

Extraction columns 6 ml disposable inter extraction cartridges packed with 200 mg styrene DVB copolymer (SDB)... 

For practical purposes, styrene—DVB copolymers have commonly been obtained by the suspension polymerization method,[53, 54] which is well known to consist of heating and agitating a solution of initiator in monomers with an excess of water containing a stabilizer of the oil-in-water emulsion. Polymerization proceeds in suspended monomer droplets and, in this way, a beaded copolymer is obtained. While looking very simple, this procedure can provide many complications that significantly change the properties of the beaded product as compared to the properties of materials prepared by bulk copolymerization. AU parameters of the suspension copolymerization have to be strictly controlled, since even small deviations from optimal conditions of the synthesis can serve as an additional source of heterogeneity in the copolymer beads. [55]... 

Table 1.3 Glass transition temperature, Tg °C), of conventional styrene-DVB copolymers...

The behavior of a real network is determined by the totality of topological parameters not less than by the density of crosslinking. Neglecting the network topology will result in misleading conclusions. As an example. Table 1.3 demonstrates glass transition temperatures of abstract styrene-DVB copolymers calculated in accordance with the approach developed by Askadskyi [100, 101]. The author depicts the DVB junction point as denoted below (one junction includes four carbon atoms) ... 

A comprehensive review of the synthesis and properties of IPNs is beyond the scope of this book, and in this section we will deal only with the properties of IPN networks formed by styrene—DVB copolymers. These IPNs were named Millar IPNs after the author who was the first to prepare this novel type of networks as early as in 1960 [225]. These materials are also named homo-IPNs, either keeping in mind the fact that they are formed by chemically identical polymers or sometimes assuming a homogeneous character of their physical structure. 

According to the lUPAC recommendations [238], the term micropores should be apphed to voids smaller than 20 A in diameter, mesopores are those with diameters between 20 and 500 A, and macropores have diameters larger than 500 A. The micropores and thin mesopores mosdy contribute to the value of the inner surface area, whereas the wide mesopores and, in particular, macropores make up most of the total pore volume of porous materials. It should be noted that the overwhelming majority of porous styrene—DVB copolymers are typically meso-porous materials however, the initially introduced name macroporous polymers became generally accepted and we will not deviate from this traditional scientific jargon. 

If the polymer does not swell with certain solvents (such as methanol or octane in combination with macroporous styrene—DVB copolymers), the pore volume may be estimated from the uptake of the solvent by simply weighing the dry and wet polymer samples [248]. 

For a large number of macroporous styrene—DVB copolymers, sulfo-nated cation exchangers KU-23, and weak basic anion exchangers AN-221, the specific volumes and the true and apparent densities were measured independently and the values of and F were correlated in accordance with Eq. [3.3]. The coefficients a and b of the above equation, obtained after statistical treatment of all the results [250], are given in Table 3.1. 

Pore size and pore size distribution. Particularly two methods have been used to determine the pore size in adsorbing materials of both organic and inorganic nature, namely, the gas adsorption technique and the mercury intrusion porosimetry. On the basis of information provided by these methods, a number of serious conclusions have been drawn on the porous structure of macroporous styrene-DVB copolymers. This necessitates a more critical analysis of the possible errors in the interpretation of the results of measuring adsorption isotherms and mercury intrusion. 

Macroporosity of styrene—DVB copolymers arises from the presence of certain diluents in the initial homogeneous solution of the comonomers these do not participate in free radical polymerization but phase-separate from the growing polymer. Three types of diluents have generally been recognized (i) precipitating media for linear polystyrene, (ii) good solvents for polystyrene, and (iii) linear polystyrene or other polymers. 

We may find confirmation for our statement about the thermodynamic incompatibility of linear polystyrene with the styrene-DVB copolymer in experiments by Wong et al. [269]. These authors reported similarities in the phase separation power of linear polystyrene and that of linear styrene-methylmethacrylate copolymer, the latter being a priori incompatible with the styrene-DVB network. Complete incompatibility of polystyrene with linear polydimethylsiloxane facihtates phase separation and results in the formation of a porous styrene-DVB network on adding as little as 0.5-1% of the above porogen to the initial comonomer mixture (Fig. 3.2, curves 4). It is also not surprising that the porosity of copolymers induced by linear polystyrene and linear polydimethylsiloxane is almost the same when the DVB content exceeds 10%. At a DVB content that hi, the network formed differs fundamentally from linear polystyrene, as from any alien polymer. 

The influence of the precipitating power of porogens on the polymeric porous structure can be illustrated by the following example. At the reaction temperature of 80°C, -butyl alcohol was found to be a better precipitant for styrene-DVB copolymers than isooctane the Xi3 parameters are 2.31 and 1.27, respectively [267]. The better precipitant favors the... 

Figure 3.6 Dependence of inner surface area upon (a) the concentration of DVB and (b) the degree of dilution with n-heptane for (1, 2) macroporous styrene-DVB copolymers and (3, 4) sulfonates based on the copolymers with (1, 3) p-DVB and (2, 4) fech-DVB (a) the volume fraction of n-heptane 0.57, (b) the concentration of DVB 20%. After [298],...

Figure 3.9b shows the same boundaries confining the macroporous domain II for real styrene-DVB copolymers prepared in the presence of 2-ethyl-1-hexanoic acid, benzyl alcohol, heptane, or pentanol [314]. Judging from the shape of the plots, 2-ethyl-1-hexanoic acid and benzyl alcohol generate macroporous copolymers with cauliflower texture and high surface area in a wider range of crosslinking densities and dilutions compared with heptane or pentanol diluents. 

With respect to sweUing in non-solvents, toluene-modified styrene— DVB copolymers have much in common with hypercrosslinked polystyrenes [330]. Both are prepared in accordance with the same basic principle, the formation of rigid networks in strongly solvated state. It will be shown in detail in Chapter 7 that rigid expanded networks possess a relaxed favorable conformation only in their swollen state and, therefore, exhibit a marked tendency to acquire this state by sweUing and incorporating any liquid, even non-solvating one. 

The third approach to the formation of macroporous structure of styrene— DVB copolymers consists of adding a linear polymer, largely polystyrene, to the monomer mixture. 

Table 3.5 Characteristics of porous styrene-DVB copolymers prepared with polystyrene and mixtures of polystyrene with xylene as the porogens... 

Table 3.6 Characteristics of the porous structure of styrene-DVB copolymers prepared in the presence of polystyrene (/M =(193, 000) and xylene...

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