Styrene swelling

The phenomenon of polymer swelling, owing to sorption of small molecules, was known even before Staudinger reported [1] in 1935 that crosslinked poly(styrene) swells enormously in certain liquids to form two-component polymer gels. The physical state of such systems varies with the concentration (C) and molecular structure of the sorbed molecules thus, the system undergoes transition at constant temperature from a rigid state (glassy or partially crystalline) at C < Cg to a rubbery state at Cg (the transition state composition). When C > Cg and the second component is a liquid, its subsequent sorption proceeds quickly to gel-saturation and of course a solution is produced if the polymer lacks covalently bonded crosslinks or equivalent restraints. Each successive physical state exhibits its own characteristic sorption isotherm and sorption kinetics. 

At equilibrium, a sample of poly(butadiene-xtflr-styrene) swelled 4.8 times its volume in toluene at 25°C. What is Young s modulus at 25 C ... 

To illustrate the specific operations involved, the scheme below shows the first steps and the final detachment reaction of a peptide synthesis starting from the carboxyl terminal. N-Boc-glycine is attached to chloromethylated styrene-divinylbenzene copolymer resin. This polymer swells in organic solvents but is completely insoluble. ) Treatment with HCl in acetic acid removes the fert-butoxycarbonyl (Boc) group as isobutene and carbon dioxide. The resulting amine hydrochloride is neutralized with triethylamine in DMF. 

Fig. 1. SAE J200 Classification system for ASTM No. 3 oil where in volume swell nr = no requirement. EPDM is ethylene—propylene—diene monomer HR, butyl mbber SBR, styrene—butadiene mbber NR, natural mbber VMQ, methyl vinyl siUcone CR, chloroprene FKM, fluoroelastomer FVMQ, fluorovinyl methyl siUcone ACM, acryUc elastomers HSN, hydrogenated nitrile ECO, epichlorohydrin and NBR, nitrile mbber.

A macroporous polystyrene-divinylbenzene copolymer, produced by copolymerizing a mixture of styrene and divinylbenzene, is dissolved in an organic liquid such as t-amyl alcohol or isooctane, which is a solvent for monomers. This solvent is unable to substantially swell the resulting copolymer. Macroporous cation-exchange beads are also produced from these macroporous copolymers (25,26). 

Figure 4 (a) Polymerization time versus degree of swelling (in toluene) curves for styrene-PEG crosslinked copolymers initiated by macroinimers ( ) MAIM-200, ( ) MAIM-400, (O) MAIM-600, (A) MAIM-1000, and ( ) MAIM-1500. (b) Polymerization time versus degree of swelling (in water) curves for styrene-PEG crosslinked copolymers initiated by ( ) MAIM-1500 and ( ) MAIM-400. Source Ref. 50. 

As shown for the synthesis of PS [291], the monomer may be localized in the vicinity of the filler surface by previously grafting a polymer capable of swelling in the base monomer. Copolymeric latex of polychloroprenemethacrylic acid was added to the aqueous dispersion of chalk. The acid groups reacted with chalk and the latex particles became chemically grafted to chalk. When further portions of styrene were added they were completely absorbed by modified chalk. 

The other main support used for solid base catalysts is polystyrene, which while it does not have a well-defined porous structure, does swell in solvents providing an accessible high surface area on which to carry out reactions. One common method of chemically attaching groups to polystyrene involves incorporation of specific amounts of styrene contain-... 

Hacroreticular resins are prepared by suspension polymerization of, for example, styrene-divinylbenzene copolymers in the presence of a substance which is a good solvent for the sononer but a poor swelling agent for the polymer [178-180]. Each resin bead is formed from many microbeads joined together during the polymerization process to create a network of holes and 7 channels. This results in greater mechanical stability,... 

Figure 13 Typical swelling and deswelling rates of cross-linked poly(acryloyl pyrroli-dine-co-styrene) between 27°C and 37°C. AS15 ( ) AS20 (A). The numbers indicate the content of styrene in the feed composition in moles during polymerization. Membrane thickness is 0.5 mm in the dried state. (From Ref. 34.)...

We have considerable latitude when it comes to choosing the chemical composition of rubber toughened polystyrene. Suitable unsaturated rubbers include styrene-butadiene copolymers, cis 1,4 polybutadiene, and ethylene-propylene-diene copolymers. Acrylonitrile-butadiene-styrene is a more complex type of block copolymer. It is made by swelling polybutadiene with styrene and acrylonitrile, then initiating copolymerization. This typically takes place in an emulsion polymerization process. 

The styrene-dvb types have better temperature stability than the other two, but most resins swell in contact with solvents. 

On each of the curves, the points at lowest X represent swelling in cyclohexane, the next in tetrahydrofuran and the last in benzene. In all cases, the samples were swollen in the pure solvent. The curves are reproduced from Figure 13 of Reference 19. The networks were made from anionically polymerized polyr-styrene using a bifunctional initiator crosslinked subsequently by divinyl benzene. The curves correspond to different ratios of divinyl benzene (DVB) per polystyrene living end (LE),... 

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