Polystyrene swelling behavior

In addition to monomers and the initiator, an inert liquid (diluent) must be added to the monomer phase to influence the pore structure and swelling behavior of the beaded resin. The monomer diluent is usually a hydrophobic liquid such as toluene, heptane, or pentanol. It is noteworthy that the namre and the percentage of the monomer diluent also influence the rate of polymerization. This may be mainly a concentration or precipitation effect, depending on whether the diluent is a solvent or precipitant for the polymer. For example, when the diluent is a good solvent such as toluene to polystyrene, the polymerizations proceed at a correspondingly slow rate, whereas with a nonsolvent such as pentanol to polystyrene the opposite is true. 

The perfluorinated, carboxylated and sulfonated ionomer membranes form the ionic clusters of a few nm in size, as in the case of the hydrocarbon-based ionomers such as polyethylene,polystyrene and polybutadiene(9). The ionic clusters strongly affect physical properties of the membranes, e.g., the swelling behavior of the membranes (amount of water uptaken by the membranes, W and... 

FACTORS DETERMINING THE SWELLING BEHAVIOR OF HYPERCROSSLINKED POLYSTYRENE NETWORKS... 

As already mentioned in Chapter 6, Section 4, appropriate solvents for conducting Friedel—Crafts crosslinking reaction of polystyrene are EDC, tetrachloroethane, nitrobenzene, and cyclohexane (at an elevated temperature). While the products prepared in the first two solvents are identical in aU their swelling behavior, the character of swelling of materials obtained in nitrobenzene is different. 

Copolymers of Styrene and Divinj benzene, Rubber Chem. Tech. 40, 476 (1967). Homo-IPNs of polystyrene and polystyrene. Swelling and mechanical behavior. 

Fig. 7 The swelling behavior of a dry gel (polystyrene resin that is cross-linked by divinyl benzene) when it is immersed in various halogenated solvents [23].

The IR spectra of all three polymers are recorded and compared with one another.The incorporation of monomeric units of 4-vinylpyridine can also be demonstrated by nitrogen analysis of the block copolymer.The solubility behavior is also determined. Po-ly(4-vinylpyridine) is soluble in pyridine, methanol, and chloroform, but insoluble in toluene and diethyl ether it swells considerably in water. On the other hand, the block copolymer, like polystyrene, is soluble in pyridine, chloroform, and toluene but unlike polystyrene, it swells significantly in methanol. 

Adsorption of block copolymers onto a surface is another pathway for surface functionalization. Block copolymers in solution of selective solvent afford the possibility to both self-assemble and adsorb onto a surface. The adsorption behavior is governed mostly by the interaction between the polymers and the solvent, but also by the size and the conformation of the polymer chains and by the interfacial contact energy of the polymer chains with the substrate [115-119], Indeed, in a selective solvent, one of the blocks is in a good solvent it swells and does not adsorb to the surface while the other block, which is in a poor solvent, will adsorb strongly to the surface to minimize its contact with the solvent. There have been a considerable number of studies dedicated to the adsorption of block copolymers to flat or curved surfaces, including adsorption of poly(/cr/-butylstyrcnc)-ft/od -sodium poly(styrenesulfonate) onto silica surfaces [120], polystyrene-Woc -poly(acrylic acid) onto weak polyelectrolyte multilayer surfaces [121], polyethylene-Wocfc-poly(ethylene oxide) on alkanethiol-patterned gold surfaces [122], or poly(ethylene oxide)-Woc -poly(lactide) onto colloidal polystyrene particles [123],... 

Much more interesting, however, than the swelling in humid air is the behavior of polyelectrolyte brushes in contact with water or salt solutions. The first experimental study of the swelling properties of a surface-attached polyelectrolyte monolayer obtained by a grafting to process has been reported by Auroy and coworkers [51]. Polystyrene sulfonate layers chemically... 

Values of Au qQ 3 calculated from stress relaxation of the swollen networks agreed fairly well with those derived from swelling of polyurethane networks. The anomalous behavior of polyurethanes has been reported (12). Swelling at different solvent activity and stress relaxation of swollen networks are valuable techniques for network characterization. Other networks such as crosslinked polystyrene will be examined by these methods. The role of the Gaussian approximation in rubber elasticity will be evaluated in calculating Mc for highly swollen networks. 

J.M O Kane and D.C. Sherrington, Hysteresis-like behavior in the swelling/deswelling of polystyrene cross-linked resins using binary solvent mixtures, Macromolecules, 1990, 23, 5286-5291. 

In order to improve the processing and end-user properties and also to simplify the preparation of the blends described above, we propose to design new copolymers which would have the same block sequences (polyisoprene and polystyrene) but not the same topology [23, 26-28]. We have already pointed out that, to obtain optimized rheological properties for a good tack, we must have a free polyisoprene sequence which explores the network of the trapped polyisoprene sequences of the triblock copolymer and swells this network. It is important to notice that this is the triblock copolymer which causes the soUd-Uke behavior [23]. This configuration can be obtained with a series of block sequences terminated by a polyisoprene sequence [26-28] ... 

---