Polystyrene networks with poly

Examples of known phosphazene polymer blends are those in which phosphazenes with methylamino, trifluoroethoxy, phenoxy, or oligo-ethyleneoxy side groups form blends with poly(vinyl chloride), polystyrene, poly(methyl methacrylate), or polyethylene oxide).97 100 IPNs have been produced from [NP(OCH2CH2OCH2CH2OCH3)2] (MEEP) and poly(methyl methacrylate).101-103 In addition, a special type of IPN has been reported in which a water-soluble polyphosphazene such as MEEP forms an IPN with a silicate or titanate network generated by hydrolysis of tetraethoxysilane or tetraalkoxytitanane.104 These materials are polyphosphazene/ceramic composites, which have been described as suitable materials for the preparation of antistatic layers in the manufacture of photographic film. 

Hamurcu EE, Baysal BM. (1995) Interpenetrating polymer networks of poly(dimethylsiloxane) with polystyrene, polybutadiene and poly(glycerylpropoxytriacrylate) Macromol. Chem. Phys. 196 1261-76... 

Scanning electron micrographs (SEMs) of (a,b) polyaniline (PANI) network in 25/25/25/25 polystyrene/polymethyl methacrylate/poly(vinylidene fluoride)/polyaniline (PS/PMMA/ PVDF/PANI) blend after extraction of all phases by dimethylformamide (DMF) followed by freeze drying, and (c,d,e) PANI network in 15/20/15/25/25 PS/PS-co-PMMA/PMMA/PVDF/ PANI blend after extraction of all phases by DMF followed by freeze drying. (Reproduced from Ravati, S., and Favis, B. D. 2010. Low percolation threshold conductive device derived from a five-component polymer blend. Polymer 51 3669-3684 with permission from Elsevier.)... 

Vollmert presented 31 examples of multipolymer compositions, some of which were IPNs, (see Table 8.1). In example 20, a crosslinked poly(n-butyl acrylate) makes up network I. Poly(n-butyl acrylate-co-acrylonitrile) crosslinked with 1,4-butane-diol diacrylate makes up network II on a separate latex. A linear poly(styrene-co-acrylonitrile) latex makes up polymer III for a third latex. The three latexes are blended to form an impact-resistant polystyrene. This particular product, however, is not an IPN, because the two crosslinked latexes were polymerized and crosslinked separately and then mechanically blended together. 

This result is confirmed by the analysis of the data obtained for several other neutral polymer networks swollen with very good diluents natural rubber-n-decane polyiso-prene-n-decane polydimethyl-siloxane-cyclohexane polystyrene (networks prepared in a radical manner)-benzene , poly(vinyl acetate)-toluene , poly(vinyl acetate)-acetone , polydimethylsiloxane-heptane. ... 

Interpenetrating networks of DMPPO and polymers such as polystyrene, polybutadiene, poly(urethane acrylate), and poly(methyl methacrylate) have been prepared by cross-linking solutions of DMPPO containing bromomethyl groups with ethylenediamine in the presence of the other polymer (68). 

In Chapters 3 and 11 reference was made to thermoplastic elastomers of the triblock type. The most well known consist of a block of butadiene units joined at each end to a block of styrene units. At room temperature the styrene blocks congregate into glassy domains which act effectively to link the butadiene segments into a rubbery network. Above the Tg of the polystyrene these domains disappear and the polymer begins to flow like a thermoplastic. Because of the relatively low Tg of the short polystyrene blocks such rubbers have very limited heat resistance. Whilst in principle it may be possible to use end-blocks with a higher Tg an alternative approach is to use a block copolymer in which one of the blocks is capable of crystallisation and with a well above room temperature. Using what may be considered to be an extension of the chemical technology of poly(ethylene terephthalate) this approach has led to the availability of thermoplastic polyester elastomers (Hytrel—Du Pont Amitel—Akzo). 

A wide range of polymer networks are constructed in this manner. Poly(vinyltrichloacetate) was used as the coinitiator with styrene, MMA and chloroprene as cross-linking units. Polycarbonates, polystyrene, N-haloge-nated polyamide, polypeptides, and cellulose acetate, suitably functionalized, have been used as a coinitiator... 

The variation of the domain sizes with crosslink density was recognized by Yeo et al. [28], investigating cross-poly(n-butyl acrylate)-inter-cross-polystyrene. Figure A shows the morphology of 50/50 compositions as a function of network I crosslinking level. The cellular structures are gradually transformed to finer, and more obviously cylindrical or worm-like shapes with increasing crosslink density. 

Figure 4. Transmission electron microscopy morphology of 50/50 cro55-poly( -butyl acrylate)-/ ler-croM-polystyrene IPNs as a function of network I cross-link density. (Reproduced with permission from ref. 18. Copyright 1982 Polymer Engineering and Science.)...

Figure 12. Radius of poly(dimethyl slloxane) phase as a function of weight fraction In cross-poly(dimethyl slloxane)-Inter-cross-polystyrene sequential IPN s with three different crosslink densities of network I. Broken lines are theoretical values from...

In a related application, polyelectrolyte microgels based on crosslinked cationic poly(allyl amine) and anionic polyfmethacrylic acid-co-epoxypropyl methacrylate) were studied by potentiometry, conductometry and turbidimetry [349]. In their neutralized (salt) form, the microgels fully complexed with linear polyelectrolytes (poly(acrylic acid), poly(acrylic acid-co-acrylamide), and polystyrene sulfonate)) as if the gels were themselves linear. However, if an acid/base reaction occurs between the linear polymers and the gels, it appears that only the surfaces of the gels form complexes. Previous work has addressed the fundamental characteristics of these complexes [350, 351] and has shown preferential complexation of cationic polyelectrolytes with crosslinked car-boxymethyl cellulose versus linear CMC [350], The departure from the 1 1 stoichiometry with the non-neutralized microgels may be due to the collapsed nature of these networks which prevents penetration of water soluble polyelectrolyte. 

By a method similar to isoporous polystyrene synthesis, poly(4-vinylpyridine) has been cross-linked with dibromoalkanes to give insoluble networks containing pyri-dinium ions (26)113). 

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