Elastomeric networked polymers

Recently, Kolel-Veetil and Keller have modified this system to produce elastomeric networked polymers. The ambient-condition hydrosilation reactions between monomeric vinyl- or ethynyl-terminated carboranylenesiloxane and three different monomeric branched siloxane cross-linkers in hexane yielding these systems were catalyzed by the Karstedt catalyst.134 The reactions involving the vinyl-carboranylenesiloxane were reported to produce a set of completely hydrosilated networked polymers (105) (Fig. 65). In the case of the ethynyl monomer, the reactions were carried out at two different ratios, yielding a partially (106) and a com-... 

In the interest of producing elastomeric network polymers, Kolel-Veetil et al. reported the modification of the preceding hydrosilation reaction system. They reported the Karstedt catalyst-catalyzed ambient-condition hydrosilation reactions of a monomeric vinyl 14 or ethynyl-containing 17 carboranylenesiloxane with three different monomeric branched siloxane crossUnkers in hexane (Figure 15.19) [36]. The reactions involving the vinylcarboranylenesiloxane were reported to... 

Sur, G. S. Mark, J. E., A Novel Method for Preparing Bimodal Elastomeric Networks. Polym. Bull. 1985,13, 505-509. 

Mark, J. E. Ning, Y.-P., Effects of Ethylamine Catalyst Concentration in the Precipitation of Reinforcing Silica Filler in an Elastomeric Network. Polym. Bull. 1984,12,413-417. 

The study of acid-base interaction is an important branch of interfacial science. These interactions are widely exploited in several practical applications such as adhesion and adsorption processes. Most of the current studies in this area are based on calorimetric studies or wetting measurements or peel test measurements. While these studies have been instrumental in the understanding of these interfacial interactions, to a certain extent the interpretation of the results of these studies has been largely empirical. The recent advances in the theory and experiments of contact mechanics could be potentially employed to better understand and measure the molecular level acid-base interactions. One of the following two experimental procedures could be utilized (1) Polymers with different levels of acidic and basic chemical constitution can be coated on to elastomeric caps, as described in Section 4.2.1, and the adhesion between these layers can be measured using the JKR technique and Eqs. 11 or 30 as appropriate. For example, poly(p-amino styrene) and poly(p-hydroxy carbonyl styrene) can be coated on to PDMS-ox, and be used as acidic and basic surfaces, respectively, to study the acid-base interactions. (2) Another approach is to graft acidic or basic macromers onto a weakly crosslinked polyisoprene or polybutadiene elastomeric networks, and use these elastomeric networks in the JKR studies as described in Section 4.2.1. 

Polymer Hydroxyl SiOH, Backbone required to form the elastomeric network. 

To produce elastomeric materials from 95, Kolel-Veetil and Keller studied the effects of reducing the concentration of the diacetylene units in 95 on the plasticities of the resulting networks.127 The ratio (1 2 1) of the carborane, disiloxane, and diacetylene moieties in 95 was altered to 2 3 1, 4 5 1, and 9 10 1, respectively, to produce polymers containing progressively lower amounts of diacetylene units. Two sets of the polymers, one an alternating type (97) and the other a blocky type (98) (Fig. 60), were synthesized. The networked polymers produced from both the blocky and the alternating sets were found to be slightly elastomeric with T values around... 

The deformation of polymer chains in stretched and swollen networks can be investigated by SANS, A few such studies have been carried out, and some theoretical results based on Gaussian models of networks have been presented. The possible defects in network formation may invalidate an otherwise well planned experiment, and because of this uncertainty, conclusions based on current experiments must be viewed as tentative. It is also true that theoretical calculations have been restricted thus far to only a few simple models of an elastomeric network. An appropriate method of calculation for trapped entanglements has not been constructed, nor has any calculation of the SANS pattern of a network which is constrained according to the reptation models of de Gennes (24) or Doi-Edwards (25,26) appeared. 

Extensive studies on different rubber compounds (see, for example, Table 1 in [105]) yield Ec 0.05 to 0.15 eV per filler-filler bond [105,106], i.e., typical values for physical (van der Waals like) bonds. Similar values were obtained within an approach which assumes a hypothetical analogy between the structure of a statistical carbon black network and that of a Gaussian elastomeric (unfilled) polymer network [107]. As in the Kraus approach, the carbon black network scission process is assumed to be thermally activated. 

In a polymer network the chains are connected through cross-links that restrict the motion of the chain ends. Consequently a polymer chain belonging to an elastomeric network can be represented as in Figure 3.6, i.e., with one end fixed at the origin O while the other is confined to a small volume dV = dx dy dz. 

A number of variations of the above-mentioned full IPNs have also been stated in the literature. One of them involves having either Polymer I or II as linear (not crosslinked) polymer, in which case it is called semi-IPN. The other variation involves the formation of Polymer I and II simultaneously through two noninterfering polymerization processes (such as stepwise and chain polymerizations) in which case it is called simultaneous IPN (SIN). If a linear polymer is formed simultaneously with a crosslinked polymer, then we have a semisimultaneous IPN (semi-SINS). Still another type is taking a mixture of two linear polymers, and crosslinking both components simultaneously, in which case it is called interpenetrating elastomeric network (lEN). The common feature of... 

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