Silicone networks functionality

Equilibrium Tensile Behavior of Model Silicone Networks of High Junction Functionality... 

Functionalization, silicone network preparation via, 22 568 Functionalized initiators, 14 255 Functional methacrylates, 16 240-242 Functional monomers methacrylate, 16 241-242 polymer colloid, 20 379-380 Functional perfume products, 18 354 Functional polyethylene waxes, 26 220 Functional properties, of wax, 26 215 Functional unit, in life cycle assessment, 14 809... 

Oxirane functionalization, silicone network preparation via, 22 568 Oxirane processes, 4 416 23 342 24 172 4-Oxo-9,ll,13-octadecatrienoic (licanic) acid... 

ADMET polymerization has been used to integrate silicon into linear and network hydrocarbon polymers in an attempt to produce novel materials with enhanced thermal and mechanical stability. While ADMET has been used to produce copolymeric architectures unattainable through conventional methods, application of this polymerization to synthesis is feasible only if the silicon-based functionality does not inhibit metathesis. This research, initiated in the early 1990s by Wagener and colleagues, has shown that the silane and siloxane... 

Model silicone networks, i.e., those prepared by end-linking of functionally terminated polymer chains, have been extensively utilized to explain the influence of molecular structure on mechanical properties. An important number of studies have been focused on the contribution of elastically active chains and trapped entanglements to equilibrium properties [1-7]. In contrast, very little work has been done to explain the influence of network structure on non-equilibrium properties [8], and the contribution of some of the main structural parameters to viscoelastic properties has been poorly explored. A few qualitative studies have shown in the past that pendant chains have a strong influence on relaxation properties, but the type of contribution was not clearly understood [9]. 

The incorporation of ablative and tethered oils into the silicone topcoat of fouling release coatings is a desirable mechanism for slow, controlled release of the silicone oil from the RTV topcoat. Once incorporated into the silicone network, the hydrolytically unstable Si-O-C bond in the ablative oil (Figure 3) should slowly degrade in water. Conversely, the tethered oil is chemically bonded into the silicone network and one end (the non-miscible portion) should phase separate to the surface of the PDMS. Both ablative and tethered oils contain diphenyldimethylsiloxane functionality, based on previous studies of the free oil. The approach was to synthesize both ablative and tethered diphenyldimethylsiloxane copolymers, incorporate the copolymers into the RTV topcoat and then measure the foul release performance of the coatings. Both oils are shown below in Figure 3. 

Silicone network with high concentration of well distributed functional moieties... 

Figure 13.1 Representation of some of the main factors that contribute towards the complex structural architecture of a silicone elastomer. Polymer structure, cure chemistry, network functionality, filler type and loading levels are just some of the variables that go into defining a final three-dimensional, multiscaled elastomer network.

In spite of the intractability of silicone elastomers towards standard spectroscopic and analytical techniques, much progress has been made towards enhancing understanding of structure-property relations in complex silicones in relation to elastomeric network theory. Notably, Mark et al. have made an extensive study of the relationship between network functionality, modality and filler content and the bulk mechanical/rheological properties of model silicone networks [26-28]. Additionally, Clarson et al. have studied modification of silicone-based materials with a range of fillers and other physical property modifiers in great depth [29]. 

Figure 23.9 illustrates the different cellular behavior of human dermal fibroblasts (FIDFs) grown on the collagen-coated silicone substrates as a function of substrate stiffness. The control silicone network formulation represented a soft substrate with relatively low elastic modulus and resulted in a round, non -stretched with few irregular protrusions morphology of HDF cells. As the stiffness increased, the substrate induced the stretching... 

Addition cure silicones can be delivered from solvent, waterborne emulsions, or 100% solids systems. The solvent free versions employ base polymers of intermediate molecular weight to achieve processable viscosity. These base polymers can have reactive moieties in terminal and/or pendant positions. These lower molecular weight, more functional systems result in a tighter crosslink network which feels rubbery to the hand. Low amounts of high molecular weight additives are included in some formulations to provide a more slippery feel [51,52]. 

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