Inter-polymer network

From the conversion dependence of the insolubilization process, it was concluded that both inter- and intramolecular propagation reactions occur during the polymerization of the epoxy ring. Blends of epoxidized polyisoprene and difunctional vinyl ether or aciylate monomers were shown to undergo a fast and extensive cross-linking polymerization, with formation of interpenetrating polymer networks. 

In some colloidal dispersions, the shear rate (flow) remains at zero until a threshold shear stress is reached, termed the yield stress (ry), and then Newtonian or pseudoplastic flow begins. A common cause of such behaviour is the existence of an inter-particle or inter-molecular network, which initially acts like a solid and offers resistance to any positional changes of the volume elements. In this case, flow only occurs when the applied stress exceeds the strength of the network and what was a solid becomes a fluid. Examples include oil well drilling muds, greases, lipstick, toothpaste and natural rubber polymers. An illustration is provided in Figure 6.13. Here, the flocculated structures are responsible for the existence of a yield stress. Once disrupted, the nature of the floe break-up process determines the extent of shear-thinning behaviour as shear rate increases. 

Exceptionally high relative selectivities are reported for sPOSS = 8.3) [144], PVdF (fir = 20) [119, 120], PANI-coated Nafion (fi = 8.0) [126], and semi-inter penetrating polymer networks of Nafion and crossfinked poly(AMPS) (fir = 16) [152],... 

Polylactides (PLA) may have many potential applications for an important set of products but some of their properties should be improved to obtain similar performance to petroleum-based commodities. One of the most important current applications of PLA is food packaging, in particular for short-shelf-life products with common applications such as rigid containers, drinking cups, over-wrap and lamination films. PLA production and consumption are expected to increase therefore research into the variation of PLA mechanical and barrier properties is currently very active. The control of barrier properties in PLA films is possible by modification of the polymer network through the formation of intramolecular and inter-molecular covalent crosslinking, for example by applying thermal treatment, or by modifying the chemical composition. Another method is to incorporate fillers, in particular layered nanoclays, and this will be the subject of this chapter. 

Proper description of nonlinear science in material science has been demonstrated in various crystallization processes of polymeric systems [90, 91]. As those systems were found to be capable to show oscillation independently by inter-molecular interfaces or transitory oscillating phases, catalytic ions and polymer network are mingled together by covalent bonding. Additional relevance of nonlinearity in materials science has effectively began with systematic study of... 

In the polymerization of the monomers, the mixture is in a liquid crystal phase. The polymerization environment is anisotropic due to the aligning effect of the liquid crystal on the monomer and the anisotropic diffusion of the monomer in the liquid crystal. After the monomers are polymerized, they phase separate from the liquid crystals to form anisotropic fiber-like polymer networks which mimic the structure of the liquid crystal during the polymerization. The polymer networks consist of cylindrical shape fibers with submicron lateral diameter and hundreds of microns in longitudinal length. The inter-distance between the fibers is typically a few microns. 

Interpenetrating polymer networks can inter-disperse two immiscible polymers down to a fine scale of phase separation, and usually use crosslinking to stabilize this morphology [13]. This can produce a remarkable synergism of properties. 

Garoushi, S., Vallittu, P.K., and Lassila, LV.J. (2007) Short glass fiber reinforced restorative composite resin with semi-inter penetrating polymer network matrix. Dent. Mater., 23, 1356-1362. 

Figure 26.7 shows the chemical structures of an NLO chromophore (APAN) and an epoxy-based polymer (BPAZO) where NLO moieties are attached to the backbone [81]. Both the dye and the polymer are functionalized with thermally cross-linkable acryioyl groups. As the dye-doped polymer is subjected to heat as part of the simultaneous poling/curing process, the inter- and intramolecular cross-linking reactions occur simultaneously (Fig. 26.8). The 7g of the cross-linked polymer-dye network is lower than that of the undoped polymer network because of the plasticizing effect of the dissolved dye. However, the temporal stability at 100°C of the polymer-dye network is better than that of the undoped polymer network (Fig. 26.9) as a direct result of the increased cross-linking density in the cross-linked guest-host system. Therefore, the addition of the thermally cross-linkable NLO dye not only increases the...

Liu, X., Guoa, H., Zhaa, L. Study of pH/ temperature dual stimuli-responsive nanogels with interpenetrating polymer network structure. Polym. Inter. 61,1144—1150 (2012)... 

Novel and smart soft materials like polymer and colloidal gels, glasses, inter penetrating network structures (IPNS) and poly electrolyte complexes (coacer-vates) have generated adequate interest in the recent past due to their enormous... 

We have provided several examples of intermolecular complex formation that has led to coacervation. In the past coacervate samples were probed by an array of techniques in order to determine the details of their micro-structure. The experimental results taken together reveals that the coacervate phase is a heterogeneous viscous material. The polymer-rich phase comprises physically crosslinked networks of constituent biomolecules. The presence of inter-penetrating networks of... 

Brovko A A, Fainleib A M, Shantalii T A, Sergeeva L M and Davidenko V V (1994) Structure and viscoelastic properties of polycyanurate-polyurethane semi-inter-penetrating polymer networks, Polym Sci 36 934-938. 

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