Crosslinked polymers, nonlinear

Two crosslinkable perfluorinated bisphenol A polymeric derivatives having nonlinear optical chromophores containing thiophene have been prepared. Both crosslinked polymers had higher Tg s and greater mechanical stability than their noncrosslinked analogues and were used as light-emitting diodes. 

Moreover, organic functionalization of a polymer chain can lead to improvement in the physical properties, such as thermal stability and mechanical strength of the resulting siloxanes (Figure 3.1). Appropriate substitution on the polysiloxane backbone can lead to diverse materials such as liquid crystals," crosslinking agents, conductive and electroluminescent polymers, nonlinear optical materials,and bactericides. ... 

Macromolecules with nonlinear structure form a special group that includes branched, graft, comb, star, cyclic and network type macromolecules. Also, macromolecular assemblies are known, such as polymer blends, interpenetrating polymers, polymer networks, polymer-polymer complexes. The names of these types of macromolecules can be made using qualifiers such as -branch-, -blend-, -i- indicating crosslinked, etc. 

Polymer product quality control The molecular architecture of a polymer is very sensitive to reaction environment. The actual customer specifications are often represented by nonmolecu-lar parameters (e.g., tensile strength, impact strength, color, crack resistance, thermal stability, etc.) that must be somehow related to fundamental polymer properties such as molecular weight distribution, composition, composition distribution, branching, crosslinking, etc. Many of these properties are influenced by more than one reaction or process variable and hence, one needs to understand complex and nonlinear relations between reaction variables and fundamental polymer properties. The lack of online... 

The modeling of homopolymerization as well as linear and nonlinear (chain transfer to polymer and crosslinking) copolymerizations can be represented with the same polymerization scheme shown in Figure 12.1. The kinetic... 

In the following sections we describe the preparation of polymers which incorporated DEC chromophores either as components of a polymer backbone which is stabilized by interchain crosslinking or as a pendant to mainchain poljmers where the DEC chromophore is acting as the interchain crosslinking agent. The objective of this research, which has been realized, is the retention of significant optical nonlinearity at elevated temperatures (e.g., 125 °C) for extended periods of time. This is accomplished with the realization of an acceptable magnitude of optical nonlinearity (x(2) = 100-300 pnVV). 

For this reaction an organometallic photoinitiator was used that absorbs at 532 nm. Photocrosslinking of the oriented polymer can be used to produce a patterned material that exhibits a stable second-order nonlinear optics signal that lasts for several weeks at 100 °C. Addition of phenol is necessary to prevent thermal crosslinking. 

Takahashi, H. Ishimuro, Y. Watanabe, H., Nonlinear Mechanical Behavior of Scarcely Crosslinked Poly(dimethylsiloxane) Gel Effect of Strand Length Poly-dispersity. Polym. J. 2007, 39,465-474. 

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