Doping crosslinking

Stable nitroxides, independent of the way of their formation, are traditionally considered as the prerequisite and the principal species of the free-radical scavenging activity of HAS [15,125]. More pathways and oxidants certainly participate in NO formation (Eq.15). The specificity of NO" generation via oxidation with ROOH may serve for a rapid evaluation of the weatherability of HAS doped crosslinked melamine and urethane acrylic copolymers [152,159]. 

The tensile strength of both doped and non-doped, crosslinked or non-crosslinked polyaniline films increases with increasing 1/1 values,. Similar conductivity and tensile strength changes are observed with stretch-oriented polyaniline fibers, 5. 9,20... 

According to a recent report, the thermal stability of self-doped polyfanilineboronic acid) [220] is greater than that of HCl-doped polyaniline and other self-doped forms of polyaniline. This is due to a self-doped structure where the anion is immobilized in the form of a crosslink, resulting in conductivity up to 500 °C. This self-doped crosslinked structure is also responsible for enhanced mechanical properties including a hardness of 0.5 GPa [221]. 

An aqueous dope of forms gel with protonic acid, alkali, oxidizing and reducing agents as formulated below. The crosslinking of S-S type would be suggested since the formation of -SH or -S was confirmed for the model compound under the similar condition. 

The less concentrated PA as the additive in a casting dope does not make long enough crosslinks among CA molecules, so the effective size of dynamic polymer aggregates in the solution prior to the phase inversion is too small - the AEy values are lower. 

At the present time aminoplasts comprise moulding compounds based on amine resins (thermosetting condensation products of formaldehyde with carbamide or melamine or a combination thereof) and organic or mineral fillers or a combination thereof doped with dyestuff and modifying substances (plasticizers, stabilizers, crosslinking agents, and the like). 

Crosslinked LC elastomers (Figure 19d) are very promising for piezoelectric and ferroelectric applications, and also as non-linear optic materials. The first synthetic step to such materials is the preparation of usual side chain or combined LC copolymers doped with a small part of side chains containing a polymerizable >C=C< double bond at the end (Figure 23 shows a particular example of a crosslinkable LC polymer64). The copolymer can be further photocrosslinked, giving an elastic polymer film which reveals... 

Sol-gel methods have been used to form membranes on sensor surfaces by the mixing of the ion-sensitive molecule with alkoxysilanes which then crosslink to form a hard, transparent coating on the sensor. For example, tridodecyl-methylammonium chloride-doped films were used as a chloride sensor and showed Hofmeister-type selectivity [91]. Long cure times (several days), however, represent a disadvantage in this process [91]. 

Silicone Polymers - Laser flash photolysis studies on poly(silylenes) generates radical cations along with silyl radicals and polysiloxane composities for the space shuttle have been found to be stable to far UV light exposure. Linear polysiloxanes have been found to be more unstable than branched or crosslinked polymers while the transparency of poly(methylphenylsilane) increases with light exposure. Photooxidised polysiloxanes doped with iodine are converted into semiconductors. ... 

The potential applications for conducting polymers are enormous and this has stimulated a large amount of research into this area. Not surprisingly, solid-state NMR spectroscopy has been applied to study these amorphous, insoluble and in many cases crosslinked materials [24]. Looking at the CP/MAS spectra of a series conducing polyacenic polymers, some of which were doped with iodine, it was possible to see the effect of the halogen upon conductivity. These resins were prepared by a conventional procedure for the preparation a Novolak-type phenol-formaldehyde resin. After synthesis, the phenol-formaldehyde resin were dissolved and solutions were cast as a film and heat treated to between 590-670°C in a N2 atmosphere to form the polyacenic film. The electrical conductivity of the films was shown to increase... 

The extent and rate of crosslinking is expected to depend on both the doping level and the concentration of polymer in solution. 

The blend of EPDM and polyacetylene was crosslinked using sulfur monochloride in a toluene solution. It should be noted that the crosslinked blend could not be doped with iodine. 

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