Polymers with intrinsic synthesis

Another approach to CPL is the synthesis of conjugated polymers with intrinsic chiro-optical properties. A variety of polymers with CPPL have been synthesized so far. Most of them are based upon well-known conjugated polymers such as poly(thiophene)s [4,111], polyphenylene vinylene)s [123], poly(thienylene vinylene)s [124], ladder polymers [125], PPPs [126], polyphenylene ethynylene)s, [127] and poly(fluorenes) [128]. All of them have been modified with chiral side-chains, which induce the chiro-optical properties. 

Polymers with intrinsic microporosity, abbreviated as PIMs, were developed for the first time by McKeown and Budd. The general design strategy involves incorporation of extended aromatic components within a rigid polymer network in order to imitate the structural layout of graphene sheets of activated carbons.The principle behind the synthesis of PIMs employs non-reversible condensation reactions to form polymers. These polymers cannot efficiently fill the space and pack together due to components that are rigid and ladder-like, and thus force the backbone of the polymer to twist or turn. 

Figure 4.11 Synthesis of polymers with intrinsic microporosity (a) PIM-1 and (b) PIM-7.

Data on the synthesis, hydrolysis, and biological activity of polymers possessing fungicidal activity are reviewed, including the properties of macromolecular systems with controlled release of the active substance and polymers possessing intrinsic biological activity. 105 refs. 

Most radicals are transient species. They (e.%. 1-10) decay by self-reaction with rates at or close to the diffusion-controlled limit (Section 1.4). This situation also pertains in conventional radical polymerization. Certain radicals, however, have thermodynamic stability, kinetic stability (persistence) or both that is conferred by appropriate substitution. Some well-known examples of stable radicals are diphenylpicrylhydrazyl (DPPH), nitroxides such as 2,2,6,6-tetramethylpiperidin-A -oxyl (TEMPO), triphenylniethyl radical (13) and galvinoxyl (14). Some examples of carbon-centered radicals which are persistent but which do not have intrinsic thermodynamic stability are shown in Section 1.4.3.2. These radicals (DPPH, TEMPO, 13, 14) are comparatively stable in isolation as solids or in solution and either do not react or react very slowly with compounds usually thought of as substrates for radical reactions. They may, nonetheless, react with less stable radicals at close to diffusion controlled rates. In polymer synthesis these species find use as inhibitors (to stabilize monomers against polymerization or to quench radical reactions - Section 5,3.1) and as reversible termination agents (in living radical polymerization - Section 9.3). 

We have already referred to the Mo/Ru/S Chevrel phases and related catalysts which have long been under investigation for their oxygen reduction properties. Reeve et al. [19] evaluated the methanol tolerance, along with oxygen reduction activity, of a range of transition metal sulfide electrocatalysts, in a liquid-feed solid-polymer-electrolyte DMFC. The catalysts were prepared in high surface area by direct synthesis onto various surface-functionalized carbon blacks. The intrinsic... 

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