Conjugated polymer systems

One of the most successful conjugate polymer systems was developed by Duncan and Kopecek (25). The polymer carrier used in their system is poly [N(2-hydroxypropyl) methacrylamide] a biocompatible polymer that was originally developed as a plasma extender. They have evaluated a number of polymer conjugated drugs for cancer chemotherapy with interesting results. The attachment of the drug is through a peptidyl spacer pendent to the polymer backbone. These peptides links are stable in aqueous media but are readily hydrolyzed intracellularly... 

Both theoretical and experimental evidence suggest that the precise nature of the charge carriers in conjugated polymer systems varies from material to material, and it is still a subject of debate in many cases. A discussion of the various theoretical models for the electronic structure of conjugated polymers is given below, using polyacetylene and poly(paraphenylene) as examples. More detailed information on these materials and the applicability of these theoretical models is given in subsequent sections. 

Fan L-J, Jones WE Jr (2006) Studies of photoinduced electron transfer and energy migration in a conjugated polymer system for fluorescence tum-on chemosensor applications. J Phys Chem B 110 7777-7782... 

The TT-conjugated polymer systems have been intensively studied during the last 25 years. They form a new class of semiconductor electronic materials with potential applications such as organic light-emitting diodes (OLEDs) [1-3], thin-film transistors (TFTs) [4], photovoltaic cells [5], spin-valve... 

In this section, we briefly review nonlinear optical spectroscopy that are related to exciton response in tt-conjugated polymer systems that will be used in this chapter. This includes EA and TPA spectroscopies. 

The ao value depends on the electron-phonon-coupling constant, while Tq is in connection with the localized density of states near the Fermi level and the decay length of the wave function, respectively. It can be seen that conductivity increases with temperature in contrast to that of the metals. This type of conductivity behavior has been verified for many conjugated polymer systems. The problem of locaKzation is less important if the molar mass of the polymer is high and only a few defects are present, as well as a relatively intense interchain coupKng prevails. In... 

Initial investigations of the photoinduced electron transfer events were carried out In solution. The conjugated polymers PANi(EB> and PDMA(eb) were readily synthesized and characterized according to literature methods [131,132]. Stem-Volmer analysis of the emission spectrum of [Ru(dmb)3] at 612 nm as a function of increasing PDMA(eb) concentration demonstrated that the conjugated polymer system was capable of quenching the MLCT state (Fig. 13). In this experiment, the emission intensities were corrected for the small amount of competitive absorption at 458 nm from the polymer, and pure polymer samples dem-... 

We now consider various types of charge carriers that can be found in electronically conducting polymers. As previously noted both experimental and theoretical evidence suggest that the precise nature of charge carriers present in conjugated polymer systems depends to a very large extent on the type of polymer. We discuss two representative polymer materials, polyacetylene and polypyrrole, which have been the subject of considerable study. 

---