Chain-growth polymerization donor-acceptor polymers

We will start this chapter with a brief review of the origin of the donor-acceptor concept, followed by a short summary of the key chemistries that are used for the synthesis of D-A copolymers e.g., Suzuki coupling and Stille coupling), with a focus on their application towards the polymer synthesis. The classical step-growth polymerization will be next discussed within the context of Pd-catalyzed polycondensation. Then we will briefly discuss two recent, interesting advances in the synthesis of D-A copolymers Pd-free polycondensation and chain-growth Suzuki polymerization. Since the synthesis of D-A... 

Chain-growth catalyst-transfer polycondensation (CTP) is a rapidly developing polymerization method, as it allows, in many cases, the above-mentioned limitations of step-growth polymerizations to be overcome. CTP provides a straightforward access to well-defined conjugated homopolymers (e.g., polythiophenes (1), polyfluorenes (2), polyphenylenes (3), etc.), alternate donor-acceptor copolymer e.g., 4) and all-conjugated block polymers (e.g., 5), Chart 20.1. 

Broadening the scope, we may briefly consider a nonexhaustive panorama of various types and features of supramolecular polymers depending on their constitution, characterized by three main parameters the nature of the core/framework of the monomers, the type of noncovalent interaction(s), and the eventual incorporation of functional subunits. The interactions may involve complementary arrays of hydrogen-bonding sites, electrostatic forces, electronic donor-acceptor interactions, metalion coordination, etc. The polyassociated structure itself may be of main-chain, side-chain, or branched, dendritic type, depending on the number and disposition of the interaction subunits. The central question is that of the size and the polydispersity of the polymeric supramolecular species formed. Of course their size is expected to increase with concentration and the polydispersity depends on the stability constants for successive associations. The dependence of the molecular weight distribution on these parameters may be simulated by a mathematical model [19]. These features are detailed in Chapters 2, 3, and 6 for various growth mechanisms. 

---