Main-chain Metal-containing Polymers

The Synthesis of Main-Chain Metal-Containing Polymers... 

Early attempts to prepare main-chain metal-containing polymers mainly focused on the use of step-growth polycondensation processes (Scheme 1.1, Route B). These routes work well for the synthesis of carbon-based polymers when difunctional organic monomers are used because the latter are generally easily accessible in a high degree of purity. This allows the stringent stoichiometry and conver-... 

For many applications, side-chain metal-containing polymers are sufficient. However, to access the most profound alterations in polymer properties that arise from the presence of metal atoms in a polymer structure, incorporation in the main chain is required. Potential advantages of including metals in the backbone of a polymer rather than the side-group structure include the following ... 

ROP methods have allowed access to a wide variety of high molecular weight polyferrocenes of which the PFSs present the prototypical example. Studies of the latter materials have provided an excellent opportunity for the systematic and detailed examination of a class of main-chain metal-containing macromolecules representative examples are included in Table 2. This section surveys some of the properties of these interesting polymers. 

A connectivity of 1 is given for side chain metal-containing polymers as 1 in which the metal complex is connected via one bond to the main chain [11]. Additional examples for other connectivities are (Fig. 1-8) connectivity 2 in metal(yne)s 2 [12] connectivity 3 in arsenic(III) sulfide 3 connectivity 4 in a polymeric methyl rhenium oxide of the formula Ho.5[(CH3)o.92Re03] co 4 [13] or polymeric phthalocyanines 5 [14] connectivity 8 in lanthanide complexes of bis(tetradendate) Schiff base bridging ligands 6 [15]. 

When the mesogen moiety is included into the main chain of the polymer, the obtained macromolecule contains inherently rigid units, which usually result in remarkable mechanical properties and thermal stability. Fibers made by these polymers compete with the best ceramic fibers and are far superior to metal fibers [83]. They therefore are ideal candidates as reinforcements for polymer-based composites. However, these materials often have a poor miscibility and adhesion to other polymeric substrates, limiting the range of their applications. This problem basically arises from weak intermolecular interactions either within the liquid-crystalline polymer itself or with the matrix of the composite. Strong ionic... 

Polymers that Contain Main-chain Metal-Metal Bonds that Involve... 

Block co-polymers exhibit outstanding potential for a variety of applications as a result of their self-assembly into supramolecular structures (see Section 1.2.4). However, the exploration of organometallic multi-block materials was only begun in the early 1990s. Block co-polymers derived from the living anionic polymerization of vinylferrocene have been already briefly mentioned in Section 12.06.2.2.l.(i). In this section, side-chain metal-containing block co-polymers are surveyed. Examples of block co-polymers with metals in the main chain are discussed in Section 3.X. 

A very promising variant on this type of condensation polymerization involves the use of monomers that possess groups X and Y, which can be eliminated from the same molecule. This circumvents the need for careful control of reaction stoichiometry. Moreover, in certain cases, polymerization of monomers of this type can follow a chain-growth type of mechanism that leads to high molecular weights much more easily. Such processes (Scheme 1.1, Route C) have not yet been explored for the formation of metal-containing polymers, but are well-established for the synthesis of certain classes of polymers based on main-group elements such as polyphosphazenes (1.2) and polyoxothiazenes (1.4) [12, 16, 26]. 

Polymers Containing Main-Chain Metal-Metal Bonds That Involve Transition Elements 1189... 

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