Pendent functionalization poly

The most interesting aminomethyl derivative of condensation polymers that we have prepared to date Is derived from direct reduction of poly(2-cyano-l,3-phenylene arylene ether), 20. Enchainment of benzonitrile repeat units Is accomplished by coupling 2,6-dichlorobenzonitrile with the potassium salt of bisphenol-A copolymers with lower nitrile contents can be produced by copolycondensation of bisphenol-A, 2,6-dichlorobenzonitrile and 4,4 -dichlorodiphenyl sulfone.21 The pendent nitrile function provides an active site for further elaboration. 

Whereas the tensile strength was not a sensitive function of the monomer structure, the tensile modulus (Young s Modulus) was clearly related to the monomer structure. This is expected since the tensile modulus is a measure of the polymer s resistance to deformation and is related to the "stiffness" of a polymeric material. The highest tensile modulus (22,000 kg/cm2,2.2 GPa) was measured for poly(BPA iminocarbonate). Replacement of BPA by Dat-Tyr-Hex reduced the tensile modulus significantly. This observation can possibly be attributed to the presence of the long hexyl ester pendent chain in Dat-Tyr-Hex. Generally, the polyiminocarbonates were somewhat "stiffer" than the corresponding polycarbonates. Thus, the tensile moduli of poly(Dat-Tyr-Hex iminocarbonate) and poly(Dat-Tyr-Hex carbonate) were 16,300 kg/cm2 (1.6 GPa) and 13,900 kg/cm2 (1.3 GPa) respectively. 

As with all supramolecular structures, one of the most important issues is whether a direct relationship between the structure of a material and its function or properties can be established. In the following, some examples of polymer systems which show such a correlation will be discussed. The materials addressed will include block copolymers, polyalkylthiophenes and a multilayer system based on the self-assembly of polyelectrolytes. Detailed studies on the electrochemical properties of redox-active polymers, based on poly(vinyl pyridine) modified with pendent osmium polypyridyl moieties, have shown that electrochemical, neutron reflectivity and electrochemical quartz crystal microbalance measurements can yield detailed information about the structural aspects of thin layers of these materials. 

Figure 1. Summary of synthetic routes for functionalization of poly(styrene-DVB) incorporation of pendent -Br, -PPht, -NHt, -CHtNRt, -CHtSH, and DIOP groups.

Protection and Deprotection of Pendent Amino Groups. Scheme V illustrates a method used recently for the preparation of polyphosphazenes with i ndent all lamino groups (76). 2-Aminoethanol was first amino-protected by reaction with di-t-butyl dicarbonate to yield a"BOC"unit. The alcohol function was then converted to the alkoxide salt by treatment with sodium hydride, and this reagent was used for halogen replacement with poly(dichlorophosphazene). Subsequent deprotection of the amino unit then took place following exposure of the polymer to acid. 

Polyol monomer like xylitol was also used to compose biodegradable polymer poly(xylitol citrate) (PXC) with citric acid by a simple thermal polycondensation. The abundant pendent hydroxyl groups on PXC, mostly introduced by xylitol, were used to react with methacrylic anhydride to obtain double bond functional PXC (PXCma), which can be formed into a bioelastomer network by photo-cross-linking [96]. 

The lowest level in complexity and functionality results from the incorporation of single AA in synthetic polymers. Frequently, one AA moiety is attached per repeat unit of the synthetic polymer, resulting in conjugates with a synthetic polymer backbone and pendent AA side chains. In these conjugates, the complex function of proteins and polypeptides is strongly reduced to the simple chemical functionalities of the AAs. However, the uniform chirality of the AAs and the hydrophobic-hydrophilic balance of the AA moieties are inherently present in the macromolecule. Particularly, in aqueous solutions interesting effects can be observed, which are clearly beyond those of classical synthetic polymers. For example, Schlaad and co-workers demonstrated that the nearly quantitative attachment of cysteine to each repeat unit of poly... 

In vitro attachment and proliferation of fibroblasts on tyrosine-derived polycarbonates w as a function of the pendent chain length (Ertel, 1994). Consistent with the hypothesis that cells favor more hydrophilic and molecularly rigid surfaces, poly(DTE carbonate), the most hydrophilic and rigid of the surfaces tested (TaWte I), supported cell growth and proliferation better than the more hydrophobic poly(DTO carbonate). Poly(DTB carbonate) and poly(DTH carbonate) were intermediate in their ability to support ceU attachment and growth. 

RGaction with Other Aldehydes. Poly(acrylamide) reacts with glyoxal [107-22-2], C2H2O2, imder mild alkaline conditions to yield a polymer with pendent aldehyde functionality. 

In addition to functionalization of polyanilines with sulfonic and carboxylic acids, the corresponding phosphonic acid derivatives have been prepared, o-Aminobenzylphosphonic acid was prepared as shown in Figure 20.54 [42,43]. Oxidative coupling of the above monomer in an acidic medium yielded poly(o-aminobenzylphosphonic acid) (Figure 20.55). Spectroscopic analysis was consistent with head-to-tail oxidative coupling through the /Jara-position. The as-prepared polymer was in its emeraldine oxidation state in which 43% of the N-atoms were protonated by the pendent acid. This polymer was insoluble in both non-aqueous solvents and aqueous acidic solutions. 

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