Electron donating polymer

Electron donating polymers Electron accepting polymers 381-386 592... 

Tazuke et al.592) reported the intermacromolecular C-T complex of a polyester bearing pendant carbazolyl groups (electron-donating polymer) with polyurethanes bearing pendant trinitrofluorenonyl groups (electron-accepting polymer). 

The procedure chosen for the calculation of the degree of linkage (0) and the stability constant of the complex (K) for a polycarboxylic add and an electron-donating polymer is indicated by the following equations for complexes with stoichiometric composition... 

Charge transfer complexes are formed in systems of electron-accepting polymers and electron-donating polymers through charge-transfer interaction [54-57]. Charge-transfer complexes are mainly characterized by their ultraviolet and visible spectra. The ratio of their repeating units is almost unity. 

Similarly at acidic pH, PEG complexed preferentially with PMAA than with PEI, whereas at pH=5.0, PMAA complexed more favorably with PEI. This behavior was attributed to the cationic nature of PEI and largely anionic nature of PMAA above pH=5.0. In the protonated form PMAA complexed with the electron donating polymers (PNVP and PEG) via hydrogen bonds, whereas upon ionization PMAA readily complexed with the cationic species. In the basic regime, the PEI was neutralized, and neither complex was formed. At pH=2, PAAm bound preferentially with PMAA over PVA. Analysis of the system PEG/PAAm/PMAA revealed that high molecular weight... 

Inagi S, Naka K, lida D, Chujo Y (2006) Synthesis of electron-donating polymer having vinylogous TTF in the main chain. Polym J 38 1146-1151... 

Naka K, Inagi S, Chujo Y (2005) Synthesis of soluble electron-donating polymers containing vinylogous TTF by oxidative dimerization of l,4-bisdithiafulvenyl-2,5-dialkoxybenzene. J Polym Sci Part A Polym Chem 43 4600 608... 

Cationic polymerizations work better when the monomers possess an electron-donating group that stabilizes the intermediate carbocation. For example, isobutylene produces a stable carbocation, and usually copolymerizes with a small amount of isoprene using cationic initiators. The product polymer is a synthetic rubber widely used for tire inner tubes ... 

Synthetic polymers can be classified as either chain-growth polymen or step-growth polymers. Chain-growth polymers are prepared by chain-reaction polymerization of vinyl monomers in the presence of a radical, an anion, or a cation initiator. Radical polymerization is sometimes used, but alkenes such as 2-methylpropene that have electron-donating substituents on the double bond polymerize easily by a cationic route through carbocation intermediates. Similarly, monomers such as methyl -cyanoacrylate that have electron-withdrawing substituents on the double bond polymerize by an anionic, conjugate addition pathway. 

For copolymers of structure I, for both types of side-chains, there is a striking similarity with the optical properties of the corresponding models the absorption and photoluminescence maxima of the polymers arc only 0.08-0.09 eV red-shifted relative to those of the models, as shown in Figure 16-9 (left) for the octyloxy-substituted compounds. The small shift can be readily explained by the fact that in the copolymers the chromophorcs are actually substituted by silylene units, which have a weakly electron-donating character. The shifts between absorption and luminescence maxima are exactly the same for polymers and models and the width of the emission bands is almost identical. The quantum yields are only slightly reduced in the polymers. These results confirm that the active chro-mophores are the PPV-type blocks and that the silylene unit is an efficient re-conjugation interrupter. 

The poly(cyclodiborazane)s containing a dithiafulvene unit in the backbone were also reported (scheme 25).38 This polymer showed an efficient extension of conjugation between the consecutive repeat units due to the strong electron donating property of the dithiafulvene unit. Before doping, this polymer exhibited an electrical... 

With these features in mind, we envisioned a new family of macrocyclic ligands for olefin polymerization catalysis (Fig. 9) [131, 132], We utilized macrocycles as the ligand framework and installed the catalytic metal center in the core of the macrocycles. Appropriate intra-annular binding sites are introduced into cyclophane framework that not only match the coordination geometry of a chosen metal but also provide the appropriate electronic donation to metal center. The cyclophane framework would provide a microenvironment to shield the catalytic center from all angles, but leaving two cis coordination sites open in the front one for monomer coordination and the other for the growing polymer chain. This could potentially protect the catalytic center and prevent it from decomposition or vulnerable side reactions. 

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