Polymer Cu

Polytetrafluoroethylene contains only C—C and C—F bonds. These are both very stable and the polymer is exceptionally inert. A number of other fluorine-containing polymers cU e available which may contain in addition C—H and C—Cl bonds. These are somewhat more reactive and those containing C—H bonds may be cross-linked by peroxides and certain diamines and di-isocyanates. 

The testing does not yet allow for setting specific input criteria. However, the testing made clear that the process probably can handle a broad spectrum of materials, such as wood, biomass, mixed plastic and pure PVC waste. For instance tests have been done on PVC waste but also with a mixture of PVC, PE, other polymers, Cu, Al, chalk, cement and fibres. 

In the present paper we describe the catalytic mechanisms of synthetic polymer-Cu complexes a catalytic interaction between the metal ions which attached to a polymer chain at high concentration and an environmental effect of polymer surrounding Cu ions. In the latter half, the catalytic behavior is compared with the specific one of tyrosinase enzyme in the melanin-formation reaction which is a multi-step reaction. To the following polymers Cu ions are combined. 

In order to study the shape of a polymer-Cu complex, viscometric measurements of a homogeneous solution of QPVP were carried out (Fig. 1). At constant QPVP concentration, an increase in the added amount of Cu ions causes a decrease in viscosity, which reveals that the polymer-ligand chain is markedly contracted due to intra-polymer chelation. An intra-polymer chelate takes a very compact form and Cu ions are crowded within the contracted polymer chain (Scheme 2). The adsorption of Cu ions on the polymer ligand is sigmoidal, as can be seen in Fig. 1. At a low... 

Kabanov et al.116 studied the oxidation of ascorbic acid by the Cu(II) complexes of poly(4-vinylpyridine) partially alkylated by bromoacetic acid. It was considered from kinetic and thermodynamic data that the higher catalytic activity of the polymer-Cu complex was caused by binding of the substrate to the catalytic site, represented as 48. 

Table 12. Catalytic activity of polymer-Cu complexes for oxidation of various substrates...

Substrate log [(Activity of polymer-Cu catalyst)/(Activity of monomeric... 

In the next chapter, we describe the catalytic mechanisms of polymer-metal complexes, using as an example the oxidative polymerization of phenols catalyzed by polymer-Cu complexes. 

The polymerization of XOH with an insoluble polymer-Cu complex was provoked by vigorous stirring of the reaction mixture (Table 14)IS1). The polymer... 

Fjg. 27. Change in visible spectra of the reaction system with time (a) and d-d absorption change of polymer-Cu catalyst with time (b)1S4 ... 

Fig. 28. Schematic profile of polymer-Cu catalyst in steady state of oxidation of 2,6-dimethylphenol About 72 Cu ions are coordinated on a partially quaternized poly(4-vinyl-pyridine) ligand (DP = 200, Q% = 28). Fraction of Cu(II) = 0.24, fraction of substrate-coordinated Cu = 0.80...

Table 16. Kinetic data for polymerization of 2,6-dimethylphenol catalyzed by polymer-Cu complex...

On the other hand, an attempt to accelerate the step of coordination of the substrate to the Cu catalyst was successful because it used the hydrophobic domain of the polymer ligand156 That was the oxidation catalyzed by polymer-Cu complexes in a dilute aqueous solution of phenol, which occurred slowly. The substrate was concentrated in the domain of the polymer catalyst and was effectively catalyzed by Cu in the domain. A relationship was found to exist between the equilibrium constant (Ka) for the adsorption of phenol on the polymer ligand and the catalytic activity (V) of the polymer-ligand-Cu complex for various polymer ligands K a = 0.21 1/mol and V = 1(T6 mol/1 min for QPVP, K a = 26 and V = 1(T4 for PVP, K a = 52 and V = 10-4 for the copolymer of styrene and 4-vinylpyridine (PSP) (styrene content 20%), and K a = 109 and V = 10-3 for PSP (styrene content 40%). The V value was proportional to the Ka value, and both Ka and V increased with the hydrophobicity of the polymer ligand. The oxidation rate catalyzed by the polymer-Cu complex in aqueous solutions depended on the adsorption capacity of the polymer domain. 

This hydrophobic polymer-Cu catalyst was utilized to remove phenol from an aqueous solution157. A dilute aqueous solution of phenol was made to flow through the column packed with the PSP-Cu resin. Phenol was adsorbed on the polymer and furthermore oxidized to insoluble polymeric compounds in the column. 

The overall reaction rate and the rate constant of the electron-transfer step are summarized in Table 17 for the polymer-Cu-catalyzed oxidation of substrates such as 2,6-dimethylphenol (XOH) and ascorbic acid15 . The ks values for polymer-Cu-catalyzed oxidation are larger than those for monomeric-Cu-catalyzed oxidation. Particularly in the oxidative polymerization of XOH, it is obvious that the electron-transfer step is accelerated by polymer ligands, and the large value of ke is in agreement with the higher rate of polymer-Cu-catalyzed polymerization. Therefore, the... 

Fig. 30. Effect of quatemization of poly-(4-vinylpyridine) ligand on rate constant of electron-transfer step (fce), rate constant of reoxidation step of catalyst ( 0), and viscosity of polymer-Cu-catalyst solution159)...

Fig. 32. Electron transfer from substrate to Cu(II) ion in polymer-Cu catalyst (a) and fluctuating profile of polymer catalyst (b)...

In the catalyst reoxidation step, contrary to the electron-transfer step, the polymer ligand should shrink because of the formation of the Cu(II) complex. Therefore, the polymer chain may partially repeat are expansion and contraction occurring during the catalytic cycle. When one has a view of the polymer-Cu catalyst as a whole, each part of the polymer catalyst domain, which is drifted in solution, is seen to be fluctuating during the catalytic process [Fig. 32(b)]. The fluctuating shape of biopolymers in enzymic reactions has been pointed out, and the dynamically conformational change of a flexible polymer chain is considered to be one of the effects of the polymer catalyst. 

The catalytic activity of the PSP-Cu complex was greater than that of the other polymer-Cu complexes, and increased with the styrene content of the PSP ligand. 

Control of the electron-transfer step was also attempted by combining two metal species on a polymer ligand167. We prepared polymer-metal complexes involving both the Cu(II) and Mn(III) ions. The oxidative polymerization of XOH catalyzed by the PVP-Cu, Mn mixed complex or the diethylaminomethylated poly(styrene)(PDA)-Cu Mn mixed complex proceeded 10 times faster than the polymerization catalyzed by either PVP- or PDA-metal complex. The maxima of the activity observed at [Cu]/[Mn] = 1 and [polymer]/[Cu,Mn] moderately small where Cu and Mn ions were crowded within the contracted polymer chain. Cooperative interaction between Cu and Mn was inferred. The rate constant of the electron-transfer step (ke in Scheme 14) for Cu(II) -> Cu(I) was much larger than that for Mn(III) -> Mn(II). The rate constants of the reoxidation step (k0) were polymer-Mn ex polymer-Cu.Mn > polymer-Cu, so the rapid redox reaction... 

The environmental effects are caused by the micro-environments constituted by the domain of a polymer ligand. The electrostatic domain of a polymer-metal complex was demonstrated in the reaction of the polymer-Co(ni) complex with ionic species (Section IVA), and was shown to be utilized in the catalytic activity of the polymer-Cu complex (Section VIA). In another case, the hydrophobic domain was predominant, ie. in the reaction with hydrophobic substrates (Sections IVB and VIIC). The environmental effects of a polymer ligand also include dynamic effects, Which vary with the solution conditions (Section IIIC). 

Leznoff and co-workers reported the structural characterization and the polymorphic nature of a gold(I)-copper(II) coordination polymer, [Cu Au(CN)2 2(dmso)2] 00 [125]. In a green polymorphic form it possessed a 1-D chain structure with five-coordinate copper(II) centers, while a 2-D corrugated sheet structure with six-coordinate copper(II) centers was characterized in the blue polymorph, both of which are linked together to form a 3-D structure via aurophilic interactions. These two polymorphs exhibited virtually identical vapochromic behavior towards water, MeCN, dioxane, dmf, pyridine and ammonia, with the formation of [Cu Au(CN)2 2(solvent)x]oc,. 

FIGURE 9. (a) View of the core unit of 2D polymer [ Cu( i-I)2Cu (dps)2] (5). (b) Solid-state emission spectrum of 5 recorded at ambient temperature. (Modified from Ref. 125.)... 

To obtain a heat and water resistant crosslinked polymer, Cu naphthenate and an alcohol (e.g. benzyl alcohol) were added to BPA/DC as a catalyst epoxide resins (cf. Sect. 6) can be used as well [19]. The use of Zn acetate together with dicumyl peroxide was also mentioned [20],... 

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