**4. Modification of urethane prepolymer by coordination compounds of copper (I, II)**

In one of the worked out highly ordered coordination compounds of transition metals for modification of polyurethanes N,N'-Diethylhydroxylamine (DEHA) is used as a ligand exhibiting the properties of a reducing agent. The most appropriate transition metal compound is copper (II) chloride. Some of the Cu (II) ions interacting with DEHA reduce the oxidation level and turn into Cu (I) (see Fig. 5).

38 Polyurethane

well.

The Mössbauer study confirms the columnar structure of the obtained metal complexes, the possibility of their fixation in a flexible-chain polymer matrix containing electron-donating groups, and the existence of magnetic ordering at temperatures below 70 K. Sizes of very

It is known that to achieve the effect of magnetic ordering it is necessary that the chain of interacting ions of iron (III) should be long enough and combine up to a few thousand ions. The criterion for judging the length of the chain of magnetic ordered iron ions is relatively high blocking temperature of supermagnetism and the barrier value of effective anisotropy field. In our view, due to significant anisotropy in the structure of the complex the most likely assumption is the increasing of the potential barrier with the increase of chain length. The longer the chain, the higher its strength and the ability to build columns in a polymer matrix, and the specific properties of the structured polymer matrix are more pronounced as

thin magnetic fields correspond to high-spin state of iron(III) ions (S=5/2).

**Figure 4.** The Mössbauer spectrum of metal complex system based on FeCl3 and EA.

The metal complex system is used for structuring urethane prepolymer containing terminal isocyanate groups. Considering the high flexibility of the urethane prepolymer chain, it can be assumed that the urethane groups will be coordinately bound with iron ions. The result of this interaction should be the formation of columnar structures directly in the polymer

**Figure 5.** The mechanism of interaction of copper (II) chloride with DEHA.

It was ascertained that the metal complex system showed the ability to interact with aromatic isocyanates to form azoaromatic compounds. The result was the formation of columnar coordination compounds (Fig. 6).

It was established, that metal-complex modification of polyurethanes results in the change of their physicomechanical properties and spasmodic reduction (by 3-4 orders) of volumetric and superficial electric resistance. The reduction of the specific bulk electrical resistance by 3-4 orders is the most significant effect accompanying the metal-complex binding of polyurethanes. In this case the electrical resistance falls spasmodically depending on the nature of flexible chains of polyurethanes, the range of transition -metal ions concentrations. If the content of metal-complex modifying agent is increased further, the electrical resistance increases to some extent. The main role in the mechanism of charge transmission in metal-coordinated polyurethanes is assigned to electron-donating groups which are included in the structure of flexible chains of polyurethane matrix and the presence of transition metal ions having two degrees of oxidation in it.

The Modification of Polyurethanes by Highly Ordered Coordination Compounds of Transition Metals 41

Cu

based on: 1-MoCl5-DEHA; 2-CuCl2-DEHA; 3-CuCl2-MoCl5-DEHA.

compounds of transition metal.

**Figure 8.** Dependence of *ρv* (Ohm.

Cu Cl

Cu Cl

Cu Cl

> = N H5C2

> > H5C2

**Figure 7.** Scheme of the formation of columnar homonuclear and heteronuclear coordination

O

Cu

N

sm) of polyurethanes on the concentration (%) of metal complexes

O

Cu Cl

Cu Cl

Cu Cl

Cu Cl

Cu Cl

C2H5

C2H5

Cu Cl

Mo Cl

**Figure 6.** Formation of columnar coordination compounds.
