KINETICS ON THE SOL-GEL PROCESS OF THE MODIFIED CU ETHOXIDE

Kinetics of the reactions and gelation of modified Cu ethoxide, Cu2(OR )2(OAC)2(HORE)4, with H2O were measured. When water was added to the m ethoxethanol solution of the modified Cu ethoxide, the first reaction was substitution reaction of H2O for methoxyethanol ligand in Cu2(OR)2 (OAC)2(HORE)4. The substitution reactions lead to forming another dime r with larger spacing between Cu atoms, then alkoxy groups were hydrol yzed. Finally, hydrolyzed dimers were formed and polymerized into a tr ansparent gel. With the transformation of a primary dimer, Cu2(OR)2(OA C)2(HORE)4, to a hydrated or hydrolyzed dimer, Cu2(OX)2(OAC)2(H2O)2(HO X)4 (X = H or R), with large spacing between Cu atoms, a 380 nm absorp tion band disappeared. Through measurements of changes in absorbance a t 380 nm and gelation time with different H2O content, kinetic express ions about the reactions and gelation for the sol-gel process of the m odified Cu ethoxide were derived. The derived relations are in a good agreement with the experimental results. It is concluded from the kine tic relationships that the effect of H2O content is to change the prop erties of the solvent involved.