Macroscopic-microscopic mechanical relaxation behavior of hybrid organic-inorganic materials

The mechanical properties of transparent hybrid organic-inorganic nanocompo sites made from siloxane and zirconium oxopolymers are investigated at two different length scales. The complex interface that associates the two phas es is made of covalent Zr-O-Si bonds and hydrogen bonding. The rubbery prop erties studied by creep and recovery present specific behaviors in comparis on with model elastomers. This is a result of the complex crosslinking unit s. The stress relaxation phenomenon has been studied at the molecular scale by H-2 quadrupolar NMR. During stress relaxation, the anisotropy of the mo lecular motion decreases slowly. This study demonstrates the straightforwar d relationship existing between the macroscopic and microscopic relaxation phenomena. (C) 2001 John Wiley & Sons, Inc.