Stability of trisilanolphenyl-POSS on pH buffered subphases

CHED 1444

Sarah M. Huffer, shuffer@vt.edu, Kevin J. Dawson, Jianjun Deng, and Alan R. Esker, aesker@vt.edu. Department of Chemistry (0212), Virginia Tech, Blacksburg, VA 24061
Polyhedral oligomeric silsesquioxanes (POSS) have been an innovative area of intense study for the past two decades. In this study, trisilanolphenyl-POSS (TPP), a molecule known to form Langmuir films at the air/water interface, was examined for stability at various pH values. Isothermal and isobaric experiments using the Wilhemy plate technique along with Brewster angle microscopy (BAM) images were used to investigate the stability of TPP on buffered subphases. This study found that the stability of TPP decreased as the basicity of the subphase increased. As the TPP rested on the subphase, hydrolysis reactions cleaved siloxane bonds and dissolution into the subphase occurred. Bicarbonate anions in the buffered subphases at pH = 10 and pH = 11 decreased the stability of TPP and affected the rates of hydrolysis and desorption relative to borate and phosphate buffers, respectively.