Surface science of a filled polydimethylsiloxane-based alkoxysilane- cured elastomer: RTV11

Steven Bullock, Erika E. Johnston, Tim Willson, Paul Gatenholm, Kenneth J. Wynne

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Characterization of a filled polydimethylsiloxane (PDMS)-based elastomer, RTV11, is reported. Included in this work is resin characterization, kinetics of cure as a function of catalyst concentration, and surface properties of pristine and water-aged films. X-ray spectroscopy for chemical analysis (ESCA), dynamic contact angle (DCA) analysis, and ATR- IR were used to characterize cured films. ESCA reveals C and Si peaks in ratios expected for PDMS, but CaCO3 which comprises 32% of the bulk is not detected. The surface of cured RTV11 films is thus predominantly a PDMS network crosslinked by a siliceous domain, the latter comprising about 1.3% by weight. The presence of Ca was confirmed by energy dispersive X-ray analysis (EDX) which probes at micron depth. Stability of films in water was evaluated by tapping mode atomic force microscopy (TM-AFM), mass loss, changes in contact angles, ESCA, and optical microscopy. TM-AFM images of films aged in water for three months show an increase in surface roughness due to the formation of micro-pits which occupy about 4% of the surface. Gravimetric analysis showed fully cured films lose mass at a rate of about 0.09%/wk over a three month period in water. The mass loss associated with pitting/surface toughening comprises only 0.85% of that measured gravimetrically and by analysis of immersion water. Analysis of Si and Ca in the storage water was performed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) in order to quantify the products of surface erosion. An unexpected finding was the surface depletion-limited loss of CaCO3 during the first two months of immersion. The results of surface analytical studies are discussed in the context of the use of alkoxysilane cured PDMS resins for nontoxic fouling release applications.

Original languageEnglish
Pages (from-to)18-36
Number of pages19
JournalJournal of Colloid and Interface Science
Volume210
Issue number1
DOIs
StatePublished - Feb 1 1999

Funding

Support from the Strategic Environmental Research and Development Program (SERDP) and the Research Opportunities for Program Officer (ROPO) program of the Office of Naval Research is gratefully acknowledged. We thank Dr. T. Ho for GPC data.

Keywords

  • Biofouling
  • Degradation
  • Siloxane networks
  • Surface science

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