Shape evolution and stress development during latex-silica film formation

Carlos J. Martinez, Jennifer A. Lewis

Research output: Contribution to journalArticlepeer-review

Abstract

The shape evolution and stress development of composite films of deformable acrylic latices and rigid silica spheres were studied using noncontact laser profilometry and a controlled environment stress apparatus that simultaneously monitors optical clarity, drying stress, and weight loss. Their shape evolution was strongly influenced by capillary forces experienced during drying, latex Tg, and the ratio of deformable/ rigid particles in the film. Their stress histories exhibited three distinct regions: (1) a period of stress rise stemming from capillary tension exerted by the liquid on the particle network, (2) a maximum stress, and (3) a period of stress decay. Significant differences in stress histories were observed between the deformable latex and rigid silica films. Latex films exhibited a gradual stress rise, a maximum stress of ∼0.1 MPa, and only a slight stress decay. In contrast, silica films displayed a sharp stress rise and a stress maximum of ∼1 MPa, followed by a decay to a nearly stress-free state at the culmination of the drying process. Composite films exhibited a marked transition from a deformable to a rigidiike response as their silica content increased above 40 vol %. The highest maximum stress was observed for composite films with 55% silica, which was near their critical pigment volume concentration. Such films also exhibited the highest amount of residual stress of all films studied.

Original languageEnglish (US)
Pages (from-to)4689-4698
Number of pages10
JournalLangmuir
Volume18
Issue number12
DOIs
StatePublished - Jun 11 2002

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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