I. Composite polymer coatings prepared in supercritical carbon dioxide. II. Chemical modification of atomic force microscope probes. III. Liquid mobility on surfaces with patterned chemistry and topography

2006 2006

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Abstract (summary)

The initial part of this dissertation describes the preparation of the first reported poly(p-xylylene) polymer/polymer composites. Poly(p-xylylene) (PPXN) and its derivatives, known collectively as parylenes, are solvent resistant and blends or composites cannot be easily made by conventional methods. Supercritical carbon dioxide was used as both a plasticizer and solvent to infuse and polymerize a variety of vinyl monomers inside the parylene films. Infrared spectroscopy, wide angle X-ray diffraction, and thermal gravimetric analysis were used to characterize the composites. Multilayer coatings of PPXN and other polymer films were prepared and selectively modified with metal nanoparticles.

The second part details the modification of atomic force microscope (AFM) probes using a variety of monochlorosilanes to improve the chemical sensitivity of AFM. X-ray photoelectron spectroscopy revealed that the silane reaction was successful. Adhesion force measurements between the modified probes and similarly modified silicon wafers were performed, but showed only a slight variance between the different tip chemistries. Surfaces with patterned chemistry were prepared and examined with the modified probes using tapping mode AFM. The contrast in the phase images was dependent on the tip chemistry.

The ability to confine and direct the motion of liquid droplets on a surface using only gravity and differences in surface chemistry is discussed in the first chapter of Part III. A hydrophobic alkylsilane surface with low contact angle hysteresis was patterned with lines of a more hydrophobic fluoroalkyl silane. Liquid droplets moved easily on the low hysteresis matrix, but pinned at the more hydrophobic lines. A variety of patterns were used to demonstrate that a decrease in the hysteresis reduces the force needed to induce drop motion and also lowers the barriers that are needed to confine the droplets.

Condensation on a variety of ultrahydrophobic surfaces was examined in the second chapter of Part III. Optical microscopy showed that water condensed between the hydrophobic surface features before being expelled to the top. The condensed liquid pinned the contact line of a macroscopic droplet and dynamic contact angle measurements revealed an increase in hysteresis which corresponded to a decrease in liquid mobility.

Indexing (details)

Analytical chemistry
0495: Polymers
0486: Analytical chemistry
Identifier / keyword
Pure sciences; Atomic force microscope probes; Composite polymer coatings; Patterned surfaces; Polymer coatings; Supercritical carbon dioxide; Topography
I. Composite polymer coatings prepared in supercritical carbon dioxide. II. Chemical modification of atomic force microscope probes. III. Liquid mobility on surfaces with patterned chemistry and topography
Wier, Kevin A.
Number of pages
Publication year
Degree date
School code
DAI-B 67/04, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780542656798, 0542656795
McCarthy, Thomas J.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
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