Accession Number:

ADA482631

Title:

Nonwettable Thin Films from Hybrid Polymer Brushes can be Hydrophilic

Descriptive Note:

Technical rept.

Corporate Author:

CLARKSON UNIV POTSDAM NY

Report Date:

2007-03-30

Pagination or Media Count:

8.0

Abstract:

Hybrid brushes composed of two liquid polymers, polydimethylsiloxane PDMS and a highly branched ethoxylated polyethylenimine EPEI, were synthesized on Si wafers by the grafting to method and by applying a combinatorial approach fabrication of gradient brushes. The combinatorial approach revealed a strong effect of layer assisted tethering, which allowed us to synthesize hybrid brushes twice as thick as the reference homopolymer brushes. The hybrid brushes are stable thin films that can rapidly and reversibly switch between hydrophilic and hydrophobic states in water and air, respectively. The switching in water affects a rapid release of amino functional groups which can be used to regulate adhesion and reactivity of the material. The switching in air rapidly returns the brush to a hydrophobic state. The hybrid brush is hydrophilic because of two mechanisms 1 exposure of EPEI chains to the brush-water interface under water, and 2 retention of some fraction of water via swollen EPEI chains the EPEI chains swell by 2-3 times, which are conserved by a PDMS cap in air. The hybrid brush is wettable under water, and at the same time, the brush is nonwettable in air because water droplets are trapped in a metastable state when the water contact angle is above 9O.

Subject Categories:

  • Polymer Chemistry
  • Electrical and Electronic Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE