Glued Langmuir-Blodgett bilayers from calix[n]arenes: influence of calix[n]arene size on ionic cross-linking, film thickness, and permeation selectivity.
A homologous series of calix[4]arene-, calix[5]arene-, and calix[6]arene-based surfactants, containing pendant trimethylammonium and n-hexadecyl groups, have been compared with respect to their ability (i) to undergo ionic cross-linking at the air/water interface, (ii) to incorporate poly(4-styrenesulfonate) (PSS) in Langmuir-Blodgett (LB) bilayers, and (iii) to act as barriers toward He, N(2), and CO(2) when assembled into cross-linked LB bilayers. As these calix[n]arenes increase in size, their ability to undergo ionic cross-linking has been found to increase, the thickness of corresponding glued LB bilayers has been found to decrease, and their barrier properties and permeation selectivities have been found to increase. The likely origin for these effects and the probable mechanism by which He, N(2), and CO(2) cross these ultrathin films are discussed.
Wang
Minghui
M
Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Janout
Vaclav
V
Regen
Steven L
SL