title: Ionic polymeric amphiphiles with cholesterol mesogen: adsorption and organization characteristics at the air/water interface from Langmuir film balance studies.
abstract: Ionic polymeric amphiphiles consisting of cholesterol mesogen were investigated for the interfacial adsorption characteristics at the air/water interface using a Langmuir film balance with an aim to understand the influence of ionic segment from 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) on the packing behavior of cholesterol at the interface. From surface pressure (pi)-area (A) isotherm characteristics, it is demonstrated that the homopolymer and the copolymer C consisting of 0.15 mol fraction CAB segments exhibit the most expanded structures contributing to surface area of about 84 A(2)/molecule. It is shown that the copolymer B with 0.1 mol fraction CAB provides optimum hydrophilic liphophilic balance to form the most compact structures contributing to a surface area of 35.75 A(2)/molecule. The high surface pressure, >40 mN/m, in contrast to that of PAMPS demonstrates significant adsorption of the copolymers at the interface. An interesting correlation among interfacial packing characteristics, thermal behavior, and solution structures is demonstrated. From molecular models developed for CAB, it is shown that the horizontal orientation of the linker group with respect to cholesterol chain in CAB underlies the expanded structures observed in PCAB and copolymer C.
authors.affiliation: Industrial Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.
authors.forename: K
authors.initials: K
authors.lastname: Chandrasekar
authors.forename: R
authors.initials: R
authors.lastname: Vijay
authors.forename: Geetha
authors.initials: G
authors.lastname: Baskar
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000388:Air; D000476:Alkanesulfonates / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002788:Cholesterol Esters / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D008823:Micelles; D008958:Models, Molecular; D013499:Surface Properties / Q000187:drug effects; D014867:Water / Q000737:chemistry*
chemical_list: D000178:Acrylamides; D000476:Alkanesulfonates; D002788:Cholesterol Esters; D008823:Micelles; C521887:cholesteryl acrylamido butyrate; D014867:Water; C056288:2-acrylamido-2-methylpropanesulfonate