Temperature-dependent interfacial properties of hydrophobically end-modified poly(2-isopropyl-2-oxazoline)s assemblies at the air/water interface and on solid substrates.
We describe herein the properties at the air/water (A/W) interface of hydrophobically end-modified (HM) poly(2-isopropyl-2-oxazoline)s (PiPrOx) bearing an n-octadecyl chain on both termini (telechelic HM-PiPrOx) or on one chain end (semitelechelic HM-PiPrOx) for different subphase temperatures and spreading solvents using the Langmuir film balance technique. The polymer interfacial properties revealed by the pi-A isotherms depend markedly on the architecture and molecular weight of the polymer. On cold water subphases (14 degrees C), diffusion of PiPrOx chains onto water takes place for all polymers in the intermediate compressibility region (5mNm(-1)). At higher subphase temperatures (36 and 48 degrees C), the HM-PiPrOx film exhibited remarkable stability with time. Brewster angle microscopy (BAM) imaging of the A/W interface showed that the polymer assembly was not uniform and that large domains formed, either isolated grains or pearl necklaces, depending on the polymer structure, the concentration of the spreading solution and the subphase temperature. The Langmuir films were transferred onto hydrophilic substrates (silica) by the Langmuir-Blodgett (LB) technique and onto hydrophobic substrates (gold) by Langmuir-Schaefer (LS) film deposition, resulting in the formation of adsorbed particles ranging in size from 200 to 500nm, depending on the polymer architecture and the substrate temperature. The particles presented "Janus"-like hydrophilic/hydrophobic characteristics.
Department of Chemistry and Faculty of Pharmacy, University of Montreal, CP 6128 Succursale Centre Ville, Montreal, QC, Canada H3C 3J7.
Rodolphe
R
Obeid
Jin-Young
JY
Park
Rigoberto C
RC
Advincula
Françoise M
FM
Winnik
D000388:Air; D000588:Amines / Q000737:chemistry; D004058:Diffusion; D006046:Gold / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D018625:Microscopy, Atomic Force; D008859:Microscopy, Polarization; D008958:Models, Molecular; D008968:Molecular Conformation; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry; D010080:Oxazoles / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties; D013500:Surface Tension; D013696:Temperature; D014867:Water / Q000737:chemistry*; D017155:Wettability
D000588:Amines; D010080:Oxazoles; D011108:Polymers; D012997:Solvents; D013438:Sulfhydryl Compounds; D014867:Water; D006046:Gold; C025540:n-butyl mercaptan; C009317:stearylamine; D012825:Silicon