Unique rodlike surface morphologies in trisilanolcyclohexyl polyhedral oligomeric silsesquioxane films.
A trisilanol derivative of polyhedral oligomeric silsesquioxane (POSS), trisilanolisobutyl-POSS, has recently been reported to form stable monolayers at the air/water interface. This paper explores the mono- and multilayer properties of another POSS derivative, trisilanolcyclohexyl-POSS, with pi-A isotherm and Brewster angle microscopy measurements. Results show that with continuously increasing surface concentration via symmetrical compression, trisilanolcyclohexyl-POSS amphiphiles at the air/water interface undergo a series of phase transitions from traditional Langmuir monolayers (one-POSS-molecule thick) to unique rodlike hydrophobic aggregates in multilayer films (approximately eight-POSS-molecules thick) that are dramatically different from "collapsed" morphologies seen in other systems. Stable and hydrophobic rodlike structure formation on water is presumably due to trisilanolcyclohexyl-POSS' unique molecular structure and strong tendency to form intermolecular hydrogen bonds in the solid state. This result is consistent with existing POSS/polymer composite research, which shows that POSS molecules tend to aggregate and crystallize into lamellar nanocrystals.
Deng
Jianjun
J
Farmer-Creely
Catherine E
CE
Viers
Brent D
BD
Esker
Alan R
AR
D008958:Models, Molecular; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
D017646:Organosilicon Compounds