Paper Number
GR21 My Program
Session
Gallery of Rheology Contest
Title
Thermally formed flowers: pFCDs in surfactant lamellae
Presentation Date and Time
October 16, 2024 (Wednesday) 6:30
Track / Room
Gallery of Rheology / Waterloo 3 & 4
Authors
- Kaboolian, Matthew (Purdue University, School of Materials Engineering)
- Erk, Kendra A. (Purdue University, School of Materials Engineering)
Author and Affiliation Lines
Matthew Kaboolian and Kendra A. Erk
School of Materials Engineering, Purdue University, West Lafayette, IN 47906
Speaker / Presenter
Kaboolian, Matthew
Keywords
surfactants; techniques
Text of Abstract
Parabolic focal conic defects (pFCDs) form when smectic and lyotropic lamellar phases experience dilation induced bending. Through solely an increase in the system’s thermal energy, concentrated 70 wt.% sodium laureth sulfate (SLEnS) surfactant in water transitioned from planer surfactant bilayers to pFCDs. Under cross-polarized microscopy the formation of these defects appears as an array of four petalled flower-like structures. Through heating SLEnS with varied n it was shown that the formation response of these pFCDs was substantially affected by the chemistry of the surfactant molecule with increased n leading to fasted growth of pFCD structures at lower temperatures. While the thermodynamics of the formation varied with surfactant chemistry, the size of the defect flowers was minorly effected with a slight decrease in the defect size for increasing n. The power in these defects is two-fold. The mechanical nature of the flower’s formation allows for a probing of the individual bilayer’s mechanical properties. Highly ordered toroidal focal conic defects are being used for semiconductor photolithography, and pFCDs for nanotempleting.