(CHEM) Planning Meeting Jonathan D. Nickels Dept. of Chemical and - PowerPoint PPT Presentation

Center For Hierarchical Materials (CHEM) Planning Meeting Jonathan D. Nickels Dept. of Chemical and Environmental Engineering, University of Cincinnati Jonathan.Nickels@uc.edu August 3-4, 2020

Introduction

Tools Inelastic Scattering / Dynamics Elastic Scattering / Structure Direct / Backscattering / Neutron Spin Echo SANS/SAXS Inelastic Light Scattering Fluorescence / FRET / Polarization GPU Accelerated Workstations Small Scale MD

Small to Big N-methylacetamide

Small to Big Comez et al Soft Matter 2016 Perticaroli et al. JACS 2017.

Phase Separation within Lyotropic Liquid Crystal Materials

Lyotropic Liquid Crystal Phases Solvent dispersed liquid crystals with 1D or quasi 1D order Baumgart, Hess, and Webb Nature (2003)

Phase behavior in mammalian model membrane mimics POPC OPC DS DSPC Choles Cholester terol ol DSPC, POPC, and Chol, in a 39/39/22 ratio

Macromolecular structure - SANS  2 ( Δρ ) 2 P(q) S(q) + B inc  (q) = N p V p neutron structure contrast factor # of scattering particles form incoherent factor background, volume of one no Q-dependence scattering particle 4𝜌 sin 𝜄 𝑟 = 𝜇 0.001 − 0.5 Å −1 • Small angle neutron scattering – SANS – Observe the angle at which neutrons are scattered from the sample. – Scattered intensity is related to the structure and composition of the sample. – 100’s nm to Å spatial resolution

Neutron Scattering - Contrast  2 (D ρ ) 2 P(Q) S(Q) + B inc  ( Q ) = N p V p σ 𝒄 𝒋 ρ = 𝑾 neutron contrast Neutron Scattering Length Density • Neutron scattering length, b , is an atomic property that varies by element and isotope. • Neutrons are especially sensitive to the isotopes of hydrogen. • Lipids are hydrogen rich – Good internal contrast – Available in deuterium substituted form. Castellanos et al. Comp. Struct. Bio. (2016)

Neutrons Scattering and Contrast Matching  2 (Dd) 2 P(Q) S(Q) + B inc ( Q ) = N p V p neutron structure contrast factor # of scattering particles form incoherent factor background, volume of one no Q-dependence scattering particle ( Dd ) 2 = ( d lipid - d water ) 2 = 0 scattering ( Dd ) 2 = ( d lipid - d water ) 2 = 0 no scattering

Neutrons Scattering - Contrast  2 (Dd) 2 P(Q) S(Q) + B inc ( Q ) = N p V p neutron structure contrast factor # of scattering particles form incoherent factor background, volume of one no Q-dependence scattering particle Lo Avg. Ld Solv. Nickels et al. JACS 2015

SANS – Structure of Raft-like Features Domains-L D L D Nanodomains (20  C) 50 C Domains-L D , 93.5% D 2 O, 20 C Model PDF 3.2 nm bilayer thickness Domains, 100% D 2 O, 20 C 93.5% D 2 O 40 C Model PDF 6.8 nm radius disc 30 C Model PDF 60 nm diam. vesicle 1 20 C I(q) [A.U.] 3 Component Fit P(r) [A.U.] P(r) [A.U.] 1 10 C 0 0 10 100 10 100 0.02 0.1 q [ Å -1 ] r [ Å] r [ Å ]

Neutrons Scattering - Contrast  2 (Dd) 2 P(Q) S(Q) + B inc ( Q ) = N p V p structure neutron factor contrast # of scattering particles form incoherent factor background, volume of one no Q-dependence scattering particle

Summary Methods to investigate coexisting lyotropic phases based on scattering contrast. Lead to new design principles to drive material properties.

An invitation An invitation NickelsLab.com Jonathan D. Nickels PhD Assistant Professor Dept. of Chemical and Environmental Engineering University of Cincinnati