charge density rules for nature-inspired materials
TRANSCRIPT
We acknowledge the support of: Perry Group, Dubin Group,
Charge Density Rules For Nature-Inspired MaterialsHansen Tjo, Sarah L. PerryDepartment of Chemical Engineering, University of Massachusetts Amherst
Polycation (+) Polyanion (-)
• Surfactant amphilicity -> flexible environments, e.g.,
hydrophobic drug encapsulation for release in polar
physiological system
• Charged micelle isotropy ~ ideal colloidal systems
How does molecular chemistry inform
coacervate phase behavior?
ComplexCoacervation
100μm
100μm
100μm
Surfactant Steric Repulsion Effects On Phase Behavior
100μm
100μm
Y(-) ~ 0.6
Precipitation Predominates
Y(-) ~ 0.8
100μm
Spherical Droplets
(Coacervates)
Y(-) ~ 0.3
100μm
L-to-S Phase Transition100μm
Y(-) ~ 0.6
• Increase in Polymer Charge
Density Decreases Critical Micelle
Surface Charge Density
• Increase in neutral surfactant
head PEG length effectively
decreases micelle surface charge
density
Taylor et al., Soft Matter, 2016, 12, 9142.
Applications:
• Drug delivery
• Vaccines stabilizers
• Sustainable oil
recovery
Electrostatically driven, associative
liquid-liquid phase separation (LLPS)
• Charge density studies inform molecular design of polymer-micelle slug injections
• High-throughput optimization of slug parameters using porous microfluidic media
• Bridging systems chemistry and microfluidic platforms for energy sustainability
Adapted from He et al., ACS Crystal Growth & Design, 2020, 20, 1021.
PDADMAC-SDS/TX-100 Phase Diagram
Surfactant Steric
Hindrance
Polymer Charge Density
Design Rules
= No Phase Separation
Inc
reas
ing
Mic
elle
Su
rface
Ch
arg
e D
en
sity
Surfactant amphilicity forms
adsorbed film lowering oil/slug
interfacial tension
Microfluidic Gradient-Tree Approach
Increasing surfactant PEG-length
increases 𝒀(−) of turbidity jump
𝒀𝒄 scales with increasing micelle
steric repulsion
Negative correlation
between polymer charge density
and 𝒀𝒄
• Determined the effects of polymer
and micelle charge densities in
driving complex coacervation
• Charge density design framework can
be generalized to broad classes of
ionic colloids, e.g., charged proteins,
nanoparticles etc. and broaden array
of coacervate-based platforms
• Further exploration into nanoscale
chemistry affects on coacervate
mechanical properties for renewable
energy applications
Polyethylene Glycol (PEG) tail on neutral
surfactant head
= 𝒀𝒄
Well-plate assays for turbidity, optical
microscopy, kinetics studies