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A Fundamental Study of the Conformational Phase Behavior of Chain Molecules at Interfaces

Summary:

Chain molecules tethered or adsorbed to solid surfaces are at the heart of a wide range of technologies. Examples include colloidal particle stabilization, chromatographic materials, and drug delivery methods.  Unfortunately, despite significant computational and theoretical efforts, important fundamental questions remain.  In particular, a basic understanding of how the conformational phase behavior of tethered and adsorbed chain molecules depends on thermodynamic constraints and surface chemistry is still lacking. To address this, we comprehensively study the conformational phase behavior of model homopolymers at solid surfaces using advanced Monte Carlo simulation techniques that provide the free energy of the system of interest to within an additive constant.  We systematically determine how factors such as chain length, chain density, and chain-surface interactions impact the resulting structure of adsorbed and tethered polymers.

Description:

Intended Impact

Predicting how the conformational phase behavior of tethered chain molecules depends on external variables is challenging.  Understanding how even simple models for tethered chain molecules depend on external variables will greatly aid our understanding of tethered chain systems.

Goals

To determine how variables such as temperature, chain density, chain length, surface interactions, etc., impact the conformational phase behavior of tethered chains.

Research Activities

We have investigated the conformational phase behavior of tethered chain systems using temperature expanded Monte Carlo techniques at thousands of state points, covering densities from the isolated chains to the thin film limit, and a broad range of temperatures.  To date, we have investigated the impact of surface interactions, chain stiffness, and tethering geometry on conformational phase behavior.

Major Accomplishments:

We have demonstrated that simulation may be used as an effective guide to understanding the conformational phase behavior of tethered chain systems.

End Date:

ongoing

Lead Organizational Unit:

mml
Contact

William Krekelberg
Email: william.krekelberg@nist.gov
Phone: 301-975-2459
Fax: 301-975-3670

Vincent Shen
Email:  vincent.shen@nist.gov
Phone: 301-975-2461
Fax: 301-975-3670