Polymers
Division
|
NIST
Combinatorial Methods Center Focused Project
|
|
High Throughput
Methods of Measuring Interfacial Tension (IFT) |
| The NIST Combinatorial Methods Center (NCMC) is pleased to announce initiation of a new focused project on interfacial tension. The focus of this project is the adaptation of microfluidic (mF) technology to materials research – specifically to automated high-throughput characterization of interfacial tension in complex polymer formulations. We are inviting NCMC member organizations and others to join this project. The members of this focused project will help NCMC prioritize the new instrumentation we will develop and specify the model systems we will use for our demonstrations of this exciting new technology. Research results will be available to focused project members throughout the project period and member organizations will be able to participate directly with NIST researchers in development of new measurement tools |
| Statement of Work |
| Contact:
Kate Beers |
| Phone:
(301) 975-2113 |
|
E-mail:
beers@nist.gov |
| Introduction: |
|
In the early stages of the project, careful choice of a
specific target area is critical to realizing a quick return for our
members. High-throughput
measurement tools for interfacial properties in emulsions will see
immediate impact in a number of applications.
The purpose of the focused project is to establish a
commitment to active exchange between the participating members and
to develop a valid test method for interfacial tension measurements
of industrially relevant model systems.
Our goal is to develop a method with deep context in
industry, based on a strong foundation of fundamental science, and
to make this project a model in itself of the range of perspective
problems that can be addressed by using high-throughput
microfluidics methods in polymer formulation technology. |
| By
developing the use of mF
instrumentation to measure the behavior of polymers in complex
fluids, we aim to demonstrate exciting new approaches to formulation
science. With fast,
flexible methods of designing and assembling milli-scale models of
emulsion or colloid processing tools, high-throughput screening and
optimization of new materials and discovery of new applications can
be achieved across multiple stages of process development.
Chemical suppliers and their customers will be able to obtain
more and higher quality data relevant to the polymer additive
properties critical to their business. |
| Most
current mF technology is directed toward life science applications
with devices designed primarily for low viscosity, aqueous
solutions. We have
developed a soft lithographic technique, which imparts solvent
resistance to our devices and facilitates the integration of both
aqueous and organic media. Using
the existing suite of technology in the NCMC, we can introduce
high-throughput methods that span multiple compositions by varying
the input of either phase. Combinatorial
mF
systems can then be developed to measure viscosity, interfacial
tension, and stability of emulsions in an automated and
high-throughput manner. Our
systems will allow multiple feedstocks to be mixed in a range of
compositions and their above-mentioned properties measured over a
range of temperatures. |
| Technical
Approach: |
|
The
interfacial tension in emulsions will be measured by continual data
acquisition of drop deformation and retraction under a known field.
The relaxation of a spheroidal droplet towards an equilibrium
spherical shape is exponential under quiescent conditions: 1,2
where
a is the droplet deformation = (L-B)/(L+B), defined by
Taylor,3
where L is the major axis of the spheroid and B is its minor
axis. td
is the drop shape relaxation time td =
heff
ao/a, where ao is the radius of the undistorted
sphere, heff
is a viscosity parameter heff =
|
| References: |
|
1
A.
Luciani, M. F. Champagne, and L. A. Utracki, “Interfacial tension
coefficient from the retraction of ellipsoidal drops,” J. Polym.
Sci. Polym. Phys. 35,
1393 (1997). 2
J.
M. Rallison, “The deformation of small viscous drops and bubbles
in shear flows,” Ann. Rev. Fluid Mech. 16,
45-66 (1984). Soc. (London) A138, 41-48 (1932). |
| Preliminary
Results: |
|
Images
of a poly(propylene glycol) drop (hd = 0.5 Pa s) in poly(ethylene glycol) (hc
= 2.7 Pa s),
Exponential
decay of drop distortion, measured at 75 °C multiple times on
different drops. The
poly(ethylene glycol) continuous phase contained 1% F127 Pluronic
surfactant, and the drop was poly(propylene glycol). |
| Project
Meetings, Website, Reports and Lab visits: |
| A meeting will be held six weeks after the formal launch of
the project as well as at six-month intervals for the duration of
the project. Quarterly
reports will be submitted to the members with updates more
frequently via conference calls and other postings. In order to
facilitate the collaboration, specifications for methods,
instruments, programs, data analysis, and other aspects of this work
will be available to members during the course of the project.
A summary report will be provided within two months of the
end of the project. The
NCMC labs will be open to prearranged visits from member scientists
interested in hands-on participation in method development. |
| As with base level membership in the NCMC, all of the research carried out in the Focused Project is non-proprietary and is intended for publication in the public domain. No proprietary information or materials will be solicited or accepted by NIST from member organizations. The scope of the work by NIST included in this focused project is limited as described in Appendix A of the focused project agreement. |
|
Project Milestones: |
| First year |
|
§
Mixing
methods for droplet phase materials (organics) will be developed
that allow varying composition of polymeric surfactants and other
additives. §
Device geometries will
be designed to produce droplets with controlled size of the organic
phase in an aqueous medium with continuously varying properties. § Device geometries will be optimized using finite element analysis to produce flow fields for sheering and elongating droplets. § Instrumentation will be fabricated using a variety of methods including soft/traditional lithography, laser ablation or imprinting techniques as appropriate for model systems of interest to focused project members. |
| Second year |
|
§
A
high-throughput sample preparation method and a new milli-fluidic
measurement platform will be integrated to demonstrate rapid
characterization of polymer formulations. § Milli-fluidics measurements will be tested against industry standards and literature methods using model systems determined in cooperation with member organizations. § Application versatility will be demonstrated with validated measurements on several model systems of interest to member organizations. |
| Membership
Fee: |
| The membership fee payable to NIST is $ 20,000 per project year. |
| Send
a completed Project Agreement Form and fee to: |
|
NIST |
| The
project is scheduled to begin on May 31, 2003.
NIST reserves the right to cancel the focused project and
refund the membership fees in the case of insufficient member
participation. |
| NIST Materials Science & Engineering Laboratory - Polymers Division |
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|
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| Contact Information: | |
| Cher H. Davis | |
| Technical Coordinator | |
| combi@nist.gov | |
| (301) 975 6488 | |
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