Discrete Combinatorial Investigation of Polymer Mixture Phase Boundaries
J Cabral, Alamgir Karim
We report a combinatorial approach for mapping bulk polymer mixture phase behavior. The technique consists of a parallel cloud point detection scheme using discrete composition libraries, which are scanned across a temperature range and optically imaged. The sample substrates are microwell arrays fabricated by contact photolithography on a glass coverslip. Polymer blend libraries are generated using a programmable liquid dispenser system. The sample arrays are placed in a uniform, but continuously varying, temperature field, so that the mixture traverses the phase boundary. Optical turbidity is detected by imaging the entire array and the cloud point curve is determined through automated parallel image analysis. The entire process is simple, flexible, inexpensive and rapid. In this demonstration, we investigate two binary mixtures of low molecular weight poly(styrene) and poly(butadiene), exhibiting upper critical solution temperature (UCST) phase behavior.The cloud point curves obtained closely approximate the bulk binodal line, and have a high composition resolution of dphi = 0.01 (volume fraction), using 10^2 sample arrays. We discuss the limitations and range of application of this high throughput methodology to other polymeric mixtures, including multi-component systems.
cloud point, combinatorial methods, miscibility and phase separation, polymer mixtures, turbidity
and Karim, A.
Discrete Combinatorial Investigation of Polymer Mixture Phase Boundaries, Measurement Science & Technology, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852384
(Accessed November 30, 2023)