Distribution of block copolymers in drying polymer films

Joeri Opdam; Stefan P W Govers; Julio Melio; Leendert G J van der Ven; Gijsbertus de With; Remco Tuinier; A Catarina C Esteves

doi:10.1016/j.jcis.2021.12.130

Distribution of block copolymers in drying polymer films

J Colloid Interface Sci. 2022 Apr 15:612:617-627. doi: 10.1016/j.jcis.2021.12.130. Epub 2021 Dec 25.

Authors

Joeri Opdam¹, Stefan P W Govers¹, Julio Melio², Leendert G J van der Ven³, Gijsbertus de With³, Remco Tuinier⁴, A Catarina C Esteves⁵

Affiliations

¹ Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands; Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands.
² Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands; Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, the Netherlands.
³ Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands.
⁴ Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands; Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands. Electronic address: r.tuinier@tue.nl.
⁵ Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands; Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands. Electronic address: a.c.c.esteves@tue.nl.

PMID: 35016021
DOI: 10.1016/j.jcis.2021.12.130

Abstract

Hypothesis: Block copolymers (BCP) consisting of a polar block and a surface active apolar block are widely used for surface functionalization of polymer films. The characteristics of the copolymer blocks determine whether surface segregation and/or phase separation occurs, for a given bulk mixture. This data can be used to find the optimal BCP composition where high surface enrichment is obtained without accumulation of phase separated BCP in the bulk.

Methods: The distribution of poly(ethylene oxide)-polydimethylsiloxane (PEO-PDMS) BCP in a polymer formulation relevant for coating applications is systematically investigated. The surface segregation is studied in liquid formulations with surface tension measurements and dried films with X-ray photoelectron spectroscopy (XPS), whereas phase separation is quantified using turbidity measurements. The results are compared with Scheutjens-Fleer self-consistent field (SF-SCF) computations, which are also applied to determine the effect of film drying on BCP phase stability and surface segregation.

Findings: Longer PDMS blocks result in lower interfacial tension of the liquid polymer mixture, whereas for the cured films, the largest PDMS concentration at the interface was obtained for intermediate PDMS block lengths. This is explained by the observation that phase separation already occurs at very low BCP concentrations for long PDMS blocks. The SCF predictions qualitatively agree with the experimental results and reveal that the BCP distribution changes significantly during film drying.

Keywords: Adsorption; Block copolymer; Film drying; Phase separation; Polydimethylsiloxane; Self-consistent field model; Surface segregation.

MeSH terms

Photoelectron Spectroscopy
Polyethylene Glycols*
Polymers*

Substances

Polymers
Polyethylene Glycols