Physical Aging of Poly(methyl methacrylate) Brushes and Spin-Coated Films

Sneha Srinivasan; Allyson L McGaughey; Zhiyong Jason Ren; Biao Zuo; Rodney D Priestley

doi:10.1021/acs.jpcb.4c05704

Physical Aging of Poly(methyl methacrylate) Brushes and Spin-Coated Films

J Phys Chem B. 2024 Nov 22. doi: 10.1021/acs.jpcb.4c05704. Online ahead of print.

Authors

Sneha Srinivasan¹, Allyson L McGaughey^{1

2}, Zhiyong Jason Ren^{2

3}, Biao Zuo⁴, Rodney D Priestley^{1

5}

Affiliations

¹ Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States.
² Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, United States.
³ Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States.
⁴ Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China.
⁵ Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544, United States.

PMID: 39576256
DOI: 10.1021/acs.jpcb.4c05704

Abstract

While there is significant attention aimed at understanding how one-dimensional confinement and chain confirmations can impact the glass transition temperature (T_g) of polymer films, there remains a limited focus on similar effects on sub-T_g processes, notably, structural relaxation. Using spectroscopic ellipsometry, we investigated the combined influence of confinement and molecular packing on T_g and physical aging, i.e., the property changes that accompany structural relaxation, at select film thicknesses and aging temperatures (T_a). We used poly(methyl methacrylate) (PMMA) films in the brush and spin-coated morphologies as model systems. We found that whether a PMMA film exhibited a decrease or increase in physical aging rate with confinement was dependent on the morphology. Notably, PMMA brushes exhibited higher physical aging rates compared to similarly thick spin-coated films at all values of T_a. These intriguing findings reveal the strong effects of confinement and molecular packing on the structural relaxation of polymer films. Results from this study have the potential to aid in the design of thin-film materials with controllable long-term glassy-state properties.