Abstract
Generating physical or chemical gradients in thin-film scaffolds is an efficient approach for screening and optimizing an interfacial structure or chemical functionality to create tailored surfaces that are useful because of their wetting, antifouling, or barrier properties. The relationship between the structure of poly(2-vinyl-4,4-dimethyl azlactone) (PVDMA) brushes created by the preferential assembly of poly(glycidyl methacrylate)-block-PVDMA diblock copolymers and the ability to chemically modify the PVDMA chains in situ to create a gradient in functionality are examined to investigate how the extent of functionalization affects the interfacial and surface properties. The introduction of a chemical gradient by controlled immersion allows reactive modification to generate position-dependent properties that are assessed by ellipsometry, attenuated total reflectance-Fourier transform infrared spectroscopy, contact angle measurements, and atomic force microscopy imaging. After functionalization of the azlactone rings with n-alkyl amines, ellipsometry confirms an increase in thickness and contact angle measurements support an increase in hydrophobicity along the substrate. These results are used to establish relationships between layer thickness, reaction time, position, and the extent of functionalization and demonstrate that gradual immersion into the functionalizing solution results in a linear change in chemical functionality along the surface. These findings broadly support efforts to produce tailored surfaces by in situ chemical modification, having application as tailored membranes, protein resistant surfaces, or sensors.
Original language | English |
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Pages (from-to) | 5204-5213 |
Number of pages | 10 |
Journal | Langmuir |
Volume | 34 |
Issue number | 18 |
DOIs | |
State | Published - May 8 2018 |
Funding
S.M.K. and B.A. gratefully acknowledge support from the National Science Foundation (award nos. 1133320 and 1512221). ATR-FTIR spectroscopy and CA measurements were performed at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.