Cyclic Topology Enhancing Structural Ordering and Stability of Comb-Shaped Polypeptoid Thin Films against Melt-Induced Dewetting
| Autor: | Ying Wu, Liying Kang, Donghui Zhang, Naisheng Jiang, Jianxia Chen, Kangmin Niu, Albert Chao, Masafumi Fukuto, Tianyi Yu, Ruipeng Li |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Polymers and Plastics Silicon fungi Organic Chemistry chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Topology 01 natural sciences Stability (probability) Article 0104 chemical sciences Inorganic Chemistry Chain (algebraic topology) chemistry Mathematics::K-Theory and Homology Materials Chemistry Thermal stability Dewetting Thin film 0210 nano-technology Topology (chemistry) |
| Zdroj: | Macromolecules |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/acs.macromol.0c01205 |
| Popis: | We investigated the effect of cyclic chain topology on the molecular ordering and thermal stability of comb-shaped polypeptoid thin films on silicon (Si) substrates. Cyclic and linear poly(N-decylglycine) (PNDG) bearing long n-decyl side chains were synthesized by ring-opening polymerization of N-decylglycine-derived N-carboxyanhydrides. When the spin-coated thin films were subjected to thermal annealing at temperatures above the melting temperature (T > Tm), the cyclic PNDG films exhibited significantly enhanced stability against melt-induced dewetting than the linear counterparts (l-PNDG). When recrystallized at temperatures below the crystallization temperature (T < Tc), the homogeneous c-PNDG films exhibit enhanced crystalline ordering relative to the macroscopically dewetted l-PNDG films. Both cyclic and linear PNDG molecules adopt cis-amide conformations in the crystalline film, which transition into trans-amide conformations upon melting. A top-down solvent leaching treatment of both l/c-PNDG films revealed the formation of an irreversibly physisorbed monolayer with similar thickness (ca. 3 nm) on the Si substrate. The physisorbed monolayers are more disordered relative to the respective thicker crystalline films for both cyclic and linear PNDGs. Upon heating above Tm, the adsorbed c-PNDG chains adopt trans-amide backbone conformation identical with the free c-PNDG molecules in the molten film. By contrast, the backbone conformations of l-PNDG chains in the adsorbed layers are notably different from those of the free chains in the molten film. We postulate that the conformational disparity between the chains in the physically adsorbed layers versus the free chains in the molten film is an important factor to account for the difference in the thermal stability of PNDG thin films. These findings highlight the use of cyclic chain topology to suppress the melt-induced dewetting in polymer thin films. |
| Databáze: | OpenAIRE |
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