Polyacrylonitrile Interactions with Carbon Nanotubes in Solution: Conformations and Binding as a Function of Solvent, Temperature, and Concentration
Abstract
Polyacrylonitrile (PAN) is among the most promising precursor polymers to produce strong and lightweight carbon fiber. Conformations in solution and the extent of binding to carbon nanotubes (CNTs) are critical during gel spinning and for alignment of graphitic layers upon carbonization. Here, quantitative insights into these processes are reported using molecular dynamics simulations at the atomic scale including virtual π electrons and comparisons to experimental data. Common solvents for fiber spinning induce significant differences in PAN conformation in dilute solutions at 25 °C with persistence lengths between 0.5 and 2 nm. Variations in conformation become smaller at 75 °C, in the presence of CNTs, and at higher PAN concentration. “Aging” of PAN conformations in dimethylformamide and dimethylsulfoxide at higher temperature is explained and a correlation between extended polymer conformations and increased binding to CNTs is identified in dilute solutions. PAN is overall barely attracted to CNTs under common solution conditions and enters significant surface contact only at higher concentration as solvent is physically removed. The impact of temperature is small, whereby binding increases at lower temperatures. The results provide guidance to control interactions of polymers with CNTs to induce distinct conformations and specific binding at the early stages of assembly.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 03, 2019
- Source ID
- 10.1002/adfm.201905247
Entities
People
- Chandrani Pramanik
- Darice Guittet
- Hendrik Heinz
- Jacob R. Gissinger
- Pedro J. Arias‐Monje
- Satish Kumar
- Tariq Jamil
Organizations
- Air Force Office of Scientific Research
- Georgia Tech
- National Aeronautics and Space Administration
- National Science Foundation
- Office of Science
- University of Colorado
- University of Colorado Boulder