Amorphous polymer dynamics and free volume element size distributions from ultrafast IR spectroscopy
Abstract
The free volume content of polymers has immense importance for polymer properties. However, it is extremely difficult to measure the properties of the free volume elements (FVEs) that make up the free volume. Here we employ ultrafast infrared (IR) pump–probe spectroscopy to measure the properties of the nanoscopic FVEs in polymers using small-molecule IR probes. With this new method, the size and size distribution of the FVEs in polymers are measured and found to agree with previous measurements. The IR measurements also show that the FVEs undergo ultrafast structural fluctuations and provide a way to measure the distribution of local electric fields in the FVEs, which are correlated with the size of the FVEs.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 08, 2020
- Source ID
- 10.1073/pnas.2003225117
Entities
People
- David J Hoffman
- Michael D. Fayer
- Sebastian M Fica-Contreras
Organizations
- Office of Naval Research
- Stanford University