Abstract
Precision polyethylenes with 21-carbon alkyl branches precisely spaced on every either 15th or 19th carbon along the polymer backbone lead to the formation of two kinds of lamellae, yielding different thicknesses during the crystallization process. Thinner lamellae originate from side-chain crystallization, whereas thicker lamellae are formed by cocrystallization of the branch and the main chain. Side-chain crystallization (separate from main chain crystallization) is favored when the branch is placed on every 15th carbon. Cocrystallization (side chain with main chain) is favored with the branch on every 19th carbon. Both form stable hexagonal crystal units. A branch spacing separation of just four carbons along the main chain makes a remarkable difference in crystallization behavior.
| Original language | English |
|---|---|
| Pages (from-to) | 3090-3096 |
| Number of pages | 7 |
| Journal | Journal of Polymer Science, Part A: Polymer Chemistry |
| Volume | 55 |
| Issue number | 18 |
| DOIs | |
| State | Published - Sep 15 2017 |
| Externally published | Yes |
Funding
The experiments at Photon Factory were performed under the approval of the Photon Factory Program Advisory Committee (Proposal Nos.: 2016G024). Preliminary SAXS and WAXS results were acquired at SPring-8 (No. 2016A7208). The authors thank the National Science Foundation (DMR-1505778) for the financial support for this project. This material is based upon catalyst work supported by, or in part by, the Army Research Office under the grant W911NF1310362. We also thank Materia Inc. for their generous donation of the catalyst used in this project. The Butler Laboratory and Sumitomo Chemical dedicate this article to Professor Grubbs on the occasion of his 75th birthday.
Keywords
- ADMET
- Metathesis
- Polymers
- alkenes
- alkyl branch
- hexagonal crystal unit
- lamellae
- polyethylene