A study on poly(indene)

Abstract

Indene was polymerized to polyindene (PI) through a cationic mechanism using TiCl₄•2THF complex as initiator. The cationic mechanism was investigated through electronic absorption spectroscopy and either the indanyl cation as well as the polyindenyl cation absorption bands were distinguished and assigned. The PI structure was investigated through the indane model compound and the indene reference compound electronic absorption spectra. Furthermore, the Raman spectrum of PI was recorded for the first time and the complete Raman and FT-IR absorption bands of PI are reported with the assignment of the main bands. The glass transition (T_g) of cationic, radiation-induced and thermally initiated PI were measured through DSC and the corresponding molecular weight estimated. DSC and TGA-FTIR analysis were used to study the thermal decomposition of PI. It was assessed that PI is pyrolyzed back into indene monomer in almost theoretical yield with an activation enthalpy of E^# = 164 kJ/mol while the decomposition enthalpy of PI was determined at 101.6 kJ/mol a value very close to the theoretical value of 108.9 kJ/mol. It was assessed that PI is a fully recyclable polymer which could be decomposed back to the monomer and re-polymerized at will.

Graphical Abstract

Keywords:

• Polyindene
• indene
• cationic polymerization
• TGA-FTIR
• DSC
• UV-VIS
• Raman spectroscopy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We acknowledge support from State Research Agency (AEI) of the Spanish Ministry of Science and Innovation (MICINN) under grant PID2020-115758GB-I00. This article is based upon work from COST Action NanoSpace, CA21126, supported by COST (European Cooperation in Science and Technology).