Terpene polymerization via a binary neodymium-based catalytic system with di-n-butylmagnesium as a co-catalyst

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Increasing demand for sustainable materials drives research into renewable resources like terpenes.
• Terpenes offer a viable alternative to fossil fuel-based isoprene in polymer production.
• Coordination polymerization provides a pathway to control polymer microstructure and properties.

Purpose of the Study:

• To investigate the coordination homopolymerization of β-myrcene and β-farnesene using a binary neodymium versatate/dibutyl magnesium catalyst.
• To analyze the effect of varying neodymium to magnesium ratios ([Nd]:[Mg]) on polymerization outcomes.
• To characterize the resulting polymers, focusing on microstructure, conversion, and thermal properties.

Main Methods:

• Homopolymerization of β-myrcene and β-farnesene using a NdV3/Mg(n-Bu)2 catalyst system.
• Systematic variation of the [Nd]:[Mg] molar ratio between 4 and 10.
• Characterization of polymer microstructure (1,4-cis, 1,4-trans, 3,4 content) using spectroscopic techniques.
• Determination of glass transition temperatures (Tg) for the synthesized polymers.

Main Results:

• High conversions achieved: 92% for polymyrcene (PMy) and 83% for polyfarnesene (PFa) at an optimal [Nd]:[Mg] ratio of 8.
• Predominantly 1,4-cis microstructure obtained for both polymers, exceeding 80% 1,4 content.
• PFa exhibited higher 1,4-cis content (83%) compared to PMy (59%), attributed to monomer structure and steric hindrance.
• Glass transition temperatures were -63.7 to -66.5 °C for PMy and -75.4 to -75.5 °C for PFa.

Conclusions:

• The binary NdV3/Mg(n-Bu)2 system is effective for the coordination homopolymerization of β-myrcene and β-farnesene.
• An [Nd]:[Mg] ratio of 8 favors high conversions and predominantly 1,4-cis microstructure in the resulting polymers.
• The catalyst system demonstrates potential for producing sustainable polymers from renewable terpenes with tunable properties.