Thiol-ene Click Chemistry Incorporates Hydroxyl Functionality on Polycyclooctene to Tune Properties

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Plastics

Background:

• Polyolefins are major plastic waste contributors.
• Mechanical recycling of polyolefins leads to property degradation.
• Developing value-added recycling methods for polyolefins is crucial.

Purpose of the Study:

• To functionalize polycyclooctene (PCOE) as a model for polyethylene.
• To introduce pendant hydroxyl ethyl thioethers using thiol-ene click chemistry.
• To evaluate the impact of functionalization on PCOE's material properties and adhesive capabilities.

Main Methods:

• Thiol-ene click chemistry reaction between PCOE and mercaptoethanol.
• Controlled functionalization by varying reagent stoichiometry and reaction time.
• Characterization of functionalized PCOE using contact angle measurements, thermal analysis (DSC), and shear stress testing.

Main Results:

• Achieved PCOE functionalization ranging from 1.4% to 22.9%.
• Increased surface polarity and glass transition temperature with higher functionalization.
• Functionalized PCOE exhibited comparable surface polarity and adhesive strength (4.10 ± 0.48 MPa at 12% functionalization) to poly(ethylene-co-vinyl alcohol) (EVOH).

Conclusions:

• Thiol-ene click chemistry offers controlled functionalization of PCOE.
• Functionalized PCOE demonstrates improved surface polarity and adhesive properties.
• This approach presents a potential pathway for enhancing polyolefin recyclability and performance.