Alternating Ring-Opening Metathesis Polymerization Provides Easy Access to Functional and Fully Degradable Polymers.

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Polymers containing hydrolyzable groups are crucial for applications in biomedicine, lithography, energy storage, and electronics.
• Developing controlled synthesis methods for functional polymers with tunable properties remains an active research area.

Purpose of the Study:

• To synthesize heterofunctional copolymers with acetal or ester groups in their backbones using alternating ring-opening metathesis polymerization.
• To investigate the influence of polymer backbone structure on degradation, thermal, and viscoelastic properties.
• To demonstrate control over polymer properties through monomer design.

Main Methods:

• Alternating ring-opening metathesis copolymerization catalyzed by a third-generation Grubbs ruthenium catalyst.
• Utilized large-ring cyclic acetal or lactone monomers combined with bicyclo[4.2.0]oct-1(8)-ene-8-carboxamide monomers.
• Characterization of copolymer molecular weight distribution, hydrolysis under acidic and basic conditions, glass transition temperature (Tg), and viscoelastic behavior.

Main Results:

• Successfully synthesized perfectly alternating copolymers with acetal or ester functionalities and low to moderate molecular weight distribution (ĐM = 1.2-1.6).
• Ester and acetal backbone copolymers showed significant hydrolysis under basic (pH 13) and acidic (pH ≤ 5) conditions, respectively, within 30 hours.
• Heteroatom-containing backbone copolymers exhibited viscoelastic behavior, with properties like crossover frequency and glass transition temperature (Tg) tunable by altering the R group size on the acetal.

Conclusions:

• Ruthenium-catalyzed alternating ring-opening metathesis copolymerization is an effective method for creating heterofunctional copolymers.
• The synthesized copolymers offer tunable degradation rates, glass transition temperatures, and viscoelastic moduli.
• This controlled synthesis opens avenues for designing advanced functional polymers for various technological applications.