Catalytic systems for controlled ring-opening polymerization reactions

The invention describes catalyst systems for ring-opening polymerization of cyclic compounds like epoxides and lactones. These catalysts, using Group 13 and 15 metals, enable controlled polymerization, producing polymers with precise molecular weights and functionalities, and can extend existing polymers to form block copolymers.

Background

Ring-opening polymerization (ROP) is a critical process in the field of polymer chemistry, offering the ability to create polymers with specific structural properties by opening cyclic monomers. This method is particularly valuable for producing polymers from cyclic substrates like epoxides, oxetanes, lactones, and cyclic carbonates.

The versatility of ROP lies in its capacity to generate polymers with controlled molecular weights, compositions, and functionalities, which are essential for applications ranging from biodegradable plastics to advanced materials. However, the effectiveness of ROP hinges on the availability of efficient catalyst systems that can facilitate the polymerization process under mild conditions, allowing both experts and non-specialists to achieve desired polymer characteristics easily.

Despite the potential of epoxides as monomers in ROP, the field faces significant challenges due to the lack of a universally accepted, user-friendly polymerization technique. Anionic ring-opening polymerization (AROP) is commonly used but is limited by its sensitivity to monomer structure and its inability to achieve high molecular weights for most epoxides, except ethylene oxide. Additionally, AROP struggles with chain-transfer issues, which complicate the control of molecular weight and chain-end functionalities.

Recent developments, such as the mono(q-alkoxo)bis(alkylaluminum) (MOB) catalysts, have shown promise by offering controlled polymerization without auto-termination or chain transfer. However, these catalysts often require extended reaction times to fully consume monomers, highlighting the need for improved catalyst systems that can deliver rapid and controlled ROP across a wide range of cyclic substrates.

Technology description

The technology involves advanced catalyst systems tailored for ring-opening polymerization (ROP) processes, which are applicable to a variety of cyclic substrates such as epoxides, oxetanes, lactones, and cyclic carbonates. These catalyst systems incorporate Group 15 and Group 13 metal adducts, facilitating efficient polymerization. They can function in the presence of additional electrophiles like carbon dioxide and utilize initiators such as benzyl alcohol to yield orthogonally protected polymers. The system can extend pre-existing polymers to form block copolymers.

The catalysts exhibit a concentration-dependent cooperative mechanism, allowing for rapid and controlled polymerization, resulting in polymers with precise molecular weights. Additionally, the technology explores the separation of catalytic and propagator functionalities into distinct species, enhancing control over polymerization rates and molecular weights.

This technology is differentiated by its ability to offer unprecedented control over polymerization processes, enabling the synthesis of polymers with specific molecular weights and functionalities. The use of Group 15 and Group 13 metal adducts allows for a broad range of cyclic substrates to be polymerized efficiently. The decoupling of catalytic and propagator functionalities into separate species provides enhanced control over the polymerization process, allowing for fine-tuning of polymerization rates and molecular weights. This level of control is particularly beneficial for creating block copolymers and orthogonally protected polymers, which are valuable in various industrial applications.

The technology’s adaptability to different substrates and conditions, along with its rapid and controlled polymerization capabilities, positions it as a versatile and powerful tool in polymer chemistry.

Benefits

Facilitates rapid and controlled polymerization of cyclic substrates
Enables production of polymers with controlled molecular weights and functionalities
Allows extension of pre-existing polymers to form block copolymers
Operates in the presence of additional electrophiles like carbon dioxide
Decouples catalytic and propagator functionalities for enhanced control over polymerization rates
Provides orthogonally protected polymers using initiators like benzyl alcohol
Exhibits strong concentration dependence, suggesting a cooperative mechanism