Heterotelechelic Silicones: Facile Synthesis and Functionalization Using Silane-Based Initiators

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• The synthesis of heterotelechelic polydimethylsiloxane (PDMS) derivatives with high chain-end fidelity is challenging, limiting their synthetic utility.
• Traditional methods often suffer from issues like intermolecular transfer, hindering precise control over polymer architecture.

Purpose of the Study:

• To develop a versatile and controlled method for synthesizing heterotelechelic PDMS polymers.
• To create a diverse library of PDMS derivatives with high chain-end fidelity.
• To demonstrate the synthesis of advanced PDMS-based materials, such as supersoft bottlebrush networks.

Main Methods:

• Anionic ring-opening polymerization (AROP) of hexamethylcyclotrisiloxane (D3) using a novel silyl hydride (Si-H)-based initiator (H-Si-C).
• In situ termination with various chlorosilanes to introduce diverse functional groups at one chain end.
• Hydrosilylation reactions to further functionalize the polymer chain ends.
• Synthesis of α-Si-H and ω-norbornene functionalized PDMS macromonomers.

Main Results:

• The novel H-Si-C initiator effectively suppresses intermolecular Si-H transfer, enabling high chain-end control.
• A library of heterotelechelic PDMS polymers with narrow dispersity (Đ < 1.2) and controllable molar masses (2-11 kg mol⁻¹) was synthesized.
• Well-defined supersoft PDMS bottlebrush networks were successfully prepared using the synthesized macromonomers.

Conclusions:

• The developed AROP strategy offers a versatile and highly controlled approach to synthesizing functionalized PDMS.
• This method overcomes limitations of previous techniques, providing access to complex PDMS architectures.
• The synthesized PDMS derivatives and networks hold potential for advanced material applications.