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

Yoichi Okayama; Taejun Eom; Michael Czuczola; Allison Abdilla; Jacob R Blankenship; Kaitlin R Albanese; Javier Read de Alaniz; Christopher M Bates; Craig J Hawker

doi:10.1021/acs.macromol.3c01802

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

Macromolecules. 2023 Oct 29;56(21):8806-8812. doi: 10.1021/acs.macromol.3c01802. eCollection 2023 Nov 14.

Authors

Yoichi Okayama¹, Taejun Eom¹, Michael Czuczola², Allison Abdilla², Jacob R Blankenship^{1

2}, Kaitlin R Albanese^{1

2}, Javier Read de Alaniz², Christopher M Bates^{1

2

3

4}, Craig J Hawker^{1

2

3}

Affiliations

¹ Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.
² Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States.
³ Materials Department, University of California, Santa Barbara, California 93106, United States.
⁴ Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States.

Abstract

The synthetic utility of heterotelechelic polydimethylsiloxane (PDMS) derivatives is limited due to challenges in preparing materials with high chain-end fidelity. In this study, anionic ring-opening polymerization (AROP) of hexamethylcyclotrisiloxane (D₃) monomers using a specifically designed silyl hydride (Si-H)-based initiator provides a versatile approach toward a library of heterotelechelic PDMS polymers. A novel initiator, where the Si-H terminal group is connected to a C atom (H-Si-C) and not an O atom (H-Si-O) as in traditional systems, suppresses intermolecular transfer of the Si-H group, leading to heterotelechelic PDMS derivatives with a high degree of control over chain ends. In situ termination of the D₃ propagating chain end with commercially available chlorosilanes (alkyl chlorides, methacrylates, and norbornenes) yields an array of chain-end-functionalized PDMS derivatives. This diversity can be further increased by hydrosilylation with functionalized alkenes (alcohols, esters, and epoxides) to generate a library of heterotelechelic PDMS polymers. Due to the living nature of ring-opening polymerization and efficient initiation, narrow-dispersity (Đ < 1.2) polymers spanning a wide range of molar masses (2-11 kg mol^-1) were synthesized. With facile access to α-Si-H and ω-norbornene functionalized PDMS macromonomers (H-PDMS-Nb), the synthesis of well-defined supersoft (G' = 30 kPa) PDMS bottlebrush networks, which are difficult to prepare using established strategies, was demonstrated.

Associated data

Dryad/10.5061/dryad.cjsxksncm