Precision Grafting-From of Diblock Copolymer Brushes on MXene Nanosheets

TL;DR

Researchers developed a new method to attach polymer brushes onto MXene nanosheets, enhancing their performance in composites.

Contribution

A robust grafting-from methodology for covalently bonding diblock copolymer brushes onto MXene nanosheets is introduced.

Findings

Diblock copolymers with controlled molecular weight and low polydispersity were successfully grafted onto MXene surfaces.

The polymer brushes formed a near-brush regime with high grafting density and shell thickness of 20–50 nm.

The grafting-from approach preserves MXene's structure in harsh environments better than physical adsorption methods.

Abstract

2D MXene materials offer outstanding optical, electrical,
and mechanical
properties, which can be used to produce multifunctional high-performance
polymer–matrix composites. Here, we demonstrate the fabrication
of robust covalently bonded polymer shells via the implementation
of surface-initiated atom transfer radical polymerization (SI-ATRP)
on heterogeneous 2D nanosheets. This robust grafting-from methodology
was demonstrated through selective esterification of hydroxyl groups
on Ti3C2T

x

MXene with 2-bromoisobutyryl bromide. This approach enables
the synthesis of diblock polymer brushes with sequential hydrophobic
and hydrophilic blocks with predetermined, narrowly dispersed molecular
weight and a low polydispersity index firmly bonded to the nanosheet
surface. The high molecular weight of diblock copolymers was achieved
by a precise design of molecular compositions (block ratio). By combining
selective chain cleavage and monitoring the evolution of polymer shell
morphology, we confirmed that the growth of polymer brushes falls
in the near-brush regime with a high grafting density of 0.18–0.25
chains/nm2 and shell thickness of 20–50 nm. Compared
to common grafting-to and physical adsorption processes, the key benefits
of this grafting-from approach lie in combining the 2D MXene nanosheets
with the versatility of firmly grafted diblock copolymer functionalities
and a core–shell brush architecture where MXene’s inherent
structure is protected in harsh chemical environments.

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