# Record‐High Latent Heat, Ultra‐Fast Relaxation and Closed‐Loop Recycling Double‐Brush Polymer Networks for Self‐Adaptive Thermal Interface Management

## TL;DR

This paper introduces a new type of polymer material with high heat storage and fast response, ideal for managing heat in high-performance computing systems.

## Contribution

The design of double-brush polymer networks with record-high enthalpy and self-adaptive thermal interface properties is novel.

## Key findings

- The material achieves a record enthalpy of 240.7 J·g−1 due to high phase-change unit content and minimized enthalpy loss.
- The polymer composite self-adaptively modulates low interfacial thermal resistance in response to temperature changes.
- The material outperforms commercial thermal interface products in thermal management efficiency.

## Abstract

In the era of artificial intelligence (AI)‐driven high‐performance computing, phase change materials (PCMs) are critical for high‐flux thermal management. PCMs are evolving toward high enthalpy, low interfacial thermal resistance (ITR), and high reliability. Herein, we design double‐brush phase‐change polymer (PVBS‐TMCn) crosslinked by B─O─B and Si─O─B dynamic bonds, characterized by the ultra‐fast relaxation time of 0.8 s under 80°C and closed‐loop cycling. This architecture enhances the content of phase‐change units for elevated theoretical enthalpy, while inherent multiple dynamic bonds and ultra‐low entanglement minimize enthalpy loss, resulting in a record enthalpy of 240.7 J·g−1. Furthermore, a composite of flexibility PVBS‐TMC14/24 and graphene foam films (PVBS‐TMC/GF) is fabricated as thermal interface materials using a stacking‐cutting strategy, which self‐adaptively modulates low‐ITR in response to temperature, owing to phase transition properties, ultra‐low modulus, and adaptive filling capability of dynamic polymer matrix. PVBS‐TMC/GF significantly generates better thermal management efficiency compared to commercial products. The topology design of double‐brush polymer dynamic networks and interfacial contact mechanisms provide fundamental insights for developing phase‐change adaptive materials and advancing thermal management.

By grafting dense long double‐brush chains, we synthesized bottlebrush networks with high theoretical enthalpy. Their low entanglement, combined with dynamic bonds, promotes crystalline domain reorganization and minimizes enthalpy loss, achieving a record enthalpy of 240.7 J·g−1. The low modulus of bottlebrush networks and interfacial reorganization ability of dynamic bonds enhance contact and micro‐void infiltration in TIMs, enabling self‐adaptive ITR under thermal stimulation.