Constructing a three-dimensional (3D) filler network in polymer thermal interface materials (TIMs) is crucial for enhancing thermal conductivity and mechanical properties. However, the discontinuous and loose network of fillers are one of the main reasons hindering the joint improvement of thermal conductivity and mechanical properties. The construction of a regular and dense 3D continuous filler network remains a significant challenge. In this study, an innovative bidirectional freezing technique was designed to create a polyvinyl alcohol (PVA)/boron nitride (BN) composite with a tree-ring-like 3D network. This technique promotes the formation of 3D network consisting of long-range lamellar BN layers with a tree-ring-like structure by controlling the nucleation and growth of ice crystals along the bidirectional temperature gradient induced by a polytetrafluoroethylene (PTFE) cone. The resulting PVA/BN composite exhibits high thermal conductivity (6.25 W/m·K) due to the lower interfacial thermal resistance between fillers (1.271 × 10−7 K m2/W), and an enhanced tensile strength of 41.71 MPa, which is attributed to the regular and dense BN network. This study presents a feasible strategy for constructing a 3D continuous network structure in polymer-based TIMs, paving the way for advancements in thermal management solutions.

中文翻译：

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在聚乙烯醇/氮化硼复合材料中构建树轮模拟 3D 网络，以增强热管理和机械性能


在聚合物热界面材料 (TIM) 中构建三维 (3D) 填料网络对于增强导热性和机械性能至关重要。然而，填料不连续、疏松的网络是阻碍导热性能和力学性能共同提高的主要原因之一。构建规则且致密的 3D 连续填料网络仍然是一个重大挑战。在这项研究中，设计了一种创新的双向冷冻技术来创建具有树环状 3D 网络的聚乙烯醇 (PVA)/氮化硼 (BN) 复合材料。该技术通过控制冰晶沿聚四氟乙烯 (PTFE) 锥体诱导的双向温度梯度的成核和生长，促进由具有树环结构的长程层状 BN 层组成的 3D 网络的形成。由于填料之间较低的界面热阻（1.271 × 10−7 K m2/W），所得PVA/BN复合材料表现出高导热率（6.25 W/m·K），并且拉伸强度提高到41.71 MPa，归因于规则且密集的 BN 网络。这项研究提出了一种在聚合物 TIM 中构建 3D 连续网络结构的可行策略，为热管理解决方案的进步铺平了道路。