Mechanically Strong Functionalized-BNNS/PVA Composite Hydrogels with Excellent Thermal Conductivities

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Polyvinyl alcohol (PVA) hydrogels offer excellent flexibility and biocompatibility, making them suitable for wearables and electronics.
• However, their poor thermal conductivity and mechanical properties hinder their use in high-integration applications.
• Enhancing these properties is crucial for advancing flexible electronic and wearable technologies.

Purpose of the Study:

• To fabricate PVA-based composite hydrogels with improved thermal and mechanical performance.
• To investigate the effect of oriented hydroxyl boron nitride nanosheets (BNNS-OH) on PVA hydrogel properties.
• To develop materials suitable for demanding flexible electronic and wearable applications.

Main Methods:

• Fabrication of BNNS-OH/PVA composite hydrogels using directional freezing, salting-out, and stretching.
• Incorporation of hydroxyl boron nitride nanosheets (BNNS-OH) as thermal-conductive fillers within the PVA matrix.
• Characterization of thermal conductivity and mechanical properties (elastic modulus, tensile strength, toughness).

Main Results:

• Oriented BNNS-OH/PVA hydrogels (9 wt.% BNNS-OH) achieved an in-plane thermal conductivity of 3.13 W/(m·K) after stretching, a 210% increase over unstretched and 502% over pure PVA hydrogel.
• Enhanced mechanical properties were observed, with elastic modulus, tensile strength, and toughness reaching 20 MPa, 18.8 MPa, and 9.9 MJ/m³, respectively.
• The fabrication method successfully created oriented structures, significantly improving material performance.

Conclusions:

• The developed oriented BNNS-OH/PVA composite hydrogels demonstrate significantly enhanced thermal conductivity and mechanical strength.
• These advanced hydrogels show great promise for high-performance flexible electronics, wearable devices, and electronic packaging.
• The directional fabrication technique offers a viable pathway for creating functional composite hydrogels with tailored properties.