# Polymer–Ceramic Hybrid Composites for Lightweight Solar Thermal Collector Absorbers: Thermal Transport, Optical Selectivity, and Durability

## TL;DR

This review explores polymer-ceramic hybrid composites for solar thermal collectors, focusing on their thermal performance, optical properties, and durability for practical applications.

## Contribution

The paper introduces a structure–property–performance mapping approach to evaluate hybrid composites for solar thermal collectors beyond just conductivity.

## Key findings

- Hybrid ceramic–carbon architectures and multilayer designs are promising for balancing thermal transport and durability.
- Ceramic fillers like boron nitride and alumina improve conduction-network stability and coating compatibility.
- Carbon fillers enhance heat spreading and solar absorption but may reduce emissivity.

## Abstract

Polymer–ceramic hybrid composites are emerging as attractive candidates for lightweight, corrosion-resistant absorber components in solar thermal collectors; however, their adoption is constrained by the intrinsically low thermal conductivity of polymers, processing-induced anisotropic heat transport, interfacial thermal resistance at tube/laminate joints, and durability challenges under outdoor exposure. This review provides a collector-centered synthesis of polymer–ceramic hybrid materials, emphasizing the translation of composite properties into collector-level outcomes rather than conductivity enhancement alone. A structure–property–performance mapping approach is presented to connect directional thermal conductivity ((k_in-plane), (k_perp)), thermal diffusivity, heat capacity, coefficient of thermal expansion, and service temperature with collector performance parameters such as heat removal effectiveness, overall heat losses, and stagnation behavior. Ceramic fillers (e.g., boron nitride, aluminum nitride, silicon carbide, alumina) are examined for stable conduction-network formation, coating compatibility, and long-term reliability, while carbon fillers (graphite, graphene nanoplatelets, carbon nanotubes) are evaluated for combined heat spreading and solar absorption benefits, with attention to emissivity penalties. Hybrid ceramic–carbon architectures and multilayer absorber designs are identified as the most promising routes to balance thermal transport, optical selectivity (high solar absorptance and low thermal emittance), manufacturability, and durability under UV, humidity, and thermal cycling.