Polymer layers are prone to local heat accumulation under solar irradiation or prolonged thermal exposure, while their thermal-state changes are often difficult to identify directly. To improve thermal-state visualization, this study proposes a multicomponent interfacial-regulation strategy to construct composite microcapsules integrating photothermal triggering, thermochromic feedback, and thermal-transition contribution for visual thermal management in polymer layers. Nonanoic acid was used as the main thermal-transition core, crystal violet lactone/bisphenol A as the reversible thermochromic unit, and gallic acid and nano-TiO₂ as organic–inorganic functional regulating components. The obtained particles exhibited irregular microcapsule-like morphology with tunable thermal-transition behavior and color response. After functionalization, the samples showed enhanced color response, with MGT reaching a total color difference of 13.1 and maintaining relatively stable photothermal output and color-recovery ability after 10 irradiation cycles. However, this response advantage was accompanied by marked decreases in melting/crystallization enthalpies and effective phase-change contribution, indicating a trade-off between multifunctional integration and latent-heat storage. A sandwich-structure model further demonstrated that the functional layer delayed heat accumulation mainly by regulating thermal-response kinetics rather than simply lowering the final equilibrium temperature. This study provides a response-oriented strategy for designing visual thermal-management materials for polymer-layer applications.
Wang et al. (2026) studied this question.