Efficient Phase-Change Polymer Composite Film from Emulsion Gels Stabilized by Cellulose Nanofiber-Based Amphiphiles

Phase-change polymers (PCPs), exhibiting solid–solid phase transition, bring advancement to the conventional solid–liquid system for thermal energy storage. Such a system obtained as an aqueous dispersion is recommended for application as a surface coating. However, achieving good colloidal stability with efficient energy-storage performance requires precise process designing. Herein, we developed a film-forming PCP that was synthesized from emulsion gels stabilized by cellulose nanofiber-based amphiphiles (CLAm’s). The CLAm was obtained by grafting an amphiphile at a significantly higher degree (0.2–2.4). Depending on the degree of substitution and type of oil, the CLAm was able to efficiently stabilize o/w emulsion gels containing a very high oil phase (>90.0%) at a concentration of about 0.1 wt %. The PCPs were produced by the copolymerization of stearyl methacrylate (SMA) and methyl methacrylate used as the oil phase in emulsion gels. The composite film obtained from the colloidal dispersion of P(SMA-co-MMA) exhibited a solid–solid (crystalline–amorphous) phase transition involving high latent heat of upto ∼98 J/g for the melting and crystallization of SMA segments at ∼35 and ∼25 °C, respectively. This approach provides significant advancement in designing an efficient energy-storage material using plant-derived biocompatible nanomaterials.