Phase change materials (PCMs) have gained significant attention for thermal energy storage applications due to their ability to store and release large amounts of latent heat during phase transitions. Among these, paraffin-based composites, particularly paraffin-SiO2 nanostructured systems, exhibit promising properties for efficient energy management. Differential scanning calorimetry (DSC) serves as a critical tool for evaluating the thermal characteristics of these materials, including latent heat capacity, supercooling behavior, and cycling stability—key parameters determining their practical utility.

Latent heat storage is a fundamental property of PCMs, measured directly using DSC. Paraffin, an organic PCM, possesses high latent heat values, typically ranging between 150–250 J/g during melting and solidification. When incorporated into a SiO2 matrix, the composite retains much of this latent heat while gaining structural stability. DSC thermograms of paraffin-SiO2 composites reveal distinct endothermic and exothermic peaks corresponding to melting and crystallization, respectively. The integration of SiO2 nanoparticles does not significantly alter the phase transition temperature of paraffin but may influence the total enthalpy due to the reduced proportion of active PCM in the composite. For instance, a composite with 70 wt% paraffin in a mesoporous SiO2 scaffold may exhibit a latent heat of approximately 170–190 J/g, demonstrating efficient energy retention despite the presence of the inorganic framework.

Supercooling is a common challenge in PCM applications, where the material remains in a liquid state below its crystallization temperature, delaying heat release. DSC analysis provides precise quantification of supercooling by measuring the temperature difference between the onset of melting and crystallization. Pure paraffin often shows supercooling of 5–10°C, which can be mitigated by incorporating nucleating agents or nanostructured supports like SiO2. The porous structure of SiO2 provides heterogeneous nucleation sites, reducing supercooling to as low as 1–3°C in optimized composites. DSC cooling curves of paraffin-SiO2 systems exhibit sharper crystallization peaks with minimal undercooling, indicating improved thermal reliability. The degree of supercooling suppression depends on the pore size distribution and surface functionalization of the SiO2 matrix, with smaller pores and hydrophilic surfaces generally enhancing nucleation.

Cycling stability is another critical factor for PCMs in long-term applications. Repeated melting and freezing cycles can lead to phase separation, degradation, or leakage, reducing thermal performance. DSC is employed to assess cycling stability by subjecting the material to multiple heating-cooling cycles and monitoring changes in latent heat and transition temperatures. Paraffin-SiO2 composites demonstrate superior cycling stability compared to pure paraffin due to the confinement effect of the SiO2 matrix, which prevents leakage and maintains dispersion. Studies indicate that after 500 thermal cycles, well-designed paraffin-SiO2 systems retain over 90% of their initial latent heat storage capacity, with negligible shifts in phase transition temperatures. The SiO2 framework acts as a mechanical stabilizer, minimizing PCM migration and preserving thermal properties over extended use.

Thermal energy storage applications of paraffin-SiO2 composites leverage these DSC-validated properties. In building temperature regulation, these materials absorb excess heat during the day and release it at night, reducing energy consumption for heating and cooling. The high latent heat ensures sufficient energy density, while suppressed supercooling guarantees predictable thermal discharge. Solar thermal systems also benefit from these composites, where they store concentrated solar energy as latent heat for later use in power generation or domestic heating. The cycling stability of paraffin-SiO2 systems makes them suitable for such repetitive processes without significant degradation.

Industrial waste heat recovery is another promising application, where PCM composites capture and store excess heat from manufacturing processes for reuse. The ability of DSC to characterize the thermal response of these materials under varying conditions ensures optimal integration into such systems. Additionally, electronic thermal management utilizes paraffin-SiO2 composites to buffer against overheating in high-power devices, where their stable phase transitions and high enthalpy provide effective heat dissipation.

In summary, DSC analysis provides indispensable insights into the performance of paraffin-SiO2 phase change nanomaterials, confirming their high latent heat, reduced supercooling, and excellent cycling stability. These properties make them highly effective for diverse thermal energy storage applications, from building climate control to industrial heat management. The precise quantification offered by DSC ensures that material formulations can be optimized for specific use cases, enhancing energy efficiency and sustainability across multiple sectors.