Nowadays, the materials commonly used to fabricate thermoelectric devices are tellurium, lead and germanium. These materials ensure from one side the best thermoelectric performances, but exhibit drawbacks in terms of availability, sustainability, cost and manufacturing complexity. Moreover, they do not guarantee a safe and cheap implementation in wearable thermoelectric applications. Here, p-and n-type flexible thermoelectric textiles are produced with sustainable and low-cost materials through green and scalable processes. Cotton is functionalized with inks made with biopolyester and carbon-nanomaterials. Depending on the nanofiller, i.e. graphene nanoplatelets, carbon nanotubes or carbon nanofibers, positive or negative Seebeck coefficient values are obtained, achieving also a remarkable value of electrical conductivity of 55 S cm -1 using carbon nanotubes. The best bending and washing stability are registered for the carbon nanofibers-based biocomposites, which increase their electrical resistance by 5 times after repeated bending cycles and only of the 30% after washing. Finally, in-plane flexible thermoelectric generators are fabricated and characterized coupling the best p-and n-type materials, achieving an output voltage of ~ 1.65 mV and a maximum output power of ~ 1.0 nW by connecting only 2 p/n thermocouples at a temperature difference of 70°C.

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Beeswax particles are homogenously emulsified in commercial aqueous polymer dispersion, without additional dispersing agents and surfactants. Emulsions display very good stability with wax droplet size distribution around 350 nm. The wax to polymer ratio in the emulsions can be tuned without compromising emulsion stability. The emulsions are spray coated in order to create either hydrophobic or superhydrophobic coatings. For superhydrophobicity, silica nanoparticles are dispersed in the emulsions at different concentrations. Beeswax‐rich coatings such as the ones with 1:1 beeswax:polymer ratio or more, including the superhydrophobic ones, demonstrate promising latent heat storage characteristics, suitable for thermal management applications. Electron microscopy studies show that as a result of emulsification, the polymer encapsulates the wax droplets/particles as a nanothin shell, preventing a major problem related to low melting point phase change materials referred to as leaching. Hence, the coatings can be heated well above the melting point of beeswax (≈62 °C) and can still demonstrate effective heat storage during the cooling stage. This water‐based coating process using ecofriendly material constituents can easily be scaled up and used in responsive coating applications, ranging from electronics to interior or exterior structural buildings requiring efficient energy management and thermal energy savings.