Flexible monolithic phase change material based on carbon nanotubes/chitosan/poly(vinyl alcohol).

• Highly flexible CNTs based monolithic support was constructed via a directional freezing method. • Monolithic CNTs based composite PCM exhibits superior mechanical and thermal properties. • Flexible mechanism of monolithic CNTs based composite PCM is proposed. • This design strategy provides a new direction for future wearable fitting-skin temperature-controlled materials. Currently, most reported composite phase change materials (PCMs) are powdery shape, which require secondary processing for practical applications. Although some monolithic composite PCMs have been developed, their flexibility usually undergoes a remarkable reduction or even complete disappearance when supporting material s are infiltrated with PCMs. To solve this problem, we fabricated a flexible supporting material with a folded layer-bridge network structure by dispersing carbon nanotubes (CNTs) in acetic acid solution of chitosan (CS) with poly(vinyl alcohol) (PVA) using a directional freezing method. Then CS/PVA/CNTs (CPC) scaffold was infiltrated with polyethylene glycol (PEG) to prepare PEG@CPC composite PCM. The resulting flexible composite PCM displays excellent mechanical properties, such as high tensile strength of 2.42 MPa and bending resistance of >100 cycles. Moreover, it displays outstanding thermal properties, such as high crystallinity of close to 100% and encapsulation ratio of 92.6 wt%. This work provides a simple method for preparation of flexible monolithic composite PCMs for many potential applications, such as wearable fitting-skin temperature-controlled materials. [ABSTRACT FROM AUTHOR]