ABSTRACT
Polymer products with precise shape recovery behavior are highly desired for practical applications owing to excellent processability and mechanical properties compared with metallic or inorganic materials. Shape memory polymers (SMPs) provide a solution for this end, but the design and scalable fabrication of photothermal controllable SMPs with accurate, rapid, and repeatable recovery behaviors are still great challenges. In this work, polyurethane/sulfonated carbon nanotube (PU/S-CNT) composite particles are introduced into a cross-linked high-density polyethylene (HDPE) as a functional dispersed phase to realize photo-driven fast shape recovery in cheap polymer composite materials. It is found that microcracks can be induced by the PU/S-CNT composite particles during deformation, generating a particular microparticle in a microcrack (MC-MP) structure. The MC-MP microstructure significantly improves the photothermal conversion efficiency, thereby accelerating the photo-driven shape self-healing of arbitrary nondestructive material damage. It is also found that proper cross-linking of the matrix, HDPE, greatly improves the recovery performance of the materials. This strategy based on the MC-MP microstructure and cross-linked matrix is also instructive for designing new SMPs using other polymer materials.
ABSTRACT
In the present work, the evaporation-induced interfacial self-assembly behavior of an amphiphilic conjugated polymer, poly(3-hexylthiophene)-b-poly(acrylic acid) (P3HT-b-PAA), at the oil-water interface is explored. Novel 2D nanotapes of P3HT-b-PAA are prepared via the interfacial self-assembly. It is inferred that P3HT segments adopt a special conformation at the oil-water interface, which facilitates the packing of alkyl side chains and π-π interaction. The UV-vis spectrum further confirms that the ordering degree of P3HT segments is increased while transmission IR and Raman spectroscopic studies suggest that the P3HT chains adopt a more planar conformation at the oil-water interface. It is proposed that the formation of the nanotapes is driven by the ordered packing of the P3HT chains at the oil-water interface. Finally, the packing model of the P3HT chains inside the nanotapes is roughly proposed.
