A room-temperature, open-air method is devised to selectively intercalate relatively low-molecular-weight polymers (approximately 10-100 kDa) from dilute, volatile solutions into open-end, as-grown, wettable carbon nanotubes with 50-100 nm diameters. The method relies on a novel self-sustained diffusion mechanism driving polymers from dilute volatile solutions into carbon nanotubes and concentrating them there. Relatively low-molecular-weight polymers, such as poly(ethylene oxide) (PEO, 600 kDa) and poly(caprolactone) (PCL, 80 kDa), were encapsulated in graphitic nanotubes as confirmed by transmission electron microscopy, which revealed morphologies characteristic of mixtures in nanoconfinements affected by intermolecular forces. Whereas relatively small, flexible polymer molecules can conform to enter these nanotubes, larger macromolecules (approximately 1000 kDa) remain outside. The selective nature of this process is useful for filling nanotubes with polymers and could also be valuable in capping nanotubes.

This study aims to encapsulate polymers, surfactants and nanoparticles from solutions or suspensions in open-ended carbon nanotubes and glass microchannels. The work also demonstrates a novel method of capping water-filled carbon nanotubes using polymer seals of relatively small polymer molecules. The self-sustained diffusion mechanism driving admixtures from solutions into carbon nanotubes, as reported in A. V. Bazilevsky, K. Sun, A. L. Yarin and C. M. Megaridis, Langmuir, 2007, 23, 7451-7455, is shown to be effective for encapsulating a number of compounds in confinements spanning sizes from 50 nm-diameter carbon nanotubes to 300 mm-diameter glass capillaries. For example, surfactants and nanoparticles are encapsulated using this self-sustained diffusion mechanism. Very high filling efficiencies can be achieved with this method. The procedure opens new opportunities for water containment in nanotubes and microchannels. Nanoparticles filling microchannels form colloidal crystals, which, upon illumination, demonstrate opalescence characteristics of long columnar photonic crystals.

Recently, more and more researchers have focused on electrical textiles that can provide or convert energy to facilitate people’s lives. Knitting conductive yarns into ordinary fabrics is a common way for electrical textiles to transmit heat or electrical signals to humans. This paper is aimed at studying the resistance values and temperatures of electrothermal knitted conductive fabric (EKCF) subjected to certain voltages over time. Six types of EKCFs with structural differences were fabricated using a computerized flat knitting machine with intarsia technology. Uniform samples 10 × 10 cm in size were made from wool, as were two different specifications of silver-coated conductive yarns. The wool yarn and one silver-coated yarn were mixed to knit a resistance area 2 × 2 cm in size in the center of the EKCF to observe heating behaviors. The experiment results showed that when the EKCFs were subjected to certain voltages over time, the resistance values of the resistance area increased over a short time and then gradually decreased, and the temperature gradually increased in the first 1000 s and tended toward stability after a certain period of time. The structural coefficient κ between different knitted structures (which predicted the thermal properties of different EKCFs subjected to different voltages) was analyzed. These results are of great significance for predicting the electrothermal performance of EKCFs with different knitted structures. On the basis of these results, an optimized knitted structure was selected as the best EKCF for wearable textiles, and the findings contribute to the field of technological and intelligent electrothermal garments and related products.

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