Tough polyvinyl alcohol-gelatin biological macromolecules ionic hydrogel temperature, humidity, stress and strain, sensors.

High strength, high toughness and high sensitivity were some of the most popular characteristics of flexible sensors. However, the mechanical properties and reproducibility of current single biomacromolecule gelatin hydrogel sensors are lower, and few hydrogel sensors have been able to provide excellent mechanical properties and flexibility at the same time so far. To address this challenge, a simple method to prepare tough polyvinyl alcohol (PVA) and gelatin hydrogel was proposed in this study. The PVA-gelatin-Fe3+ biological macromolecules hydrogel was prepared by a freeze-casting-assisted solution substitution method, which exhibited high strength (2.5 MPa), toughness (7.22 MJ m-3), and excellent temperature, humidity, stress, strain, and human motion sensing properties. This combination of mechanical properties and flexibility makes PVA-gelatin biological macromolecules hydrogel a promising material for flexible sensing. In addition, an ionic immersion strategy could also impart multiple functions to the hydrogel and be applied to various hydrogel sensor materials. Thus, this work provided an all-around solution for the preparation of advanced and robust sensors with good application prospects.

Highly Stretchable, Self-Healing, and Low Temperature Resistant Double Network Hydrogel Ionic Conductor as Flexible Sensor and Quasi-Solid Electrolyte.

With the rapid development of flexible energy storage and wearable strain sensing, conductive hydrogels are attracting attention as electrolyte materials for flexible strain sensors and flexible supercapacitors due to their excellent flexibility and wetting properties. In this work, antifreezing hydrogels with high stretchability, adhesion, and conductivity are designed and prepared by introducing phosphoric acid solutions into polyacrylamide and chitosan systems. The multifunctional hydrogel samples prepared by this method can be used as both quasi-solid electrolytes and wearable strain sensors. The hydrogel-based supercapacitor shows a charge/discharge efficiency of 99.67% and a capacitance retention of 98.85% after 10 000 cycles charge/discharge tests at -30 °C. The tiny characteristic heartbeat wave forms are detected by the hydrogel as a flexible strain sensor. It is foreseeable that PCP multifunctional hydrogel can be a promising flexible material for a new generation of flexible sensors and flexible energy storage devices in a certain range of temperatures.

Sorting and decoration of semiconducting single-walled carbon nanotubes via the quaternization reaction.

A study for the selective separation and functionalization of alcohol-soluble semiconducting single-walled carbon nanotubes (sc-SWCNTs) is carried out by polymer main-chain engineering. Introducing tertiary amine groups endows the functionalized sc-SWCNTs with alcohol-soluble properties and introducing the pyrimidine rings allows to increase the selective purity of sc-SWCNTs. In this study, a series of poly[(9,9-dioctylfluorene)-2,7-(9,9-bis(3'-(N,N-dimethylamino)propyl)-fluorene)] m -alt-[2-methylpyrimidine-2,7-(9,9-dioctylfluorene)] n (PFPy) are used for the selective dispersion of semiconducting single-walled carbon nanotubes, where n and m are the composition ratio of the copolymer. When m = n, the effective isolation of sc-SWCNTs with purity greater than 99% is achieved. The alcohol-soluble sc-SWCNTs with a diameter in the range of 1.1-1.4 nm are obtained through designing reasonable molecular structure. Moreover, the particular preference of PFPy (m = n) for sc-SWCNTs was studied via density functional theory (DFT) calculations and it was proved to be a promising method for the separation and functionalization of sc-SWCNTs.

Enrichment of highly pure large-diameter semiconducting SWCNTs by polyfluorene-containing pyrimidine ring.

The use of copolymers to extract and purify semiconducting SWCNTs (sc-SWCNTs) and metallic SWCNTs (m-SWCNTs) is widely employed. In this paper, the performances of two pyrimidine-alt-dioctylfluorene conjugated polymers in the enrichment of semiconducting SWCNTs are compared, and the subtle structural effects on them are discussed. It was found that both pyrimidine-polymers were more effective in wrapping the semiconducting SWCNTs than the metallic SWCNTs under the co-action of the pyrimidine and fluorene rings. Moreover, methyl groups on the pyrimidine ring of the polymer slightly contributed to the semiconducting purity, and the minor differences of sc-SWCNTs extraction between two pyrimidine-polymers are compared. Additionally, the average diameter of the selected SWCNTs is larger than that of the raw SWCNTs. The experimental results show the excellent selectivity for sc-SWCNT from both co-polymers: the index Φ i values for determining the purity of sc-SWCNTs were increased from 0.408 for P2 to 0.465 for P1, of which the selected sc-SWCNT purity is up to 99.9%. The resulting purity and the inexpensive availability of pyrimidine co-polymers make them suitable to be considered for effective sc-SWCNT enrichment.