\”Plaything not despondent.\” – The black Plasticine \”play out\” new uses photothermal conversion

Plasticine-based materials due to the nature of its tunable mechanical properties, unique and reproducible viscoelastic behavior shaping, has potential applications in the emerging field of bio-robot, and energy conversion and storage devices like smart sensor. In the process of the function-based rubber clay materials tend to add additional nanofillers, such as metal nanowires, carbon nano material, or a conductive polymer. But these nano-fillers will add extra heterogeneous aggregation and phase separation occurs in materials like rubber cement, to the detriment of macroeconomic stability and mechanical properties of the material. To solve this problem, team Institute of Marine Advanced Materials, Harbin Engineering University by the hydrogel structural design, combined with in-situ oxidative polymerization and were prepared by dynamic coordination bond and a hydrogen bond black rubber based mud gelling material having a good self-healing properties, electrical conductivity and the photothermal conversion characteristics (PPFe gel). The preparation of such hydrogel material is simple, uniform structure, and having a rubber cement can be freely shaped like characteristics, for the self-healing material, deformable material may be prepared and the light-heat conversion material provides a new strategy.

Type 1 configuration diagram rubber mud gelling material (PPFe gel) is a schematic view

In our previous study, the phytic acid (PA) may be polyvinyl alcohol (PVA) formation of hydrogen bonds, so as to adjust a polyvinyl alcohol hydrogel forming conditions ( ACS Appl. Mater. Interfaces , 2019, 11, 32441-32448). In order to develop coordinated action of phytic acid, we use urea as a catalyst, the phytic acid by esterification of polyvinyl alcohol was grafted phytates (PPVA) on the PVA chains, while the use of oxidation of iron ions in the system polypyrrole is formed. PPVA iron ions can form a coordinate bond, a hydrogen bond can be formed with the polypyrrole. Unique viscoelastic properties IPN hydrogel having similar plasticine This use of phytic acid complexation enhancing effect and polypyrrole formed.

2 PPFe FIG injectable hydrogel and self-healing properties

As can be seen from the rheological data, with the shear strain and the shear rate increase, PPFe hydrogel occurred sol – gel transition (shear thinning behavior), a large / small strain earthquakesSwing shear test, PPFe hydrogel gel / sol state can quickly switch. This is due to the driving force of the hydrogel-forming PPFe – hydrogen bonds and coordination bonds with reversible dynamic properties, the gel state can be maintained stable by external energy dissipated dynamic reorganization of chemical bonds, the characteristics of the hydrogel is PPFe injectable class plasticine state, shaping and can be a source of self-repair.

FIG. 3 is patterned photothermal chip

polypyrrole (of PPy) as a common black organic conjugated polymer, in the visible – light region has a strong infrared absorption performance, polypyrrole gel formed in situ polymerization inside imparts hydrogel PPFe preferred photothermal conversion characteristics. Hydrogels binding PPFe plasticine injectable state, it can be packaged in a patterned PDMS mold and a chip into light heat. PDMS has good transparency and low thermal conductivity, so almost all of the near infrared light irradiated on the PDMS will pass through the hydrogel, while the low thermal conductivity of PDMS weakens heat exchange with the outside of the hydrogel, the maximum ensuring the timeliness and accuracy of the hydrogel solar thermal test chip extent.

FIG. 4 and the light-heat treatment temperature sensing

light and heat treatment is one of the more popular physical therapy, can effectively relieve fatigue, especially muscle aches and joints damage has a special effect. Design and manufacture a portable flexible solar thermal chip is one of the challenges currently facing. This gel-based flexible photothermal chip satisfy this demand, it can be produced in large quantities, and the pattern shape can be designed. When the hydrogel patch PPFe photothermal chip on a back of the hand, under a sunlight intensity, the surface temperature in the vicinity of the chip may additionally increased within 30 s of about 14 ℃. This rapid local mild non-contact heating method will have potential applications in optical heat treatment, drug release and other fields. While raising the temperature to speed up the rate of migration of ions inside the gel, to reflect change in resistance, so the chip can also be used for real-time monitoring the surface temperature of the object under test. The innovation of this study is to expand the application range of the esterification reaction by complexation of phytic acid by in situ polymerization of pyrrole adjusted manner viscoelastic properties of the hydrogel, the hydrogel further combined injectable and light the heat transfer characteristics of the applied chips and the patterned heat-sensing light. The research results\”Readily producing a Silly Putty-like hydrogel with good self-healing, conductive and photothermal conversion properties based on dynamic coordinate bonds and hydrogen bonds\” was published in the Journal of Materials Chemistry C Journal (DOI: 10.1039 / d0tc00814a), Master of Harbin Engineering University students Zhang Shuai is the first author of the paper. Original link: https: //pubs.rsc.org/en/content/articlelanding/2020/TC/D0TC00814A# divAbstract!