Ultrafast and Programmable Shape Memory Hydrogel of Gelatin Soaked in Tannic Acid Solution

Abstract

Shape memory hydrogels have been paid plenty of attention as a kind of intelligent soft material. However, complicated preparation and slow and uncontrollable shape change have hindered their applications in smart actuators. In this work, a temperature-responsive strong hydrogel was prepared by a facial soaking method without any chemical reactions, i.e., soaking gelatin hydrogel in aqueous tannic acid solution. The hydrogel was constructed by hydrogen bonding between gelatin and tannic acid beside the triple helix of gelatin chains without any chemical crosslinkers. The hydrogel showed ultrafast shape memory and bodytemperature response. The hydrogel can be fixed in temporary shape in only 1 s at 25 °C and recover to the original shape in also 1 s at 37 °C, superior to the reported shape memory hydrogels. Furthermore, the hydrogel shape change can be programmed by fixing the temperature, and the designed shape is achieved stepwise by adjusting the recovery temperature. In addition, the hydrogel is stable in water without further swelling. These excellent features will initiate new prosperity of the shape memory hydrogel in biomedical technology, underwater actuators, and soft robots.

Natural Biocidal Compounds of Plant Origin as Biodegradable Materials Modifiers

“…Gelatin/tannic acid films exhibit antibacterial properties which are desired in biomedical materials [ 264 ]. Gelatin/tannic acid hydrogels with shape memory are interesting materials for potential biomedical and robotic applications [ 265 ]. Biocomposite nanofibers with tannic acid could be used as a biocompatible wound dressing material with an antibacterial effect [ 266 ].…”

The solvent effect modulates the formation of homogeneous polyphenol composite hydrogels with improved transparency and mechanical strength for antibacterial delayed sternal closure films

“…The post-immersion (PI) method, in which the as-prepared materials are immersed into TA solution followed by an adequate wash, is a facile method to introduce polyphenols into hydrogels. 31–33 We previously used this method to prepare a TA strengthened PEG–lysozyme (LZM) hydrogel which utilized the hydrogen bonding between TA and PEG and the hydrophobic interactions between TA and lysozymes. The resultant PEG–LZM–polyphenol hydrogel presents super toughness and high elasticity in comparison to pristine PEG–LZM, and it can even withstand the super pressure from suture.…”

Ultra‐Stretchable, Variable Modulus, Shape Memory Multi‐Purpose Low Hysteresis Hydrogel Derived from Solvent‐Induced Dynamic Micelle Sea‐Island Structure

“…[18] These types of hydrogels have more potential applications in chemical converters, memory element switches, sensors, controlled release of drugs, artificial muscles, chemical storage, molecular separation systems, and entrapment of active enzymes. [19][20][21] If hydrogels have excellent mechanical properties, variable modulus, and "smart" performance simultaneously, the hydrogels will inevitably be very popular and have a promising application. Although researchers have made exciting achievements in the preparation of hydrogels with good mechanical properties or intelligence through unremitting efforts, most hydrogels are difficult to integrate versatile performance together and are hard to meet the complex multipurpose applications well, which is a dilemma in need of being solved urgently.…”

“…[ 18 ] These types of hydrogels have more potential applications in chemical converters, memory element switches, sensors, controlled release of drugs, artificial muscles, chemical storage, molecular separation systems, and entrapment of active enzymes. [ 19–21 ]…”