Dear Readers,

A warm welcome to the 8 new readers who’ve joined us at the American Chemical Society (ACS) Fall Meeting 2023.

It was great meeting everyone and discussing not only hydrogel research, but also polymers and polymer engineering.

For our new readers, I’d like to take this opportunity to quickly introduce the structure of this newsletter.

1. a brief message from author

2. news articles related to hydrogel (if any)

3. research updates (summary of 2-3 papers)

4. image of the week (cool science image)

Feel free to send me your feedback regarding any sections of this newsletter. And with that, hope that you enjoy this week’s newsletter.

In The News

Research Updates

Cellulose-based bi-layer hydrogel evaporator with a low evaporation enthalpy for efficient solar desalination (Link)

• The article describes a bi-layer hydrogel evaporator made of cellulose and polyaniline (PANi) that can efficiently convert solar energy into steam for water purification.

• It was prepared by cross-linking cellulose with epichlorohydrin and coating PANi on the surface. Water interacts favorably with the coated surface helping it to evaporate with less energy. This can be condensed and collected as desalinated water.

• Note that epichlorohydrin is toxic and can cause irritation to the eyes, respiratory tract, and skin of workers. Be careful when replicating this synthesis protocol.

• The hydrogel can achieve a high evaporation rate of 3.07 kg m^-2 h^-1 and a photothermal conversion efficiency of 94.42% under 1 sun irradiation. It can also remove heavy metal ions and organic dyes from wastewater and has good stability and salt resistance.

• This technology can be used in areas with limited access to clean water and can help reduce the dependence on fossil fuels for water purification.

Recent progress in the development of conductive hydrogels and the application in 3D printed wearable sensors (Link)

• This review article discusses the ways to classify conductive hydrogels and categorizes various applications of these hydrogels. They are namely: electron versus ionic conduction; and applications rely on piezoresistive, capacitive, triboelectric and piezoelectric.

• Most conductivity relies on adding fillers. A critical limitation is poor interface properties between filler and hydrogel matrix, resulting in competition between electrical versus mechanical properties.

• The authors also raise concerns about optical and rheological restrictions to 3D printing, poor signal to noise ratio, poor conformation onto human skin, among other areas for improvement.

• A comprehensive read for those working on wearable electronics and hydrogels.

Dual network zwitterionic hydrogels with excellent mechanical properties, anti-swelling, and shape memory behaviors (Link)

• A conductive, physical, and chemical crosslinked SPT hydrogel with shape memory and anti-swelling was successfully fabricated through [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), Tannic Acid (TA), and Polyvinyl alcohol (PVA).

• The resultant hydrogels exhibit simultaneously high tensile strength (18.5 MPa), toughness (14.7 ± 2.9 MJ/m³ ), tearing resistance (35 N/mm), flexibility and excellent environment adaptability without compromising transparency

• Interestingly, selecting this zwitterionic monomer enabled anti-swelling. Upon pH decrease, the polymer becomes net positively charged, regulating the osmotic pressure through electrostatic interaction, thus achieving the effect of anti-swelling.

• This hydrogel has good ionic conductivity and thus has potential applications in strain sensors, touch screens, and flexible actuators.

Image Of The Day

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