Thiourea as a "Polar Hydrophobic" Hydrogen-Bonding Motif: Application to Highly Durable All-Underwater Adhesion.
J Am Chem Soc
; 146(30): 21168-21175, 2024 Jul 31.
Article
in En
| MEDLINE
| ID: mdl-39031475
ABSTRACT
Here, we report that, in contrast to urea, thiourea functions as a "polar hydrophobic" hydrogen-bonding motif. Although thiourea is more acidic than urea, thiourea exchanges its N-H protons with water at a rate that is 160 times slower than that for urea at 70 °C. This suggests that thiourea is much less hydrated than urea in an aqueous environment. What led us to this interesting principle was the serendipitous finding that self-healable poly(ether thiourea) adhered strongly to wet glass surfaces. This discovery enabled us to develop an exceptionally durable all-underwater adhesive that can maintain large adhesive strength for over a year even in seawater, simply by mechanically mixing three water-insoluble liquid components on target surfaces. Because thiourea is hydrophobic, its hydrogen-bonding networks within the adhesive structure and at the adhesive-target interface are presumed to be dehydrated. For comparison, a reference adhesive using urea as a representative "polar hydrophilic" hydrogen-bonding motif was durable for less than 4 days in water. Highly durable all-underwater adhesives are needed in various fields of marine engineering and biomedical sciences, but their development has been a major challenge because a hydration layer that spontaneously forms in water always inhibits adhesion.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Am Chem Soc
Year:
2024
Document type:
Article
Affiliation country:
Japan