Stiff Gel Adhesives for Underwater Use


Project ID: D2014-08


Underwater adhesion has several potential medical, household and industrial applications. Generally, underwater adhesives have been prepared using methods that rely on in situ polymerization, covalent crosslinking, or the use of highly specialized biological or biomimetic polymers. Despite current strategies, many challenges have limited the yield and application of biomimetic adhesives including cost, inefficient recombinant protein production, complicated syntheses, the use of potentially harmful oxidants and the need for highly specialized polymer structures. Older strategies have also suffered from deficiencies such as reliance on chemical reactions to set the adhesive, formation of permanent underwater bonds (in cases where a bond might need to be reversed) or the requirement for in situ polymerization. There is, thus, a need for more improved underwater adhesives.


Sustained release technologies, on the other hand, have diverse applications that range from pharmaceutics and medicine, to home and personal care products, foods and agriculture. These technologies rely on encapsulation of actives in various types of materials, among which hydrogels are a popular choice. When the active molecules are small, however, gel-like materials tend to not provide strong barriers to diffusion. Consequently, multiple-week and -month release of small molecules from hydrogels remains technologically challenging.


Invention Description

Researchers at the University of Toledo, led by Dr. Yakov Lapitsky, have developed a new class of self-assembled adhesive gels that may be prepared from inexpensive and readily available ingredients that may be used for underwater adhesion and long-term controlled release. 



•       Emergency household, industrial and outdoor leak repair

•       Biomedical and cosmetic technologies

•       Bio-adhesive drug delivery systems

Sustained release vehicles for home and institutional disinfection products


•       The gels form via self-assembly and, thus, require no chemical crosslinking, which minimizes any risk of harmful side effects or reactions

•       The gels are very stiff, which helps immobilize the bonded surfaces

•       The gel adhesives demonstrate excellent adherence to hydrophilic and hydrophobic substrates

•       The gels can be re-dissolved on demand by changing ambient solution conditions

•       The polymer, poly(allylamine) (PAH) is FDA approved

•       The ionic crosslinkers, pyrophosphate (PPi) and tripolyphosphate (TPP), are both on FDA’s generally recognized as safe (GRAS) list

•       Material preparation requires common, commercially available polymers and salts that are already approved for use in food and drug delivery technologies

•       This platform can combine wet adhesion and long-term sustained release functionality 

Patent Issued (US 9814778)

Publications:       1.        Huang Y et al., Self-assembly of stiff, adhesive and self-healing gels from polyelectrolytes. Langmuir, 2014, 7771-7777

2.        Lawrence, P.G.; Lapitsky, Y. Ionically crosslinked poly(allylamine) as a stimulus-responsive underwater adhesive: Ionic strength and pH effects. Langmuir, 2015, 1564-1574.

3.        Lawrence et al., Ionically crosslinked polymer networks for the multiple-month release of small molecules. ACS Appl. Mater. Interfaces, 2016, 4323-4335.

4.        de Silva et al., Poly(allylamine)/tripolyphosphate coacervates enable high loading and multiple-month release of weakly amphiphilic anionic drugs: An in vitro study with ibuprofen. RSC Advances, 2018, 19409-19419.


Patent Information:
For Information, Contact:
Katherine Pollard
Licensing Associate
The University of Toledo
Yakov Lapitsky
Yan Huang
Controlled Release