5 research outputs found
Single-Phase Photo-Cross-Linkable Bioinspired Adhesive for Precise Control of Adhesion Strength
A bioinspired,
modular terpolymer adhesive, poly(<i>N</i>-methacryloyl-3,4-dihydroxyl-l-phenylalanine<i>-<i>co</i>-</i>9-(acryloyloxy)butyl
anthracene-9-carboxylate<i>-<i>co</i>-</i>acrylic
acid), has been synthesized
containing three different functionalities: a photo-cross-linking
segment, a wet interfacial adhesion segment, and a water-soluble segment.
The synthesized adhesive polymer is the first example of a single-phase,
photo-cross-linkable adhesive which does not require additional photoinitiator
or other cross-linking agents. The terpolymer demonstrates strong
adhesion when it swells in water and/or ethanol. The terpolymer is
composed of three repeating units: <i>N</i>-methacryloyl-3,4-dihydroxyl-l-phenylalanine (MDOPA), which has been known to generate strong
adhesion under wet conditions, poly(acrylic acid), which has been
known to increase water solubility of polymers, and a photo-cross-linking
segment consisting of an anthracene-based monomer used for enhancement
of cohesion properties via UV irradiation (352 nm). A photomediated
[4 + 4] cycloaddition reaction of anthracene results in the cross-linking
of individual polymer chains after interfacial adhesion between substrates
and adhesive polymers. Chemically, the covalent photo-cross-linking
was confirmed by UV–vis, <sup>1</sup>H NMR, and gel permeation
chromatography (GPC). The cross-linking-fortified cohesion of the
adhesive polymer network yields strengthened cohesion properties of
the bulk material. The photoreaction was conveniently controlled via
the duration of UV-irradiation. The adhesion properties of new adhesives
were characterized by lap shear strength on transparent Mylar film
and glasses after the adhesive was swollen in biologically friendly
solvents including water and ethanol. The adhesion strength (J/m<sup>2</sup>) was enhanced by 850% under 352 nm UV-irradiation. Multiple
application variables were tested to determine the optimal conditions,
such as solvent, concentration, polymer composition, and substrate.
The best adhesion properties were obtained from a 1:1 weight ratio
of polymer:solvent in water on a Mylar film surface. As a single-phase
system, the synthesized terpolymer is very convenient to use, and
its adhesion strength can be easily modified by UV light. Additionally,
the terpolymer’s high water compatibility makes it ideally
suited for application in the biomedical field