2021 Volume 42 Issue 4 Pages 151-157
Dopamine-modified carboxymethyl cellulose (DOPA-CMC)s with various degrees of DOPA substitution (DS)(7~9%) were synthesized, and their solution behaviors and adhesion properties toward pig skin were investigated under various conditions. DOPA-CMC (DS9%) in phosphate buffer solutions (PBS, pH6.0, pH7.0, pH8.0) was a colorless liquid, while its solution in tris(hydroxymethyl)animomethane buffer solution (Tris buffer solution, pH8.0) changed to a brown gel.The polymer solution was cast on a pig skin strip to obtain the polymer film. The test piece was prepared by crimping the polymer film to another pig skin strip and by drying for 24 h. Then the tensile shear strength of the sample was measured; this value was evaluated as dry adhesion strength. An analogously prepared sample was further immersed in water for 1 h and the tensile shear strength was measured; this value was evaluated as wet adhesion strength. The dry adhesion strengths of the test piece prepared from the PBS (pH6.0-8.0) solutions were high and almost constant at 0.71 MPa－0.53 MPa, while the wet adhesion strengths remained low at 0.04 MPa－0.07 MPa. The dry adhesion strength of the test piece prepared from the Tris(pH8.0) buffer solution was 0.63 MPa, but its wet adhesion strength rose to 0.16MPa, which was significantly higher than those of the PBS solutions. This high wet adhesion strength of the Tris buffer solution was supposed to be caused by the crosslink of the DOPA-CMC due to the oxidative coupling of the DOPA groups. We also found that composite materials prepared by mixing DOPA-CMC (DS7%) and DOPA in the Tris buffer solution showed higher wet adhesion strength than that without DOPA.
