ABSTRACT
Adhesion to chemically inert materials without surface modification through noncovalent interactions represents a challenging task in adhesion science. We successfully develop for the first time a strategy utilizing multiple CH/π interactions that use poly(methacrylate) with an aromatic group (H acceptor) in the ester part and polyolefin materials (H donor). The strength increases with the number of π electrons and aromatic rings. The trityl methacrylate polymer emerges as the most effective H-acceptor polymer for obtaining strong adhesion to various polyolefin materials. This work will provide not only a promising adhesion strategy that does not require surface activation for polyolefin materials, but also a novel approach using weak noncovalent interactions.
ABSTRACT
The monomer-aggregate equilibrium of four phenothiazine (PN) dyes, containing thionine (TH), methylene blue (MB), new methylene blue (NMB), and 1,9-dimethylmethylene blue (DMB), in the tungsten(VI) oxide (WO(3)) nanocolloid solution has been investigated by means of UV-vis spectroscopy. Addition of PN dye into the WO(3) nanocolloid solution brought about significant changes in the absorption spectrum, suggesting the formation of H-type (face-to-face fashion) trimer on the WO(3) nanocolloid surface. The adsorptivity of PN dyes onto the WO(3) nanocolloid surface was diminished by the raising the ionic strength, indicating the evidence of the electrostatic interaction between cationic PN dye and negatively charged WO(3) nanocolloids. The detail analysis of each spectral data provided insight into the effect of molecular structure of PN dyes on the adsorption and aggregation behaviors on the WO(3) nanocolloid surface. Moreover, in situ measurement of PN dye aggregation using the centrifugal liquid membrane (CLM) technique revealed that the aggregation of PN dyes on the WO(3) nanocolloid surface proceeded in a two-step three-stage (monomer --> dimer --> trimer) formation. The aggregation mechanism of PN dyes on the WO(3) nanocolloid surface was discussed on the basis of Kasha's exciton theory.
