Dual Polarization Interferometric Analysis on the Interaction between Fullerene Grafted Polymer and Nonionic Surfactants

作者：Wang Qiqiang; Tam Kam C^*

来源：Langmuir, 2009, 25(17): 9898-9902.

DOI：10.1021/la901052b

The interaction between polyelectrolyte grafted fullerenes and surfactants was elucidated using a dual polarization interferometer (DPI). The deposition of poly(2-(dimethylamino)ethyl methacrylate) (PDMA(50)-b-C(60)) at pH 6 on the surface of silicon oxynitride induced by electrostatic interaction between charged PDMA segments and negatively charged surface revealed an adsorption thickness similar to the diameter of a fullerene molecule. A second deposition of poly(acrylic acid)-block-C(60) (PAA(83)-b-C(60)) on adsorbed PDMA(50)-b-C(60) at pH 6 was facilitated by electrostatic interaction between negatively and positively charged PAA and PDMA segments, respectively. A monolayer of PAA(83)-b-C(60) adsorbed on PDMA(50)-b-C(60) layer yielded a thickness twice the diameter of C(60) molecules. As a comparison, a two end-capped C(60)-PAA(83)-C(60) was examined, where the packing thickness and mass were smaller than the monocapped system due to steric hindrance effect of fullerene molecules. The adsorption of two nonionic surfactants (i.e., polyoxyethylene 9 lauryl ether (Brij 76) and octyl phenol ethoxylate (Triton X-100 or TX 100)) on the adsorbed PDMA-C(60) layer was examined. Both Brij 76 and TX 100 interacted with the PDMA-C(60) layer. For TX 100, the interaction was promoted by pi-pi interaction between the C(60) headgroup and phenyl ring of the surfactant. Beyond the critical micellar concentration of TX 100, the adsorption was greatly reduced. The concentration effect of first layer PDMA-C(60) was evaluated, where the PDMA-C(60) molecules adsorbed on the chip at higher density, resulting in a larger layer thickness. The densely packed fullerene headgroup hindered the penetration of TX 100 aromatic ring into the first layer.

• 出版日期2009-9-1
• 单位南阳理工学院