On the basis of the relationship between macromolecular aggregate and resonance Rayleigh scattering (RRS) intensity, RRS spectra were utilized to monitor macromolecular aggregating process in poly(acrylic acid) (PAA). No probe and labeling were incorporated; RRS can reveal the macromolecule extension or contraction under external stimuli such as the changes in pH and ionic strength, as well as the addition of surfactant. Results indicated that the addition of base, acid and NaCl altered macromolecular phase behavior of PAA in aqueous solution due to electrostatic effect. Besides, sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB) interacted with PAA in solution to form polymer-surfactants complexes, inducing macromolecular chain aggregate. On the basis of the analysis of the results, two models were proposed in this work to explain the observed phenomena. RRS is a sensitive method to characterize the macromolecular aggregate.
Large-area metamaterial nanostructures of a Janus gold nanoparticle (AuNP) film decorated with thiolterminated polymers have been fabricated and tuned at an oil/ water interface by a facile and innovative process. The results show that AuNPs had been arrayed with ultrasmall gaps between neighboring particles laminated with polymer which is called a Janus film. This film exhibits a sensitive property for surface-enhanced Raman scattering (SERS) for determination of both hydrophilic methylene blue and hydrophobic thiram. The structure-dependent SERS of the Janus AuNP film has also been confirmed by a finite-difference time domain (FDTD) method.
In this work, kinetics of phase separation in the blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was investigated by a simple and sensitive method, i.e., resonance light scattering (RLS) spectroscopy. Owing to the aggregation of chromophores (phenyl rings) in the systems when phase separation occurred, RLS intensities were drastically enhanced and hence acted as a characteristic indicator. At the early stage of phase separation, two different RLS behaviors corresponding to spinodal decomposition (SD) and nucleation and growth (NG) were observed. The Cahn-Hilliard (C-H) linearization theory was found not applicable for kinetics analysis of the scattering data at lambda < 346 nm due to RLS effect near the absorption band. Based on a decomposition reaction model, the apparent activation energy of SD phase separation was estimated by the Arrhenius equation. In view of its simplicity and sensitivity of measurement, affordability and availability of instrument, and wide application range of polymer blends, RLS proved to be an effective means for characterization of microstructural variation in polymer blends.
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