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The coating industry has been interested in incorporating water-soluble polymers into latex formulations to promote coalescence and enhance the mechanical properties of the coating without using any volatile organic compounds (VOCs). In this study, we investigate the effects of blending an acid-rich oligomer (ARO1), which contains sufficient −COOH groups to dissolve in water upon full neutralization with ammonia, into latex dispersions. We carried out fluorescence resonance energy transfer (FRET) measurements to examine the polymer diffusion and molecular mixing of ARO1–latex dispersions and the resulting films. The results show that ARO1 and latex polymers are partially miscible but not completely mixed in the film, suggesting that differences in the physicochemical properties of the two components influence their compatibility and interdiffusion behavior. ARO1 acts as a retardant to coalescence in the films, reducing polymer diffusion rates and thereby affecting film formation. Atomic force microscopy (AFM) mechanical mapping and confocal microscopy further elucidate the complex interplay between blend composition and film structure, demonstrating that ARO1 enhances the mechanical properties at the film surface and promotes macroscopic phase separation at higher concentrations. Our findings show that ARO1 significantly impacts the structural arrangement within these films, forming interstitial membranes between latex nanoparticle cells or phase-separated domains. These insights improve our understanding of the role of ARO1 in modulating latex membrane microstructure and properties, paving the way for the rational design of colloidal films for diverse applications.

The mechanical properties of individual multiwall boron nitride nanotubes (MWBNNTs) synthesized by a growth-vapor-trapping chemical vapor deposition method are investigated by a three-point bending technique viaatomic force microscopy. Multiple locations on suspended tubes are probed in order to determine the boundary conditions of the supported tube ends. The bending moduli (EB) calculated for 20 tubes with diameters ranging from 18 to 58 nm confirm the exceptional mechanical properties of MWBNNTs, with an average EBof 760 ± 30 GPa. For the first time, the bending moduli of MWBNNTs are observed to increase with decreasing diameter, ranging from 100 ± 20 GPa to as high as 1800 ± 300 GPa. This diameter dependence is evaluated by Timoshenko beam theory. The Young’s modulus and shear modulus were determined to be 1800 ± 300 and 7 ± 1 GPa, respectively, for a trimmed data set of 16 tubes. The low shear modulus of MWBNNTs is the reason for the detected diameter-dependent bending modulus and is likely due to the presence of interwall shearing between the crystalline and faceted helical nanotube structures of MWBNNTs.

We propose a practical method to obtain near-field infrared absorption spectra in apertureless near-field scanning optical microscopy (aNSOM) through homodyne detection with a specific choice of reference phase. The underlying mechanism of the method is illustrated by theoretical and numeric models to show its ability to obtain absorptive rather than dispersive profiles in near-field infrared vibrational microscopy. The proposed near-field nanospectroscopic method is applied to obtain infrared spectra from regions of individual multiwall boron nitride nanotubes (BNNTs) in spatial regions smaller than the diffraction limit of the light source. The spectra suggest variations in interwall spacing within the individual tubes probed.