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Poly(ester amide)s (PEAs) composedof variable diols, dicarboxylicacids, and α-amino acids were synthesized and characterizedto elucidate structure–property relationships. The PEAs weresynthesized using both solution and interfacial approaches to obtainvarying molecular weights (MWs) and polydispersities. Studies usingdifferential scanning calorimetry and powder X-ray diffraction revealeda range of amorphous and semicrystalline behavior that was dependenton structure. The viscosities of the PEAs as a function of temperaturewere studied by rheology, and phase transitions were confirmed forsome polymers. Mechanical properties were also investigated, and itwas found that the PEAs could be tuned to exhibit elastomeric or brittlebehavior by varying both the length of the diol and the amino acidmoiety. This information provides new insights into the effects ofPEA structure, MW, and MW distribution on PEA properties and willaid in the design and selection of PEAs with optimal properties fortargeted applications. [ABSTRACT FROM AUTHOR]

Coalescence of a falling droplet with a stationary sessile droplet is studied experimentally. High-speed video images are presented to show coalescence dynamics, shape evolution and contact line movement. Emphasis is put on spread length, which is the length of two coalesced droplets along their original centers. Experimental results have shown that the spread length can be larger or smaller than the ideal spread length, which is the spread diameter of individual droplet plus the center-to-center distance between the two droplets. Three different coalescence mechanisms based on comparing the maximum and the minimum spread lengths to the ideal spread length are identified. Correlations for the maximum and the minimum spread lengths are developed, which can be combined with the coalescence domains to determine the deposition conditions for forming continuous or discontinuous lines. [ABSTRACT FROM AUTHOR]