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[摘要]：The aim of the present work has been to gain a fundamental understanding of the mechanisms governing encapsulation in the multiphase systems as a blend or multilayer structures. The model systems chosen for this study are based on (i) Newtonian poly(dimethylsiloxane) polymers of varying molar masses and (ii) high molecular weight, viscoelastic, and compatible pair polymers of PVDF and PMMA The same approach was applied to functionalized polymers to investigate the effect of physicochemical affinity on two pairs of asymmetrical reactive polymers based on PE-GMA (glycidyl methacrylate)/PVDF-g-MA (maleic anhydride) and a PE/PVDF as a reference. The linear viscoelastic and surface properties of the neat and bilayer model systems structures have been investigated. The optical obeservations of the encapsulation kinetic of two drops were recorded using a homemade device. Specific experiments were carried out to follow up the kinetic of encapsulation, and the results were rationalized as a function of the effect of the viscosity, elasticity ratios, drop geometry, the interfacial tension, and the physicochemical affinity: Throughout all the experiment, the mechanisms were purposed for each system and discussed based on the theories of molecular forces or Brownian motion governing diffusion and Ostwald ripening, in contrast to the theories of coalescence. The viscosity ratio coupled to the drop geometry of the material was found to be a key parameter and that it has to be linked to the interfacial tension and spreading parameters. Furthermore, the encapsulation appeared to be hindered by the interdiffusion process in the case of compatible pair system despite their elasticity and surface tension contrast Finally, the encapsulation kinetic could be reduced or eliminated by the creation of a copolymer at the interface for a reactive system. The results obtained by the optical investigation of two drops corroborated the rheological data of the bilayer systems. Hence, the obtained results rendered it possible to decouple the influence of the viscoelastic parameters to flow, interfacial tension, thereby highlighting a number of macroscopic effects that were governed by the interdiffusion or reaction of macromolecular chains at the interface to give a better understanding of encapsulation phenomenon in multiphase systems. |
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