Fabrication Of Single And Double Layered Polyamide Microcapsules

The size-controllable,multi-layered and multi-chambered multiple microcapsules,can be prepared by means of the micro-fluid technology,and the hydrophobic and hydrophilic drugs are respectively wrapped in oil droplets and water droplets of multiple emulsions to control the drug release through different methods,which have drawn much attention recently.Common methods to produce multi-layer microcapsules are generally based on microfluidic techniques which quite cost and require a precise control.As for polyamide,up to now,only simple microcapsules with one membrane layer have been generated.In this paper,we take Terephthaloyl Dichloride and Hexamethylene Diamine as reactant monomers to prepared mono-disperse microcapsules with one membrane layer through microfluidic techniques;then,by taking full advantages of the rippled morphology and permeability of the polyamide microcapsules,we generate the second membrane layer inside the simple microcapsules just by immersing them in the aqueous solution of some relevant reactant.First of all,the single-layered microcapsules are prepared.The effect of the flow rate,the monomer concentration,the protective colloid content,the surfactant content on size and surface morphology of the microcapsules are investigated.The flow rate has the greatest influence on the size of the microcapsules,and the protective colloid content has the greatest influence on the surface morphology.These studies lay the foundation for the preparation of the double-layered microcapsules.The double-layered microcapsules can be fabricated by immersing the single-layered microcapsules in the aqueous solution.A variety of influencing factors on the fabrication of the complex microcapsules have also been investigated.The diameter ratios of the inner membrane to the outer could be adjusted.However,they do not depend on the initial sizes of the oil cores when other reaction conditions are fixed.The viscous shear force is the main cause of the change of the inner and outer diameter ratio.When the viscous shear force is larger,the inner and outer diameter ratio is smaller.