Microencapsulation of a Dyestuff by Interfacial Polycondensation

Safety precautions Before this experiment is carried out. Sect. 2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

Microencapsulation means the envelopment of liquid droplets or solid particles with natural or synthetic polymers.The encapsulation of a substance with a polymer membrane is undertaken for various reasons, for example, as protection against moisture, or to obtain delayed dissolution of fertilizers, herbicides, or drugs by microencapsulation with semipermeable membranes. 

Various techniques have been developed for the preparation of microcapsules with diameters of 1-5000 pm one of these involves the method of interfacial polycondensa-tion.The following example describes the microencapsulation of a dyestuff, which has practical application in the manufacture of carbon-free copy paper. 

The amine solution (4) is now immediately run in dropwise over a period of 30 s and the stirrer speed reduced to 2000 rpm After 2-3 min the high-speed stirrer is replaced by a normal paddle stirrer and the dispersion stirred (500 rpm) for a further 30 min at room temperature to complete the interfacial polycondensation between terephthaloyl dichloride and diethylenetriamine. 

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