Amino starches as pH-sensitive coatings: Synthesis and application

The aim of this work was to carry out a systematic investigation of the preparation conditions of starch materials with pH-dependent solubility. Furthermore, appropriate conditions for application of those materials as surface coatings should be established. Thus, samples of starch derivatives with tertiary amino substituents were synthesised and characterised by H-1-NMR spectroscopy and pH-turbidimetry. Variation of both kind and molar mass of the used starch substrate and the nature and degree of substitution of the amino component led to two materials containing diisopropylamino groups with the desired properties in a single- or two-component coating. Using a commercial fluidised-bed coating procedure spherules of a waxy surfactant were coated with different modified starches. The stabilities of the shells were examined under dishwasher-like conditions and monitored by tensiometry.