The Fabrication Of Multilayer And Capsule By LBL

Layer by layer (LbL) technology is an efficient method in the fabrication of multilayers and hollow capsules. As far as the year 1966, Iler reported this method. In the year 1991, Decher put forward it again. Since then this method has been used wildly. Beside electrostatic attraction, diverse other interaction such as hydrogen bonding, covalent bonding, specific molecular recognition and so on can be employed as driving force for LbL assembly. In this thesis we have employed this technique to assemble multilayers and hollow capsules with the materials of ALG and PNIPAAm. PNIPAAm is a thermosensitive material which has a low critical solution temperature(LCST) behavior around 32℃in aqueous solution. PNIPAAm chains hydrate to form expanded structures in water when the solution temperature is below its LCST but become compact structure by dehydration when heated up above the LCST. ALG is a biocompatible material which is widely used in the biology, pharmacy, and foodstuff. In low pH environment, there is a weak hydrogen bonding between ALG and PNIPAAm which can be used to fabricate multilayers and hollow capsules.We have successfully assembled multilayers (PNIPAAM/ALG)n on the quartz slide, and measured the increasing of the numbers of layers with the UV-visible spectrum, which has certified the success of assembly. MF and MnCO3 have been used as template to fabricate hollow capsules which both had temperature-responsive property. There were some differences between the two kinds capsules. The capsules which were taken MnCO3 as template could be stable in high pH solution and had pH-responsive property comparing with thecapsules which were taken MF as template. The microstructure, morphology, component and composition of the capsules had been investigated using CLSM, SEM, TEM, AFM etc. In addition, we utilized the temperature-responsive property of capsules to load macromolecular by heating the solution temperature above LCST.