Study On The Preparation And Application Of Chitosan Ultrafine Capsules

In this paper, we put forward the concept of ultrafine capsules, expatiated on the preparation methods, application fields and technology progress, reviewed the structure and function of chitosan, and analyzed the feasibility and preparation significance of capsule from chitosan. According to these, we put forward the research scheme of the ultrafine capsules preparation from chitosan as wall and vitamin E, solution of crystal violet lactone (CVL), nano-TiO₂ as core by monophasic coagulation and complex coagulation process. We studied the technological process conditions, such as emulsifying conditions, fixing conditions, wall-material concentration, wall-material ratio, the ratio of core to wall, drying temperature, and determined the optimum process parameters. The capsule performance and capsule formation mechanism were characterized, tested and analyzed by some apparatus and means such as laser particle sizer, SEM (Scanning Electron Microscope), FTIR (Fourier Transformation Infrared Spectrum) and HPLC (High Performance Liquid Chromatogram).Ultrafine capsules were prepared by monophasic coagulation process using chitosan as wall material and V_e as core material. The deacetylation degree of chitosan should be more than 85%, molecular weight of chitosan about 9× 10⁵, solution concentration 1.0%, core/wall ratio 1:1, emulsifier dose 6.0%, emulsifying stirring rate 9 000-10 000r/min. Through the characterization, test and analysis of capsule performance, we knew the capsule particle size is less than 3μm, the particle uniformity is good, the shape is basically sphericity, the embedding ratio of core material V_e is 86.1%, the heat endurance and stability of capsule is good. The product performance has reached the overseas advanced level.Ultrafine capsules were prepared by complex coagulation process using chitosan- sodium alginate as wall material and CVL as core material. The wall material ratio is 1:1, wall material concentration 1.0%, emulsifier dose 6.0%, emulsifying time 30min, hardener dose 10ml, hardening time 1h. Through the characterization, test and analysis of capsule performance, we knew the capsule particle size is less than 3μm, the particle uniformity is good, and the embedding ratio of core material is 82.6%. The heat endurance, stability and core material embedding ratio of capsule have reached the highest level compared with the capsules prepared from natural materials by complex coagulation process.Ultrafine capsules were prepared by monophasic coagulation process using chitosan as wall material and nano-TiO₂ as core material. The optimum core/wall ratio 1:1 1.6:1. Nano-TiO₂ can be dispersed in wall material solution by ultrasonic. The dispersion results are good. This is propitious to the chitosan embedding or the absorption in the capsule surface. Through the characterization, test and analysis of capsule performance, we knew the capsule particle size is less than 2μm, the particle uniformity is good, and the capsule has very good dispersion in organic phase. The Ultraviolet ray absorption of capsules is higher than that of nano-TiO₂. The Ultraviolet-visible light reflectivity of capsules corresponds with that of nano-TiO₂. Theultrafine capsule was used in cosmetics.The experiment confirmed that the sense and physical and chemical index of cosmetics reached the national standard when adding the chitosan -Ve ultrafine capsules and the chitosan -nano-TiC>2 ultrafine capsules in cosmetics. Though test and analysis, the Ve content of cosmetics reduced 8.7% after adding chitosan -Ve ultrafine capsules in cosmetics 15 days and the Ve content of cosmetics reduced 22.3% after adding Ve in cosmetics directly 15 days. This result showed that chitosan -Ve ultrafine capsules have the effect of protection and insulation Ve. The chitosan -nano-TiC?2 ultrafine capsules have very good dispersion in cosmetics and no flocculation after adding chitosan -nano-TiC>2 ultrafine capsules in cosmetics. The chitosan -nano-TiC>2 ultrafine capsules have very good solubility in organic phase. The Ultraviolet-visible light reflectivity of cosmetics with chitosan -nano-TiC>2 ultrafine capsules is no obvious difference from that with nano-TiC>2. CB paper of carbonless copy paper prepared with chitosan-sodium alginate-CVL ultrafine capsules. All the properties reached the domestic advanced level of congeneric products.The reserves of chitosan is only inferior to cellulose. Chitosan is a very abundant regenerable resource. The preparing process of capsules by monophasic coagulation process using chitosan as wall material is relatively simple. The formation mechanism of capsules is clear. The period of the preparing process is short, and the whole period is about 150 min. Water is medium in the whole process, without high temperature and high pressure. It is friendly with human and environment. Therefore, the development and application of chitosan ultrafine capsules have very broad foreground.