Preparation Of Controlled-release, Skin-care Microcapsules And Their Applications To Fabrics

With improving people’s living standard, more and more attentions are attached to clothing. In recent years, a novel kind of high-additional-value agent and fabrics has become a research spot in overseas, which functionalize as wetting, anti-bacteria, skin-care. Microcapsules with squalane （high-effective wetting agent） as core materials and polyurethane as wall materials were firstly prepared in this thesis and applied onto fabrics. Compared with common wall materials of microcapsules, generally came from gelatin, acacia, melamine resin and epoxy resin, polyurethane overcome the shortcomings owned by the mentioned walls, such as existing formaldehyde problem for the former three walls and reacting easily with the core materials due to using of the active monomers for epoxy resin. The release behavior of squalane was fitted by release kinetics models and the result shows a zero-order model. Base on this, the release rate, apparent diffusion coefficient and permeability constant of squalane microcapsules were studied detailedly. Obtaining the three parameters, we can design process to prepare the desirable microcapsules. The prepared squalane microcapsules agents are aqueous systems, which could be treated to fabrics directly or did with other agents in the same bath, so it is very easy to operate. In addition, the inclusion behavior between miconazole nitrate （high-effective antibacterial agent） and natural microcapsuleβ-cyclodextrin （β-CD） was firstly investigated. The anti-bacterial agent, miconazole nitrate, was firstly fixed onto fabrics grafted withβ-CD, and a kind of anti-bacterial fabrics with good result was gained, which offered a novel thought to develop new functional fabrics.The thesis mainly consists of four parts:1. Preparation of squalane microcapsulesInterfacial polymerization method was employed to prepare polyurethane microcapsules using 2,4-toluene diisocyanate （TDI） and polyethylene glycols （PEG） as reaction monomers, dibutytin dilaurate （DBTDL） as the catalyst and ethylene diamine （EDA） as chain extender. The polymers produced by interfacial polymerization between TDI and PEG could entrap core materials squalane to form polyurethane microcapsules, which was characterized by IR-spectra. No TDI residue was determined when adding solidifier EDA after the reaction running 2 hours, and adding a little quantity of catalyst at the same time.UY-M image analyzer and laser granularity tester were employed to investigate the shape, the mean particle size and distribution of formed microcapsules. Many factors affecting the preparation of microcapsules were studied, such as dosage of emulsifier and disperser, emulsifying conditions, phase ratio, core/wall ratio, molecular weight of monomer and reaction conditions. The results indicated that the mean particle size and distribution of microcapsules became smaller and narrower, and the wall thickness became thinner when improving core/wall ratio and emulsifying speed, prolonging emulsifying time, increasing dosage of emulsifier and disperser, declining the phase ratio and molecular weigh of monomer PEG. Vice versa, the mean particle size, distribution, and the wall thickness got broader, larger and thicker respectively. The optimum conditions of preparing squalane microcapsules had been got as follows: emulsifier polyvinyl alcohol （PVA） 2%, disperser sodium alginate （SA） 0.15%, PEG400, core/wall ratio 1:2, phase ratio of w/o 10:90, emulsifying 9500 r/min for 5 min and reaction at room temperature for3h. Microcapsules manufactured under the optimum conditions had uniform particle size distribution, the mean particle size and wall thickness were about 7μm and 0.3μm respectively and loading of squalalne was over 85%.2. Release property of squalane microcapsulesThe percentage of the released core materials were measured by UV-absorbancy. Zero-order model of release kinetics was employed to calculate the release rate （K）, apparent diffusion coefficient (D_am) and permeability constant （P）. The results showed that K, D_am and P of squalane microcapsules increased when improving disperser concentration, prolonging emulsifying speed, enhancing emulsifying speed and shortening reaction time. The three parameters declined with increasing the phase ratio and reducing the core/wall ratio. K and D_am went down with augmenting PEG molecular weight, but P altered little. K, D_am, and P increased with improving the emulsifier concentration. But no obvious changes on the permeability constant were found when the concentration was below 1.5%.3. Application of squalane microcapsules to fabricsExtract and UV-absorbancy were introduced to test the squalane content of the fabrics and the state of microcapsules existed on the fabrics were observed by SEM. Factors affecting the squalane content on the fabrics were investigated, including the treating methods, dosage of adhesive and microcapsule agent, and curing conditions. The results presented that exhaustion was better than one pad and two pad under the same conditions, because the former could gain more squalane for the fabrics than the latter two. Adhesive agent SCJ939 was a good one for treating squalane microcapsules onto the fabrics. The optimum process was: adhesive agent 40g/L, microcapsules agent 50g/L, curing temperature 100℃and curing time 3min. The skin-care fabrics prepared under the conditions could get 1.2% squalane content. Squalane on the fabrics decreased with increasing washing times, but the content could keep up 30-40% of the whole squalane content even after washing 20 times.4. Investigation of inclusion between miconazole nitrate andβ-cyclodextrin and Preparation of anti-bacterial fabricsMiconazole nitrate could be encapsulated byβ-CD, forming inclusion complex which was characterized by IR spectra, DSC and X-ray diffraction. In IR spectra of inclusion complex, absorption peak of N-hybrid ring still existed, while that of benzene ring disappeared, which mean that only part of drug molecular—benzene ring entered into the cavity of CD, leaving the N-ring outside. The phase solubility curve betweenβ-CD and miconazole nitrate was AL-type （Higuchi & Connors） and the ratio of inclusion complex was calculated by phase solubility method as 1:1. The change of entropy （ΔS）, enthalpy （ΔH） and free energy （ΔG） of the reaction were calculated through thermodynamics. The results showed that the inclusion process was a spontaneous one. Furthermore, the inclusion reaction betweenβ-CD and miconazole nitrate was an exothermic one. So, it was better to react under low temperature. For modifiedβ-CD （MCT-β-CD）, it is possible to treat them onto cellulosic fabrics, not using adhesive agents, instead of the covalent linkage, due to covalent binding between the active groups ofβ-CD and -OH of the cellulosic fibers. For the same reason, sulfonation-β-CD could also be fixed onto wool fabrics due to its’ negative charge group SO₃^-, which could be attracted by NH₄⁺. Investigating the factors affecting grafting MCT-β-CD onto the cellulosic fibers, the suitable grafting conditions were: MCT-β-CD 60～100g/L, Na₂CO₃ 50～60g/L, cure temperature 150-160℃and cure time 6-8min. For the wool fabrics, the suitable grafting conditions were: sulfonation-β-CD 60 g/L, Na₂SO₄ 5g/L, pH=2～3, keeping fabrics into solution in 90～95℃for 50～60min. The inclusion ability ofβ-CDs’ cavities didn’t change whenβ-CD grafted onto fabrics. Compared with the unmodified fabrics, the fabrics modified withβ-CD increased the uptake of antibacterial agent, miconazole nitrate, enhancing the antibacterial properties of the modified fabrics. In addition, the activity of anti-candida albicans was a little better than that of anti-aurococcus and anti-colon bacillus. The anti-bacterial abilities of fabrics declined with increasing washing times. The binding ofβ-CD onto the textile fibers improved the resistance of the entrapped antibacterial agents to washing cycles, prolonging the antibacterial effect. The anti-bacterial abilities of the unmodified fabrics was almost lost when washing 10 times, while MCT-β-CD-modified fabrics still kept over 70% and sulfonation-β-CD-modified fabrics kept 60%～70% even after washing 10 times.