pan1351355312013-05-23

chitosan

Chitosan is chitin off after the reaction of products， acetylation level （de-acetylating D。D） determines the macromolecular chain amino （NH2） how many， and the content of D。D increase， because of the son and amino matrix chitosan in dilute acids solution charged groups increased， polyelectrolytes charge density increases， the result will inevitably lead to its structure， properties and performance since the change， TangXi shell gather solution properties research have neglected D。D value on the equation。 Such VANDUM had studied in different ionic strength in dilute solution of chitosan molecules in the influence of size and viscosity。 Results showed that ionic strength different can change the expansion of the linear cluster without rules changed molecular size and degree of viscosity， according to the different characteristics of D。D chitosan MARK - HOUWINK equation， the results show that the measuring constant K A value D。D value with the change。 Thus HOUWINK equation by MARK - A regular constant K， depends on the deacelation degree of chitosan， take off， and in the same changes， when the molecular weight off the deacelation degree with increased， chitosan in dilute solution viscosity and molecular size， characteristics， and expand factor etc increase than and spatial characteristics of A resistance factor as the deacelation degree off decreased。 Thus in any one within the scope of chitosan samples by relatively simple characteristics can be calculated its viscosity measurements， the average molecular weight， thus can accumulate some basic data for further research work。

Because of chitosan and chitin has following reactivity and easy to be some chemical reagent decorate， so this research work more， also have achieved remarkable results。 Through various methods to the properties of chitosan by freezing sodium hydroxide modified。 Abroad - sodium dodecyl sulfate system of simple steps the preparation of CHITIN fibers fluoroalkyl - success。 Alkylation produced different chain long and body let degrees of alkyl quaternary ammonium compounds， the QinGeXing acid or water of the increase of QinGeXing increases， this is because of molecule crystals structural damage and of generation。 Mri （magnetic resonance imaging） study shows that the C6 position than C3 position is being replaced hydroxyl group。 Also CHITIN fibers were alkyl - and thin QinGeXing significant improvement。 This， in the later application of chitosan， a good value。 Additionally also prepared the chitosan porous beads， for heavy metal with a claw cooperation， can also be used for biological materials immobilized reaction。 Through iodinated halogenating preparation of chitosan transplant copolymers。 Halogenating and iodinated are the main methods for chitosan function transform， which the group milder conditions， iodinated and can produce all sorts of reaction precursor。 This reaction is easy to occur in C6 location value， plus for the preparation of cationic copolymer transplantation。 The reaction conditions 308NM place in room temperature and ultraviolet light。 All sorts of function group of chitosan rebuilding also includes preparation hydroxyl chitosan。

殼聚糖

殼聚糖是甲殼質經脫乙醯反應後的產品，脫乙醯基程度（D。D）決定了大分子鏈上胺基（NH2）含量的多少，而且D。D增加，由於胺基質子化而使殼聚糖在稀酸溶液中帶電基團增多，聚電解質電荷密度增加，其結果必將導致其結構，性質和效能上的變化，至今殼聚糖稀溶液性質方面的研究都忽略了D。D值對方程的影響。VANDUM等人曾研究了不同離子強度對殼聚糖在稀溶液中的分子尺寸和粘度的影響。結果認為離子強度不同會改變無規線團的膨脹度進而改變分子尺寸和特性粘度，透過對不同D。D殼聚糖進行MARK-HOUWINK方程常數的測定，結果表明K，A值隨D。D值的變化。從而由MARK-HOUWINK方程常數K，A有規律地依賴於殼聚糖的脫乙醯度而變化，而且在相同分子量時，隨著脫乙醯度的增加，殼聚糖在稀溶液中分子尺寸，特性粘度和擴張因子等增加，而特性比和空間位阻因子隨著脫乙醯度的增加而減少。從而在適用範圍內的任意一個殼聚糖樣品透過比較簡單的特性粘度測量，即可計算其平均分子量，從而可積累一些基礎資料用於進一步的研究工作。

由於殼聚糖和甲殼質具有高化學反應活性並且易於被一些化學試劑修飾，因此這方面的研究工作進行的較多，也取得了可喜的成果。從而透過各種方法對殼聚糖進行了性質改良。國外透過冰凍氫氧化鈉-十二烷基硫酸鈉系統的簡單步驟製備成功了烷基-CHITIN纖維。烷基化產生了各種不同鏈長和體容度的烷基鹵素化合物，對水或甲酸的親合性的增加，這種親合性的增加是由於部分分子晶體結構破壞而產生的。核磁共振的研究表明C6位置上的羥基優於C3位置被取代。同時也製備了烷基-CHITIN纖維和薄膜。這種親合性質的改善，在以後的殼聚糖應用中有良好的價值。另外還製備出了殼聚糖多孔小珠，對重金屬有螯合作用，也可以用於生物材料的固定化反應。透過碘化鹵化製備了殼聚糖移植共聚物。鹵化與碘化的方法主要進行殼聚糖功能集團的改造，其中碘化條件溫和，並可以產生各種反應的前體。該反應易於發生在C6位值上，另外用於製備陽離子移植共聚物。其反應條件在室溫和紫外光308NM處進行。對殼聚糖各種功能集團的改造還包括製備羥基殼聚糖。