树形分子表面接枝

1、Surface Modification of Chitosan Powder by Grafting of dendrimer-like Hyperbranched Polyer onto the Surface Introduction Chitin and chitosan exist widely in nature,chemical modifications will open ways to use this natural polymer. Hyperbranched polymers,dendrimer ,receive great attention because of

2、their unique topological feathers and potential for novel properties. people have succeeded in the grafting of dendrimer-like hyperbranched polymer onto the surface of ultrafine silica. The grafting of dendritic hyperbranched PAMAM onto the surface of chitosan powder was investigated .Experimental M

3、aterials and reagents Chitosan obtained from Tokyo Kasei Kogyo Co.,Ltd MA and EDA were refluxed over sodium and distilled MeOZO and IBVE were purified Methanol ,THF,acetonitrile and toluene were purified by ordinary methods. Grafting of dendritic PAMAM from chitosan powder surface by repeating two p

4、rocesses: (1)Michael addition of MA to amino groups on the surface (2)amidation of terminal ester groups by EDA.NH2+CH2CHCOOCH32MeOHNCH2CH2CCH2CH2COOCH3OOCH32H2NCH2CH2NH2MeOHNCH2CH2CCH2CH2CONHCH2CH2NH2ONHCH2CH2NH2N(CH2)2CN(CH2)2N(C)2CHNH(CH2)2NHOH(CH2)2CN(CH2)2NOHChitosan Powder1 st-generation2 nd-g

5、enerationn th-generation Preparation of living polymer cation of MeOZO and IBVE Postgrafting of living polymer cation to PAMAM grafted on chitosan powder Determination of percentage of grafting Determination of percentage of postgrafting and overall grafting Wettability of polymer-grafted chitosan p

6、owder surface Solubility of dendritic PAMAM- grafted chitosan Results and discussion Grafting of dendritic polymer from chitosan powder surfaceGenerationGrafting(%)ObservedTheoretical413.513.5657.457.68180.6230.49313.2460.8 IR spectra of (A) untreated, (B) PAMAM dendrimer-grafted chitosan powder at

7、fourth generation (grafting = 13.5%), and (C) at eighth generation (grafting = 180.6%)SEM aspects of dendritic PAMAM-grafted chitosan powderSEM aspects of (A) ungrafted and (B) PAMAM dendrimer-grafted chitosan powder at ninth generation (grafting = 313.2%).100m10mABSolubility of dendritic PAMAM- gra

8、fted chitosan powderGenerationGrafting(%)Soluble part (%)Insoluble part (%)0-100020.987.413.2413.525.474.6657.401008180.601009313.20100Solubility of dendritic PAMAM-grafted chitosan powder in acidic waterPostgrafting of dendritic polyamidoamine- grafted chitosan powderGenerationPAMAMgrafting(%)PolyM

9、eOZO graftingOverall grafting (%)(%)(mol/g)0-26.220.914.264.515.2413.518.483.634.4657.443.9194.5126.58180.677.5352.2398.1Postgrafting reaction of living polyMeOZO with terminal amino groups of dendritic PAMAM-grafted chitosan powder.GenerationPAMAMgrafting(%)PolyMeOZO graftingOverall grafting (%)(%)

10、(mol/g)0-44.020.920.340.621.4413.532.164.236.5657.441.082.0121.98180.661.8123.6354.0Postgrafting reaction of living polyIBVE with terminal amino groups of dendritic PAMA-grafted chitosan powderWettability of dendritic PAMAM- grafted chitosan powderPenetrating rate of water through the column packed

11、with untreated, PAMAM-grafted (grafting = 180.6%), polyMeOZO-postgrafted (overall grafting = 398.1%), and poly IBVE-postgrafted (overall grafting = 354.0%) chitosan powderConclusions1 The grafting of hyperbranched dendritic PAMAM from chitosan powder surface was successfully achieved by repeating tw

12、o processes: (1) Michael addition of MA to surface amino groups on chitosan powder surface and (2) the amidation of the resulting ester moieties with ethylenediamine.2 The percentage of hyperbranched dendritic PAMAM grafting increased with the number of generations, but it was considerably smaller than that of theoretical value. 3 PolyMeOZO and polyIBVE were readily postgrafted onto the hyperbranched dendritic PAMAM-grafted chitosan powder surface by the termination of the corresponding living polymer cation with terminal amino groups of the PAMAM-grafted chito