Synthesis Of Polyamidoamine Dendrimers And Their Templating And Solubility Enhancing Properties

Dendrimers are a kind of synthetic highly branched macromolecules which have been studied for nearly thirty years.Due to the unique synthesis strategy,these macromolecules remain many structural merits such as well-defined molecular structure,controlled molecular weight,highly geometric symmetry,a large number of surface functional groups,intramolecular cavities,nano-sized molecule and spherical shape.These features make them extensively applicable in various fields like biomedical,nano template,dye industry etc.In this thesis,the research history,synthetic methods,structure,performance and applications of dendrimers are briefly overviewed.Traditional polyamidoamine(PAMAM)dendrimer are usually synthesized through divergent approach.By choosing different core structure,the flexibility and the end-group density of dendrimers can be adjusted,which in turn regulate their properties in nano template and dye industry.In this work,tris(2-aminoethyl)amine(TAEA)is considered to be a proper core for dendrimer synthesis.Comparing with the traditional dendrimers,these dendrimers possess higher end-group density and lower molecular flexibility.Nano particles with small size and uniform distribution can be prepared using these dendrimers as nano template.Meanwhile,ammonia-core dendrimers were synthesized.These two dendrimers were characterized by FT-IR and 1H-NMR spectra and the results showed that their structures were consistent with the theoretical ones.We also investigated the template effect of ’TAEA-core dendrimer in the’ preparation of gold nanoparctices.The obtained nanoparticles were characterized by ’TEM,UV-vis,DLS,etc.The results showed that a large molar ratio of primary amine groups and HAuCl4 could lead gold nanoparctices possess small size and uniform distribution.When the molar ratio of G2.0 dendrimers’ primary amine groups and HAuCl4 reached 4/1,gold nanoparctices with the particle size of 4.65 nm.The diameter of gold nanoparctices decrease with the increasing generation of dendrimers.The diameter of gold nanoparctices prepared by G3.0 dendrimers is 2.43 nm.Low temperature and a large molar ratio of dendrimers and HAuCl4 could promote the stability of gold nanoparctices.Further more,we investigated the solubility enhancing performance of dendrimers.phthalocyanine blue B was used as a model molecule and its solubility in the presence of dendrimers with different generations and end groups.Small molecules were employed to study the mechanism of solubility enhancing of dendrimers.The results showed that the ammonia-core PAMAM dendrimers can significantly improve the dissolution of phthalocyanine blue B.The aqueous solubility of Sudan Ⅲ increases with both the concentration and the generation of dendrimers and the solubility in the presence of amine-terminating dendrimers is much higher than that in the presence of ester-terminating dendrimers.G1.0 dendrimers are found to improve the dissolution of phthalocyanine blue B by electrostatic interaction,whereas encapsulation capability for phthalocyanine blue B played a major role when the generation increase to G3.0.