Preparations And Properties Of Star Block Co-polymer Environmental Sensitive Nano-Micelles

First,γ-Aminopropyl triethoxysilane and Glycidol as the reactant,methanol as the solvent,and HF as the catalyst,a multi-hydroxy Polyhedral Oligomeric Silsequioxane was synthesised successfully. The composition and structure of product was characterized by IR,NMR and Differential Scanning Calorimeter.The results show that the methods is feasible,but the products is not pure ,that's a mixture of Polyhedral Oligomeric Silsequioxane with different structure.And then,multi-hydroxy Polyhedral Oligomeric Silsequioxane POSS-OH and D,L-Lactide as the reactant,Sn(OCt)2 as the catalyst,a star-shaped polymer Polyhedral Oligomeric Silsequioxane-PolyLactic Acid was synthesized successfully.The reaction is suitable for the feature of Living Polymerization through the relations of molecular and PDI with the ratio.The composition and structure of product was characterized by IR,NMR,Differential Scanning Calorimeter and Thermo Gravimetry Anylysis.The results show that pruducts is synthesised successfully.Later,the star-shaped polymer POSS-PLA reacted with 2-Bromoisobutyryl bromide,a star-shaped macroinitiator POSS-PLA-Br was synthesised, the composition and structure of product was characterized by IR and NMR also.The star-shaped macroinitiator initiaed Atom Transfer Radical Polymerization of 2-(Dimethylamino)ethyl methacrylate,a star-shaped block co-polymer POSS-PLA-PDMAEMA which Polyhedral Oligomeric Silsequioxane-polylactic acid as the core and poly(2-(Dimethylamino)ethyl methacrylate) as the shell was synthesized.The composition and structure of product was characterized by IR,NMR,Differential Scanning Calorimeter and Thermo Gravimetry Anylysis.The results of Video microscopy image show that Polyhedral Oligomeric Silsequioxane-PolyLactic Acid is a structure of ball,but the star-shaped block co-polymer POSS-PLA-PDMAEMA is star-shaped.The polymer was prepared to become nano-micelle,studied the patterns of micelle with Transimission Electron Microscopy,it has core-shell structure,and the size is 150-300nm.Then studied the pH and temperture sensitive properties and size of nano-micelle through Dynamic Laser Light Scattering.The size of nano-micelle reduced with the pH value's increase,reduced with the temperature's increased.The results show that the polymer has the pH and Temperture sensitive properties.We researched the controlled-release behavior of Nano-micelle by choosing Ibuprofen as a model.The ratio of cumulative release is higher at 40℃than 37℃, the ratio of cumulative release reduced with the pH value's increase.The results show that the pH and Temperature to the drug's release is influential.