Synthesis And Properties Of Thermoresponsive Amphiphilic Starch Derivative

2-Hydroxy-3-butoxypropyl starch (HBPS) was synthesized by environmentally friendly process using butyl glycidyl ether (BGE) as hydrophobic reagent, water as solvent and sodium hydroxide as a catalyst. The reaction conditions were investigated and optimized. Optimum conditions were obtained as follows:n(BGE):n(AGU)=0.615, amount of solvent was m(H2O):m(AGU)=2:1, amount of catalytical NaOH was n(NaOH):n(AGU)=0.5:1, reaction time was 6h, reaction temperature was 75℃, molar substitution (MS) of 2-hydroxy-3-butoxypropyl was up to 0.53, the reaction efficiency(RE) was 86%. Under those conditions, different MS of 2-hydroxy-3- alkoxy -propyl starch were prepared. The MS of the products were determined by1H-NMR. The 3- alkoxy-2- hydroxypropyl starch and corn starch were characterized by IR,1H-NMR and 13C-NMR. In addition, the TG result indicates that hydrophobic modification can improve the thermal stability of stach. Hydrophobic modification can improve dissolve performance in organic solvents.Thermoresponsive 2-hydroxy-3-butoxypropyl hydrolysis starches (HBPHS) are being newly synthesized by using degraded corn starch, and butyl glycidyl ether as hydrophobic reagent. The lower critical temperature (LCST) of HBPHS can be easily adjusted at any desired temperature between 4.5 and 32.5℃by controlling the molar substitution (MS) of 2-hydroxy-3-butoxypropyl group. The surface tensions of aqueous solution of HBPHS have been investigated. The critical micelle concentrations (cmc) of HBPHS were in range of 10 mg/L to 150 mg/L depended on MS. The micelles self-assembled from thermoresponsive HBPHS were investigated by using fluorescence techniques and dynamic light scattering (DLS). Drug release in vitro experiment show that drug release strongly depended on temperature:high temperature accelerated drug release markedly due to the temperature-induced intermicellar aggregation.HBPHS were carboxy methylated by chloroactic acid to prepare different mole substitution (MS) of 2-Hydroxy-3-butoxypropyl-carboxymethyl hydrolysis starch (HBPCMHS). HBPCMHS have the thermo/ pH- responsive properties. They were characterized by IR,1H-NMR,13C-NMR and HSQC. The LCST of HBPCMHS can be easily adjusted at any desired temperature between 4.5 and 57.0℃by controlling the molar substitution. Furthermore the LCST of 2-hydroxy-3-butoxypropyl-carboxymethyl starch was highly sensitive to pH changes. The surface tensions of aqueous solutions of HBPCMHS have been investigated.