Preparation Of Hyperbranched Polyglycerol Derivatives And Its Thermoresponsive Behaviours

In this paper,a series of hyperbranched polyglycerol derivatives with LCST properties were prepared by different methods,and we studied their thermoresponsive behaviours.First,a series of hyperbranched polymers were synthesized through the esterification reaction between the hyperbranched polyglycerol(HPG)and the aliphatic acids of different carbon numbers.Turbidity method shows that only when the number of fatty acid is less than or equal to 8,the derivative of HPG is sensitive to temperature.And when the fatty acid carbon number less than or equal to 4,it shows normal thermoresponsive phenomenon,if the number between 5-8,shows the abnormal thermoresponsive properties.That is,as the concentration of polymer in water increases,its phase transition temperature increases.This phenomenon is rarely,if ever,has very broad prospects for research.Fluorescence method with nile red as the fluorescent probe shows that the existence of relatively strong hydrophobic interaction is a key factor to ensure that the polymer exhibits an abnormal thermoresponsive behaviour in water.Secondly,glycidol and different structures of glycidyl ethers through the anionic ring-opening multibranching copolymerization were used to synthesize the copolymer.Trimethyl propane was used as the core,the glycidol and benzyl glycidyl ether copolymerized,and we found that at 90 ? mixed the monomer had the best thermoresponsive behavior.Moreover,we also used triethanolamine as the core and found that the cloud point of glycidol and butyl glycidyl ether copolymer decreases with increasing concentration.The phase transition temperature of glycidol and octyl glycidyl ether copolymer increases with the increase of concentration,and also shows the abnormal thermoresponsive behaviour.Finally,we used HPEI-PG as the core,glycidol and n-butyl glycidyl ether copolymer was prepared will be able to have LCST behavior.Different methods to treat with product have influence on the purity and thermoresponsive behaviour.It demonstrated that the cloud point decreases with concentration increasing,but the sensitivity was not as good as that of the small molecule as a core.