| Thermresponsive polymers have important application prospects in the fields of separation membrane,actuator,sensor and intelligent carrier materials.Alcohols and alcohol/water solvent mixture are important environment-friendly solvents.The study of the thermresponsive properties of polymers in these solvents is of great theoretical and practical value for the application of thermresponsive polymers.However,the literature on this subject has been less documented.On the other hand,polypeptides have gained remarkable attention in recent years due to their great biocompatibility,stable secondary structure,and chemical diversity.In this thesis,poly(γ-4-(propargoxycarbonyl)benzyl-L-glutamate)with different degree of polymerization(DP = 48-86)were prepared from triethylamine initiated ring-opening polymerization of γ-4-(propargoxycarbonyl)benzyl-L-glutamic acid based N-carboxyanhydride.Then,a series of thermoresponsive polypeptides bearing 1-butyl,1-hexyl,or 1-dodecyl side-chains were synthesized by copper-mediated 1,3-dipolar cycloaddition(click chemistry).1H NMR,FTIR,and GPC results revealed the successful preparation of the resulting polypeptides.The polypeptide with alkyl side-chain showed reversible upper critical solution temperature(UCST)type phase behaviors in methanol,ethanol,and ethanol/water solvent mixtures depending on the polymer main-chain length,alkyl side-chain length,weight percentage of ethanol(fw)in the binary solvent,and so forth.FTIR analysis revealed the presence of the van der Waals interaction between the alkyl pendants of polypeptides and alkyl groups of alcoholic solvents.Variable-temperature UV-vis spectroscopy revealed that the UCST-type phase transition temperature(Tpt)increased as polymer main-chain length or concentration increased.In ethanol/water solvent mixtures,polypeptide with short alkyl pendant(i.e.,1-butyl group)and short main-chain length(DP = 41)showed the widest fw range and Tpts in the range of 61.0-71.1 °C. |
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