Preparation And Characterization Of Responsive Amphiphilic Polymer

Functional polymer materials,also called stimuli-responsive materials,can respond to physical stimuli and chemical stimuli in environmental conditions to change their solubility,configuration,conformation,etc.These materials are usually composed of macromolecule polymers,and the specific responsive groups on the main or side chains of the polymer are introduced by ring-opening polymerization or post-polymerization modifications to control the molecular structure,molecular weight and chemistry properties of the polymer.Because of their unique properties,these intelligent macromolecules have broad application prospects in the fields of aerospace,engineering materials,biomedicine,and energy science.In this paper,we synthesized the following two different types of stimuli-responsive polymers:?1?A maleimide derivative?TLAMID?containing a thiolactone functional groupwassynthesizedfrommaleicanhydride,glycine,and DL-homocysteinethiolactone hydrochloride.Through RAFT polymerization,using AIBN as initiator,synthesize macro RAFT reagent PNIPAM-CTA,and then copolymerize with NIPAM to synthesize block copolymer PTLAMID-b-PNIPAM with different degree of polymerization.Since the polymer contains thiolactone groups,it can be opened by primary amines,releasing thiol groups.Therefore,we used mPEG₁₁-NH₂ as a ring-opening primary amine,and o-nitrobenzyl acrylate as a thiol-ene click monomer to double modification of the polymer to obtain polymer PTLAMID-b-PNIPAM^DM.The polymer contains a thermosensitive PNIPAM segment and a photosensitive o-nitrobenzyl ester group,which is a double-responsive polymer.The chemical structure,molecular weight and molecular weight distribution of the polymer were verified by ¹H NMR and GPC.The thermo-and light-responsive of the polymer were analyzed by UV-vis spectrophotometer,¹H NMR and DLS.And the polymer can self-assemble into micelles in water.The change of particle size and morphology of the micelles,and the controlled release of Nile Red were tested by DLS,TEM,Steady State/Transient State Fluores cence Spectrometer.?2?A cinnamaldehyde-containing cyclic carbonate monomer?CAMPC?was synthesized from cinnamaldehyde,pentaerythritol and ethyl chloroformate.Then,using DBU as a catalyst and mPEG₁₁₃ as a macroinitiator,the block copolymers of different degrees of polymerization mPEG₁₁₃-b-PCAMPC,were synthesized by ring-opening polymerization.The chemical structure,degree of polymerization,molecular weight and molecular weight distribution of the polymer were verified by¹H NMR and GPC.The polymer was able to self-assemble into micelles in water,and the critical micelle concentration?CMC?of the polymer was measured by a fluorescence spectrometer.Due to the acetal structure contained in the polymer,it can be cleaved under acidic conditions.The particle size and pH response of polymer micelles was analyzed by DLS and fluorescence spectrometry,and measured the controlled release of Nile Red at different pH.