Self-assembly And Functionalization Of Carbon Dioxide/Electrochemical Redox Responsive Polymers

Stimuli-responsive polymers are a class of intelligent polymers which can cause the change of its properties with the tiny variation of physical or chemical conditions in the environment.In recent years,this kind of macromolecule is widely used in the construction of nano assemblies,gels,etc.,further showing great application values in the drug controlled release,tissue engineering,self-repairing materials and other fields.However for pH,ion,redox,enzymes and several kinds of other traditional stimulus modes,substances of external stimulus source were always added repeatedly to the polymer solution,which may cause the accumulation of by-products and unnecessary pollution to the system.Herein we focus on two kinds of new sources of stimulation,namely carbon dioxide gas?CO₂?and electrochemical redox stimuli,in order to achieve more abundant functions.CO₂ is one of the important metabolic substances in the body,which has good membrane permeability and biocompatibility.Tolerance limit to CO₂ concentration in human body is relatively high for exploring applications.CO₂ can specifically change the polymer structure and properties,while able to be removed by inert gas.The whole process do not produce any by-products and pollution,greatly enhancing practicality and biocompatibility of the smart macromolecule in industrial or in vivo applications.We have studied and developed the CO₂ responsive characteristics of poly[?N,N-diethylaminoethyl methacrylate?]?PDEAEMA?,which can realize transformation from the hydrophobic to the hydrophilic segment under the stimulation of CO₂.The temperature responsive monomer N-isopropylacrylamide?NIPAM?was copolymerized to afford block copolymers PDEAEMA-b-PNIPAM,whose self-assemblies realized schizophrenic micelle to vesicle morphological transition using CO₂ and temperature as trigger.Then we have constructed hyperbranched star triblock copolymers with PDEAEMA as inner chains,which can self-assemble into vesicles in water.We have found for the first time that CO₂ gas can not only make the vesicle volume expansion and contraction,but also construct macropores in the vesicle wall as molecular drills,which can provide more possibilities as nanocontainers for biological macromolecules.On the other hand,with a combination of gold nanocatalysts and magnetic nanoparticles as core,PDEAEMA has been fabricatied as a catalyst-supportfor CO₂ adjustable and magnetic recyclable catalysis,which should play an important role for utlizing precious metals as catalyst.Electrochemical redox stimulus is also considered to be one of "green" stimuli by applying means of potential stimulation to achieve redox reaction,not changing the chemical composition,concentration,volume and temperature of system.Based on the host-guest interaction between beta-cyclodextrin??-CD?and ferrocene?Fc?,we have constructed a novel brush-like supramolecular block copolymers,which can self-assemble into micelles in aqueous solution with a potential regulated reversible self-degradation and self-repair behaviors.Secondly,we have developed a surface modification methods of single wall carbon nanotube?SWNT?through noncovalent interaction of SWNT surface and polymers.Based on the responsive pair of ?-CD and Fc,hybrid SWNTs system achieved electrochemical redox potential regulation of reversible dispersion and aggregation.