Fabrication And Mechanism Research Of Multi-Responsive Ion Channels Via RAFT Controlled Polymerization

Environmental-stimuli-responsive ion channels have received intensive attention because of the various prominence including drug release,biological sensors,biological simulation and battary materials.One of the important scientific challenges is how to build ion channels that possess high transmission efficiency,stable chemical structure,clear mechanism of ion transport and apply to the frontier fields,such as nanoscience,clinical medicine and biochemistry etc.This thesis presents the fabrication of multi-responsive ion channels based on the SBA-15 matrix and functional polymer brushes grafted from the mesopores' surfaces via RAFT controlled polymerization.The specific work is as follows:1)Grafted functional polymer,poly(2-(dimethylamino)ethyl methacrylate)(PDMAEMA),on the surface of mesoporous channels using the "Grafting from" method,constructed pH/temperature dual-stimuli-responsive controlled ion channels and gated “on-off” effects of Fe(CN)64-/3-and Ru(NH3)62+/3+ transportion performance at pH range of 4-10 and temperature range of 30-50?,respectively.The chain length and structure of PDMAEMA not only can control the mesoporous diameter,but also can promote the migration rate.At DPn = 75,anionic transportion rate is more quickly than cationic conditions with low pH.while pH increase to 10,the deprotonation of anionic polymer chain cause the reduction of ionic transportion rate.While temperature increased to 50?,the shrinking of polymer chain would induce the increase of effective pore size,which increase both anionic and cationic transportion rate.Results showed that external environment conditions including pH and temperature can affect ion transportion efficiency through the mesoporous channels.2)As similar to the above,the fabrication of pH/temperature/light tri-stimuli-responsive controlled ion channels by grafting functional polymer,poly(2-(dimethylamino)ethyl methacrylate)(PDMAEMA)and poly(acrylamide-azobenzene)(PAAAB)on the surface of mesoporous channels,and the ionic transportion performance was investigated.Under the optimal polymer chain length(DPn=75),the transportion rate of ions can be controlled by regulating the block polymer structure and proportion and be investigated under the condition of different pH,temperature,light.Experimental results showed that the grafting block polymer for the mesoporous surface has obvious pH and temperature responsive as similar single polymer PDMAEMA.Moreover,PAAAB by trans into cis structure at UV irradiation.As results,hydrophilicity will be enhanced and the LCST of block polymer also will be increased.Especially,with the increasement of the PAAAB proportion,the LCST of copolymers increased too.The experiments show that the external conditions of pH,temperature and light can control ion intelligent release is expected to be used in intelligent membrane separation system,also have potential applications in micro-nanofluidics and lithium battery separator.