Synthesis And Application Of Brush-Like Polymers Based On Ethoxyethyl Glycidyl Ether

Brush-like polymers are widely used in catalysis,biomineralization,drug delivery,medical diagnostics and optoelectronic materials due to their unique conformation,compact molecular size and chain-end effects.As one of the most common biocompatible polymers at present,poly(ethylene oxide)is always used to design the molecular structure of medical brush-like polymers.However,due to the chemical inertness of the ethylene oxide repeating unit,it can only be linked to the molecular backbone via "grafting-onto" method for biocompatibility modification,which limits the possibility of further molecular structure modification design.Ethoxyethyl glycidyl ether(EEGE)is prepared from glycidol and vinyl ether.It not only has the structure of alkylene oxide for the structural design of the biocompatible molecular chain,but also can release the active site-terminal hydroxyl group under acidic conditions to provide possibility for further introduction of other molecular structures.Therefore,the controlled synthesis of polymer molecular brushes based on EEGE has attracted the attention of polymer synthesis workers.Based on EEGE,two types of brush-like polymers:star-shaped brush-like polymers a-CD-g-[(PEO-g-PAA)-b-PEO]and ring-shaped brush-like polymers c-PEO-g-P3HT were designed and synthesized.The application of a-CD-g-[(PEO-g-PAA)-b-PEO]in the controllable preparation of titanium dioxide(TiO2)nanocrystal clusters was explored.The main results have been obtained as follows:(1)Design and synthesis of star-shaped brush-like polymers a-CD-g-[(PEO-g-PAA)-b-PEO]:Based on a-cyclodextrin(a-CD),star-shaped brush-like block copolymers a-CD-g--[(PEO-,g--PAA)-b-PEO]were synthesized by the combination of anionic ring-opening polymerization(ROP)with atom transfer radical polymerization(ATRP).The PAA side chains were grafted to the PEO main chain by "grafting-from"method.The characterization results confirmed that the star-shaped brush-like block copolymers a-CD-g-[(PEO-g-PAA)-b-PEO]were successfully prepared with a narrow molecular weight distribution and low polymer dispersibility index(PDI)(<1.2).(2)Design and synthesis of ring-shaped brush-like polymers c-PEO-g-P3HT:A novel ring-shaped brush-like copolymers poly(ethylene oxide)-g-poly(3-hexyl thiophene)(c-PEO-g-P3HT)which contains the PEO ring-shaped main chains and the P3HT side chains were designed and synthesized by the combination of GRIM,anionic ROP and "click" chemistry.The functional ring main chains were prepared by end-to-end closed-loop method,while the P3HT side chains were grafted to the main chains by "graft-onto" method.The characterization results confirmed that we got the ring-shaped brush-like copolymers c-PEO-g--P3HT with controlled molecular weight and low PDI(<1.2).The polymers c-PEO-g-P3HT can form the macrocyclic nanostructures with 189±16 nm outer diameter,the width and height were 32±2.1 nm and 2±0.1nm,respectively when self-assembed in toluene.(3)Application study of star-shaped brush-like polymers a-CD-g-[(PEO-g-PAA)-b-PEO]:Using the star-shaped brush-like block copolymers a-CD-g--[(PEO-g-PAA)-b-PEO]as unimolecular micelle template,the TiO2 nanocrystal clusters were prepared in situ by the strong coordination between the precursor TTIP and the carboxyl group of the PAA segments.The results confirmed that we prepared TiO2 nanocrystal clusters successfully.When other conditions were fixed,as the molecular weight of each PEEGE arm in a-CD-g-PEEGE increased from 23.5 kgr/mol to 50.2 kg/mol,the average diameter of TiO2 nanocrystal clusters increased from 28±2.1 nm to 39±3.3 nm.With the increasing of the molar ratio of TTIP to AA unit from 2:1 to 10:1,the size of the nanoparticles of the TiO2 nanocrystal clusters increased from 3.5±0.3 nm to 8.9±1.6 nm.In addition,combined with photocatalytic degradation experiments,we found that the photocatalytic activity of TiO2 nanocrystal clusters increased with the increasing of the size of TiO2 nanoparticles,but it was almost independent of the diameter of the TiO2 nanocrystal clusters.