| Synthetic hydrophilic polymer has been widely used in thickening,water absorbent resin and intelligent microgels because of its raw materials easily obtained,controllable structures and properties.It has become a research focus in the field to furtherly improve the water absorption and the use safety of the hydrogel,and endow the polymer with high efficiency,functionality and intelligence.In this thesis,a series of functional hydrophilic polymers based on acrylic acid were designed and prepared,and the structure and properties were characterized and studied in detail.(1)The study on synthesis and application of chemically crosslinked acrylic microgel.Acrylic acid microgels were synthesized by the method of precipitation polymerization of acrylic acid with three functional monomer pentaerythritol allyl ether,which was mainly used as water thickener.The structure of the gel was characterized by nuclear magnetic resonance,infrared spectroscopy and scanning electron microscopy,and the dynamic modulus,viscosity,transmittance and polymerization stability were studied.The results showed that the polymerization temperature was 68 oC,the amount of crosslinking agent was 0.4% of monomer concentration,monomer concentration was 14%,the amount of dispersant was 1.2%mass fraction of monomer,and the mole fraction of initiator LPO was 0.15% of monomer,the comprehensive performance of acrylic acid homopolymer microgel was excellent,the viscosity of 0.5% gel dispersion was 8.08×104mPa·s,the viscosity of0.2% gel dispersion was 1.45×104 mPa·s,the transmittance was 97.4%.At the same time,the salt and dilution resistance of the gel was improved by copolymerization with long hydrophobic chain monomer octadecyl acrylate.The results showed that it couldimprove the resistance of dilution,salt tolerance and other rheological properties by the modification of copolymerization with the hydrophobic monomer octadecyl acrylate and formation of physical crosslinking points in the molecular network.While adding comonomer will lead to the increase of powder wetting time,when the comonomer content was 3%,the gel has excellent rheological properties in the low concentration,pH,ionic environment,organic solvent environment and high temperature.(2)The synthesis and properties of supramolecular hydrogels based on coordination.The 4’ position of phenyl was modified by introducing a polymerizable double bond in synthesizing the monomer 4-(2,2’:6’,2″-terpyridin-4’-yl)styrene,The monomer was copolymerized with acrylic acid,a water-soluble linear polymer containing 2,2’:6’,2″-terpyridine ligands was prepared,which can easily coordinate with transition metal ions in aqueous system to form supramolecular gels.The properties of sol and gel such as inherent viscosity,dynamic rheology,absorption rate,thermal analysis and microstructure analysis were fully characterized.The ligands can form coordination interaction with trace metal ions in low concentration solution.The results showed that the high concentration of ligand could be instantly complexation with metal ion solution to be 3D structures,the dynamic modulus of sol and gel changed significantly.Further,the gel showed intelligent environmental response,pH and ionic environment can reduce the water absorbency of the gel,and the crosslinking structures did not damage,which exhibited the metal coordination bond has certain bonding strength.The spectrum of the low concentration of ligand solution and complex showed that the UV-visible absorption peak of the ligand solution is 305 nm,and adding a certain concentration of Fe2+,Ni2+,Cu2+,Cd2+,Zn2+ respectively,the absorption peak redshifted with different degrees,the absorption intensity changed to some extent,and obvious linear relationship is shown in certain metal ions concentration range.The ligand has fluorescence emission properties,while Fe2+,Ni2+,Cu2+ could causes the ligand a quenching on fluorescence emission,and the ligand has fluorescence emission after complexation with Cd2+and Zn2+,and the fluorescence emission redshifted.These molecules exhibit excellent ion sensing function and expected to be applied to trace analysis of specific metal ions in water systems. |
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