Research On Preparation And Properties Of Functional Hydrogel Based On Acrylamide

Hydrogel is a kind of three-dimensional reticulated polymer material with high water content,which is cross-linked physically or chemically through a large number of long molecular chains to form a reticulated structure.Due to its excellent biocompatibility,it is widely used in the field of artificial tissues and organs,drug controlled release,ophthalmic materials,intelligent sensors and so on.However,with the development of the times,the use conditions of materials have become more stringent,and traditional hydrogels have been unable to meet the needs of different fields.How to design and prepare hydrogels with different functions has always been a hot research direction in the polymer field.In this paper,polyacrylamide（PAM）,which has certain stability,good biocompatibility and is easy to modify,was selected as the research object.In order to endow polyacrylamide hydrogel with different functions,it was compounded with other monomers to prepare a series of functional hydrogels with shape memory performance,catalytic performance,adsorption reaction performance,and its performance was studied and analyzed.（1）A chemical shape-memory hydrogel containing crystalline structure is prepared via micellar copolymerization of hydrophilic monomer acrylamide（AM）and hydrophobic monomer tetradecyl acrylate（C14）,hexadecyl acrylate（C16）and octadecyl acrylate（C18）in a sodium dodecyl sulfate（SDS）-sodium chloride（Na Cl）micellar solution.The results of differential scanning calorimetry（DSC）show that there is a crystallization microzone in these hydrogels,which is formed by the long alkyl hydrophobic side chains of alkyl acrylate monomer,and the crystallization temperature changes with the number of carbon atoms in the side chain.Therefore,the physical properties of this type of gel will change significantly near the melting point,showing a sensitivity to temperature.The result of U-type quantitative shape memory experiment show that the fixation rate of PAM/C14,PAM/C16 and PAM/C18composite gel was 67%,95%and 100%respectively,and the recovery rate was 100%.The recovery time was 180s,80s and 20s respectively.So the PAM/C18 composite gel has the best shape memory performance because of their shortest recovery time.（2）The micellar copolymerization method was adopted,with APS initiator and MBA as crosslinking agent,and the feed ratio of C18 was adjusted to copolymerize with AM.The effect of crystalline side chains on the performance of chemical hydrogels was further studied,and the effect of the presence of SDS on the shape memory performance of gel was deeply explored.The results showed that with the increase of C18 content,the transparency,water content and crystallinity of the hydrogel decreased.Through the research and analysis of the thermal behavior of gel and the microstructure evolution behavior at different temperatures,it was found that SDS had no effect on the microstructure evolution of gel,it was only used to solubilize C18 in the synthesis process,the long side chain part similar to C18 in SDS did not produce shape memory ability for gel,and the shape memory ability of gel only came from the hydrophobic monomer C18.Secondly,at the same time and temperature,gel without SDS returns to its original shape faster than gel with SDS,which proves that SDS limits the shape memory behavior of gel to a certain extent and reduces its sensitivity to temperature response.（3）PAM/Fe₃O₄ composite gel catalyst which used for the degradation of methylene blue was prepared by loading Fe₃O₄ nanoparticles on the PAM matrix material.This can solve the problem that Fe₃O₄ nanoparticles are easy to agglomerate.The test results show that the removal rate of methylene blue increases with the content of Fe₃O₄ nanoparticles,PAM/Fe₃O₄（20）can exhibit 95.61%of methylene blue removal within 60 minutes.And at the same time,the produced dominate oxidizing species for MB degradation in the system were identified as SO₄^-·by the radical quenching experiments.The as-prepared catalytic material exhibited unique stability after five consecutive oxidation cycles.（4）The introduction of 2-acrylamido-2-methylpropane sulfonic acid monomer（AMPS）into the above PAM/Fe₃O₄ composite gel improves the adsorption performance of the gel,and prepares the adsorption reactive PAM-AMPS/Fe₃O₄composite gel catalyst to efficiently degrade methylene blue.Firstly,a series of PAM-AMPS gel with different proportions were prepared by adjusting the feeding ratio of monomer AM and AMPS.In the test of adsorption performance,swelling rate and mechanical properties,it was found that with the increase of AMPS content,the adsorption capacity of gel for methylene blue increased,but the mechanical properties became worse.When AM:AMPS was 10:1,the comprehensive performance was the best.PAM-AMPS/Fe₃O₄ composite gel was prepared by adding different contents of Fe₃O₄ into the double monomer.Compared with PAM/Fe₃O₄ composite gel,the adsorption capacity of PAM-AMPS/Fe₃O₄ composite gel for methylene blue was increased by 6 times.Therefore,the gel can enrich PMS and methylene blue through adsorption,improving the efficiency of dye removal.The degradation test results showed that under the synergistic effect of adsorption and catalytic degradation,PAM-AMPS/Fe₃O₄ composite gel could remove 93.84%of methylene blue within 20minutes.Meanwhile,free radical quenching experiments have proved that persulfate radical（SO₄^-·）plays the most important role in the degradation of methylene blue.The cyclic experiment of tertiary adsorption catalytic degradation shows that PAM-AMPS/Fe₃O₄ composite gel has good stability for methylene blue adsorption and the performance of activated PMS for methylene blue degradation,and has good recycling ability.