Design,Synthesis And Application Of The Molecular Structured Of Carbon Dioxide / Hydrophilic Hydrocarbon Polymers

Liquid or supercritical carbon dioxide?LCO₂ or ScCO₂?is non-toxic,non-polluting,widely sourced,non-combustible,chemically inert,easily realized under supercritical conditions?Tc=31.1?,Pc=7.38 MPa?and recyclable,it is a recognized green solvent,which can greatly reduce environmental pollution if it can replace traditional organic solvents.This paper studied the use of CO₂ as solvent from three aspects from the point of view of preparing emulsion of CO₂/water system.Firstly,using potassium hydroxide as catalyst,two water-soluble monomers,glucose and maltose,were prepared by methacrylamide acylation.Then,CO₂-in-water high internal phase emulsion?80%of internal phase volume?was prepared using commercially available PVA as surfactant,CO₂ as dispersion phase,aqueous solution of the above monomers as continuous phase,and polyethylene glycol acrylate?M_n:1000 g/mol?as crosslinker.The effect of monomer presence on emulsion stability was investigated.Finally,glucosyl and maltose-based macroporous materials were prepared using tetramethylenediamine/ammonium persulfate as initiator.The experimental results show that the obtained emulsion has good stability,the highest stability time is 48 h.The obtained material has rich open-hole structure,the average pore size is 10²5?m,and there is a large number of open-hole structure,which is suitable for the field of tissue engineering.Secondly,the market PVA was selected as the surfactant to study the effect of three structurally similar monomers,methacrylic acid-?-hydroxyethyl ester,methacryloxyethyl trimethyl ammonium chloride,methacrylic acid–N,N?-dimethylaminoethyl ester,on the stability of high internal phase emulsion CO₂ water package.The results show that the presence of HEMA is not conducive to the formation and stability of high internal phase emulsion,while the presence of DMC and DMAEMA can promote the formation of high internal phase emulsion,such as using the aqueous solution of DMC as the continuous phase,the highest can obtain the high internal phase emulsion with 90%volume of internal phase.Finally,polyethylene glycol diacrylate was selected as the cross-linker to prepare two macroporous materials,poly(methacryloxyethyl trimethylammonium chloride group and poly(methacrylic acid N,N?-dimethylaminoethyl ester group.Thirdly,a Gemini surfactant[PVAc₂-?OSO₃Na?₂]was synthesized by Reversible Addition-Fragmentation Chain Transfer?RAFT?polymerization using polyvinyl acetate as the carbon dioxide-friendly group and sodium sulfate as the hydrophilic group.Experimental results show that the surfactant can be dissolved in the CO₂,and the solubility is related to the pressure of the system,the molecular weight of the surfactant.The emulsification experiment found that when the system pressure is low?<20 MPa?,the inner phase?CO₂?volume accounts for 80%of the CO₂-in-water high inner phase emulsion can be formed;when the system pressure is high?>30 MPa?,the water-in-CO₂reverse phase emulsion can be formed.