Determination Of Properties Of Deep Eutectic Solvents Based On Polymers And Their Applications

Polymerization and polymer processing in deep eutectic solvent（DES）have attracted more and more research attention.For most polymers,their solubilities in DES are very low or even insoluble,so the search for a well-miscible polymer-DES pair or polymer-based DES is of great importance.For the first time,this study discovers 3 polymer-DES systems with good miscibility or polymer-based DES:PEG/ZnCl₂/EG,Boltorn/PEG,and PEI/EG from mass screening.The thermodynamic properties and kinetic properties of the above systems were determined experimentally and relevant tests were conducted to explore the intermolecular interactions in the mixtures.The study results showed the increase in temperature of all systems led to decrease in density and viscosity and increase in conductivity due to the enhancement of molecular thermal motion and weakening of hydrogen bonds.（1）PEG/ZnCl₂/EG system:With increase in ZnCl₂/EG molar ratio,density and viscosity increase and electrical conductivity decreases.As the molecular weight of PEG increases,viscosity and surface tension increase,while density and conductivity show a tendency to decrease-increase and increase-decrease.Sensitivity analysis of conductivity and viscosity to PEG concentration showed that[ZnCl（EG）]⁺has stronger association ability with[ZnCl（EG）²]⁺at low temperature,and the latter becomes stronger at high temperature.The"end"effect of the polymer chain and the effect of the polymer chain entanglement against the hydrogen bond competition results in the"decreasing-increasing"density and the"increasing-decreasing"conductivity of the solution as the molecular weight of the PEG increases.As the molar ratio of ZnCl₂ to EG increases,E_ηand E_κincreases,and V₀ is in the range of 0.61-0.66 cm³/g and increases with PEG concentration.（2）Boltorn/PEG system:The solubility of Boltorn in PEG increases with temperature.For the same PEG,the solubility order is:H20<H30<H40;for the same Boltorn,the solubility of Boltorn in PEG decreases with the molecular weight of PEG.The Boltorn/PEG intermolecular hydrogen bond strength increases with Boltorn concentration.In addition,the particle size of Boltorn in PEG200 is H20>H30>H40,but when the temperature is higher than 323.15 K,the sensitivity of H40 to temperature causes a larger particle size.As H40/PEG200 increases with H40,b_ρdecreases,and E_ηand E_κactivation energy increases.The V₀ of Boltorn/PEG is in the range of 0.86-0.89cm³/g and V₀ increases with the H40 concentration.（3）PEI/EG system:The branched PEI and EG are mutually soluble at any ratio,while the solubility of linear PEI is very low.The increase of PEI concentration causes the hydrogen bond to increase and the ultraviolet absorption peak shifts.The particle size of PEI in EG increases with temperature and the particle size of PEI in EG,water and ethanol is ethanol>water>ethylene glycol.At the same concentration,an increase in the molecular weight of the PEI causes a decrease in density,viscosity,and electrical conductivity.The values of b_ρ,E_η,Eκ,and V₀ obtained from correlation are in the range of 0.88-2.85E-04 kg/m³/K,23.82-48.82,1.72-11.66 kJ/mol,and 0.88-0.98 cm³/g,respectively.PEI/EG is a new type of green CO₂ absorbent.It absorbs CO₂ up to 1.31mol/kg at ambient temperature and pressure.The results show that low density,viscosity and surface tension are beneficial to CO₂ absorption.