| In this paper,Waxy corn starch was modified by etherification,using different pretreatment methods to prepare high degree of substitution of hydroxybutyl waxy corn starch to increase its hydrophilicity.Then starch-based thermo-sensitive materials were prepared by radical copolymerization of hydroxybutyl starch and NIPAM.The lowest critical solution temperature of this material is about 32 ?.It can swell and absorb water at low temperature.It can undergo volumetric phase change and shrink when heated.It is a temperature-sensitive intelligent hydrogel.This feature has potential applications in the direction of separation and purification.In order to improve the hydrophilicity of starch,starch was modified by etherification.Etherification of starch with ethylene oxide and propylene oxide is the most common nowadays,and modification of starch with butylene oxide is rare.In this paper,a series of hydroxybutyl waxy corn starch was prepared by acid pretreatment,alkali pretreatment and acid-base synergistic pretreatment.The results showed that hydroxy-butyl waxy corn starch prepared by acid-base synergistic pretreatment has the highest degree of substitution and the highest hydrophilicity.The starch can be dissolved in water after heating,which is favorable for copolymerization with NIPAM.A series of thermosensitive hydrogels with different mass ratios were prepared by copolymerization of NIPAM and hydroxybutyl starch with the highest degree of substitution under the action of crosslinkers,initiators,accelerators and catalysts.The results show that when the starch content is added to help the formation of the pore structure.With the increase of starch content,the pore structure first increases and then decreases,and the equilibrium swelling degree first increases and then decreases.However,when the starch content is more than 50%,many microporous structures are formed in the gel,many pores are penetrated,capillary action is adopted,the specific surface area is increased,and the hydrophilicity of the starch is increased,and the equilibrium swelling degree is increased.The swelling rate is very fast and the rate of retreat swelling is slow.The increase of starch content contributes to the explanation and application of the gel.Therefore,we choose 60% starch as the proportion of the prepared hydrogel,adding different content of glutaraldehyde to study the influence of the fully interpenetrating network on the gel.The results showed that the temperature-sensitive nature of the all-Penetration starchbased hydrogel prepared by one-step method was not destroyed.The temperature of the LCST was about 33 ? by DSC and hot-stage polarization microscope.After glutaraldehyde crosslinking,the equilibrium swelling decreased;glutaraldehyde increased pore structure decreased,the structure collapsed or even superimposed together,reducing the entry of water molecules.The temperature-sensitive properties of intelligent hydrogels can be used to concentrate protein solutions.Porous hydrogels based on starch-based hydrogels were prepared by PEG to obtain fast-reacting porous hydrogels,and the adsorption and concentration of bovine serum albumin(BSA)solutions were investigated.The results showed that PEG with different macroporous structures prepared hydrogels.But its temperature sensitivity basically no change and LCST are about 33 ?.With the increase of pH value,the equilibrium swelling degree of hydrogel decreased,the swelling degree under acidity was the largest,and the minimum under alkaline condition.Moreover,the smart hydrogels can swell repeatedly,which is beneficial to a wider range of applications.Separation and concentration of BSA solution with different hydrogels showed that the separation effect was better with the increase of macropore structure.When the content of PEG is too high,the pores will easily collapse,and the separation effect will decrease.The same hydrogel was used to separate and concentrate BSA solution of different concentrations.The lower the BSA concentration,the better the separation. |
PDF Full Text Request