Preparation And Penetration Properties Of Porous Polymer Microspheres

Porous polymer micro spheres are widely used in drug carriers,catalyst carriers and ion adsorption due to their large specific surface area,abundant pore channels,and available internal storage space.The internal cavity of porous polymer microspheres can be used as a storage place for various functional substances.In order to make full use of the internal space of porous polymer micro spheres,the simplest,most direct,and effective way is to fill in functional materials from the outside to play a role.Therefore,in order to make the internal storage space of porous polymer microspheres available,the microspheres must have internal and external penetrability.Based on the preliminary work in the laboratory,this paper proposes a solvent volatilization method,using a low-boiling porogen,and controlling the temperature to adjust the synergistic effect of the porogen and the volatile solvent,While the microspheres are solidified.The porogen causes vaporization and expansion to achieve perforation,thereby obtaining polymer micro spheres with a inter-connecting properties.This article first discusses the influencing factors of microsphere's particle size,and then focuses on the effects of polymer concentration,porogen dosage,initial temperature on the micro sphere pore morphology and inter-connecting properties;then exp lores the solvent composition,heating rate,effects of process parameters such as porogen type,porogen dosage,and polymer type on the morphology and inter-connecting properties of microspheres.Finally,microspheres with typical structures were characterized by pore parameters and mechanical properties.Research indicates:1)The stirring rate and protective colloid concentration have a significant effect on the particle size of the microspheres.With the increase of the stirring rate or the increase of the protective colloid concentration,the particle size of the microspheres generally decreases.In the range of 1:3 to 1:10,the particle size of the microspheres does not change significantly,but as the oil-water ratio increases,the microspheres become less and less spherical.When the oil-water ratio is 1:1,not into a ball.2)Polymer concentration,porogen dosage,initial temperature,etc.have a greater impact on the microsphere pore structure and inter-connecting properties With the increase of polymer concentration and the decrease of porogen,the microspheres gradually changed from hollow to porous structure.When the polymer mass fraction is 6%,the microspheres have a hollow structure.When the polymer mass fraction is 8%,10%,12%,15%,the microspheres are porous structures,and as the polymer concentration increases,The pore diameter of the microsphere becomes smaller,and the pore density increases.When the ratio of porogen to polymer is 1:3,the microspheres have a hollow structure;when the ratio of porogen to polymer is reduced to 1:2,1:1.75,1:1.5,1:1,the microspheres have a porous structure.And as the amount of porogen is reduced,the pore diameter of the microspheres decreases and the pore density increases.As the initial temperature of the reaction increases,The interior of the microsphere changes from a porous structure to a hollow structure,and the pore size gradually decreases,and the pore density gradually increases Regardless of the polymer microspheres prepared under any conditions,the permeability of the microspheres to water is closely related to the structure.With the increase of the pore size,the sedimentation rate of the micro spheres in water gradually increases.When the micro spheres are hollow structures The highest sedimentation rate in water3)Under mixed solvent conditions,the pore structure of the microspheres does not change significantly,but the penetrability in water has significantly improved;at different heating rates,the pore structure of the microspheres changes slightly,with the increase of the heating rate,the sedimentation rate of microspheres in water increases first and then decreases.When the elevation rate is 40?/25min,the sedimentation rate of micro spheres is the largest.Exp lore the micro sphere morphology and penetrability under different porogen types,dosages,and different polymer system conditions.The results show that for different porogens,with the growth of the porogen carbon chain,the microspheres gradually change from a porous structure to a hollow structure;as the amount of porogen increases,the microspheres change from a porous structure to a hollow structure;When the polymer is PS and PMMA,the micro spheres are porous,and when the polymer is P(St-MMA)or P(MMA-BA),the microspheres have a hollow structure.Changing the type,amount and polymer type of porogen will affect the pore structure of micro spheres.During the transition of microspheres from porous to hollow,the sedimentation rate of microspheres in water gradually increases.When the micro spheres are hollow,The corresponding settlement rate is the highest in the structure4)Characterizing the pore structure parameters and mechanical properties of the penetrating polymer micro spheres with typical structures,the results show that for two kinds of penetrating porous polymer microspheres with different pore sizes,the pore density increases,pore area increases,pore volume decreases and the porosity decreases of the microspheres with the pore diameter decreases.With the transition of the microspheres from hollow to porous structure,the breaking force of the microspheres gradually increases,and the deformation of the microspheres increases first and then remains almost unchanged.