Liquid Crystal-Templated Synthesis of Anisotropic Ultrafiltration Membranes


Büküşoğlu E. , Karausta A.

Eastern Mediterranean Chemical Engineering Conference 9, Ankara, Türkiye, 30 Ağustos - 01 Eylül 2018, ss.1

  • Basıldığı Şehir: Ankara
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.1

Özet

Liquid crystal (LC) is a phase of material which is intermediate to a crystalline solid and an isotropic liquid such that the molecules flow but retain a degree of long-range orientational ordering. LCs, due to their long range orientational ordering and fluidic properties, can be used in templated synthesis of polymeric materials.[1–4] In the past studies of oil-in-water emulsion based polymeric microparticle synthesis, it was shown that control over the particle shape, organization of polymer chains  and incorporation of porosity can be achieved when LCs were used as the oil phase.[4] In this study, we developed a method that provides determination of the internal structure of the polymeric films by using LCs as template. For the synthesis of the material, we photopolymerized the mixture of reactive (4-(3-acryloyoxypropyloxy) benzoic acid 2-methyl-1,4-phenylene ester (RM257)) and non-reactive (4-cyano-4′-pentylbiphenyl (5CB)) mesogens confined in film geometries with thickness of 20-200 µm, and then extracted nonreactive mesogens with solvent to yield polymeric films of area in the order of 10 cm2. When the polymer films were restricted to an area either through a mechanical or a configurational constraint, open pores were incorporated into the films. The average diameter of the pores was found to be in the range 10-40 nm and can be tuned by varying the reactive mesogen concentration. In fact, the average direction of the pores was found to be determined by the nematic director which can further be controlled by the functionality of the contacting surfaces. Having control over the sizes and directions of the pores has enabled the material to be involved in many application areas. We found that the range of the pore sizes and the alignment behavior of the pores can potentially be used for the ultrafiltration purposes as one of these applications. We demonstrated a successful separation of protein molecules and solid nanoparticles from aqueous media using polymeric films templated from LC media, the mass transfer performance of which was also dependent on the alignment direction of the pores with respect to the surfaces. For the synthesized polymeric materials, we used characterization methods such as thermal, optical, mechanical, nitrogen adsorption porosimetry and electron microscopy. Overall, the outcomes of this study provide basic tools for the synthesis of porous polymeric films with predetermined pore directions that can potentially be suitable for separation purposes, drug delivery, catalysts, etc. 

Liquid crystal (LC) is a phase of material which is intermediate to a crystalline solid and an isotropic liquid such that the molecules flow but retain a degree of long-range orientational ordering. LCs, due to their long range orientational ordering and fluidic properties, can be used in templated synthesis of polymeric materials.[1–4] In the past studies of oil-in-water emulsion based polymeric microparticle synthesis, it was shown that control over the particle shape, organization of polymer chains  and incorporation of porosity can be achieved when LCs were used as the oil phase.[4] In this study, we developed a method that provides determination of the internal structure of the polymeric films by using LCs as template. For the synthesis of the material, we photopolymerized the mixture of reactive (4-(3-acryloyoxypropyloxy) benzoic acid 2-methyl-1,4-phenylene ester (RM257)) and non-reactive (4-cyano-4′-pentylbiphenyl (5CB)) mesogens confined in film geometries with thickness of 20-200 µm, and then extracted nonreactive mesogens with solvent to yield polymeric films of area in the order of 10 cm2. When the polymer films were restricted to an area either through a mechanical or a configurational constraint, open pores were incorporated into the films. The average diameter of the pores was found to be in the range 10-40 nm and can be tuned by varying the reactive mesogen concentration. In fact, the average direction of the pores was found to be determined by the nematic director which can further be controlled by the functionality of the contacting surfaces. Having control over the sizes and directions of the pores has enabled the material to be involved in many application areas. We found that the range of the pore sizes and the alignment behavior of the pores can potentially be used for the ultrafiltration purposes as one of these applications. We demonstrated a successful separation of protein molecules and solid nanoparticles from aqueous media using polymeric films templated from LC media, the mass transfer performance of which was also dependent on the alignment direction of the pores with respect to the surfaces. For the synthesized polymeric materials, we used characterization methods such as thermal, optical, mechanical, nitrogen adsorption porosimetry and electron microscopy. Overall, the outcomes of this study provide basic tools for the synthesis of porous polymeric films with predetermined pore directions that can potentially be suitable for separation purposes, drug delivery, catalysts, etc.