Permanent hydrophilic polymer film with high mechanical property and preparation method thereof

Abstract

The invention discloses a permanent hydrophilic polymer film with a high mechanical property and a preparation method thereof. A porous film is prepared from a hydroxyl-containing polymer which serves as a blend polymer and has high compatibility with polyvinylidene fluoride and a strong adhesion effect with a melt spinning method or coating-rolling preparation method through solid-liquid phase separation of a thermally-induced phase separation technology, so that the porous film with a three-dimensional penetrated mesh-shaped structure can be obtained or controlled easily under control by adjusting the adding amount of the polymer blend; the film is prepared at a temperature which is lower than a curing temperature of a polymer material, so that the problem of decomposition of the blend polymer under the conventional spinodal decomposition film-preparing condition is solved; the blend polymer has a strong adhesion effect, so that the blend polymer can be combined with the polyvinylidene fluoride with high adhesion without falling easily, the adhesion effect is equivalent to binding crosslinking, and the mechanical property of the film can be improved remarkably. Meanwhile, the preparation process of the porous film is simple, has high adaptability, does not require equipment updating, is convenient to popularize and has good industrial prospect.

Description

technical field [0001] The invention relates to the technical field of polymer materials, in particular to a durable hydrophilic polymer film with high mechanical properties and a preparation method thereof. Background technique [0002] Polyvinylidene fluoride is currently widely used to prepare porous membrane materials, and is widely used in water treatment, membrane contactors, battery separators, and medical tissue engineering and other fields. Non-solvent induced phase technique and thermally induced phase separation technique are two commonly used phase inversion techniques for the preparation of porous membranes. Compared with non-solvent-induced phase separation technology, thermally induced phase separation technology has the advantages of easy regulation of pore structure, high membrane mechanical properties, and dry storage of the membrane. It is especially suitable for the preparation of polymer porous membranes without suitable solvents at room temperature. Po...

AI Technical Summary

Problems solved by technology

There are currently three main problems in the preparation of separation membranes by thermally induced phase separation technology: (1) The mechanical properties of the membrane are obtained by increasing the polymer content, which undoubtedly reduces the water flux of the membrane; (2) It is difficult to modify hydrophilicity, The method of blending hydrophilic inorganic nanoparticles is not only difficult to ensure its uniform dispersion in the polymer, but also will be lost with the acid-base washing during the membrane cleaning process and lose the hydrophilic modification effect; (3) only When the spinodal phase separation occurs in the cast film liquid system, the through-network pore structure can be obtained, and the conditions for the spinodal phase separation to occur are difficult to control and the temperature is usually high (about 50 degrees higher than the melting temperature of the polymer).

Studies have shown that in the process of preparing polyvinylidene fluoride porous membranes by thermally induced phase separation technology using binary non-water-soluble mixed diluent systems, if amorphous polysulfone (ChengQ, CuiZY, LiJB, et al., Preparation and performance of polymer electrolyte based on poly (vinylidenefluoride) ) / polysulfoneblendmembraneviathermallyinducedphaseseparationprocessforlithiumionbattery,JournalofPowerSources,2014,266(15):401-413.), due to the almost incompatibility between polysulfone and polyvinylidene fluoride and the solidification and precipitation temperature of polysulfone is lower than that of polyvinylidene fluoride, so polysulfone can As a non-diluent, it destroys the polyvinylidene fluoride to form spherulites, thus forming a network structure surrounded by lamellar crystals, but because there is almost no compatibility between polyvinylidene fluoride and polysulfone, polysulfone When the mass ratio of polyvinylidene fluoride increases to 10 / 100, although a network pore structure is obtained, the film undergoes obvious macroscopic phase separation, and the mechanical properties of the film are significantly reduced

Moreover, since polysulfone is not hydrophilic, the hydrophilicity of the membrane is hardly improved