Liquid-polymer mixed-matrix preparation

Preparation of Liquid-Polymer Mixed-Matrix Membranes In one... 

In another approach, a liquid-polymer mixed-matrix membrane was prepared by first soaking a wet porous support membrane (e.g., polysulfone) in a solution containing liquid fillers (e.g., glycerol) for a period of 2 h, followed by drying for a period of 10 h at room temperature. The treated porous support membrane was then coated with the emulsified solution described above to form a liquid-polymer mixed-matrix membrane. 

Another potential application for zeolite/polymer mixed-matrix membranes is the separation of various liquid chemical mixtures via pervaporation. Pervapora-tion is a promising membrane-based technique for the separation of liquid chemical mixtures, especially in azeotropic or close-boihng solutions. Polydime thy 1-siloxane (PDMS), which is a hydrophobic polymer, has been widely used as the continuous polymer matrix for preparing hydrophobic mixed-matrix membranes. To achieve good compatibility and adhesion between the zeolite particles and the PDMS polymer, ZSM-5 was incorporated into the PDMS polymer matrix, the resulting ZS M -5/ P DM S mixed-matrix membranes showed simultaneous enhancement in selectivity and flux for the separation of isopropyl alcohol from water. It was demonstrated that the separation performance of these membranes was affected by the concentration of the isopropyl alcohol in the feed [96]. 

Polymer-dispersed liquid crystals (PDLCs) are made up of nematic liquid crystals dispersed in a solid continuous polymer matrix. These are prepared by mixing a reactive monomer into a non-polymerisable LC medium and then polymerising the reactive monomer to create a polymer matrix, at the same time capturing the LCs as dispersed droplets, greater than 1 pm in diameter, i.e. the wavelength of visible light.3 -33... 

The interface in a polymer blend is important both in the preparation of the blend and in determining its ultimate properties. During mechanical melt mixing, the break up of the drops of one polymer within a matrix of the other is determined in part by the interfacial tension. For a Newtonian liquid drop in a Newtonian matrix the process can be simply described. In a shear... 

The ratio of polymer matrix components, a fast curing TMPTA and < >-metha-cryloxyalkyltrialkoxysilane, was changed from 80 10 to 10 80 wt% in the relative ratio with 10 wt% reactive diluent NVP. Recording solution was prepared by mixing the matrix components (65 wt%) and liquid crystal (35 wt%). 

The symmetry approach to ferroelectricity in liquid crystals can be realized not only for individual substances but also for multicomponent systems. For low-molar-mass ferroelectric liquid crystals, most applications use LC mixtures with two main components a nonchiral matrix providing the tilted smectic structure and a chiral dopant [7]. As for the preparation of FLCPs, mixing of a smectic C polymer with a chiral dopant also results in a ferroelectric chiral smectic system [74]. Japanese authors [75,76] have carried out systematic studies on mixing tilted smectic polymers with low-molar-mass ferroelectric liquid crystals. 

Essentially two strategies have been considered to prepare polymerlayered silicate nanocomposites. In the so-called intercalative polymerization, the layered silicate is swollen within the liquid monomer (or a monomer solution) so as the polymer formation can occur in between the intercalated sheets. Polymerization is usually promoted either by heat or an appropriate catalyst. In another technique, the layered silicate is mixed with the polymer matrix in the molten state. Under these conditions and if the layer surfaces are enough compatible with the chosen polymer, the polymer can crawl into the interlayer space and form either an intercalated or an exfoliated nanocomposite. In this melt intercalation technique, no solvent is required. 

In this chapter I have reviewed some experimental results of highly dispersed (nearly exfoliated) nanocomposites, prepared by mixing, based on thermoplastic polymers, block copolymers, and liquid-crystalline polymers. In this chapter I have presented the experimental results mostly from my own publications during the past 5 years, because I know very well how the experimental results were obtained and I have confidence in the accuracy of the experimental results. This does not imply that the experimental results reported in the literature by other investigators are less important than mine. However, the readers are reminded that the primary objective of this chapter is to summarize the importance (or necessity) of having sfiong attractive interactions, via specific interaction, between the polymer matrix and the surface of clay, pristine or chemically modified, in order to obtain exfoliated nanocomposites. 

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