Hydrophilic surface modifying macromolecules

Abu Tarboush, B. J., Rana, D., Matsuura, T, Arafat, H. A., and Narbaitz, R. M. 2008. Preparation of thin film composite polyamide membranes for desalination using novel hydrophilic surface modifying macromolecules. Journal of Membrane Science 325 166-175. 

Rana D, Matsuura T, Narbaitz RM, Feng C. Development and characterization of novel hydrophilic surface modifying macromolecule for polymeric membranes. J. Membr. Sci. 2005 249 103. 

B.J. Abu Tarboush, D. Rana, T. Matsuura, H.A. Arafat, R.M. Narbaitz, Fbeparation of thin-fibn-composite polyamide membranes for desalination using novel hydrophilic surface modifying macromolecules, J Memb Sci, 325 (2008) 166-175. 

It is known that, in a polymer blend, thermodynamic incompatibility between polymers usually causes demixing of polymers. If the polymer is equilibrated in air, the polymer with the lowest surface energy (hydrophobic polymer) will concentrate at the air interface and reduce the system s interfacial tension as a consequence. The preferential adsorption of a polymer of lower surface tension at the surface was confirmed by a number of researchers for a miscible blend of two different polymers. Based on this concept, surface modifying macromolecules (SMMs) as surface-active additives were synthesized and blended into polymer solutions of polyethersulfone (PES). Depending on the hydro-phobic or hydrophilic nature of the SMM, the membrane surface becomes either more hydrophobic or more hydrophilic than the base polymeric material. ... 

Surface modification in order to improve the hydrophilicity of membrane surface can be achieved by blending surface modifying macromolecules to the base material. Blends of phenolphthalein poly(ether sulfone) and poly(acrylonitrile-co-acrylamido methylpropane sulfonic acid), a material that contains charged groups, have been prepared. It was found... 

Integrating Hydrophobic Surface-Modifying Macromolecules into Hydrophilic Polymers to Produce Membranes for Membrane Distillation... 

The objectives of this chapter are to describe the fabrication of novel composite hydrophobic/hydrophilic membranes for DCMD using different surface-modifying macromolecules (SMMs) and a hydrophilic polymer polyetherimide (PEI). The membrane characteristics are related to the DCMD performance. 

Qtaishat, M., Rana, D., Matsuura, T. and Khayet, M. 2009b. Effect of surface modifying macromolecules stoichiometric ratio on composite hydrophobic/hydrophilic membranes characteristics and performance in direct contact membrane distillation. A10iE. 55(12) 3145-3151. 

Khayet and Matsuura (2003a) found that the FEP values of both the modihed hydrophilic polyetherimide (PEI) membranes by surface modifying macromolecules (SMMs) and the unmodihed ones increased with the increase of the PEI concentration in... 

Other strategies for producing hydrophobic membranes for MD are the modification of hydrophilic polymers or ceramic materials. Qtaishat et al. [144] produced two different types of hydrophobic surface-modifying macromolecules (SMMs) and prepared hydrophobic/hydrophilic polyetherimide composite membranes. The SMMs blended PEI membranes achieved better DCMD fluxes than those of a commercial PTFE membrane tested under the same conditions. Similarly fluorinated SMMs were used to modify hydrophilic poly(sulfone) [145]. Krajewski et al. [146] used lH,lH,2H,2H-perfluorodecyltriethoxysilane to create a hydrophobic active layer on commercial tubular zirconia membranes supported on alumina. The produced membranes were tested in air-gap MD (AGMD). Hendren et al. [147] used 1H,1H,2H,2H-perfluorodecyltriethoxysilane, trichloromethylsilane, and trimethylchlorosilane to modify, by surface grafting, two types of alumina Anodise ceramic membranes. The authors demonstrated that this surface treatment was effective and tested the produced membranes in DCMD. 

To make the modified surface properties (hydrophilic/hydrophobic) more permanent, siuface-modifying macromolecules (SMMs) were developed. SMM has an amphi-phatic structure consisting theoretically of a main polyurethane chain terminated with two low polarity polymer chains (i.e., fluorine segments) [65]. 

Many other types of solid phase adsorbents, including those based on conventional and specialty materials like restricted access media (RAM), can increase analysis speed and improve assay performance. These types of materials, also known as internal reversed-phase packings, are especially useful for assaying target compounds in biological samples such as serum and plasma. They are chemically modified porous silicas that have hydrophilic external surfaces and restricted-access hydrophobic internal surfaces. The ratio of interior to external surface areas is large. Macromolecules such as proteins cannot enter the pores of the RAM (they are excluded from the hydrophobic internal surface) and they elute quickly through the column. However, the smaller analyte molecules that can enter the pores are retained via interactions with the hydrophobic bonded phase within... 

An important group of surface-active nonionic synthetic polymers (nonionic emulsifiers) are ethylene oxide (block) (co)polymers. They have been widely researched and some interesting results on their behavior in water have been obtained [33]. Amphiphilic PEO copolymers are currently of interest in such applications as polymer emulsifiers, rheology modifiers, drug carriers, polymer blend compatibilizers, and phase transfer catalysts. Examples are block copolymers of EO and styrene, graft or block copolymers with PEO branches anchored to a hydrophilic backbone, and star-shaped macromolecules with PEO arms attached to a hydrophobic core. One of the most interesting findings is that some block micelle systems in fact exists in two populations, i.e., a bimodal size distribution. 

Emulsion electrospinning can be also used. Maretschek et al. produced protein-loaded nanofibre non-wovens based on PLLA via emulsion electrospinning. As the hydrophobicity of the non-woven nanofibres affects the release of macromolecules, PLLA was blended with hydrophilic polymers such as poly(ethylene imine) and poly(L-lysine) to modify the release profiles, resulting in an increase in fibre diameter and a decrease in the specific surface area and highly hydrophobic surfaces. 

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