Hydrophobic modifier

Chain-Growth Associative Thickeners. Preparation of hydrophobically modified, water-soluble polymer in aqueous media by a chain-growth mechanism presents a unique challenge in that the hydrophobically modified monomers are surface active and form micelles (50). Although the initiation and propagation occurs primarily in the aqueous phase, when the propagating radical enters the micelle the hydrophobically modified monomers then polymerize in blocks. In addition, the hydrophobically modified monomer possesses a different reactivity ratio (42) than the unmodified monomer, and the composition of the polymer chain therefore varies considerably with conversion (57). The most extensively studied monomer of this class has been acrylamide, but there have been others such as the modification of PVAlc. Pyridine (58) was one of the first chain-growth polymers to be hydrophobically modified. This modification is a post-polymerization alkylation reaction and produces a random distribution of hydrophobic units. 

Hydrophobically Modified Alkali-Swellable Emulsions. The hydrophobe modification of acryHc acid represents an important class of... 

Hydrophobe-modified copolymers of acrylate esters with acryflc or methacryflc acid are finding increasing use as high quality thickeners for both trade sales and industrial paints (186). Formulations thickened with these unique water-soluble polymers show excellent flow and leveling characteristics. 

A hydrophobically modified guar gum can be used as an additive for drilling, completion, or servicing fluids [93,94]. The modified gum is used together with polymers or reactive clay. 

Guar gum, hydrophobically modified used together with [93]... 

Fluidized aqueous suspensions of 15% by weight or more of hydroxyethyl-cellulose, hydrophobically modified cellulose ether, hydrophobically modified hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, and polyethylene oxide are prepared by adding the polymer to a concentrated sodium formate solution containing xanthan gum as a stabilizer [278]. The xanthan gum is dissolved in water before sodium formate is added. Then the polymer is added to the solution to form a fluid suspension of the polymers. The polymer suspension can serve as an aqueous concentrate for further use. 

Polydimethylsiloxane is active in nonaqueaous systems, but it shows little foam-inhibiting effect in aqueous systems. However, when it is compounded with a hydrophobic-modified silica, a highly active defoamer emerges. 

A. Audibert and J. F. Argillier. Process and water-based fluid utilizing hydrophobically modified guar gums as filtrate (loss) reducer (procede et fluide a base d eau utilisant des guars modifiees hydrophobiquement comme reducteur de filtrat). Patent EP 722036, 1996. 

A. Audibert, J. F. Argillier, L. Bailey, and P. I. Reid. Procedure and water-based fluid utilizing hydrophobically modified cellulose derivatives as filtrate reducer. Patent EP 670359, 1995. 

M. Ramesh and A. Sivakumar. Hydrophobically-modified demulsifiers for oil-in-water systems. Patent US 5635112, 1997. 

A class of systems extensively investigated by means of PFG-NMR are colloids. They are usually hydrophobically modified water-soluble polymers, that is, polymers with a water-soluble skeleton bearing one or more hydrophobic units, which allow the self-assembling of the polymer in water solution and the interaction with surfactants.77... 

Hydrophobically modified HA derivatives,91 obtained through the partial esterification of the HA carboxyl groups with methylprednisolone (45% in HYCp45 and 60% in HYCp60),92 have been deeply studied 93 A key point prior to any in vivo study of the biomaterial is the assessment of the so-called "stealth character" of the species itself. Such characteristic corresponds to be invisible towards the immune system, so that colloids are not recognized as foreign objects by body fluid components, as plasma proteins fibrinogen, BSA and lipidic components.94,95... 

Talhout, R. Villa, A. Mark, A.E. Engeberts, J.B.F.N., Understanding binding affinity a combined isothermal tritration calorimetry/molecular dynamics study of the binding of a series of hydrophobically modified benzamidinium chloride inhibitors to trypsin, J. Am. Chem. Soc. 2003,125, 10570-10579. 

Fig. 3.5 Representation of a scheme of an experiment (upper set of drawings) and the obtained experimental results presented as AFM images (middle part) and cross-sectional profiles (bottom) that provides evidence of silica nucleation and shell formation on biopolymer macromolecules. Scheme of experiment. This includes the following main steps. 1. Protection of the mica surface against silica precipitation. It was covered with a fatty (ara-chidic) acid monolayer transferred from a water substrate with the Langmuir-Blodgett technique. This made the mica surface hydrophobic because of the orientation of the acid molecules with their hydrocarbon chains pointing outwards. 2. Adsorption of carbohydrate macromolecules. Hydrophobically modified cationic hydroxyethylcellulose was adsorbed from an aqueous solution. Hydrocarbon chains of polysaccharide served as anchors to fix the biomacromolecules firmly onto the acid monolayer. 3. Surface treatment by silica precursor. The mica covered with an acid mono-...

Philipp A, Zhao X, Tarcha P, Wagner E, Zintchenko A (2009) Hydrophobically modified oligoethylenimines as highly efficient transfection agents for siRNA delivery. Bioconjug Orem 20 2055-2061... 

Recently, many studies have focused on self-assembled biodegradable nanoparticles for biomedical and pharmaceutical applications. Nanoparticles fabricated by the self-assembly of amphiphilic block copolymers or hydrophobically modified polymers have been explored as drug carrier systems. In general, these amphiphilic copolymers consisting of hydrophilic and hydrophobic segments are capable of forming polymeric structures in aqueous solutions via hydrophobic interactions. These self-assembled nanoparticles are composed of an inner core of hydrophobic moieties and an outer shell of hydrophilic groups [35, 36]. 

Leonard M, Boisseson MRD, Hubert P et al (2004) Hydrophobically modified alginate hydrogels as protein carriers with specific controlled release properties. J Control Release 98 395 105... 

Akagi T, Higashi M, Kaneko T et al (2005) In vitro enzymatic degradation of nanoparticles prepared from hydrophobically-modified poly (y-glutamic acid). Macromol Biosci 5 598-602... 

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