Hydrophobic polymer

Proteins may be stabilized by encapsulation in polyanhydride microspheres. Stability of proteins with respect to water-induced aggregation has been demonstrated to be a function of polymer hydrophobicity for insulin and bovine somatotropin as model proteins (Ron et al., 1993). Encapsulation and enzymatic activity of a variety of other proteins encapsulated in P(SA FAD) was studied by Tabata et al. (1993). 

Catalysts. Catalyst addition was weight percent on polymer solids. Solution polymers employed, for example, 2-hydroxycyclohexane-p-toluene sulfonate or Nacure 155 (King Industries, dlalkylnaphthalene disulfonic acid) as organic soluble acids. A variety of catalysts were tested with emulsion polymers, the best choice varied with base polymer hydrophobicity and functional monomer distribution. Some of these Included p-toluenesulfonic acid (PTSA), ammonium chloride,... 

Both synthetic and natural polymers have superstructures that influence or dictate the properties of the material. Many of these primary, secondary, tertiary, and quaternary structures are influenced in a similar manner. Thus, the primary structure is a driving force for the secondary structure. Allowed and preferred primary and secondary bondings influence structure. For most natural and synthetic polymers, hydrophobic and hydrophilic domains tend to cluster. Thus, most helical structures will have either a hydrophobic or hydrophilic inner core with the opposite outer core resulting from a balance between secondary and primary bonding factors and steric and bond angle constraints. Nature has used these differences in domain character to create the world around us. 

In aqueous solutions of Cm-(EO)n amphiphilic molecules, two interesting features are observed. First, isotropic micellar solutions undergo phase separation on heating. Such behavior is typical of hydrophobic interaction and is also observed for several water-soluble polymers. Hydrophobic interaction results from a change of order in the water structure [54]. Second, at high concentration, liquid crystalline phase behavior is observed with several structures [55]. 

These synthetic hydrophilic polymers hydrophobically modified can be good systems with which to try to establish relationships between chemical structure and interfacial characteristics. It was determined the surface pressure - area (tt - A) isotherms at the air - water interface for poly(4-vinylpyridine) quaternized as a function of the methylene group number of the alkyl lateral chains (n). The film formation of these polymers on aqueous subphase at constant pH and ionic strength... 

Polymer Hydrophobicity/ hydrophilicity Hydrogen-bonding capacity... 

Cordes and co-workers 191 found that the alkaline hydrolysis of p-nitrophenyl hexanoate is subject to catalysis by polyvinylpyridine-based polysoaps. For example, k bs is increased from 0.1 mm to 1.4 mm in the presence of 5 x 10 7 M 38% polysoap (23) (the same material used in the Strauss work). With 5 x 10-7 M polymer having a 15 % dodecyl content, the rate is increased only 3 times above background. The simplest rationale for the kinetics invokes both hydrophobic and electrostatic forces. Thus, dodecyl chains on the polymer hydrophobically bind p-nitrophenyl hexanoate to the polymer surface. Since the polymer possesses a high density of cationic nitrogens, hydroxide ions also accumulate at the polymer surface where they catalyze the hydrolysis of bound ester. Addition of nitrate ion to the aqueous reaction... 

Solid-phase matrices used for hydrophobic interaction chromatography are composed of hydrophilic structures such as agarose, dextran, and hydrophilic polymers. Hydrophobic sites such as methyl, butyl, octyl, dodecyl, and phenyl groups are chemically attached by means of activation reactions. 

Folmer-Andersen JF, Lehn JM (2009) Constitutional adaptation of dynamic polymers hydrophobically driven sequence selection in dynamic covalent polyacylhydrazones. Angew Chem Int Ed Engl 48 7664—7667... 

PCL, PLLA, or both were included. The a-CD-IC resulting from the suspension of PLLA-a-CD-IC in the PCL solution was found to contain only PCL guest chains, while the a-CD-IC resulting from the suspension of PCL-a-CD-IC in the PLLA solution contained only a very small amount of PLLA guest chains. The above results were interpreted to signify the importance of both guest polymer hydrophobicity and guest/host steric compatibility in the formation of polymer-CD-ICs. 

FIG. 11 Schematic illustration of the different types of complexes (a) with long polymers (interchain aggregates are formed essentially in the case of Coulombic complexation of polyelectrolyte and protein) (b) with short amphiphilic polymers (hydrophobic association). 

Porcar I., Cottet H., Gareil P, Tribet C. Association between protein particles and long amphiphilic polymers effect of the polymer hydrophobicity on binding isotherms. Macromolecules 1999 32(ll) 3922-3929. 

The cyclopentadiene structure makes the polymer hydrophobic. The manufacturer s specified contact angle for the polyolefin we used was 94°. The observed contact angle for the untreated Zeonor 1020R in our experiment was 91 2°.21 We found that surface oxidation of cyclo-olefin surface using an... 

Because of the instability of the anhydride bond in the presence of water, special properties are required for stable polyanhydride devices. A critical element in the development of polyanhydride biomaterials is controlling hydrolysis within a polymeric device. To obtain implants where hydrolysis is confined to the surface of the polymer, hydrophobic monomers can be polymerized via anhydride linkages to produce a polymer that resists water penetration, yet degrades into low molecular weight oligomers at the poly-mer/water interface. By modulating the relative hydrophobicity of the matrix, which can be achieved by appropriate selection of monomers, the rate of degradation can then be adjusted. For example, copolymers of sebacic acid, a hydrophilic monomer, with carboxyphenoxypropane, a hydrophobic monomer, yield ... 

Then, the hydrophilic polymer/hydrophobic photoresist coating is baked at an appropriate temperature above the 7g of the hydrophilic polymer, but below or at the Tg of the photoresist polymer. Baking will enhance the diffusion of the melted glassy hydrophilic polymer into the photoresist polymer, leading to the... 

These data indicate that the environment of CnPN in PMA and in PA-I8K2, both at pH 8, where both polyelectrolytes are almost fully ionized, is quite different. C PN experiences a water phase in PMA, and the interaction between CnPN and PMA is electrostatic in nature. In PA-I8K2 solution, CijPN was solubilized in polymer hydrophobic microdomains because of a hydrophobic interaction between the long hydrocarbon chains and because of electrostatic bonding. 

Incorporation of long-chain hydrocarbon hydrophobes into a cellulose ether backbone leads to an interesting new class of polymeric surfactants. Their enhanced solution viscosity can be explained in terms of intermolecular associations via the hydrophobe moieties. Entropic forces cause the polymer hydrophobes to cluster to minimize the disruption of water structure. The same thermodynamic principles that are used to explain the micellization of surfactants can be applied to explain the solution behavior of HMHEC. HMHECs interact with surfactants that modify their solution viscosities. The chemical nature and the concentration of the surfactant dictate its effect on HMHEC solution behavior. The unique rheological properties of HMHEC can be exploited to meet industrial demands for specific formulations and applications. 

OR AQUEOUS POLYMERS, HYDROPHOBIC INTERACTIONS can be important determinants of molecular conformation and intermolecular association. For... 

X HE RHEOLOGICAL PROPERTIES OF WATER-BASED FLUIDS can be controlled with hydrophobically associating polymers. Hydrophobically associating polymers are synthetically derived, water-soluble polymers that contain a small number of oil-soluble or hydrophobic groups. When these polymers are dissolved in aqueous solution, the hydrophobic groups aggregate to minimize their exposure to water, in a fashion analogous to that of surfactants... 

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