Permanently hydrophilic polymer

Aqueous degreasing processes use alkaline or acid solutions containing chemicals and various additives. These baths become contaminated with oil and when the bath loses its efficiency, its contents have to be renewed, at a high cost, or the oil must be removed. A well tested method for oil removal is based on using CFCC (carbon fibre-carbon composite) filter membranes, and permanently hydrophilic polymer membranes. 

Rabinow BE, Ding YS, Qin C et al (1994) Biomaterials with permanent hydrophilic surfaces and low-protein adsorption properties. J Biomater Sci Polym Ed 6 91-109... 

Permanent modification by covalently bonded or physically adhered phases. Basically, hydrophilic polymers, polar functional groups, or even positively charged residues, for... 

Surface modification with hydrophilic polymers, such as poly(ethylene oxide) (PEO), has been beneficial in improving the blo( compatibility of polymeric biomaterials. Surface-bound PEO is expected to prevent plasma protein adsoiption, platelet adhesion, and bacterial adhesion by the steric repulsion mechanism. PEO-rich surfaces have been prepared either by physical adsorption, or by covalent grafting to the surface. Physically adsorbed PEO homopolymers and copolymers are not very effective since they can be easily displaced from the surface by plasma proteins and cells. Covalent grafting, on the other hand, provides a permanent layer of PEO on the surface. Various methods of PEO grafting to the surface and their effect on plasma protein adsorption, platelet adhesion, and bacterial adhesion is discussed. 

HIPS Hydrophilic polymer Toray Permanent antistatic properties... 

There are two generic types of permanent antistats hydrophilic polymers and inherently conductive polymers. Hydrophilic polymers are currently the dominant permanent antistats in the market. Typical materials that have been used successfully are such polyether block copolymers as PEBAX from Atochem. Typical use levels for these materials are in excess of 10%. B.F. Goodrich is supplying compounds utilizing their permanent antistat additive, STAT-RITE. Office automation equipment, such as fax and copier parts, is the principal application for permanent antistats based on hydrophilic polymers. The most common resins are ABS and high-impact polystyrene (HIPS). 

When the fibrinogen adsorption is reduced upon hydrophilization of Tecoflex surfaces, an improved blood compatibility is expected. Since the hydrophihcity of the surface under common storage conditions is not permanent the development of stable hydrophilic polymer surfaces is desirable. 

More recently controlled free radical polymerization methodologies have been employed for the preparation of novel smart AB diblock copolsrmers. Nitroxide-mediated polymerization was utilized for the synthesis of sodiiun 4-styrenesulfonate-block-sodium 4-vinylbenzoate block copolymer (133). These strong acid/weak acid species exhibit reversible pH-induced self-assembly, with the sodium 4-styrenesulfonate residues remaining ionized and thns permanently hydrophilic over the useful pH range whereas the sodium 4-vinylbenzoate block can be reversible protonated (the carboxylate residue has a pa s 4.0). The same block polymers can also be prepared via RAFT, albeit with somewhat more control. Other workers reported the preparation of such AB diblock copolymers as well as some analogous amine-based styrenic diblock copolymers, (48) shown in Figure 54. 

ADS or HIPS Hydrophilic polymer Adion Asahi Chem. To ray Permanent antistatic properties... 

Incorporating a temperature-responsive polymer structure in block copolymer architectures provides control over the solubility of a part of the copolymer structure. As such, a double hydrophilic block copolymer consisting of a permanently hydrophilic block and a LCST polymer block is converted into an amphiphilic block copolymer when the solution is heated above the LCST (Figure 22.3). This phenomenon has intrigued polymer scientists and the temperature-induced self-assembly of a large variety of different double hydrophilic thermo-responsive block copolymers into micellar structures has been extensively studied. These results have been captured in a large number of review articles and will not be further addressed here (Gil. and Hudson, 2004 Dimitrova et al., 2007 McCormick et al, 2008 Wei et al, 2009 Rodriguez-Hernandez et al, 2005 Smith et al, 2010). 

The use of lightly crosslinked polymers did result in hydrophilic surfaces (contact angle 50°, c-PI, 0.2 M PhTD). However, the surfaces displayed severe cracking after 5 days. Although qualitatively they appeared to remain hydrophilic, reliable contact angle measurements on these surfaces were impossible. Also, the use of a styrene-butadiene-styrene triblock copolymer thermoplastic elastomer did not show improved permanence of the hydrophilicity over other polydienes treated with PhTD. The block copolymer film was cast from toluene, and transmission electron microscopy showed that the continuous phase was the polybutadiene portion of the copolymer. Both polystyrene and polybutadiene domains are present at the surface. This would probably limit the maximum hydrophilicity obtainable since the RTD reagents are not expected to modify the polystyrene domains. 

Table 1 presents the results of fractionations of the DOM. The result of mass balance calculation of the DOC system shows that more than 55 % of the total DOC was retained by XAD-8 resin column, involving the portions of Ho A and HbN/B, and DOC concentrations of the portion eluted by blackwashing (HoA) accounted for 47.4 % of total DOC, as compared with 26.25 % hydrophilic acids (HiA) of the total DOC. More than 11% of the total DOC passed through two resin columns, indicating that small molecular weight polar components were not absorbed onto by XAD-8 and XAD-4. The fractionation did cause potential loss of organic matter by permanent adsorption onto resin s polymers, which were 8.34 % for the XAD-8 resin and 6.41 % for the XAD-4 resin, respectively. 

Vehicles that exhibit the unusual property of Bingham-type plastic rheological flow are characterized by the need to overcome a finite yield stress before flow is initiated. Permanent suspension of most pharmaceutical systems requires yield-stress values of at least 2-5 Pa (20-50 dyn/cm ). Bingham plastic flow is rarely produced by pharmaceutical gums and hydrophilic colloids. National Formulary (NF) carbomers exhibit a sufficiently high yield value at low solution concentration and low viscosity to produce permanent suspensions. The carbomers, however, require a pH value between 6 and 8 for maximum suspension performance. The polymer is essentially incompatible... 

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