Hydrophilicity polyamides

In connection with studies on the ring-opening polymerization of cyclic acetals, we have undertaken investigations on the polymerization of bicyclic acetals, bicyclic oxalactone, and bicyclic oxalactam, which yield polysaccharide analogs, macrocyclic oligoesters, and a hydrophilic polyamide, respectively, some of which can be expected to be useful as novel speciality polymers. The monomers employed in the studies were prepared via synthetic routes presented in Scheme 1, starting from 3,4-dihydro-2H-pyran-2-carbaldehyde (acrolein dimer) I. 

The formulator must be aware of the potential for binding when filtering protein solutions. Because of the cost of most protein materials, a membrane should be used that minimizes protein adsorption to the membrane surface. Typical filter media that minimize this binding include hydrophilic polyvinylidene difluoride and hydroxyl-modified hydrophilic polyamide membranes [17a]. Filter suppliers will evaluate the compatibility of the drug product with their membrane media and also validate bacterial retention of the selected membrane. 

Some other water-soluble fully sugar-based polyamides have also been obtained from activated hexaric acids 28 and 29 and the 1,5-diamino-2,3,4-tri-O-methyl-pentitols (37 and 38) and a series of hydrophilic polyamides (PA-nSu) derived from these hexaric acids and noncarbohydrate alkylenediamines with even numbers of methylenes n = 4, 6, 8, 10, 12) has also been prepared [80]. 

Hydrophilic polyamides 88 and 89 were prepared by the polycondensation reaction of 2,3,4,5-tetra-O-acetyl-galactaroyl dichloride with the diaminoanhy-droalditols 54-57 [82]. 

A new class of hydrophilic polyamides, poly(tetrahydropyran-2,6-diylimino-carbonyl) 1 was prepared by the anionic polymerization of a bicyclic oxalactam (abbreviated as BOL, 2) 38-42). The resulting polyamide / has glass transition, fusion, and decomposition points at 130,260-285, and 315 °C, respectively, and its membrane can be obtained by casting from a polyBOL solution. The solubility parameter... 

The nature of the supporting membrane also plays an important role in the performance of supporting ionic liquid membranes. In this context, de los Rios et al. [3] nsed two polymeric membranes, nylon and mitex, as supporting membranes. Nylon membrane was a hydrophilic polyamide membrane with a pore size of 0.45 pm and a thickness of 170 pm. Mitex membrane was a hydrophobic polytetrafluoroethylene membrane with a pore size of 10 pm and a thickness of 130 pm. It was observed that less ionic liquid was absorbed into the mitex membranes, which was explained by the different textural properties and the high hydrophobic character of these membranes, which probably restrict interaction with the hydrophilic ionic liquids used [27]. 

External plasticization is a solvation (swelling) process in which the low molecular plasticizer is bound to the polymer by secondary valence forces. The effectiveness of external plasticization, which only the processor can access, is particularly pronounced in polar polymers (for example the softening effect of moisture in hydrophilic polyamides). The solvation is not a chemical reaction, despite the strong dipolar forces involved. 

A variety of membrane materials have been tested for SILM preparation, including, among others, polymeric Nylon (hydrophilic polyamide) [57] and PTFE (hydrophobic polytetrafluoroethylene) [58], PES (hydrophiHc polyethersuUbne) [59,... 

HYDROPHILIC POLYAMIDE MEMBRANE PREPARED FROM OPTICALLY ACTIVE BICYCLIC OXALACTAM... 

The electrical conductivity of hydrophilic polyamides " and the photoconductivity of nylon-6,6" are reported. The time dependence of two transient photocurrents suggest the possible formation of a space charge in the polymer. Time-dependent effects in the form of creep measurements have also been used to examine the influence of moisture on the behaviour of nylon-6,6. Other low molecular weight molecules, whose effects on the properties of this polymer have been reported are surfactant and both acid and disperse dyes. Also with a textile connotation was a paper with more general application describing the determination of amino-acid N groups in nylon-6 and -6,6. ... 

Figure 13.9 gives an example of droplet volume density distributions of emulsions obtained by pressing an emulsion premix through a membrane at transmembrane pressure differences varying from 3 bar to 11 bar. These pressure differences are 7.5- to 27.5-fold the minimum pressure difference required (capillary pressure). A hydrophilic polyamide membrane with a mean pore size of 0.8 pm was used. The emulsion premix consisted of 20% dispersed phase (vegetable oil). As continuous phase water containing emulsifier Tween 80 at a concentration of 2% was used. The Sauter diameter of the emulsion premix was X3,2 = 25 pm. 

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