Polyaldehyde

Selective staining of polysaccharide in the cell is said to depend upon the oxidizing action of periodate on such chemical configurations as a, p glycols and a-hydroxyketones. Polyaldehydes generated by this selective oxidation react with sulfite-decolorized fuchsin. Polysaccharide areas in the cell are colored red by the stain. 

Figure 25.12 Dextran polymers can be oxidized with sodium periodate to create a polyaldehyde derivative. Note that additional oxidation may occur to cleave off another carbon atom and create an aldehyde on the adjacent C—OH group.

Figure 25.13 Polyaldehyde dextran may be used as a multifunctional crosslinking agent for the coupling of amine-containing molecules. Reductive amination creates secondary amine or tertiary amine linkages.

The following protocol for creating the polyaldehyde dextran derivative is based on the method of Bernstein et al. (1978). 

Remove excess reactant by extensive dialysis against water. The purified polyaldehyde dextran may be lyophilized for long-term storage. 

Prepare polyaldehyde dextran according to the method of Section 2.1 (this chapter). 

Dissolve polyaldehyde dextran in the ethylene diamine (or adipic dihydrazide) solution at a concentration of 25 mg/ml. 

Figure 25.19 Polyaldehyde dextran may be modified with the hydrazide end of M2C2H to create a thiol-reactive polymer.

Heindel, N.D., Zhao, H., Leiby, J., VanDongen, J.M., Lacey, C.J., Lima, D.A., Shabsoug, B., and Buzby, J.H. (1990) Hydrazide pharmaceuticals as conjugates to polyaldehyde dextran Syntheses, characterization, and stability. Bioconjugate Chem. 1, 77-82. 

Zhao, H., and Heindel, N.D. (1991) Determination of degree of substitution of formyl groups in polyaldehyde dextran. Pharm. Res. 8, 400M02. 

Lung, kidney liver parts polyester, polyaldehyde, PVC... 

Ito has also extended this type of photochemistry to the electron-beam-induced catalytic acidolysis of acid-labile main chain acetal linkages in polyphthaldehyde. These polymers, like the poly(2-methylpentene-l-suIfone) (PMPS) sensitizer in NPR resist described earlier have ceiling temperatures on the order of -40 °C. As normally used, the polyaldehydes are end-capped by acylation or alkylation and are thus quite stable. The main chain bonds are very sensitive to acid-catalyzed cleavage which in turn allows the whole chain to revert to monomer in an unzipping sequence similar to that occuring in irradiated PMPS. Irradiation of polyphthaldehyde containing 10% of a suitable sensitizer such as triphenylsulfonium hexafluoroarsenate with either deep UV... 

In this article we will describe two different types of positive electron-beam resists, which were briefly reported in our previous communications (2,3). One is the homopolymer or copolymer with methyl methacrylate and a-substituted benzyl methacrylate, which forms methacrylic acid units in the polymer chain on exposure to an electron-beam and can be developed by using an alkaline solution developer. In this case, the structural change in the side group of the polymer effectively alters the solubility properties of the exposed polymer, and excellent contrast between the exposed and unexposed areas is obtained. The other is a self developing polyaldehyde resist, which is depolymerized into a volatile monomer upon electron-beam exposure. The sensitivity was extremely high without using any sensitizer. 

The resist films of polyaldehydes were made from xylene, toluene or chloroform solutions by spin-coating or dip-coating, and were 0.04 3.4 mt in thickness. 

Another inconvenience of polyaldehyde resists was the softness of the films. The copolymer of 4,4,4-triphenylbutanal and butanal prepared using a C2H5MgBr-(-)-sparteine complex (24) dissolves easily in certain organic solvents and forms a fairly hard resist film. The copolymer containing 8 mol% of the former monomer units showed a sensitivity of 1.7 x 10-6 C/cm2 (25). 

The polyaldehydes obtained on periodate oxidation of polysaccharides are alkali-labile, as discussed in previous articles in this Series.74,103 The products are, however, generally intractable mixtures, and this mode of degrading polysaccharides (with alkali) has... 

Furukawa, J., Saegusa,T., Fujii,H., Kawasaki, A., Imai,H., Fujii,Y. Crystalline polyaldehydes. Makromol. Chem. 37,149 (I960). 

Isomorphous replacement in isotactic polyaldehydes was shown by A. Tanake, Y. Hozumi, K. Hatada, S. Endo, and R. Fujishige (42). These authors studied the binary polymer systems formed by acetaldehyde, propionaldehyde, n-butyraldehyde, iso-butyraldehyde and w-heptanal. All the copolymers are crystalline over the whole range of compositions. In the case of binary copolymers of acetaldehyde, propionaldehyde and K-butyraldehyde the unit cells have the same tetragonal space group UJa, with the same chain axis (4.8 A), while the dimensions of the a axis change continuously as a function of the copolymer composition. In the case of copolymers of isobutyraldehyde with other aldehydes, the continuous variation of the lattice constants a and c were observed. 

Statistical substitution between chains having the same helix handedness, but different orientations of the side groups ("up" and "down chains) was proved or at least suggested as probable for a variety of isotactic vinyl polymers. In particular we will mention here the cases of isotactic polypropylene (53), isotactic poly-w-butene-1 (54), isotactic polyaldehydes (55) and isotactic-1,2-poly-4-methylpentadiene (56). 

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