Poly , geometrical parameters

Fig. 12. Variation with the swelling ratio of the polystyrene block of the geometrical parameters of the hexagonal structure. D distance between the axis of two neighbouring cylinders, 2 R diameter of the poly butadiene cylinders, specific surface. Copolymers SB. 31 and SB. 32 containing, respectively, 20.2% and 30.5% polybutadiene.

Fig. 14. Variation with solvent concentration of the geometrical parameters of the body centered cubic structure. Copolymer SB. 122 containing 11% poly butadiene in MEK solution.

We shall examine the range of stability of the ordered structures of copolymers containing an amorphous polystyrene, polybutadiene or poly(ethyl methacrylate) block and acrystallizable polyethylene oxide) (PEO) or poly(e-caprolactone) (PCL) crystallizable block and the factors that determine the existence and the geometrical parameters of such periodic structures. 

Mesophases prepared by dissolution of the copolymer in a preferential solvent for the poly(vinylpyridine) block (acrylic acid, nitromethane, dfoxane, octanol, methylethyl ketone, ethyl acetate, vinyl acetate, styrene and methyl methaaylate) and dry copolymers obtained by slow evaporation of the solvent from the mesophases have been studied by low-angle X-r diffraction electron microscopy Copolymers of isoprene and vinylpyridine exhibit cylindrical hexagonal or lamellar structures dependii upon their comi siton.The influence of the nature, concentration, and polymerization of the solvent, molecular weight and composition of the copolymer, microstructure of the polyisoprene block, and position of the nitrogen atom in the vinylpyridine block on the values of the geometrical parameters of the periodic structures have been establidied ... 

The fact that random and block copolymers of the same composition present the same hexagonal lattice with the same geometrical parameters means that the helices can slide along the direction of their axis and that there is no phase separation between the poly[carbobenzoxy-L-lysine] and the poly[y-benzyl-L-glutamate) blocks. 

The geometrical parameters, V/Lm, cr, and I, required for this computation were obtained as follows. jLm has already been shown to be 0.41 for the polypeptide chain in the a-helical and fully extended forms. Since we have assumed that there is one amino acid residue per statistical element for simplicity, the value of V is 3.6 X 10 cm. A reasonable value for square centimeter cross section of the fiber, is obtained from X-ray data on poly-7-benzyl-L-glutamate. Pauling and Corey (1951) interpreted the X-ray data for this synthetic polypeptide in terms of a parallel array of a-helices with two helices per unit cell of cross section 25.0 X 14.42 A. Dividing the number of chains per unit cell by the cross-sectional... 

Hamza, A.A., and El-Farahaty, K.A., Optical Properties and Geometrical Parameters of Poly(p-phenylene Terephthalamide) Fibers , Textile Research Journal, 56, 580-584, 1986. 

Fig. 2.23. Plots of the current at +0.1 V vs. SCE for a poly(aniline)/poly(vinylsulfonate)-coated glassy carbon electrodes (geometric area 0.38 cm2) rotated at 9 Hz in 0.1 mol dm-3 citrate/phosphate buffer at pH 7 as a function of the total charge passed during polymer growth (Qi). Results are shown for four different concentrations of NADH (O) 0.15 mmol dm- 1 ( ) 0.3 mmol dm-1 (V) 0.6 mmol dm-1 and ( ) 0.8 mmol dm-1. The solid lines were calculated from equations (2.4), (2.19) and (2.20) using the best-fit parameters derived from the analysis of each dataset (given in Table 2.4).

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