Size distribution in linear condensation

Flory, P. J., Molecular size distribution in linear condensation polymers,... 

Expressions for molecular size distributions in multifunctional condensation leading to three-dimensional polymers are derived (Flory, 1941, 1946, 1953 Stock-mayer, 1943, 1952, 1953) by following much the same approach as for linear polymers, though with much more difficulty. Only the results of these derivations will, however, be considered here. The derivations are based on three simplifying assumptions of ideal network formation (1) all functional groups of the same type are equally reactive and independent of size of molecules to which they are attached (2) all groups react independently of one another and (3) no intramolecular reactions (cyclization) occur. 

Fig 4 shows the /-plots of the four mesoporous silica samples These plots consist of three linear stages According to Branton et al the initial stage represents multilayer adsorption on the pore wall the following steep one, capillary condensation in mesopores, and the last one, adsorption on the external surface It is noted that the second stage for the two commercial silicas covers a broader / range (over 3 A), compared to the range for the two MCM-41 samples (less than 0 5 A). The capillary condensation over a wide / values implies a broad pore size distribution in the samples. 

Proteins are linear condensation products of various a-L-amino acids (a.a.) that differ in molecular weight, charge, and nonpolar character (Table 7.1), bound by trans-peptide linkages. They differ in number and distribution of various a.a. residues in the molecule. The chemical properties, size of the side chain, and sequence of the a.a. affect the conformation of the molecule, i.e., the secondary structure containing helical regions, [3-plcalcd sheets, and [3-tunis the tertiary structure or the spatial arrangement of the chain and the quaternary structure — the assembly of several polypeptide chains. 

The super-linear region of the isotherm at higher values of relative pressure is used to determine the pore size distribution. As the super-Unear behavior is due to the early onset of condensation in the pores, a mathematical relationship was developed by Barrett, Joyner and Helena (BJH) which equated the change in desorbed volume from one measurement point to the next to a release of condensate from pores of a particular radius, plus the thinning of the adsorbed layer in pores which were already empty [37]. The pore volume is then calculated according to the following equation [37] ... 

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