Handbook of Solvents - George Wypych - ChemTech - Ventech!

264 Valery Yu. Senichev, Vasiliy V. Tereshatov
R van der Waals (intermolecular) radius of a considered atom
hi a height of segment calculated from the formula:
R + di −Ri
hi = R −
2d
2 2 2
i
[5.3.5]
where:
di bond length between two atoms
Ri van der Waals radius of the atom adjacent to the covalently-bonded atoms under
consideration
The increments to the van der Waals volume for more than 200 atoms in various neighborhoods
is available elsewhere. 11
Using data from Tables 5.3.2 and 5.3.3, van der Waals volumes of various molecules
can be calculated. The increments to the cohesion energy are given in Table 5.3.4. An advantage
of this method is that the polymer density that is important for estimation of properties
of polymers that have not yet been synthesized does not need to be known.
The calculation methods of the solubility parameters for polymers have an advantage
over experimental methods that they do not have any prior assumptions regarding interactions
of polymer with solvents. The numerous examples of good correlation between calculated
and experimental parameters of solubility for various solvents support the assumed
additivity of intermolecular interaction energy.
The method has further useful development in calculation of components of solubility
parameters based on principles of Hansen’s approach. 12 It may be expected that useful results
will also come from analysis of donor and acceptor parameters used in TDM-approach
(see Chapter 4).
In Table 5.3.5, the increments required to account for contributions to solubility parameters
related to the dipole-dipole interactions and hydrogen bonds are presented. 13 Table
5.3.6 contains Hansen’s parameters for some common functional groups.
Table 5.3.2. Intermolecular radii of some atoms
Atom R, � Atom R, � Atom R, � Atom R, �
C 1.80 F 1.5 Si 2.10 P 1.90
H 1.17 Cl 1.78 Sn 2.10 Pb 2.20
O 1.36 Br 1.95 As 2.00 B 1.65
N 1.57 I 2.21 S 1.8
Table 5.3.3. Lengths of bonds between atoms
Bond di, � Bond di, � Bond di, � Bond di, �
C−C 1.54 C−F 1.34 C−S 1.76 N−P 1.65
C−C 1.48 C−F 1.31 C=S 1.56 N−P 1.63
1,40 C−Cl 1.77 H−O 1.08 S−S 2.10
C=C 1.34 C−Cl 1.64 H−S 1.33 S−Sn 2.10
C−C arom