Specific refractive index increments poly

Dilute solution properties in water are very important for water-soluble polymers [27], not only in their characterization but also in determining their performance under actual use conditions. These polymers include the acrylamide polymers, namely polyacrylamide and its structural variants, whose range of applications encompasses their use as soil modifiers. The results of calculations [28] of the specific refractive index increments of random copolymers of acrylamide with N-benzyl methacrylamide and with N-methyl methacrylamide are shown in Figure 8.3. (See Section 17.E for the method used to calculate the properties of random copolymers.) The details of the calculations (not shown) indicate that (a) the specific volumes of the homopolymers are in the order polyacrylamide < poly(N-benzyl methacrylamide) < poly(N-methyl methacrylamide), and (b) the refractive indices are in the order polyacrylamide poly(N-methyl methacrylamide) poly(N-benzyl methacrylamide). The results shown for the copolymers in Figure 8.3 arise from the multiplicative combination of these trends. 

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