| Interpolymer specific interactions, attracting extensive attention in recent decades, have been known to result in unusual behavior and material properties that are dramatically different from the nonfunctional parent polymers. It is of great theoretical significance and practical value to study the interpolymer specific interactions in solutions. In this paper, poly (styrene-co-acrylate-co-acrylic acid) as proton-donating polymer (PDF) and poly (styrene-co-acrylate-co-4-vinylpyridine) as proton-accepting polymer (PAP) with various macromolecular chain compositions were prepared by emulsion copolymerization. The emulsion polymerization processes, the specific interpolymer interactions (include hydrogen bond and coordinate complexation interaction) between component polymers and drag reduction of the complexed polymers were investigated.The functional unit and octyl acrylate level on molecular weight of the copolymers were studied. The results show that molecular weights are decreased as a result of increasing the acrylic acid level because the decomposition of K^SaOg is rapid under the acidic medium compared to the neutral medium. Because of the high CM and reactivity ratio of 4-vinylpyridine relative to octyl acrylate, molecular weights are decreased with the increase of 4-vinylpyridine and octyl acrylate level in PAP. By comparison, when the octyl acrylate level is increased, the molecular weight of PDP is enhanced.The compositions of copolymers prepared by emulsion polymerization were characterized by chemical titration and 'HNMR. The apparent molecular weights were determined by SLS. Measurements of the reduced viscosities of the solutions were conducted and the results show that the relationships of the reduced viscosities with concentrations follow Schulz-Blaschke equation. The values of intrinsic viscosity, [r\], and Schulz-Blaschke coefficient, k$B, were determined by the regression analysis of Schulz-Blaschke equation.The interpolymer specific interactions formed by PDP and PAP were studied by viscometry. The effects of the polymer solution concentration, copolymer compositionsand solvent nature on the interpolymer interactions were investigated through a comparison of the reduced viscosity enhancement factor R of the different complexed solutions. The results show that the reduced viscosities of PDP/PAP complexed solutions are higher than weight-average of their constituents when blend concentration is higher than a critical concentration C* and R increases with increasing complexed polymer solution concentration. With the change in molar fraction of AA (FAA) in blends, there existed a Rmax indicating the strongest complexation between PDF and PAP. The interpolymer interaction in toluene is stronger than in THF and toluene/methanol (v/v, 95:5) due to the solvation of the latter two. In addition, the ability to interpolymer interaction between PDF and PAP is increased with increasing OA content and side chain length of acrylate unit in component copolymers due to Van der Waals force between side chains of acrylate unit on unlike macromolecular chains.The decrease of A[r|]m/[r|]m;Cai is the result of increasing the interpolymer specific interaction. In toluene as an inertia solvent not impacting on acid-base interaction, due to steric shield effect of side chains of octyl acrylate unit together with intra-association of carboxyl in PDF, molar fraction of AA corresponding to the minimum of A[t|]m/[r|]m;cai, the complex stoichiometry, increases gradually up to 0.5 as OA content decreases in PDF and relatively insensitive to composition of PAP. Whereas in THF as solvent, the complex stoichiometry is generally independent of composition of PDF and approximates to 0.5 due to THF being capable of destroying interpolymer complexation as well as self-association of carboxyl.Based on the definition of macromolecular aggregation degree and the relationship of reduced viscosity enhancement factor with theoretical specific viscosity, the two interpolymer interaction parameters, ka' and ka, were propos...
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