The isothermal titration calorimetry was applied to investigate the effect of molecular weight (MW) of poly(acrylic acid) (PAA) on the interaction of tetradecyltrimethyl ammonium bromide (C₁₄TAB) with PAA in the bulk phase. The initial formation of PAA/C₁₄TAB complexes was driven by electrostatic interactions between the cationic head groups of C₁₄TAB and the oppositely charged PAA chains, resulting in enhanced hydrophobicity of the complexes. The further addition of C₁₄TAB would induce either complex-C₁₄TAB interaction or complex–complex interaction due to hydrophobic effect. Increasing the MW of PAA would enhance the tendency of complex–complex interaction to form aggregation and even precipitation. For PAA MW ≥ 130,000, significant precipitation of interpolymer complexes was consistently observed and all the obtained critical micelle concentration, phase separation concentration, heat of complexation, and heat of micellization were independent of MW. For PAA MW of 25,000, the complexes formed visible millimetric aggregates at phase separation concentration. With further addition of C₁₄TAB, these aggregates gradually dissolved, and the solution became clear again. For PAA at an MW of ≤5000, turbidity was observed in a wide range of concentrations, but no macroscopic precipitation was observed and the solutions were always homogeneous.

采用等温滴定热法研究了聚丙烯酸（PAA）的分子量（MW）对十四烷基三甲基溴化铵（C ₁₄ TAB）与本体相中PAA相互作用的影响。PAA / C的初始地层₁₄ TAB复合物通过静电相互作用C的阳离子头部基团之间被驱动₁₄ TAB和带相反电荷的PAA链，从而导致复合物的增强的疏水性。进一步添加C ₁₄ TAB会诱导复合物C ₁₄由于疏水作用，TAB相互作用或复合物-复合物相互作用。增加PAA的分子量将增强复合物之间相互作用形成聚集甚至沉淀的趋势。对于PAA MW≥130,000，始终观察到互聚物配合物的大量沉淀，并且所有获得的临界胶束浓度，相分离浓度，络合热和胶束化热均与MW无关。对于25,000的PAA MW，复合物在相分离浓度下形成可见的毫米聚集体。进一步添加C ₁₄TAB，这些聚集体逐渐溶解，溶液再次变澄清。对于分子量≤5000的PAA，在很宽的浓度范围内都能观察到浊度，但是没有观察到宏观的沉淀，溶液始终是均匀的。