Reactivity ratios are a pair of parameters (r1 and r2) that describe the relative reactivity of two monomers in a copolymerization reaction. They reflect the tendency of a growing polymer chain with a specific terminal monomer unit to add the same monomer (r1) or the other monomer (r2). Reactivity ratios are important for predicting the composition and microstructure of copolymers.

反应活性比是一对参数（r1 和 r2），描述了共聚合反应中两种单体的相对反应活性。它们反映了具有特定末端单体单元的不断增长的聚合物链添加相同单体 (r1) 或其他单体 (r2) 的趋势。反应活性比对于预测共聚物的组成和微观结构很重要。