如将苯乙烯蒸气通到金属鈉薄膜上时,可发生由金属鈉催化的离子型聚合。停止通苯乙烯,改通α-甲基苯乙烯时,α-甲基苯乙烯就于生成的聚苯乙烯阴离子端基上继续进行聚合。如此交替通入苯乙烯及α-甲基苯乙烯,即可得到可控制嵌段长度及嵌段数的镶 Metal sodium catalyzed ionic polymerization can occur when styrene vapor is passed over a metal sodium membrane. When stopping the passage of styrene and switching the α-methylstyrene, the α-methylstyrene continues to polymerize on the resulting polystyrene anion end groups. So alternating access to styrene and α-methyl styrene, can be controlled block length and number of blocks inlay