甲基丙烯酸十二酯-甲基丙烯酸十八酯共聚物的可控合成及其降凝性能

以甲基丙烯酸十二酯（LMA）、甲基丙烯酸十八酯（SMA）为原料，Salen-N-Salicylaldehyde配合物/偶氮二异丁腈(AIBN)为催化体系，在甲苯溶剂中，通过溶液聚合，在Schlenk装置上合成了甲基丙烯酸十二酯-甲基丙烯酸十八酯共聚物(PHMA)。采用红外光谱、核磁共振氢谱表征了共聚物的结构，利用凝胶渗透色谱(GPC)测定了共聚物的相对分子质量及其分布，并对其降凝性能进行了评价。结果表明：当甲基丙烯酸十八酯与甲基丙烯酸十二酯摩尔比为5∶1、助催化剂(偶氮二异丁腈(AIBN))与催化剂(Salen-N-Salicylaldehyde)摩尔比为6∶1、反应温度为90 ℃、反应时间为10 h、单体总量与催化剂摩尔比为3600∶1时，催化剂的活性为11.035×10.4 g/(mol·h)。合成的共聚物(PHMA)的数均相对分子质量范围为0.864×10⁵～2.532×10⁵，相对分子质量分布指数较窄，反应可控。当油品中共聚物(PHMA)加剂质量分数为0.5%时，可将300～350℃柴油馏分和380～400℃润滑油馏分凝点分别降低7～10 ℃和10～15 ℃，且共聚物的降凝效果比相应均聚物的共混物降凝效果好。

Controllable Synthesis of Lauryl Methacrylate-Stearyl Methyl Acrylate Copolymer and Its Pour Point Depression Performance

Poly (lauryl methacrylate-stearyl methyl acrylate) (PHMA) was controllably synthesized with Salen-Ni-Salicylaldehyde/azodiisobutyronitrile (AIBN) catalyst system by solution polymerization in the toluene through a Schlenk device. The structure of PHMA was characterized by FT-IR and ¹H NMR. Meanwhile, the relative molecular mass and its distribution of the copolymer were determined by gel permeation chromatography (GPC). In addition, the performance of the synthesized pour point depressant was evaluated. Experimental results show that the optimum synthetic conditions are: lauryl methacrylate to stearyl methyl acrylate molar ratio 5∶1, co-catalyst (AIBN) to catalyst (Salen-Ni-Salicylaldehyde) molar ratio 6∶1, reaction temperature 90 ℃, reaction time 10 h, and total monomer to catalyst molar ratio 3600∶1. Under the above conditions, catalyst activity can be 11.035×10⁴ g/(mol·h). Relative molecular mass of the synthesized polymer is in the range of 0.864×10⁵-2.532×10⁵. When 0.5% mass fraction synthesized copolymer was added, pour point of diesel fraction (300-350 ℃) and lubricant fraction (380-400 ℃) could decrease 7-10 ℃ and 10-15 ℃, respectively. It was also found that pour point depression performance of copolymer is better than that of blend polymer.