摘要
本论文采用同时加入核单体和控制滴加的方法,在单体为苄氯/苄溴、核单体为苯及苯系衍生物、催化剂为无水三氯化铁/无水三氯化铝、溶剂为二硫化碳的体系中,成功的一步合成出极窄分子量分布和分子量可控的含有苯甲撑结构的超支化聚合物。并通过对新旧合成方法的比较;单体、核单体、催化剂和滴加方式变化对与实验结果的影响等方面研究,得出了如下的结论:
(1)通过对新旧合成方法的比较,说明同时采用加入核单体和控制滴加的方法比单单加入核单体的方法或者是常规缩聚的方法更容易获得窄分子量分布的超支化聚合物,而且此方法对于分子量的控制也更好。
(2)改变所加入的核单体,在体系中加入活性更高的核单体或者是含B官能团更多的核单体,其所得产物的分子量分散系数与加入原有核单体所得产物的分子量分散系数相差并不大,而两者的分子量却相差较大,原因是活性更高的核单体有空间位阻的影响,含B官能团更多的核单体则受到了反应活性的影响。
(3)改变所加入的单体,发现在单体反应活性越大时采用同时加入核单体和控制滴加的方法,更能体现出对于产物分子量分布的控制。
(4)通过改变所加入催化剂的量,可以得出两方面的结论。其一,产物的分子量分散系数随着催化剂量的减少,其趋势为先变小然后再增大。不过,这种现象存在于一定的区域中,当催化剂的量减少到一定程度时,催化作用急剧下降,不能得到反应后的产物。其二,产物的分子量随催化剂量的变化并不大,基本保持在某个值左右,没有象分子量分散系数一样,有存在最小值的趋势。
(5)对滴加速度的变化的研究并没有得到有规律性的结果。原因应该是由于单体活性不足造成在反应体系中的积累,从而影响了对反应的控制。
上述研究结果表明在实验条件发生变化时,同时采用加入核单体和控制滴加的方法合成所得的超支化聚合物的分子量分布要比采用单单加入核单体和常规的聚合方法所得的要更窄,对于产物分子量的控制也能做的更好。因此,同时采用加入核单体和控制滴加的方法是合成分子量分布极窄和分子量可控的超支化聚合物的十分理想的方法。
本论文还对端基为羧基的超支化聚酯对于环氧树脂的改性作用做了初步的
华东师范大学申请硕士学位论文
研究。通过将进行本体熔融缩聚一步合成所得的端基为梭基的超支化聚酷与环氧
树脂共混后的环氧树脂所做的DMA测试和扫描电子显微镜测试的结果来看,
DMA测试的结果类似于加入了端基为轻基和酷基的超支化聚酷改性的环氧树脂
的DMA结果,其玻璃化转变温度随着超支化聚酷含量的增加而有所下降,并且
在谱图上出现分峰的现象;但是,SEM的结果却刚好与文献所得的结果相反,
未观察到有分相的结构。以上对于端基为梭基的超支化聚酷对环氧树脂改性研究
所得的有关热力学和共混形态方面的结果,从某些方面反映了加入端基为梭基的
超支化聚酷对环氧树脂的影响,但要最终确定这种超支化聚酷对于环氧树脂是否
存在增韧改性作用还需进行抗冲击和拉伸断裂的力学性能测试。
This article provides a controlled one-step process for preparing a hyperbranched polymer with benzenyl unit. The controlled one-step process is to add core monomers and drop monomers into the reaction system. Polymerization of monomer benzyl choride/benzyl bromide have been carried out under condition using ferric chloride anhydnous/aluminum chloride anhydnous catalyst with benzene/benzene derivate used as core monomer and carbon-disulfide as solvent. The molecular weight distribution of resulting hyperbranched polymer is very narrow and the molecular weight can be adjusted. This reaction system is investigated in different condition such as comparing novel synthesis method with old synthesis method, monomer, core monomer, catalytic agent and dropping speed of monomer. The conclusion collectively indicate the following:
(1) Comparing novel synthesis method with old synthesis method, the molecular weight distributions of resulting hyperbranched polymer which are different. The result of novel synthesis method is narrower than those two. And the molecular weight can be controlled easier by the controlled one-step process.
(2) Adding higher reaction activity core monomer and core monomer which have more B group into the reaction system, the molecular weight distributions of resulting hyperbranched polymer which are prepared by these three methods are not different widely. But the molecular weights are different widely. The reason of this phenomenon is that more active core monomers are effected on steric hindrance and the core monomers which have more B group are effected on reaction activity.
(3) The molecular weight of product can be better controlled by the controlled one-step process when monomers have higher reaction activity.
(4) Two conclusion can be gotten when catalytic agent content is changed. First, the molecular weight distributions of product has the minimum at one range when catalytic agent content is decreased. No product can be got when catalytic agent
content is decreased to one value. Second, the molecular weights of product are stable when catalytic agent content is decreased.
(5) No regular pattern is not gained in the research of dropping speed. The reason is that the reaction control is effected by the accumulation of the less monomer activity in the reaction system.
These experiment results show that the controlled one-step process can get the product that has narrower molecular weight distribution and the molecular weight can be better controlled. Therefore, the controlled one-step process is one of ideal processes to preparing hyperbranched polymer.
The carboxyl-funtionalized hyperbranched polyester as tougher for epoxy resin is also studied in this paper. The glass transition temperature of the thermoset decrease with the increased of the content of the hyperbranched polyester content is and there is peak disintegrate in the spectra. The phenomena are the same when the adding hyperbranched polyester which ending-group is hydroxy and ester group. But phase separation is not observed by scanning electron microscope(SEM). The thermomechanical properties and morphyology of blends of the carboxyl funtionalized hyperbranched polyester and epoxy resin is not decisive. To determine whether the carboxyl-funtionalized hyperbranched polyester is tougher for epoxy resin, compact tension experiment is needed.
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