结构规整的高密度两亲性接枝聚合物刷的合成及其自组装研究

Synthesis and Self-assembly of Well-defined Polymer Brushes with High Grafting Density of Hydrophobic Poly(ε-caprolactone) and Hydrophilic Poly(2-(dimethylamino)ethyl methacrylate) Side Chains

大分子单体通过两种可控聚合方法,即开环易位聚合(ROMP)和原子转移自由基聚合(ATRP)的联用,合成一种新型两亲性接枝聚合物刷.具有高环张力的降冰片烯单侧链大分子单体norbornene-graft-poly(ε-caprolactone)/Br(PCL-NBE-Br)首先进行ROMP反应,生成聚合物主链,每个单体单元上含有一条PCL链和一个溴官能团;然后用含溴的ROMP聚合物poly(norbornene)-graft-poly(ε-caprolactone)/Br(PCL-PNBE-Br)作为大分子引发剂引发单体2-(dimethyl-amino)ethyl methacrylate)的ATRP反应,生成结构明确的高密度两亲性接枝聚合物刷poly(norbornene)-graft-poly(ε-caprolactone)/poly(2-(dimethylamino)ethyl methacrylate)(PCL-PNBE-PDMAEMA),其主链每个单体单元上均含有一条疏水性PCL接枝链和一条亲水性PDMAEMA接枝链.最后,研究此类高密度两亲性接枝聚合物刷的自组装行为,用动态激光光散射(DLS)研究其在混合溶剂(THF/H2O)中的胶束行为,考察胶束溶液的浓度以及不同长度的亲水性接枝链对胶束尺寸的影响;利用透射电镜(TEM)观察胶束为球形,具有类似线团或草莓状的形态.

A novel amphiphilic polymer brush consisting of alternating poly（ε-caprolactone） （PCL） and poly（2-（dimethylamino）ethyl methacrylate） （PDMAEMA） side chains was synthesized via the combination of two controlled polymerization methods, ring-opening metathesis polymerization （ROMP） and atom transfer radical polymerization （ATRP） with good control over the polymerization processes. ROMP of macromonomer norbornene-graft-poly（ε-caprolactone）/Br （PCL-NBE-Br） was first carried out to convert into a macroinitiator poly（norbornene）-graft-poly（ε-caprolactone）/Br via ＂grafting through＂ technique, and then ATRP of DMAEMA initiated by the macroinitiator was performed to generate the densely grafted polymer brushes via ＂grafting from＂ technique. Thus, the well-defined polymer brushes with two different grafts high densely distributed on the same unit along the backbone were obtained by aforementioned strategy. The molecular weights of the polymer brushes were estimated by gel permeation chromatography and 1H NMR measurements. The self-assembly behavior and the micellar characteristics of the polymer brushes in selective solvent were investigated by DLS and TEM. The TEM image showed spherical micelles with clew or strawberry-like morphology.