Controllable preparation of polymer brushes from mesoporous silica SBA-15 via surface-initiated ARGET ATRP
Controllable preparation of polymer brushes from mesoporous silica SBA-15 via surface-initiated ARGET ATRP
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DOI：
10.1016/j.micromeso.2017.12.019
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发表时间：
2018-06
影响因子：
5.2
通讯作者：
Mingsen Chen;L. Qin;Yuanli Liu;Faai Zhang
中科院分区：
文献类型：
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作者：
Mingsen Chen;L. Qin;Yuanli Liu;Faai Zhang
采用电子转移原子转移自由基聚合（ARGET ATRP）再生表面引发剂，在介孔SiO2 SBA-15表面可控接枝聚甲基丙烯酸缩水甘油酯（PGMA）和聚甲基丙烯酸缩水甘油酯-b-聚甲基丙烯酸甲酯（PGMA-PMMA）刷。引发剂2-溴异丁酰溴（BiBB）通过与游离硅醇基团反应固定在SBA-15的内表面。聚合在环己酮/N，N-二甲基甲酰胺混合溶剂中进行。利用混合溶剂的策略产生了合适的聚合速率，并导致在SBA-15框架内的PGMA生长的良好控制，并可以获得具有良好保存的链端官能度的聚合物链。采用凝胶渗透色谱（GPC）、X射线粉末衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、N2吸附/脱附测试、傅立叶变换红外光谱（FT-IR）和热重分析（TGA）对接枝物的分子量、功能化SBA-15的结构、形貌和组成进行了表征。通过调节聚合时间可以控制接枝物的厚度、聚合物接枝密度和分子量。当孔几乎完全被聚合物填充时，失活剂不能有效地扩散以将增长链转化为休眠物质，因此，增加接枝密度导致接枝聚合物链的更高分子量和多分散指数（PDI）值。本工作为制备结构明确的介孔二氧化硅/聚合物杂化材料提供了一条简便的途径。
Surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) was employed for controlled grafting of poly(glycidyl methacrylate) (PGMA) and poly(glycidyl methacrylate)-b-poly(methyl methacrylate) (PGMA-PMMA) brushes from mesoporous silica SBA-15. Initiator 2-bromoisobutyryl bromide (BiBB) was immobilized onto the inner surface of SBA-15 by reaction with free silanol groups. The polymerizations were conducted in the mixed solvents cyclohexanone /N, N-dimethylformamide. The strategy of utilizing mixed solvents gave rise to a suitable polymerization rate and resulted in a good control of the PGMA growth within the SBA-15 framework and could obtain polymer chains with well-preserved chain end functionality. Molecular weight of grafted polymer, structure, morphology, and composition of the functionalized SBA-15 were characterized by using gel permeation chromatography (GPC), X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2adsorption/desorption measurements, fourier transform infrared spectroscope (FT-IR), and thermogravimetry analysis (TGA), respectively. The thickness, polymer grafting density and molecular weight of the grafted polymer can be controlled by adjusting the polymerization time. The deactivator cannot efficient diffuse to convert the propagating chains to the dormant species when the pores are nearly completely filled with the polymer, therefore, increasing grafting density resulted in higher molecular weight and polydispersity index (PDI) values for the grafted polymer chains. This work provides a facile route for preparation of well-defined mesoporous silica/polymer hybrids.