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首页> 外文期刊>RSC Advances >Sub-5 μm balls possessing forest-like poly(methyloxazoline)/polyethyleneimine side chains and templated silica microballs with unusual internal structures
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Sub-5 μm balls possessing forest-like poly(methyloxazoline)/polyethyleneimine side chains and templated silica microballs with unusual internal structures

机译：具有森林般的聚（甲基恶唑啉）/聚乙烯亚胺侧链的亚5μm球和内部结构异常的模板化二氧化硅微球

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摘要

Herein, sub-5 μm microballs, with unusual forest-like structures consisting of a polystyrene network and forest-like poly(2-methyl-2-oxazoline) (PMOZ) and/or linear polyethyleneimine (LPEI) side chains, were synthesized by combining two isolated processes. The first process is the dispersion radical polymerization of 4-chloromethylstyrene (CMS) and divinylbenzene (DVB) in the presence of a stabilizer, polyvinylpyrrolidone (PVP), using 2,2′-azobis(isobutyronitrile) (AIBN) as an initiator, which produces a poly(4-chloromethylstyrene) type microgel (μ-PStCl). The second process is the cationic ring-opening polymerization of 2-methyl-2-oxazoline (MOZ) using μ-PStCl as a solid initiator, which produces poly(2-methyl-2-oxazoline)-grafted microballs (μ-PSt-g-PMOZ). The latter, possessing PMOZ side chains, was transformed into poly(ethyleneimine)-grafted microballs (μ-PSt-g-PEI) via treatment with HCl (aq). Moreover, the three types of microballs μ-PStCl, μ-PSt-g-PMOZ, and μ-PSt-g-PEI of 1–3 micrometer in diameter were characterized by FT-IR, 13C CP/MAS NMR, elemental analysis, XRD, and SEM. Both the microballs μ-PSt-g-PMOZ and μ-PSt-g-PEI, which resembled the assemblies of hydrophilic comb polymers in their chemical structure, exhibited good wettability in an aqueous phase. In particular, the μ-PSt-g-PEI microballs, which have forest-like basic polyamine chains throughout the microballs, act as catalytic templates in the hydrolytic polycondensation of tetramethoxysilane (TMOS) at room temperature to produce polymer/silica hybrid microballs of μ-PSt-g-PEI@SiO2 with 2.5–3.5 μm diameter and 35–70 wt% silica content depending upon the mediation conditions. Calcination of the μ-PSt-g-PEI@SiO2 hybrid microballs at 700, 800, and 900 °C resulted in silica microballs possessing 2–4 nm mesopores with reduced diameter from 3.5 to 1.2 μm and reduced BET surface area from 582 to 189 m2 g?1. It was confirmed that the sub-5 μm microballs of μ-PSt-g-PEI were very effective catalytic templates for the construction of silica microballs of different sizes (1–4 μm), different surface areas, and different (large hollow or co-continuous) internal structures.
机译：在此，合成了亚5微米以下的微球，其具有由聚苯乙烯网络和森林状聚（2-甲基-2-恶唑啉）（PMOZ）和/或线性聚乙烯亚胺（LPEI）侧链组成的异常森林状结构，结合两个孤立的过程。第一个过程是在2,2'-偶氮二（异丁腈）（AIBN）作为引发剂的情况下，在稳定剂聚乙烯吡咯烷酮（PVP）的存在下，对4-氯甲基苯乙烯（CMS）和二乙烯基苯（DVB）进行分散自由基聚合，产生聚（4-氯甲基苯乙烯）型微凝胶（μ-PStCl）。第二个过程是使用μ-PStCl作为固体引发剂的2-甲基-2-恶唑啉（MOZ）的阳离子开环聚合反应，该反应产生了聚（2-甲基-2-恶唑啉）接枝的微球（μ-PSt- g -PMOZ）。后者具有PMOZ侧链，通过用HCl（aq）处理，转化为聚乙烯亚胺接枝的微球（μ-PSt- g -PEI）。此外，表征了三种直径为1-3微米的微球μ-PStCl，μ-PSt- g -PMOZ和μ-PSt- g -PEI FT-IR， 13 C CP / MAS NMR，元素分析，XRD和SEM进行分析。 μ-PSt- g -PMOZ和μ-PSt- g -PEI的微球在化学结构上均类似于亲水性梳状聚合物的组装体，在水中的润湿性良好。水相。特别是，μ-PSt- g -PEI微球在整个微球中都具有类似森林的碱性多胺链，在室温下四甲氧基硅烷（TMOS）水解缩聚反应中作为催化模板发挥作用， μ-PSt- g -PEI @ SiO 2 的聚合物/二氧化硅杂化微球，直径为2.5–3.5μm，二氧化硅含量为35–70 wt％内容取决于调解条件。在700、800和900°C下煅烧μ-PSt- g -PEI @ SiO 2 杂化微球导致二氧化硅微球具有2-4 nm中孔，直径从3.5减小到1.2μm，BET表面积从582减小到189 m 2 g ？1 。已证实，μ-PSt- g -PEI的亚5μm亚微米微球是构建不同尺寸（1-4μm），不同表面积的二氧化硅微球的非常有效的催化模板。和不同的（大型空心或共同连续）内部结构。

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