Sulfate-based anionic diblock copolymer nanoparticles for efficient occlusion within zinc oxide.
Sulfate-based anionic diblock copolymer nanoparticles for efficient occlusion within zinc oxide.
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DOI：
10.1039/c5nr00535c
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发表时间：
2015-04
期刊：
影响因子：
6.7
通讯作者：
Yin Ning;L. Fielding;Thomas S. Andrews;D. Growney;S. Armes
中科院分区：
文献类型：
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作者：
Yin Ning;L. Fielding;Thomas S. Andrews;D. Growney;S. Armes
共聚物颗粒在无机晶体宿主内的遮挡不仅为理解结晶过程提供了一个模型，而且可能为制备具有新兴性能的新型纳米复合材料提供了一条直接途径。本文通过可逆加成-断裂链转移（RAFT）水乳液聚合，通过聚合诱导自组装（PISA）合成了一系列新的定义良好的阴离子二嵌段共聚物纳米颗粒，并对其作为水溶液中原位形成ZnO的晶体习惯调节剂进行了评价。系统研究表明，阴离子稳定剂嵌段的化学性质（即硫酸盐基还是羧酸基）和平均聚合度（DP）在决定晶体形态方面起着至关重要的作用。特别是，硫酸盐功能化纳米颗粒有效地结合在ZnO晶体中，而羧酸功能化纳米颗粒被排除在外，因此阴离子特性是成功遮挡的必要条件，但不是充分条件。此外，根据硫酸盐基纳米颗粒浓度的不同，ZnO相内纳米颗粒的遮挡程度可高达23%（质量比）。研究了合成的纳米复合晶体的光学性质、化学组成和晶体结构，并根据观察到的ZnO在硫酸盐基阴离子纳米粒子存在下的形貌演变，提出了一种遮挡机制。最后，在多孔ZnO颗粒（有机纳米颗粒煅烧后产生）上控制沉积5nm的金溶胶，显著提高了暴露于相对弱紫外源下模型罗丹明B染料的光催化分解速率。
Occlusion of copolymer particles within inorganic crystalline hosts not only provides a model for understanding the crystallisation process, but also may offer a direct route for the preparation of novel nanocomposite materials with emergent properties. In the present paper, a series of new well-defined anionic diblock copolymer nanoparticles are synthesised by polymerisation-induced self-assembly (PISA) via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerisation and then evaluated as crystal habit modifiers for the in situ formation of ZnO in aqueous solution. Systematic studies indicate that both the chemical nature (i.e. whether sulfate-based or carboxylate-based) and the mean degree of polymerisation (DP) of the anionic stabiliser block play vital roles in determining the crystal morphology. In particular, sulfate-functionalised nanoparticles are efficiently incorporated within the ZnO crystals whereas carboxylate-functionalised nanoparticles are excluded, thus anionic character is a necessary but not sufficient condition for successful occlusion. Moreover, the extent of nanoparticle occlusion within the ZnO phase can be as high as 23% by mass depending on the sulfate-based nanoparticle concentration. The optical properties, chemical composition and crystal structure of the resulting nanocomposite crystals are evaluated and an occlusion mechanism is proposed based on the observed evolution of the ZnO morphology in the presence of sulfate-based anionic nanoparticles. Finally, controlled deposition of a 5 nm gold sol onto porous ZnO particles (produced after calcination of the organic nanoparticles) significantly enhances the rate of photocatalytic decomposition of a model rhodamine B dye on exposure to a relatively weak UV source.