Preparation of polymer single chain nanoparticles using intramolecular photodimerization of coumarin
Preparation of polymer single chain nanoparticles using intramolecular photodimerization of coumarin
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DOI：
10.1039/c0sm01383h
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发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Zhao, Yue
中科院分区：
文献类型：
--
作者：
He, Jie;Tremblay, Luc;Zhao, Yue
提出了一种制备聚合物单链纳米粒子（SCNPs）的新方法。它利用位于同一链上的香豆素基团的光二聚化来获得链在溶液中坍塌所需的链内交联。为了验证该方法，通过可逆加成-断裂链转移（RAFT）聚合，合成了N， N-二甲氨基甲基丙烯酸乙酯（DMAEMA）和4-甲基-[7-（甲基丙烯酰）氧-乙基氧]香豆素（CMA）的无规则共聚物样品，CMA的浓度分别为7和13 mol%。我们发现香豆素基团在稀释的共聚物溶液中，在λ > - 310 nm紫外线照射下，可以通过链内光二聚化获得定义良好的SCNPs。利用H-1核磁共振自旋弛豫时间（T-2）研究了链内光交联诱导的线圈到球的转变。结果表明，光诱导链坍塌伴随着迁移率降低的链段比例的急剧增加。进一步利用SCNPs作为纳米反应器原位合成金纳米颗粒（AuNPs）。在四氢呋喃中，发现AuNP的形成速率依赖于由香豆素二聚化程度决定的聚合物链构象和迁移率。这提供了一种光学控制AuNP形成动力学的方法。
We present a new and easy method for preparing polymer single chain nanoparticles (SCNPs). It uses the photodimerization of coumarin groups located on the same chain to obtain the intrachain cross-linking required for chain collapse in solution. To demonstrate the approach, samples of a random copolymer composed of N, N-dimethylaminoethyl methacrylate (DMAEMA) and 4-methyl-[7-(methacryloyl) oxy-ethyl-oxy]coumarin (CMA), with 7 or 13 mol% of CMA, were synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization. We show that well-defined SCNPs could be obtained by the intrachain photodimerization of coumarin groups upon lambda > 310 nm UV irradiation in a dilute copolymer solution. The coil-to-globule transition induced by intrachain photo-cross-linking was investigated by means of H-1 NMR spinspin relaxation time (T-2). The result indicates that the photoinduced chain collapse is accompanied by a sharp increase of the fraction of chain segments having reduced mobility. SCNPs were further used as a nanoreactor to synthesize gold nanoparticles (AuNPs) in situ. In tetrahydrofuran, the rate of AuNP formation was found to be dependent on the polymer chain conformation and mobility determined by the dimerization degree of coumarin. This provides a means to optically control the kinetics of AuNP formation.