Impurity partitioning during colloidal crystallization.
Impurity partitioning during colloidal crystallization.
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DOI：
10.1021/jp309550y
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发表时间：
2013-04
期刊：
影响因子：
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通讯作者：
J. Nozawa;S. Uda;Yuhei Naradate;H. Koizumi;K. Fujiwara;A. Toyotama;J. Yamanaka
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文献类型：
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作者：
J. Nozawa;S. Uda;Yuhei Naradate;H. Koizumi;K. Fujiwara;A. Toyotama;J. Yamanaka
我们发现，在胶体晶体的生长过程中发生的杂质分配，这是公认的事实，杂质浓度在固体（CS）中的不同，在初始溶液（C 0）。通过改变颗粒直径比d（imp）/d（cryst）和生长速率V，研究了纯聚苯乙烯和荧光颗粒染色聚苯乙烯的有效分配系数k（eff）（=CS/C 0）。对于聚苯乙烯杂质，在每个粒径比下，k（eff）都小于1，并随着V的增加而增加到1，而在给定的生长速率下，当d（imp）/d（cryst）接近1时，k（eff）增加到1。这些结果与使用Burton、Prim和Slichter（BPS）模型分析的溶质行为一致。从BPS图中获得的平衡分配系数k 0随着d（imp）/d（cryst）接近1而增加。相反，虽然荧光颗粒也遵循BPS模型，但它们显示出比相同尺寸的聚苯乙烯颗粒更高的k 0值。对于尺寸与宿主颗粒相似的杂质，获得了大于1的k 0值。这种行为归因于与荧光颗粒结合到主体基质中相关的正的熔合自由能。这种正的聚变自由能意味着存在与粒子之间相互作用相关的焓。
We have found that an impurity partitioning takes place during growth of colloidal crystals, which was recognized by the fact that the impurity concentration in the solid (CS) was different from that in the initial solution (C0). The effective partition coefficient k(eff) (=CS/C0) was investigated for pure polystyrene and polystyrene dyed with fluorescent particles by changing the ratio of particle diameters d(imp)/d(cryst) and growth rate V. At each size ratio for the polystyrene impurity, k(eff) was less than unity and increased to unity with increasing V, whereas at a given growth rate, k(eff) increased to unity as d(imp)/d(cryst) approached unity. These results were consistent with the solute behavior analyzed using the Burton, Prim, and Slichter (BPS) model. The obtained k0, equilibrium partition coefficient, from a BPS plot increased as d(imp)/d(cryst) approached unity. In contrast, while the fluorescent particles also followed the BPS model, they showed higher k0 values than those of the same size of polystyrene particles. A k0 value greater than unity was obtained for impurities that were similar in size to the host particle. This behavior is attributed to the positive free energy of fusion associated with the incorporation of the fluorescent particles into the host matrix. Such positive free energy of fusion implies the presence of the enthalpy associated with interaction between particles.