Abstract Many toothpastes and personal care products consist of suspensions of silica particles in aqueous gels of humectants and other soluble constituents. It is highly desirable to develop new formulations that retain the desired characteristics of the original products but also have high optical transparency. Here, we used the refractive index matching method to manufacture highly transparent toothpastes. Accordingly, we determined the refractive indexes of different liquid gels, each containing a different humectant concentration, and measured the light transmittance and turbidity of formulations containing those gels and the silica. By fine tuning the humectant fraction in the gel, we obtained toothpastes with optimal transparency and also determined the effective refractive indexes of different commercial silica. All silica had similar indexes irrespective of their supplier, particle size distribution, and morphology. We believe that this approach could be extended to other commercial products and therefore contribute to the development of new advanced formulations.

中文翻译：

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使用折射率匹配法优化个人护理产品的光学透明度

摘要 许多牙膏和个人护理产品由二氧化硅颗粒悬浮在湿润剂和其他可溶性成分的水凝胶中组成。非常需要开发新的配方，既保留原始产品的所需特性，又具有高光学透明度。在这里，我们使用折射率匹配方法来制造高透明牙膏。因此，我们确定了不同液体凝胶的折射率，每种凝胶都含有不同的保湿剂浓度，并测量了含有这些凝胶和二氧化硅的制剂的透光率和浊度。通过微调凝胶中的保湿剂比例，我们获得了具有最佳透明度的牙膏，并确定了不同商业二氧化硅的有效折射率。无论其供应商、粒度分布和形态如何，所有二氧化硅都具有相似的指数。我们相信这种方法可以扩展到其他商业产品，因此有助于开发新的先进配方。