Of several samples of polyvinyl pyrrolidone (PVP) used to coat and stabilize freshly manufactured aqueous dispersions of silver nanoparticles, one batch gave anomalous results: the dispersion maintained continued stability, even on extensive dilution. Our efforts to understand this desirable feature concluded that the generally used spectral method of PVP purity verification, Fourier transform infrared (FTIR) spectroscopy, was incapable of answering our inquiry. This led to the employment of several other methods, including X-ray photoelectron and nuclear magnetic resonance spectroscopies, which ultimately revealed several possible reasons for the dilution stability, including incomplete PVP hydrolysis during manufacture and the presence of hydroperoxide contaminants. It led, as well, to explanations for the shortcomings of FTIR spectroscopy as a verification method for PVP purity.

中文翻译：

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聚乙烯吡咯烷酮的理化表征：两种聚乙烯吡咯烷酮的故事

在用于涂覆和稳定新鲜制造的银纳米颗粒水分散液的聚乙烯吡咯烷酮（PVP）的几个样品中，一批给出了异常结果：即使在广泛稀释下，分散液仍保持持续的稳定性。我们为理解此理想功能而做出的努力得出的结论是，通常使用的PVP纯度验证光谱法，傅里叶变换红外（FTIR）光谱法无法回答我们的问题。这导致采用了其他几种方法，包括X射线光电子能谱和核磁共振波谱学，这些方法最终揭示了稀释稳定性的几种可能原因，包括制造过程中PVP水解不完全和氢过氧化物污染物的存在。它也导致了