Hunter Geoffrey, Lane Deirdre M, Scrimgeour Sheelagh N, McDonald Peter J, Lloyd Charles H
Division of Physical and Inorganic Chemistry, School of Life Sciences, University of Dundee, Dundee DD1 4HN, Scotland UK.
Dent Mater. 2003 Nov;19(7):632-8. doi: 10.1016/s0109-5641(03)00006-x.
The purpose of this investigation was to determine the diffusion mechanism for water/ethanol mixtures in a diacrylate dental resin by direct observation of the absorbed liquid profiles using NMR microimaging.
Frequency-swept stray-field magnetic resonance imaging (STRAFI) was used. Solutions containing 25-65% by volume ethanol remained in contact with visible light cured 54% TEGDMA: 46% modified TUDMA sheets while measurements were made. The diffusion profiles were recorded periodically for diffusion times up to 10 h, to a depth of 360 microm and with readings taken at 24 microm intervals.
For all liquid mixtures, diffusion was found to be Fickian with coefficients that increased progressively and smoothly with alcohol content in the diffusing mixture, from 2.4 x 10(-13) to 150 x 10(-13) m2 s(-1). A rule of mixtures approach, as suggested by Kwei and Zupko, gave a satisfactory description of the ethanol fraction dependence of the diffusivity.
Frequency-swept STRAFI offers a new and unique opportunity to produce spatially resolved measurements of the liquids in dental resins to high resolution. In this study, absorption was investigated since an understanding of its mechanism is fundamental to limiting consequent environmental degradation. STRAFI has great potential for other applications, for example drying, liquid exchange, etc. Since STRAFI can discriminate 1H in the liquid from those in softened polymer additional applications are envisaged.
本研究旨在通过使用核磁共振显微成像直接观察吸收液体的分布情况，确定水/乙醇混合物在双丙烯酸酯牙科树脂中的扩散机制。
采用频率扫描杂散场磁共振成像（STRAFI）。在测量过程中，含有25%-65%（体积分数）乙醇的溶液与可见光固化的54%TEGDMA:46%改性TUDMA片材接触。定期记录扩散分布，扩散时间长达10小时，深度达360微米，每隔24微米读取一次数据。
对于所有液体混合物，发现扩散符合菲克定律，扩散系数随着扩散混合物中乙醇含量的增加而逐渐平稳增加，从2.4×10⁻¹³到150×10⁻¹³平方米每秒。正如Kwei和Zupko所建议的，混合法则方法对扩散系数的乙醇分数依赖性给出了令人满意的描述。
频率扫描STRAFI提供了一个新的独特机会，可以对牙科树脂中的液体进行高分辨率的空间分辨测量。在本研究中，对吸收进行了研究，因为了解其机制对于限制随之而来的环境降解至关重要。STRAFI在其他应用中具有很大潜力，例如干燥、液体交换等。由于STRAFI可以区分液体中的¹H和软化聚合物中的¹H，因此设想了更多应用。
