Babeva Tzwetanka, Naydenova Izabela, Martin Suzanne, Toal Vincent
Centre for Industrial and Engineering Optics, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
Opt Express. 2008 Jun 9;16(12):8487-97. doi: 10.1364/oe.16.008487.
A novel approach for measuring the diffusion coefficients in photopolymerisable materials is proposed. The method is based on studying the evolution of the surface relief profile in a single illuminated spot using an interferometric surface profiler. It is shown that the observed post-exposure swelling in the illuminated spot is due to mass-transport of monomer from the unexposed to the exposed area driven by a monomer concentration gradient set up by the monomer polymerization in the exposed area. Appropriate choice of the thickness of the studied layers ensures both lateral movement of monomer and negligible contribution from the depth. The diffusion coefficient is retrieved from the standard one-dimensional diffusion equation where the height of the profile in the center of the illuminated spot is used instead of the monomer concentration. In contrast to other techniques for measuring the diffusion in photopolymerisable materials, no assumptions or preliminary information about the polymerization rates are required. It is shown how the method can be used for studying the intensity and polymer density dependence of diffusion coefficient.
提出了一种测量光聚合材料中扩散系数的新方法。该方法基于使用干涉表面轮廓仪研究单个照明光斑中表面起伏轮廓的演变。结果表明，观察到的照明光斑曝光后肿胀是由于单体从未曝光区域向曝光区域的质量传输，这是由曝光区域中单体聚合建立的单体浓度梯度驱动的。适当选择研究层的厚度可确保单体的横向移动以及深度的贡献可忽略不计。扩散系数从标准的一维扩散方程中获取，其中使用照明光斑中心处轮廓的高度代替单体浓度。与测量光聚合材料中扩散的其他技术相比，不需要关于聚合速率的假设或初步信息。展示了该方法如何用于研究扩散系数对强度和聚合物密度的依赖性。
