KINETICS OF FILM FORMATION IN ACRYLIC LATICES STUDIED WITH MULTIPLE-ANGLE-OF-INCIDENCE ELLIPSOMETRY AND ENVIRONMENTAL SEM
KINETICS OF FILM FORMATION IN ACRYLIC LATICES STUDIED WITH MULTIPLE-ANGLE-OF-INCIDENCE ELLIPSOMETRY AND ENVIRONMENTAL SEM
复制标题
DOI：
10.1021/ma00112a012
复制
发表时间：
1995-04-10
期刊：
影响因子：
5.5
通讯作者：
DONALD, AM
中科院分区：
文献类型：
--
作者：
KEDDIE, JL;MEREDITH, P;DONALD, AM
多角度入射椭圆光度 (MAIE) 和环境扫描电镜 (ESEM) 的组合用于表征丙烯酸乳胶在成膜的所有四个阶段中的微观结构，从水性胶体分散体（第一阶段）开始，发展到没有内部固-固界面的连续涂层（第四阶段）。第二阶段通常被定义为具有充满水的间隙的密堆积阵列，而第三阶段被定义为变形粒子的密堆积阵列。该分析确定了一个额外的阶段 II*，它是传统定义的阶段 II 和 III 的中间阶段。这一新阶段的开始与光学透明度的发展同时发生，几乎同时发生（通过最终薄膜厚度标准化），无论乳胶聚合物的玻璃化转变温度 (T-g) 是多少。另一方面，阶段 II* 的持续时间和阶段 III 中粒子聚结的动力学是 T-g 的函数。 T-g 远低于环境温度的乳胶可以迅速变形以填充水蒸发留下的空间。具有较高 T-g 的乳胶则不能，因此气孔和表面粗糙度会在可测量的时间内形成并持续存在。
A combination of multiple-angle-of-incidence ellipsometry (MAIE) and environmental SEM (ESEM) was used to characterize the microstructure of acrylic latices during all four stages of film formation, starting from an aqueous colloidal dispersion (Stage I) and evolving to a continuous coating having no internal solid-solid interfaces (Stage IV). Stage II is usually defined as a close-packed array with water-filled interstices, and Stage III is defined as a densely packed array of deformed particles. This analysis identified an additional stage, II*, intermediate to the conventionally defined Stages II and III. The onset of this new stage, which coincides with the development of optical clarity, occurs at nearly the same time (normalized by the final film thickness), regardless of the glass transition temperature (T-g) of the latex polymer. The duration of Stage II* and the kinetics of particle coalescence in Stage III, on the other hand, are a function of T-g. A latex with a T-g well below the ambient temperature can deform rapidly to fill the space left by the evaporation of water. A latex with a higher T-g cannot, and so air voids and surface roughness develop and persist over measurable times.