Huang Z, Thiagarajan VS, Lyngberg OK, Scriven LE, Flickinger MC
Department of Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455
J Colloid Interface Sci. 1999 Jul 15;215(2):226-243. doi: 10.1006/jcis.1999.6178.
The microstructure evolution of two poly(vinyl acetate-co-acrylic acid) latex coatings was elucidated by cryogenic scanning electron microscopy (cryo-SEM) and atomic force microscopy. The stages documented are particle suspension, consolidation, deformation, partial coalescence into a coherent film, and rehydration of the latter. Of particular interest is formation of a porous polymeric matrix of desired porosity and permeability of remnant interstices between deformed and partially coalesced particles; the application is to biocatalytic coatings in which viable bacteria are imprisoned in porous latex coatings. Effects of drying condition and time, rehydration behavior of latex, and the presence of glycerol on the microstructure of latex coatings were revealed by time-sectioning and cryofracture techniques of cryo-SEM. Results showed that porosity and permeability can be controlled by choice of drying and rehydration protocols. Evidence showed that glycerol retarded particle deformation, compaction, and coalescence and that substantial amounts of glycerol were expelled to the surface of the coating as drying proceeded. Implications for design of bacteria-laden and bacteria-free coating layers are discussed. Copyright 1999 Academic Press.
通过低温扫描电子显微镜（cryo-SEM）和原子力显微镜阐明了两种聚（醋酸乙烯酯-共-丙烯酸）乳胶涂料的微观结构演变。记录的阶段包括颗粒悬浮、固结、变形、部分聚结形成连贯薄膜以及后者的再水化。特别令人感兴趣的是形成具有所需孔隙率和变形及部分聚结颗粒之间残余间隙渗透率的多孔聚合物基质；其应用是在生物催化涂料中，其中活细菌被囚禁在多孔乳胶涂料中。通过cryo-SEM的时间切片和冷冻断裂技术揭示了干燥条件和时间、乳胶的再水化行为以及甘油的存在对乳胶涂料微观结构的影响。结果表明，孔隙率和渗透率可以通过选择干燥和再水化方案来控制。证据表明，甘油会延迟颗粒的变形、压实和聚结，并且随着干燥的进行，大量甘油会被排出到涂层表面。讨论了对含细菌和无细菌涂层设计的影响。版权所有1999年学术出版社。
