Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka, Japan.
J Colloid Interface Sci. 2012 May 1;373(1):20-6. doi: 10.1016/j.jcis.2011.09.071. Epub 2011 Oct 2.
Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO(101)-PPO(56)-PEO(101), Pluronic F127) was investigated as a function of PAA concentration (0.4-1.2 mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel. In this study, the concentrated alumina aqueous suspensions (φ=35 vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10 mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ~0.6 mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as "solid" inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.
聚（丙烯酸）（PAA）和三嵌段共聚物（PEO（101）-PPO（56）-PEO（101），Pluronic F127）与浓度氧化铝悬浮液的温敏胶凝行为作为陶瓷无模成型的陶瓷固体自由形成的功能，研究了 PAA 浓度（0.4-1.2 质量%）的影响。共聚物在高于 15°C 的温度下组装成胶束，产生水相物理凝胶。在本研究中，首先使用 PAA 的阴离子分散剂制备浓度氧化铝水悬浮液（φ=35 体积%），然后在冷却温度 10°C 下溶解共聚体（10 质量%）。共聚体的添加对 PAA 在氧化铝表面的吸附状态几乎没有影响。PAA 在氧化铝表面达到饱和吸附所需的浓度约为 0.6 质量%。当 PAA 浓度为该值或略低时，悬浮液在 30°C 下从 10°C 下的低粘性状态变为凝胶状态。热诱导氧化铝凝胶具有优异的粘弹性能，因此通过直接胶体印刷方法成功制备了三维周期性陶瓷结构，该方法将凝胶用作“固体”油墨在室温下。另一方面，当超过饱和吸附极限时，未观察到胶凝行为，表明部分非吸附 PAA 物种可能会在加热时部分抑制共聚物的胶束化。
