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首页> 外文期刊>JCT research >The diacetone acrylamide crosslinking reaction and its influence on the film formation of an acrylic latex
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The diacetone acrylamide crosslinking reaction and its influence on the film formation of an acrylic latex

机译：双丙酮丙烯酰胺的交联反应及其对丙烯酸胶乳成膜的影响

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Waterborne colloidal polymers (i.e. latex) represent a promising alternative to organic solvent-based systems in coatings applications. The development of mechanical strength and hardness is often enhanced by chemical crosslinking that creates a three-dimensional network. If extensive crosslinking occurs within the particles prior to their coalescence, however, interdiffusion will be prevented. A weaker product will result. We have explored the inter-relationship between coalescence, crosslinking, and surfactant exudation in an acrylic latex containing diacetone acrylamide exploiting the "keto-hydrazide" crosslinking reaction. The complementary use of spectroscopic techniques on a model system determined that the crosslinking reaction yields an imine, not an enamine as has been proposed in some literature. Gel fraction measurements were used to probe the rate and amount of crosslinking and identified a slower rate in larger particles, suggesting that the transport of crosslinking agent is rate-limiting. The keto-hydrazide reaction was found to be acid catalyzed and favored at lower water concentration. Measurement of the latex pH relative to the polymer mass fraction during film formation clarified the expected point of onset for crosslinking in relation to particle packing. Atomic force microscopy was used to follow surface leveling relative to the competing influence of crosslinking. The rate and total amount of surfactant exudation were found to be influenced by crosslinking, particle deformability (as determined by the temperature relative to the polymer glass transition temperature), and the evaporation rate (as controlled by the relative humidity). There is evidence that surfactant exudation can be triggered by the particle deformation that occurs at film formation temperatures well above the glass transition temperature.
机译：在涂料应用中，水性胶体聚合物（即胶乳）是有机溶剂基体系的有前途的替代品。机械强度和硬度的发展通常通过产生三维网络的化学交联来增强。但是，如果在聚结之前颗粒内部发生了广泛的交联，则将防止相互扩散。将导致产品变弱。我们利用“酮-酰肼”交联反应探索了含双丙酮丙烯酰胺的丙烯酸胶乳中聚结，交联和表面活性剂渗出之间的相互关系。光谱技术在模型系统上的互补使用确定了交联反应产生的是亚胺，而不是某些文献中提出的烯胺。凝胶分数测量用于探测交联的速率和数量，并确定较大颗粒中的速率较慢，这表明交联剂的运输是限速的。发现酮-酰肼反应是酸催化的，并且在较低的水浓度下是有利的。在膜形成过程中相对于聚合物质量分数的胶乳pH值的测量阐明了与颗粒堆积有关的交联的预期起始点。相对于交联的竞争影响，使用原子力显微镜观察表面的水平。发现表面活性剂渗出的速率和总量受交联，颗粒可变形性（由相对于聚合物玻璃化转变温度的温度确定）和蒸发速率（由相对湿度控制）的影响。有证据表明，在远高于玻璃化转变温度的成膜温度下，颗粒变形会触发表面活性剂渗出。

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