Abstract Waterborne polyurethane dispersions (PUDs) currently have a wide spectrum of applications as coating resins for biomedical products, food packaging, cosmetics and traditional coatings. At present, PUDs are commonly prepared by the “prepolymer extension” method in which isocyanate terminated self-dispersing prepolymers are dispersed in water, followed by chain extension via the terminal isocyanate groups. The preparation of such self-dispersing prepolymers from diisocyanates, ionizable diols and non-ionizable diol blocks is a stochastic process with poor control over the prepolymer molecular weight and functionality distribution, which may result in sub-optimal properties of the PUDs. We investigated a new route in which we prepare ionizable macro-diol blocks, out of hydrophobic polycaprolactone (PCL) blocks, covalently bonded to the ionizable diol dimethylolpropionic acid (DMPA) via Cationic Ring Opening Polymerization (CROP), which subsequently are coupled via isocyanate chemistry to prepare the PUDs. During the preparation of the pre-polymer the reaction was steered towards a DMPA-diblock-PCL macro-emulsifier, with controlled molecular weight and molecular weight distribution. The waterborne PUDs prepared afterwards with the designed DMPA-PCL building block showed the desired particle size, Zeta-potential and improved stability over time, when compared to a highly analogous traditional system. Furthermore, the preparation of the DMPA-PCL self-dispersing block allowed reducing up to 63% the amount of diisocyanate used compared to the commonly used “pre-polymer extension” method, without sacrificing long-term colloidal stability. The interesting features of the new DMPA-PCL self-dispersible building blocks ensure a wide range of applications, via a safer, more efficient and economic preparation route.

中文翻译：

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用于水性聚氨酯分散体的自分散带电聚合物结构单元的设计

摘要 水性聚氨酯分散体 (PUD) 目前作为生物医学产品、食品包装、化妆品和传统涂料的涂料树脂具有广泛的应用。目前，PUDs通常通过“预聚物延伸”方法制备，其中异氰酸酯封端的自分散预聚物分散在水中，然后通过末端异氰酸酯基团进行扩链。由二异氰酸酯、可电离二醇和不可电离二醇嵌段制备此类自分散预聚物是一个随机过程，对预聚物分子量和官能度分布的控制不佳，这可能导致 PUD 的性能欠佳。我们研究了一种新途径，在该途径中，我们从疏水性聚己内酯 (PCL) 嵌段中制备可电离的大二醇嵌段 通过阳离子开环聚合 (CROP) 与可电离的二醇二羟甲基丙酸 (DMPA) 共价键合，随后通过异氰酸酯化学偶联以制备 PUD。在预聚物的制备过程中，反应转向具有受控分子量和分子量分布的 DMPA-二嵌段-PCL 大分子乳化剂。与高度相似的传统系统相比，随后使用设计的 DMPA-PCL 构建块制备的水性 PUD 显示出所需的粒度、Zeta 电位和随时间改进的稳定性。此外，与常用的“预聚物延伸”方法相比，DMPA-PCL 自分散嵌段的制备可将二异氰酸酯的用量减少多达 63%，而不会牺牲长期胶体稳定性。