Hydrophobically modified ethoxylated urethanes (HEURs), as a representative class of associative polymers, are widely used as rheology modifiers in waterborne systems such as coatings, emulsions, inks etc. due to their unique associative network structure and finite relaxation behavior in solution. However, conventional HEURs are non-reactive and generally stay free in final cured films, which may induce some damages to the performance of the coatings. To solve the problem, a new concept of reactive HEUR has been proposed. That is, a reactive HEUR should bear reactive hydrophobic end-groups which can chemically crosslink with matrix resins during the curing process of waterborne coatings. In this work, with the help of the hydrogen abstraction photo-initiating reactivity of benzophenone (BP) group, a reactive HEUR (BPC₁₁HEUR) end-functionalized by a photo-initiator BP moiety has been prepared. In aqueous solution, as demonstrated by steady shear measurement, an exponential increment of solution viscosity along with the increasing of polymer concentration (C) was found when C surpassed its critical percolation concentration (Cp ≈ 23.6 g/L). Besides, ultraviolet (UV) light induced photolysis in aqueous solution manifested a typical photochemical reaction behavior of BPC₁₁HEUR polymer with a final photolysis degree (D) of approximate 78% after 300 s of irradiation. In situ ¹H NMR and rheological measurements collectively revealed the efficient photo-initiating reactivity of BPC₁₁HEUR for waterborne UV monomers or resins. Further, rheological measurements demonstrated that the emulsion zero/low shear viscosity can be greatly enhanced by ca. 50 folds for a commercially available waterborne UV polyurethane acrylate emulsion when the addition amount of BPC₁₁HEUR varied from 0 to 1.0 wt%. These results shown that the reactive BPC₁₁HEUR polymer can not only be used to efficiently modify the rheological properties of solutions or emulsions but also can chemically crosslink with waterborne UV acrylic monomers or resins by light irradiation. The work may be of interest for development of reactive HEURs used in waterborne UV coatings, inks, and adhesives, etc.

疏水改性的乙氧基化氨基甲酸乙酯（HEURs），作为缔合聚合物的代表，由于其独特的缔合网络结构和在溶液中的有限松弛行为，被广泛用作水性体系（如涂料，乳液，油墨等）的流变改性剂。然而，常规的HEURs是非反应性的，通常在最终的固化膜中保持游离状态，这可能会对涂层的性能造成一些损害。为了解决该问题，提出了反应性HEUR的新概念。也就是说，反应性HEUR应该带有反应性疏水端基，该端基可以在水性涂料的固化过程中与基体树脂化学交联。在这项工作中，借助二苯甲酮（BP）基团的氢提取光引发反应性，反应性HEUR（BPC ₁₁已制备了由光引发剂BP部分末端官能化的HEUR）。在水溶液中，如通过稳定剪切测量所证明的，当C超过其临界渗滤浓度（C p≈23.6 g / L）时，发现溶液粘度随聚合物浓度（C）的增加呈指数增加。此外，紫外线在水溶液中引起的光解表现出BPC ₁₁ HEUR聚合物的典型光化学反应行为，辐照300 s后的最终光解度（D）约为78％。在现场¹1 H NMR和流变学测量共同揭示了BPC ₁₁ HEUR对于水性UV单体或树脂的有效光引发反应性。此外，流变学测量表明，乳液的零/低剪切粘度可以通过约3％而大大提高。当BPC ₁₁ HEUR的添加量在0至1.0 wt％之间变化时，对于市售的水性UV聚氨酯丙烯酸酯乳液而言，其分子量是其50倍。这些结果表明，反应性BPC ₁₁HEUR聚合物不仅可以用来有效地改变溶液或乳液的流变性，而且可以通过光照射与水性UV丙烯酸单体或树脂化学交联。这项工作可能对开发用于水性UV涂料，油墨和胶粘剂等中的反应性HEUR感兴趣。