Influence of substituted structure of Percec-type mini-dendritic end groups on aggregation and rheology of hydrophobically modified ethoxylated urethanes (HEURs) in aqueous solution. (17th January 2018)

• Record Type: Journal Article
• Authors: Du, Zhukang; Wang, Feng; Chang, Xueyi; Peng, Jun; Ren, Biye
• Is Part Of: Polymer. Volume 135(2017)
• Page Start: 131
• Page End: 141
• Publication Date: 2018-01-17
• Subjects: Associative polymers -- Telechelic polymers -- Hydrophobically modified ethoxylated urethanes -- Thickeners -- Thickening performance -- Rheology; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.12.022
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Percec-type substituted benzyl alcohol mini-dendrons as new hydrophobic end-cappers can effectively improve the thickening performance of hydrophobically modified ethoxylated urethanes (HEURs) in aqueous solution. To demonstrate the effects of substituted structure of Percec-type mini-dendritic end groups on aggregation and rheological properties of HEURs in aqueous solution and latex, three model HEURs end-functionalized by mono-, di- and tri-substituted benzyl alcohol mini-dendrons were synthesized, respectively. For a reasonable comparison, the total carbon number of substituted alkyl tails is set to be 24 for the three mini-dendritic end groups: HOCH2 - Ph -C24 H49 (C24 ), HOCH2 - Ph -(C12 H25 )2 (2C12 ) and HOCH2 - Ph -(C8 H17 )3 (3C8 ), which respectively correspond to single-, two- and three-tail according to their substituted degrees. Interestingly, rheological properties of these HEURs in aqueous solution and latex significantly depend on the substituted degree of mini-dendritic hydrophobes. The high-substituted mini-dendritic hydrophobes help HEURs to form a strong physical network with high thickening performance and fast relaxation in both aqueous solution and latex, because shorter alkyl tails in high-substituted dendritic hydrophobes will lead to a smaller aggregation number and a lower rheological activation energy. This work not only provides new insights into the connection of networks in solutions of mini-dendron functionalized HEURs but also offers a new approach to preparation of high performance thickeners used in water-borne systems. Graphical abstract: Highlights: Three HEUR model polymers with different dendritic end groups were synthesized. The solution aggregation and rheology of these HEURs depend on the substituted degree of dendrons. High-substituted dendrons lead to strong hydrophobic networks and rapid solution relaxation. This work opens a new approach to highly efficient thickeners in waterborne systems.