Please cite this article in press as: S. Jafarifard, et al., The chemo-rheological behavior of an acrylic based UV-curable inkjet ink: Effect of surface chemistry for hyperbranched polymers, Prog. Org. Coat. (2015), http://dx.doi.org/10.1016/j.porgcoat.2015.08.007 ARTICLE IN PRESS G Model POC-3750; No. of Pages 8 Progress in Organic Coatings xxx (2015) xxx–xxx Contents lists available at ScienceDirect Progress in Organic Coatings j o ur na l ho me pa ge: www.elsevier.com/locate/porgcoat The chemo-rheological behavior of an acrylic based UV-curable inkjet ink: Effect of surface chemistry for hyperbranched polymers Samane Jafarifard a , Saeed Bastani a,b,∗ , Atashe Soleimani Gorgani a , Morteza Ganjaee Sari c a Department of Printing Science and Technology, Institute for Color Science and Technology, Tehran, Iran b Center of Excellence for Color Science and Technology, Institute for Color Science and Technology, Tehran, Iran c Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology, Tehran, Iran a r t i c l e i n f o Article history: Received 31 May 2015 Received in revised form 4 August 2015 Accepted 6 August 2015 Available online xxx Keywords: Hyperbranched polymers Chemo-rheology UV-curable inks Time-resolving rheometry Curing behavior a b s t r a c t A polyester-amid based hyperbranched polymer (HBP) with hydroxyl terminal groups is modified by the aid of saturated fatty acid groups with 7 carbon lengths. FTIR results reveal that about 85% of hydroxyl terminal groups were replaced by fatty acid chains. Having prepared and characterized the inferred modified HBP, the effect of both neat and modified forms of HBP was tested on the curing behavior of an acrylic based UV-curable inkjet ink by time-resolving photo rheo-mechanical spectroscopy (TRP-RMS). The chemo-rheological results of TRP-RMS show that the hyperbranched polymers, in both neat and modified forms affected the rheological behavior of the ink during the curing process. In this research, slope of estimated line on the chemo-rheological curves was used to measure the rate of complex viscosity growth of ink formulation during the curing process. Accordingly, slope in the blend without HBPs was 180.56 Pa and it increased to about 300 Pa on addition of HBPs even at a loading of as much as 2 wt.%. Results demonstrate that hyperbranched polymers have altering influence at the various different stages of the curing process. © 2015 Elsevier B.V. All rights reserved. 1. Introduction UV-curable polymer technology has had much research atten- tion because it has great potential for application in various industries such as coatings, inks and adhesives. The UV-curable polymer technology has several desirable advantages such as high quality, high efficiency, excellent energy saving, low VOC, less extractable species and it can be applied for heat sensitive sub- strates [1–4]. Advantages such as good printability on a variety of substrates, not drying out before curing thus low probability of blocked the nozzles during the process, stable chemical properties and results with high printing resolution have given UV-curable inkjet inks widespread attention and are currently considered a hot topic for research [5–8]. UV curable inkjet inks can be used for printing RFID, barrier ribs, and color filter [9–11]. Hyperbranched polymers have emerged as the third category of dendritic polymers in recent decades; they have attracted sig- nificant attention mostly because of their unique architecture and ∗ Corresponding author at: Department of Printing Science and Technology, Insti- tute for Color Science and Technology, Tehran, Iran. E-mail address: bastani@icrc.ac.ir (S. Bastani). special properties, among which the most important are, lower degree of entanglement, a significant chain-end effect, low viscosity in solution and in the molten state compared to their linear coun- terparts [12–14]. Hyperbranched polymers are usually prepared by a one-pot synthesis technique that is relatively simple, and rapid polymerization reactions [15,16]. Other research has mostly con- sidered HBPs as processing aids, branching agents, compatibilizers, and toughener in prepolymer and polymer blends [17–20]. Prop- erties of HBPs such as globular structure and the large number of functional end groups make these polymers appropriate for use as rheological modifiers. Furthermore, surface properties and reac- tivity of HBPs may be tailored by replacing functional end-groups with hydrophilic or hydrophobic functionalities; either reactive or non-reactive ones. Altogether these properties present HBPs as an attractive candidate for many applications such as coatings, inks, and additives [11,20–22]. The curing behavior of UV curable blends containing HBPs has been studied extensively in the related literature. Studies on photo polymerization kinetics indicate that HBPs influence the maximum rate of the curing process and the final degree of polymeriza- tion. This research demonstrates that the functional end groups of hyperbranched polymer also have the effect of increasing blend viscosity [23–25]. For example, an investigation of the effect of http://dx.doi.org/10.1016/j.porgcoat.2015.08.007 0300-9440/© 2015 Elsevier B.V. All rights reserved.