Effect of polymer chain architecture on the aqueous solution properties of amphiphilic copolymers: A study of poly(N- vinylpyrrolidone-co-vinyl laurate) Kate A. Knapp a , Ivan M. Nu ~ nez b , Devon A. Shipp a, * a Department of Chemistry & Biomolecular Science, Clarkson University, Potsdam, New York 13699-5810, United States b Bausch & Lomb, 1400 North Goodman Street, Rochester, New York, 14603, United States article info Article history: Received 19 November 2017 Received in revised form 24 February 2018 Accepted 26 February 2018 Available online 1 March 2018 Keywords: Amphiphilic copolymers Gradient copolymers RAFT polymerization abstract The synthesis and aqueous solution properties of copolymers comprised of N- vinylpyrrolidone (NVP) and vinyl laurate (VL) with three different architectures is reported. By using reversible addition- fragmentation chain-transfer (RAFT) polymerization, statistical, forced gradient, and block copolymers were synthesized with varying compositions and molecular weights. Surface tension, critical micelle concentrations (CMCs) and micelle size were determined, and related to copolymer composition, mo- lecular weight and architecture. It was observed that more block-like polymer architectures produced from the block copolymerizations and forced gradient copolymerizations were likely to self-assemble in solution, indicating that the degree and placement of the hydrophilic (NVP) and hydrophobic (VL) monomer units are important in predicting solution behavior of such copolymers. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Amphiphilic copolymers are widely used in solution-based ap- plications as surfactants, flocculants and compatibilizers [1-6]. Much work has been devoted to examining the relationship be- tween polymer structure and aqueous solution properties, and it has been found that the solution properties of such polymers are dictated by many factors, including the hydrophilicity/hydropho- bicity of the monomer repeat units, stereochemistry, molecular weight, and the arrangement of monomers within polymer chains [7 ,8]. Hence, in order to fully appreciate these structure-property relationships, in-depth studies are required to understand the various affects and nuances each factor has on the particular property (or properties) being examined. Reversible-deactivation radical polymerization (RDRP) methods [9, 10] such as nitroxide-mediated polymerization [11-17], atom transfer radical polymerization [18-23] and reversible addition- fragmentation chain transfer (RAFT) polymerization [17 ,24-33], provide the capacity to make copolymers with excellent control over several structural features, most commonly molecular weight, dispersity, functionality and, under the correct conditions, repeat unit sequence distribution [34-37]. One manifestation of this con- trol, and a particularly significant advantage that RDRP methods have over conventional radical polymerizations, is their ability to produce copolymers of various architectures from a given set of monomers [38,39]. For example, two monomers can be used to make statistical copolymers, gradient copolymers and/or block copolymers, simply through the appropriate choice of how the monomers are polymerized together in a RDRP. Statistical co- polymers are easily made by adding both monomers at the beginning of the reaction. Gradient copolymers are made either by the addition of one of the monomers at some stage during the polymerization (either gradually via a syringe pump or similar, or in one shot), or if the reactivity ratios for each monomer are suitably different then a so-called ‘spontaneous’ gradient copolymer will be formed even if the two monomers are added together at the start of the reaction. In some cases, again if the monomers are added in the correct order and the reactivity ratios are appropriate, a block-like gradient (BLG) copolymer will form. A ‘true’ block copolymer can be formed by polymerizing one monomer, isolating the resulting polymer, and then using this to reinitiate the polymerization of the second monomer. The effect that such architectures have on the properties, particular in thin films but also in solution, has been examined by many researchers. However, these have often been based on * Corresponding author. E-mail address: dshipp@clarkson.edu (D.A. Shipp). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer https://doi.org/10.1016/j.polymer.2018.02.064 0032-3861/© 2018 Elsevier Ltd. All rights reserved. Polymer 141 (2018) 54e61