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Poly(Alkyl Methacrylate-co- Acrylic Acid) Copolymers of Varying Architecture for Improved Adhesion Sarah Louise Canning A Thesis submitted for the Degree of Doctor of Philosophy Department of Chemistry, University of Sheffield March 2015 Acknowledgements I would firstly like to thank my supervisory team, Prof. Steve Rimmer and Prof. Mark Geoghegan at the University of Sheffield and Dr Trevor Wear, Dr Stuart Reynolds and Dr Jon Morgan at Domino UK Ltd for all their help, support and guidance throughout this project. Thanks also go to the rest of the R&D team at Domino for being so welcoming to me. Domino UK Ltd and the EPSRC are gratefully acknowledged for providing financial support for the project. To everyone in the Chemistry Department at the University of Sheffield, I’m grateful for their assistance and for making the department such a friendly place to work. I particularly want to thank Melanie Hannah for her technical assistance and support. I am grateful to Richard Bottomley for allowing me to borrow equipment from the teaching labs, to Rob Hanson for his help with chromatography, to Sue Bradshaw for her assistance with NMR, and to Jenny Louth for elemental analysis. Thank you also to Pete Farran and Nick Smith for their storekeeping and footballing excellence, and to Pauline Bould for being a cheerful face every morning. I am very grateful to Dr Svet Tsokov in the EM Department for training me to use the TEM and for his continued advice, and to Chris Hill who assisted with the SEM imaging. I must thank Dr Ann Terry and Dr Steve King, instrument scientists at the ISIS facility, for their assistance with the SANS experiments. I am also extremely grateful to Prof. Patrick Fairclough for his help with fitting the SANS data. I’m thankful to all the members of the Geoghegan group past and present, especially Jason Zhang who trained me on the AFM with utmost patience. I must also thank the past and present members of F floor and the Rimmer group for their advice, support and friendship over the past three and a half years, particularly Laura Platt, Laura Shallcross, Simon Finnegan and Pavintorn (Mew) Teratanatorn. i I also want to thank the undergraduate students who have worked with me on summer placements, Sammi Hassan, Joe Ferner and Natalie Paul; I appreciate their hard work and enthusiasm. Thanks to Lizzy Jones and Vicki Cunningham for being excellent friends and housemates, I’m glad we’ve experienced this journey together. Thank you to Nathan Rutland for his support, patience and understanding (not to mention top banter!) You made the writing process much less painful than I expected. I hope I can return the favour when your turn comes. Finally I want to thank my family for their continuous support and encouragement throughout my studies and my entire life. I want to dedicate this thesis to my grandmother Pam Penhale, who will always be an inspiration to me. ii Abstract Amphiphilic copolymers composed of hydrophilic polyacrylic acid segments and hydrophobic poly(alkyl methacylate) segments were targeted as adhesion-promoting additives for use in printing inks. Methyl, butyl and lauryl methacrylates were chosen to vary hydrophobicity. Initially, a phase transfer-catalysed backbone functionalisation and a reversible addition-fragmentation chain transfer (RAFT)-controlled grafting step were employed to form graft copolymers, although polyacrylic acid homopolymer was also produced. The lauryl methacrylate synthesis proved more difficult due to the steric effect of the long alkyl chain. Branched and linear poly(alkyl methacrylate-acrylic acid) copolymers were then synthesised using RAFT, in either a one-pot polymerisation, producing random copolymers, or a two-step procedure forming block copolymers. Molecular weights of close to 20 000 g mol-1 were achieved, with methacrylate:acrylic acid ratios close to 1:1, as targeted. Branching was confirmed through calculation of Mark-Houwink parameters using GPC with viscometric detection, and a 13C NMR method was developed to identify block or random monomer sequence distribution. Due to their amphiphilic nature, the copolymers were found to self-assemble in water to form macromolecular structures. These varied according to architecture, monomer distribution, and hydrophobicity of the methacrylate segment. Small angle neutron scattering was used to study the copolymers in a range of solvent systems. Whilst Gaussian coils were formed in d-THF and self-assembled spheres or multi-lamellar micelles were formed in D O, the copolymers were found to aggregate into fractal 2 structures in intermediate solvency conditions. The behaviour of the copolymers when coated on polyolefin substrates was studied by contact angle measurements, and the random materials created more polar surfaces compared to the segmented analogues. A force spectroscopy technique showed potential for accurate comparison of copolymer adhesion. Ink formulations containing the butyl methacrylate copolymers jetted well on both thermal inkjet and drop on demand printers. Adhesion was assessed using industry standard tests, and better overall performance was observed for the branched copolymers. iii iv List of Abbreviations α Mark-Houwink parameter γ surface energy of liquid L γ surface energy of liquid-solid interface LS γ surface energy of solid S AA acrylic acid AFM atomic force microscope AIBN azobisisobutyronitrile ACVA 4,4’-azobis (4-cyanovaleric acid) ANOVA analysis of variance ATRP atom transfer radical polymerisation BMA butyl methacrylate BN α-bromonaphthalene CDCl deuterated chloroform 3 CIJ continuous inkjet CRP controlled radical polymerisation CTA chain transfer agent Ð dispersity DB degree of branching d-DMSO deuterated dimethyl sulfoxide d-EtOH deuterated ethanol D fractal dimension f v D O deuterium oxide 2 DOD drop on demand D degree of polymerisation p d-THF deuterated THF EG ethylene glycol g’ contraction factor GPC gel permeation chromatography HB highly branched HD 1,2-hexanediol HDPE high density polyethylene I(Q) scattering intensity IV, [η] intrinsic viscosity K Mark-Houwink parameter LDPE low density polyethylene LMA lauryl methacrylate MMA methyl methacrylate M number-average molecular weight n M weight-average molecular weight w nMA alkyl methacrylate monomer NIP non-impact printing NMP nitroxide mediated polymerisation NMR nuclear magnetic resonance Q scattering vector vi PAA polyacrylic acid PALS phase analysis light scattering PE polyethylene PnMA poly(alkyl methacrylate) (n = M methyl, B butyl or L lauryl) PNIPAM poly(N-isopropyl acrylamide) PP polypropylene P(Q) form factor PTC phase transfer catalysis RAFT reversible addition-fragmentation chain transfer polymerisation RB repeat units per branch R radius of gyration g RI refractive index SANS small angle neutron scattering SCVP self condensing vinyl polymerisation SEM scanning electron microscopy SLD scattering length density S(Q) structure factor tBA t-butyl acrylate TBAB tetrabutyl ammonium bromide TEM transmission electron miscroscopy TIJ thermal inkjet VBC 4-vinylbenzyl chloride vii viii

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Ink formulations containing the butyl methacrylate copolymers jetted well on both thermal inkjet and drop . RAFT Polymerisation of Alkyl Methacrylates and Acrylic Acid 245 using Benzyl-1-pyrrole nevertheless serve as an empirical guide to the monomer sequence distribution within the copolymers.