Block and Graft Copolymers Containing Carboxylate Or Phosphonate Anions
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Block and Graft Copolymers Containing Carboxylate or Phosphonate Anions Nan Hu Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry Judy S. Riffle S. Richard Turner Richey M. Davis Kevin J. Edgar September 26, 2014 Blacksburg, VA Keywords: phosphonate, graft copolymers, polyelectrolytes, polyphosphonate, poly(acrylic acid), polyamide, poly(ethylene oxide), radical polymerization, ring-opening polymerization, ATRP Block and Graft Copolymers Containing Carboxylate or Phosphonate Anions Nan Hu Department of Chemistry and the Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA Abstract This dissertation focuses on synthesis and characterization of graft and block copolymers containing carboxylate or phosphonate anions that are potential candidates for biomedical applications such as drug delivery and dental adhesives. Ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate monomers were synthesized based on aza-Michael addition reactions. Free radical copolymerizations of these monomers with an acrylate-functional poly(ethylene oxide) (PEO) macromonomer produced graft copolymers. Quantitative deprotection of the alkylphosphonate groups afforded graft copolymers with zwitterionic ammonium bisphosphonate or anionic phosphonate backbones and PEO grafts. The zwitterionic copolymers spontaneously assembled into aggregates in aqueous media. The anionic copolymers formed aggregates in DMF and DMSO, while only small amounts of aggregates were present in copolymer/methanol or copolymer/water solutions. Binding capabilities of the acrylamide phosphonic acids were investigated through interactions with hydroxyapatite. Previously our group has prepared poly(ethylene oxide)-b-poly(acrylic acid) (PEO-b- PAA) copolymers and used these polymers as carriers for both MRI imaging agents and cationic drugs. To enhance the capabilities of those carriers in tracking and crosslinking, we have designed, synthesized and characterized amine functionalized PEO-b-PAA copolymers. First, heterobifunctional poly(ethylene oxide) (PEO) with three different molecular weights were synthesized. Modification on one of these afforded a PEO macroinitiator with a bromide on one end and a protected amine on the other end. ATRP polymerization of tert-butyl acrylate (tBuA) in the presence of this initiator and a copper (I) bromide (CuBr) catalyst yielded a diblock copolymer. The copolymer was deprotected by reaction with trifluoroacetic acid (TFA) and formed an amine terminated H2N-PEO-b-PAA. Recently our group has utilized the novel ammonium bisdiethylphosphonate (meth)acrylate and acrylamide phosphonate copolymers to incorporate Carboplatin. The resulting complexes exhibited excellent anticancer activity against MCF-7 breast cancer cells which might be related to ligand exchange of the dicarboxylate group of Carboplatin with the phosphonic acid moieties in the copolymer. Hence, complexation of small-molecule phosphonic acids with Carboplatin was investigated. Three compounds, vinylphosphonic acid, 3- hydroxypropyl ammonium bisphosphonic acid and 2-hydroxyethyl ammonium phosphonic acid were complexed with Carboplatin under acidic and neutral conditions. Covalent bonding of these acids to carboplatin was only observed under acidic pH. The covalently bonded percentage was 17%, 37% and 34%, respectively. More in-depth investigation was of great importance to further understand this complexation behavior. iii This work is dedicated to my husband: Chen Qian My parents: Yunpeng Li and Linshan Hu and My parents-in-law: Jianhua Wang and Junhua Qian iv Table of Contents Abstract ........................................................................................................................................... ii Table of Contents ............................................................................................................................ v Acknowledgement ......................................................................................................................... xi Abbreviations ................................................................................................................................ xii List of Figures ............................................................................................................................... xv List of Tables ............................................................................................................................... xxi CHAPTER 1 - Introduction ............................................................................................................ 1 1.1 References ................................................................................................................................. 4 CHAPTER 2 - Literature Review ................................................................................................... 6 2.1 Overview ................................................................................................................................... 6 2.2 Chemistry, Synthesis and Applications of Phosphonate or Phosphonic acid-containing Monomers and Polymers ............................................................................................................. 6 2.2.1 Phosphonate and Phosphonic acid ..................................................................................... 6 2.2.2 Synthesis and Applications of Phosphonate Monomers and Polymers ........................... 12 2.2.2.1 Synthesis of (Meth)acrylate Phosphonate Monomers and Polymers .................... 13 2.2.2.1.1 (Meth)acrylates with Phosphonate Linked to the Vinyl Bond ........................ 13 2.2.2.1.2 (Meth)acrylates with Phosphonate Linked to the Ester .................................. 16 2.2.2.2 Synthesis of (Meth)acrylamide Phosphonate Monomers and Polymers ............... 26 2.2.2.3 Applications of (Meth)acrylate and (Meth)acrylamide Phosphonate Monomers and Polymers ............................................................................................................................ 34 2.3 Properties, Synthesis and PEO-containing Ionomers for Biomedical Applications ............... 35 2.3.1 Properties of PEO ............................................................................................................. 35 2.3.2 Synthesis of PEO .............................................................................................................. 36 2.3.2.1 Synthesis and Applications of mPEO-(meth)acrylate ........................................... 37 v 2.3.2.2 Synthesis and Applications of NH2-PEO-OH ....................................................... 38 2.3.2.2.1 Synthesis of NH2-PEO-OH via a Schiff Base-containing Initiator ................. 39 2.3.2.2.2 Synthesis of NH2-PEO-OH via Silyl or Sila Protected Amino Initiators ....... 40 2.3.2.2.3 Synthesis of NH2-PEO-OH via an Allyl Initiator ........................................... 41 2.3.2.2.4 Synthesis of NH2-PEO-OH via Cyano-based Initiators .................................. 42 2.3.3 Block and Graft Polyion Complexes ................................................................................ 43 2.3.4 PEO-containing Ionomers as Therapeutic Agent Carriers ............................................... 47 2.3.4.1 PEO-PAA or PEO-PMAA copolymers ................................................................. 47 2.3.4.2 PEO-PAsp copolymers .......................................................................................... 50 2.3.4.3 PEO-Poly(amino aspartamide) copolymers ........................................................... 53 2.3.4.4 PEO-PLL copolymers ............................................................................................ 56 2.4 References ............................................................................................................................... 58 CHAPTER 3 - Synthesis of Ammonium Bisphosphonate Monomers and Polymers .................. 73 3.1 Abstract ................................................................................................................................... 73 3.2 Introduction ............................................................................................................................. 74 3.3 Experimental ........................................................................................................................... 75 3.3.1 Materials ........................................................................................................................... 75 3.3.2 Synthesis ........................................................................................................................... 76 3.3.2.1 Synthesis of Hydroxypropyl Ammonium Bisdiethylphosphonate ........................ 76 3.3.2.2 Synthesis of an Ammonium Bisdiethylphosphonate Acrylate Monomer ............. 76 3.3.2.3 Synthesis of an Ammonium Bisdiethylphosphonate Methacrylate Monomer ...... 77 3.3.2.4 Synthesis of Acrylate-functional PEO ................................................................... 77 3.3.2.5 Synthesis of a 67:33 wt:wt Poly(ammonium bisdiethylphosphonate methacrylate)- g-PEO Copolymer .............................................................................................................. 77 vi 3.3.2.6 Deprotection of the 67:33 poly(ammonium bisdiethylphosphonate