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The work described in this thesis is divided into three major parts, and all of which involve the exploration of the chemistry of polyphosphazenes. The first part (chapters 2 and 3) of my research is synthesis and study polyphoshazenes for biomedical applications, including polymer drug conjugates and injectable hydrogels for drug or biomolecule delivery. The second part (chapters 4 and 5) focuses on the synthesis of several organic/inorganic hybrid polymeric structures, such as diblock, star, brush and palm tree copolymers using living cationic polymerization and atom transfer radical polymerization techniques. The last part (chapters 6 and 7) is about exploratory synthesis of new polymeric structures with fluorinated side groups or cycloaliphatic side groups, and the study of new structure property relationships.Chapter 1 is an outline of the fundamental concepts for polymeric materials, as such the history, important definitions, and some introductory material for to polymer chemistry and physics. The chemistry and applications of phopshazenes is also briefly described.Chapter 2 is a description of the design, synthesis, and characterization of development of a new class of polymer drug conjugate materials based on biodegradable polyphosphazenes and antibiotics. Poly(dichlorophosphazene), synthesized by a thermal ring opening polymerization, was reacted with up to 25 mol% of ciprofloxacin or norfloxacin and three different amino acid esters (glycine, alanine, or phenylalanine) as cosubstituents via macromolecular substitutions. Nano/microfibers of several selected polymers were prepared by an electrospinning technique. The hydrolysis rate and the antibiotic release profile can be well tuned by either the polymer compositions, or the surface area monitored by a six week in vitro hydrolysis experiment. All the polymers gave a near-neutral hydrolysis environment with the pH ranging from 5.9--6.8. In an in vitro antibacterial test against E.coli, the antibacterial activity of the hydrolysis media was maintained as long as the polymer hydrolysis continued.Chapter 3 is concerned with the development of a class of injectable and biodegradable hydrogels based on water-soluble poly(organophosphazenes) containing oligo(ethylene glycol) methyl ethers and glycine ethyl esters. The hydrogels can be obtained by mixing [alpha]-cyclodextrin aqueous solution and poly(organophosphazenes) aqueous solution in various gelation rates depending on the polymer structures and the concentrations. The rheological measurements of the supramolecular hydrogels indicate a fast gelation process and flowable character under a large stain. The hydrogel system also exhibits structure-related reversible gel-sol transition properties at a certain temperature. The formation of a channel-type inclusion complex induced gelation mechanism was studied by DSC, TGA, 13C CP/MAS NMR and X-ray diffraction techniques. In vitro bovine serum albumin release of the hydrogel system was explored and the biodegradability of poly(organophosphazenes) was studied.Chapter 4 outlines the preparation of a number of amphiphilic diblock copolymers based on poly[bis(trifluoroethoxy)phosphazene] (TFE) as the hydrophobic block and poly(dimethylaminoethylmethacrylate) (PDMAEMA) as the hydrophilic block. The TFE block was synthesized first by the controlled living cationic polymerization of a phosphoranimine, followed by replacement of all the chlorine atoms using sodium trifluoroethoxide. To allow for the growth of the PDMAEMA block, 3-azidopropyl-2-bromo-2-methylpropanoate, an atom transfer radical polymerization (ATRP) initiator, was grafted onto the endcap of the TFE block via the 'click' reaction followed by the ATRP of 2-(dimethylamino)ethyl methacrylate (DMAEMA). Once synthesized, micelles were formed by a standard method and their characteristics were examined using fluorescence techniques, dynamic light scattering, and transmission electron microscopy. The critical micelle concentrations of the diblock copolymers as determined by fluorescence techniques using pyrene as a hydrophobic probe were between 3.47 and 9.55mg/L, with the partition equilibrium constant of pyrene in these micelles ranging from 0.12x105-1.52x105. The diameters measured by dynamic light scattering were 100-142nm at 25oC with a narrow distribution, which were also confirmed by transmission electron microscopy. Chapter 5 is a report on the design and assembly of polyphosphazene materials based on the non-covalent "host--guest" interactions either at the terminus of the polymeric main-chains or the pendant side-chains. The supramolecular interaction at the main chain terminus was used to produce amphiphilic palm-tree like pseudo-block copolymers via host-guest interactions between an adamantane end-functionalized polyphosphazene and a 4-armed [beta]-cyclodextrin ([beta]-CD) initiated poly[poly(ethylene glycol) methyl ether methacylate] branched-star type polymer. The formation of micelles of the obtained amphiphiles was analyzed by fluorescence technique, dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The supramolecular interactions involving polymer side-chains were achieved between polyphosphazenes with [beta]-CD pendant units and other polyphosphazene molecules with adamantyl moieties on the side-chains. These interactions worked as physical crosslinks which were responsible for the formation of a supramolecular hydrogel. The results of this work demonstrated the synthetic possibilities for these novel polymeric structures. These materials show potential for applications as smart drug delivery micro-vehicles, responsive hydrogels, and self-healing materials.Chapter 6 is an investigation of the influence of bulky fluoroalkoxy side groups on the properties of polyphosphazenes. A new series of mixed-substituent high polymeric poly(fluoroalkoxyphosphazenes) containing trifluoroethoxy and branched fluoroalkoxy side groups was synthesized and characterized by NMR and GPC methods. These polymers contained 19--29 mol% of di-branched hexafluoropropoxy groups or 4mol% of tri-branched tert-perfluorobutoxy groups, which serve as regio-irregularities to reduce the macromolecular microcrystallinity. The structure--property correlations of the polymers were then analyzed and interpreted by several techniques: specifically by the thermal behavior by DSC and TGA methods, the crystallinity by wide-angle X-ray diffraction, and the surface hydrophobicity/oleophobicity by contact angle measurements. Ultraviolet crosslinkable elastomers were prepared from the new polymers through the incorporation of 3mol% of 2-allylphenoxy and photo-irradiation. The mechanical properties and the elastomeric deformation--recovery behavior were then monitored by varying the time of ultraviolet irradiation. Side reactions detected during the synthesis of the high polymers, such as side group exchange reactions and alpha-carbon attack, were analyzed via use of a cyclic trimer model system.Chapter 7 is an outline of the exploratory synthesis of a new series of phosphazene model cyclic trimers and single- and mixed- substituent high polymers containing cyclic aliphatic rings, --CnH2n-1 (where n = 4--8). The cylco-aliphatic side group containing phosphazenes expand the structural and property boundaries of phosphazene chemistry, and suggest additional approaches for studying slow macromolecular substitution reactions and substituent exchange reactions. Polymer structure--property relationships are interpreted and correlated to glass transition temperatures, thermal decomposition temperatures, hydrophobicity, and membrane mechanical properties. Films prepared from these polymers are low cost, tough and non-adhesive. They can be used in variety of applications especially where transparency is important.
A symposium titled "Polyphosphazenes in Biomedicine, Engineering & Pioneering Synthesis" was held at a recent meeting of the American Chemical Society (ACS) in August 2017 in Washington, DC. The chapters in this book provide a summary of the international contributions reported at that meeting, the purpose of which was to bring together a broad range of topics, research investigators, and representatives from industry to discuss the current status of different aspects of this field.
Brings together, analyzes, and contextualizes the latest findings and practical applications Polyphosphazenes, an emerging class of polymers, include macromolecules, which have been proven to be biocompatible, biodegradable, and bioactive. Their unprecedented structural diversity and unique properties make them suitable as vaccine adjuvants, microencapsulating agents, biodegradable materials, scaffolds for tissue engineering, biocompatible coatings, and carriers for gene delivery. Polyphosphazenes for Biomedical Applications offers a thorough review of polyphosphazene research findings in the life sciences, chemistry, and chemical engineering. It emphasizes biomedical applications as well as recent advances in polyphosphazene development such as high-throughput discovery and the latest controlled methods of synthesis. The book brings together, analyzes, and contextualizes a wealth of knowledge that previously could only be found scattered throughout the scientific literature. Following two introductory chapters, the book reviews: Vaccine delivery and immunomodulation Biomaterials Drug delivery systems Biodetection Well-defined polyphosphazenes: synthetic aspects and novel molecular architectures All the chapters have been written by leading researchers in the field. Editor Alexander Andrianov, who has led the effort to commercialize polyphosphazenes for biomedical applications, has carefully reviewed and edited all chapters to ensure readability, accuracy, and thoroughness. Polyphosphazenes for Biomedical Applications is not only intended for researchers working in polyphosphazene chemistry, but also for all researchers seeking solutions to problems arising in the areas of biomaterials, drug delivery systems, and controlled release formulations.
Polyphosphazenes are a new polymers with unique properties which include a combination of high temperature stability, low temperature flexibility, low surface energy, biofriendliness, and inflammability. We focused our research on polymerization of phosphoranimines catalyzed by Lewis acids and Lewis bases and synthesis of poly(diarylphosphazenes) by silyl azide intermediates and characterized the new polymers and copolymers using various techniques. The catalyzed polymerization of phosphoranimineshas been successfully used for the synthesis of random copolymers and the first block copolymers between two different polyphosphazenes. Additonally, we prepared polyphosphazene-organic polymer diblock structures using macromolecular phosphoranimines. The second part of the research was devoted to the preparation of new branched and hyperbranched polymers by controlled radical polymerization. We used atom transfer radical polymerization (ATRP) to prepare hyperbranched polystyrenes and polyacrylates. In addition, the novel class of compounds being simultaneously monomers and initiators (AB ̂monomers or inimers) were used successfully to design and prepare polymers and copolymers with novel topologies, compositions and functionalities. We prepared first molecular bottle-brush structures, multi arm star block and star diblock copolymers and also novel polar thermoplastic elastomers by entirely radical processes.
This book describes preparation techniques for well-defined, customizable poly(organo)phosphazene materials and their applications in nanomedicine, i.e. as macromolecular carriers for drug delivery, immunology, gene therapy, or tissue regeneration. This 2nd edition of Polyphosphazenes for Medical Applications has been updated and extended for researchers in the field as well as those considering using polyphosphazenes for a specific application.
This book addresses plasma modification of polyolefin surfaces. It comprises 21 chapters divided into three major sections. The first section covers the different techniques used for plasma modification of polyolefin surfaces and the effects of various gases as a surrounding medium, while the second provides a detailed analysis of the physics and chemistry of plasma modification and discusses various innovative characterization techniques, as well as ageing of the modified surface. It focuses on the analysis of changes in polymers’ surface chemistry using various spectroscopic techniques, and of changes in their surface morphology after plasma treatment using optical microscopy, electron microscopy and atomic force microscopy. In addition, it provides detailed information on the characterization of modified polymer surfaces. The book’s third and last section covers a range of applications of plasma-modified polyolefin surfaces varying from the packaging industry to the biomedical field, and shares valuable insights on the lifecycle analysis of plasma modification and modified surfaces.
Gleria (National Research Council, Italy) and De Jaeger (chemistry, University of Sciences and Technologies, France) present material dedicated to the use of poly(organophosphazenes) in biology, photochemistry, and high energy radiation chemistry. Their use as hybrid materials, flame and fire retardants, blend components, ionic conductors, membranes, and catalysts is also examined. Research on cyclomatrix polyphosphazene for membrane applications, sulfonated polyphosphazene membranes for direct methanol fuel cells, and synthesis and applications of phosphazene compounds is described. Annotation : 2004 Book News, Inc., Portland, OR (booknews.com).
Gleria (materials science, Padova University, Italy) and De Jaeger (chemistry, University of Sciences and Technologies, France) present the latest work in the synthesis and characterization of poly(organophosphazenes). The book opens with a general introduction on background, developments, and future perspectives, then covers the synthetic aspects of phosphazene polymers, with chapters on areas such as ambient temperature cationic condensation synthesis of polyphosphazenes and high molecular weight polyspirophosphazenes. Chapters on the characterization of phosphazene polymers in solution explore topics including thermal and mechanical properties of polyphosphazenes and electrochemical behavior of phosphazenes. Annotation : 2004 Book News, Inc., Portland, OR (booknews.com).
Polymers are important and attractive biomaterials for researchers and clinical applications due to the ease of tailoring their chemical, physical and biological properties for target devices. Due to this versatility they are rapidly replacing other classes of biomaterials such as ceramics or metals. As a result, the demand for biomedical polymers has grown exponentially and supports a diverse and highly monetized research community. Currently worth $1.2bn in 2009 (up from $650m in 2000), biomedical polymers are expected to achieve a CAGR of 9.8% until 2015, supporting a current research community of approximately 28,000+. Summarizing the main advances in biopolymer development of the last decades, this work systematically covers both the physical science and biomedical engineering of the multidisciplinary field. Coverage extends across synthesis, characterization, design consideration and biomedical applications. The work supports scientists researching the formulation of novel polymers with desirable physical, chemical, biological, biomechanical and degradation properties for specific targeted biomedical applications. Combines chemistry, biology and engineering for expert and appropriate integration of design and engineering of polymeric biomaterials Physical, chemical, biological, biomechanical and degradation properties alongside currently deployed clinical applications of specific biomaterials aids use as single source reference on field. 15+ case studies provides in-depth analysis of currently used polymeric biomaterials, aiding design considerations for the future