Currently, many polymeric biomaterials do not possess the most desirable surface properties for direct bone bonding due to the lack of suitable surface functionalities. The incorporation of negatively charged groups has been shown to enhance calcium phosphate formation in vitro and bone bonding ability in vivo. However, there are some conflicting literature reports that highlight the complicated nature of the mineralisation process as well as the sometimes apparent contradictory effect of the negatively charged groups. Surface modification using well-defined polymers offer a more precise control of the chain structures. The aims of this study were to synthesise well-defined polymers containing phosphate and carboxylic acid groups, and perform various surface modification techniques. The influence of the polymer structure on mineralisation was examined using a series of specially synthesised phosphate-containing polymers. The mineralisation ability of the fabricated surfaces was also tested. Soluble poly(monoacryloxyethyl phosphate) (PMAEP) and poly(2-(methacryloyloxy)ethyl phosphate) (PMOEP) were synthesised using reversible addition fragmentation chain transfer (RAFT)-mediated polymerisation. The polymerisation conversions were monitored by in situ Raman spectroscopy. Subsequently 31P NMR investigation revealed the presence of large amounts of diene impurities as well as free orthophosphoric acids in both the MAEP and MOEP monomers. Elemental analyses of the polymers showed loss of phosphate groups due to hydrolysis during the polymerisation. Both gel and soluble PMAEP polymers were found to contain large amounts of carboxyl groups indicating hydrolysis at the C-O-C ester linkages. Block copolymers consisting of PMAEP or PMOEP and poly(2-(acetoacetoxy) ethyl methacrylate) PAAEMA were successfully prepared for the purpose of immobilisation of these polymers onto aminated slides. Well-defined fluorinated polymers, (poly(pentafluorostyrene) (PFS), poly(tetrafluoropropyl acrylate) (TFPA) and poly(tetrafluoropropyl methacrylate) (TFPMA)) were synthesised by RAFT-mediated polymerisation. It was found that the Mn values of PFS at higher conversions were significantly lower than those calculated from the theory, although the PDI's were low (&lt1.1). One possible explanation for this is that it may be a result of the self-initiation of FS which created more chains than the added RAFT agents. Both TFPA and TFPMA showed well-controlled RAFT polymerisations. Chain extension of the fluorinated polymers with tert-butyl acrylate (tBA) followed by hydrolysis of the tBA groups produced the amphiphilic block copolymers containing carboxylic acid groups. Block copolymers consisting of PAAEMA segments were further reacted with glycine and L-phenylalanyl glycine. Three types of surface modifications were carried out: Layer-by-Layer (LbL) assemblies of the soluble phosphate- and carboxylic acid-containing homopolymers, coupling reactions of block copolymers consisting of phosphate and keto groups onto aminated slides, and adsorption of fluorinated homo and block copolymers containing carboxylic acid groups onto PTFE. For LbL assemblies XPS analyses revealed that the thickness of the poly(acrylic acid) (PAA) layer was found to be strongly dependent on the pH at deposition. AFM images showed that the PMAEP LbL had a patchy morphology which was due to the carboxylate groups that were not deprotonated at low pH. Successful coupling of the block copolymers consisting of phosphate and keto groups onto aminated slides was evident in the XPS results. The conformation of attached P(MOEP-b-AAEMA) was investigated by ToF-SIMS. Adsorption of the fluorinated polymers onto the PTFE film was examined using different solvents. PFS showed the best adsorption onto PTFE. The block copolymers consisting of PFS and PtBA or PAA were successfully adsorbed onto PTFE. Contact angle measurements showed that the adsorbed block copolymers reorganised quickly to form a hydrophilic surface during the investigation. In vitro mineralisation of various phosphate-containing polymers and the fabricated surfaces were studied using the simulated body fluid (SBF) technique. The SEM/EDX investigation showed that either brushite or monetite, with a tile-like morphology, was formed on both soluble and gel PMAEP polymers after seven days in SBF. The PMOEP gel formed a similar layer as well as a secondary growth of hydroxyapatite (HAP) that exhibited a typical globular morphology. Fourier transform infrared (FTIR) spectroscopy of the PMOEP film prepared from soluble PMOEP showed large amounts of carbonated HAP formation after seven days in SBF. Carbonated HAP is the phase that most closely resembles that found in biological systems. Both the LbL surfaces and the block copolymer-attached aminated slides showed only patchy mineralisation even after 14 days in SBF. This indicates that ionic interactions of the negatively charged phosphates or carboxylates and protonated amines prevented chelation of calcium ions, which is believed to be the first step in mineralisation. The P(FS-b-AA) adsorbed PTFE film also showed only small amounts of mineral formation after 14 days in SBF. These results highlight the many features controlling the mineralisation outcomes.

Thesis (M.Eng.)--University of South Australia, 1995.

Polymer organosilicate nanocomposites have attracted significant attention over the last decade due to improved mechanical, thermal, and barrier properties. Several nanocomposite researchers have recognised potential for biomedical applications, however none have conducted biological investigations. In this project, the predicted ability of the organosilicate to enhance biostability, modulate the release of included drugs, and confer biofunctionality and control over the host response, were assessed as the three primary hypotheses. The studies were conducted with the objective being employment as urinary device biomaterials. Of prime importance was that no detrimental change in cytocompatibility was resultant. Biomedical thermoplastic elastomeric polyurethane organosilicate nanocomposites were prepared from poly(ether)urethane of 1000g/mol poly(tetramethylene oxide) polyol, 4,4??? diphenylmethane diisocyanate, and 1,4 butanediol chain extender chemistry, and various organosilicates with loadings from 1w% to 15w%, using a solution casting technique. Initially, partially exfoliated nanocomposites were produced using a commercially available organosilicate, Cloisite?? 30B. These nanocomposites displayed several advantageous properties, namely i) significant anti-bacterial activity, reducing S. epidermidis adherence after 24h to ~20% for a 15w% organosilicate loading, ii) enhanced biostability, with a 15w% organosilicate loading displaying only slight degradation after a 6 week subcutaneous in vivo ovine implantation, and iii) static modulation of model drug release as a factor of drug properties and organosilicate loading. The former was attributed to the Cloisite?? 30B quaternary ammonium compound, while the latter two were likely primarily barrier effect related and due to changes to poly(ether)urethane permeability. Electrostatic and chemical interactivity between drug and organosilicate was also implicated in the observed drug release modulation. Unfortunately, a lack of in vitro cytocompatibility and poor in vivo inflammatory response will limit in vivo use. Utilising bioinert 1-aminoundecanoic acid as an alternative organic modification, cytocompatible intercalated nanocomposites were produced thus likely allowing in vivo nanocomposite use and exploitation of the barrier effect related properties. However, these nanocomposites were not antibacterial. Variation of the organic modification and/or use of co-modification were viable means of modulating host response and biofunctionality, however nanoscale dispersion of co-modified silicate was poor. Use of nanocomposite technology was concluded beneficial to existing biomaterials, and specifically to biomaterial application as urinary catheters / stents.

My research has focussed on the development of a technique to tailor photochromic switching rates by creating a customised local environment for the dye within an otherwise rigid host matrix. Living radical polymerisation offers the potential to design such a system. A living radical initiator based on a spirooxazine compound was used to polymerise a polymer chain of well controlled molecular weight and polydispersity. This technique facilitated the construction of a conjugate with every photochromic moiety convalently attached to a polymer chain with uniform characteristics. The photochromic behaviour of these new polymer-spirooxazine conjugates were investigated in a cross-linked polymer matrix with a Tg of approximately 120??C. It is well known that photochromic switching is susceptible to local environment effects such as rigidity, free volume and polarity.1, 2 The goal of these systems was to create a uniform local environment which would facilitate controlled changes in the photochromic switching rates. The photophysical investigation of these systems demonstrated the success of this technique. The photochromic rates were directly related to the characteristics of the polymer conjugate. It was postulated the conjugates acted as a customised local environment for the photochromic moiety, encapsulating it from the host matrix. Consequently systematic tailoring of the photochromic switching rates was achieved by changes in the characteristics of the attached polymer. To our knowledge this is the first technique to control local environment of a photochromic compound and thus the first example of systematic tuning of photochromic switching rates. Throughout this research, several characteristics of the attached polymer were modified to give a series of rules for the tuning of photochromic switching rates using this technique. The largest variation in switching speed is achieved through variation of Tg. A range of photochromic rates from extremely slow to near solution-like can be easily achieved. The necessary variations in Tg can be achieved easily using living radical polymerisation techniques. The use of different homopolymers, block and random copolymers were all demonstrated successfully in this work. For finer tuning of the photochromic rates, changes in chain length can be used. It was also found the best living radical polymerisation method for this work was ATRP due to the bulky or incompatible halogen which contributed to efficient encapsulation. However this endgroup effect is only important in systems which do not have a low Tg component. The incorporation of such a component overrides all other contributions to the overall behaviour.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Includes bibliographical references (leaf 80).

Thesis (Ph. D.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.Sc.)--University of Massachusetts Lowell, 2002. / Includes bibliographical references (p. 224-241).

Thesis (Ph. D.)--University of New South Wales, 2004. / Also available online.

Thesis (Ph. D.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2007. / Committee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 120-133). Also available in electronic version.