Polyesters have been realised as a viable replacement for slow or non-degrading petroleum derived polymers. A variety of aliphatic polyesters, e.g. poly(lactic acid), have received a lot of attention because they are produced from renewable feedstocks and have the ability to biodegrade and bioassimilate. Poly(lactic acid)'s broader family, poly(α-hydroxy acid)s, have been produced with a wide variety of properties, that has given polyesters the potential for a more diverse range of applications. However, their synthesis has proven difficult. This thesis investigates a family of 1,3-dioxolan-4-ones as a monomer source to ease difficulties in current synthetic routes. Polymerisation of the parent 1,3-dixoxolan-4-one was tested. The copolymerisation of Llactide and 1,3-dioxolan-4-one was conducted with various monomer feedstocks. Ringopening polymerisation of 1,3-dioxolan-4-one led to the formation of paraformaldehyde as a polymerisation by-product. The copolymerisation was found to be best controlled when using a coordination-insertion type catalyst. 1,3-dioxolan-4-one was also copolymerised with ε-caprolactone and β-butyrolactone to produce copolymers with various compositions. The formation of poly(lactic acid) and poly(mandelic acid) from 5-methyl-1,3-dioxolan- 4-one and 5-phenyl-1,3-dioxolan-4-one was investigated. Poly(lactic acid) and poly(mandelic acid) were synthesised with either isotactic or atactic tacticities. Molecular weights were found to be lower than the expected values. A variety of MeAl(salen) catalysts were explored for the polymerisation of 5-methyl-1,3-dioxolan-4-one and catalysts ligated with tertiary-butyl substituted salens were found to have higher rates of polymerisation and reached high conversions. Altering the diimine bridge in the ligand led to variations in rates of polymerisation and molecular weights. The cause of the decrease in molecular weight was found to be caused by a side reaction. The side reaction was bypassed by polymerising 2,2,5- trimethyl-1,3-dioxolan-4-one and 2,2-dimethyl-5-phenyl-1,3-dioxolan-4-one to form poly(lactic acid) and poly(mandelic acid), respectively, with the expulsion of acetone. The scope of 1,3-dioxolan-4-ones capable of being polymerised to form poly(α-hydroxy acid)s was expanded to include iso-propyl, cyclohexyl, normal-butyl, iso-butyl, propargyl, chloromethyl and benzyloxymethyl substituents at the five position. The glass transition temperatures accessible from this synthetic route was expanded (22-105 °C). Kinetic experiments revealed the impact of the substituents steric bulk on the rate of polymerisation and points toward a coordination-insertion mechanism. Poly(lactic acid-co-glycolic acid) was copolymerised with 5-propargyl-1,3-dioxolan-4-one to incorporate alkynyl functionality and hence Raman spectroscopy showed the polymer had a distinct peak at 2128 cm-1. Following post-polymerisation modification of poly(lactic acid-co-3-chloro-2-hydroxypropanoic acid) copolymers, acrylate functionalised polymers were produced. The copolymers were shown to be capable of crosslinking poly(α-hydroxy acid) and poly(methyl methacrylate).

No description available.

L'assemblage de matériaux par collage pour l'aéronautique est une solution à laquelle les industriels pensent depuis longtemps pour alléger les structures. Cependant, les adhésifs développés de nos jours ne sont pas suffisamment performants pour remplacer les méthodes traditionnelles (rivetage, boulonnage, etc..). Notamment, la température de service limite la performance d'un joint adhésif. Pour élargir l'opérabilité d'un assemblage collé, la première solution proposée a consisté à utiliser deux adhésifs dans un même joint : c'est le concept du joint multi-adhésif. Plus récemment, plusieurs travaux de recherche ont fait évoluer ce concept en utilisant un joint adhésif avec des propriétés variables discontinues le long de la surface encollée. Le présent manuscrit propose une nouvelle évolution de ce concept, où cette fois-ci la variation de propriétés est continue le long du joint adhésif : on parlera de concept de joint adhésif aux propriétés graduées (JAPG). L’idée du concept du JAPG réside dans la possibilité de diffusion de copolymères au sein d’une résine époxyde-amine, créant ainsi un gradient de concentration en copolymères, et donc un gradient de propriétés le long du joint. Suite à l’optimisation de la mise en œuvre de ce type de joint, le cœur du travail s’est articulé autour de la définition de méthodes de caractérisation d’assemblages collés sensibles à la modularité des propriétés d’adhérence induites par ces adhésifs hybrides. Plus précisément la puissance d’adhérence a été quantifiée lors de la phase d’encollage dans laquelle l’adhésif est sous forme de gel, puis lorsque l’adhésif est rigide au sein de la structure collée en service. Les tests choisis sont un test de tack à poinçon plat et un test de clivage en coin. Cette volonté de suivre l’évolution de l’adhérence durant toute la transformation de l’état physique de l’adhésif s’explique par la nécessité de maitriser la compétition entre forces de cohésion internes à l’adhésif qui prédominent quand l’adhésif est rigide et forces d’adhésion qui se créent lors de la mise en contact de l’adhésif avec le substrat. Les tests mécaniques sélectionnés et adaptés se sont finalement révélés être des outils sensibles et fiables pour caractériser l'adhérence d'un JAPG. Cette étude a montré qu’un tel joint possède des propriétés d’adhérence supérieures à celles de ses contreparties mono-adhésives de par la distribution hétérogène des copolymères dans le joint. / Bonded assemblies are a solution for which the aeronautical industry is looking forward to lighten airplanes since a long time. However, adhesives used nowadays are not equivalent to traditional methods, performance-wise. Particularly, in life temperature is one of the parameters that limit the performance of adhesive joints. A first attempt to solve this problem saw the birth of the multi adhesive joint, where two adhesive are used in the same joint. Recently, several works proposed an evolution of this concept, where the properties are changed gradually along the joint. This thesis moves one step forward by proposing yet another evolution. We designed an adhesive joint where the properties are continually graded over the joint: an adhesive joint with a gradient of properties (AJGP). Continuous grading is obtained by designing an adhesive joint with two adhesives. One of those is obtained from a classical epoxy-amine system. The other adhesive is made with the same epoxy-amine matrix, with the addition of amphiphilic tribloc copolymers. The latter is a nanostructured adhesive, which exhibit higher toughness than the former. When those adhesives are placed in the same joint, an interdiffusion phenomenon occurs. This allows copolymers diffusion along the joint. This work is split in two complementary research axis: first, a AJGP joint is designed and realized, to be tested either during bonding or in-life. Second, experimental tests are used to assess fracture toughness of the AJGP joint, with the challenge in mind to be able to detect an adherence variation along the joint. We chose a probe tack test and two wedge tests (cleavage test and driven wedge test) as mechanical tests. Those mechanical tests proved useful to assess adherence properties of an AJGP, which exhibits higher properties than its mono-adhesives counterpart

Ces travaux ont pour objet la synthèse et la caractérisation de nouveaux électrolytes polymères pour batterie lithium métal polymère (LMP). L’objectif principal de ces électrolytes est de combiner une conductivité ionique élevée jusqu’à basse température et une résistance efficace contre les dendrites de lithium. Pour y parvenir, trois catégories de copolymères à bloc ont été élaborés, ils permettent d’obtenir une synergie de propriétés à priori antagonistes au sein d’un même matériau. Premièrement, la rigidité du polystyrène (PS) a été combinée à la conductivité du polyoxyéthylène (POE) dopé avec un sel de lithium (LiTFSI). Le POE a été préalablement modifié pour en abaisser la température de fusion (Tf) initialement située à 60°C, ce qui permet d’atteindre de hautes conductivités (7.10-5 S.cm-1) à 40°C, associées à un module d’Young de 0,3 MPa. Cependant, les bonnes conductivités de ces matériaux ne sont assurées que par une petite fraction de Li+ (t+=0,15). Cela crée des gradients de concentration qui limitent les performances des batteries. Pour pallier cela, l’anion TFSI a été greffé sur le bloc PS (PSTFSI), augmentant le t+ à 1. Le bloc PSTFSI combiné à du POE modifié a permis des conductivités remarquables pour un électrolytes solide (10-6 S.cm-1 @ 40°C). Dans un second temps, l’ajout d’une chaine perfluorée entre le PS et l’anion a permis un gain supplémentaire de conductivité par rapport au PSTFSI (2.10-5 S.cm-1 @ 60°C), uniquement assurée par les Li+. Dans chacune des trois catégories d’électrolytes plusieurs compositions ont été synthétisées, nous permettant de suivre l’impact de cette composition sur les morphologies, les propriétés thermodynamique et mécanique ainsi que sur les propriétés de transport. Finalement, des batteries LMP de laboratoire ont été assemblées avec les meilleurs électrolytes. / This work deals with synthesis and characterization of new polymer electrolytes for lithium metal polymer (LMP) batteries. The main challenge of polymer electrolytes is to combine both high ionic conductivity at low temperature and good mechanical properties. To overcome these issues, block copolymers have been designed. Remarkable properties are reached thanks to the self-assembly of these triblock copolymers. Mechanical properties are given by stiff polystyrene (PS) domains whereas ionic mobility operates in an ionophilic phase, polyoxyethylene (POE) with a lithium salt (LiTFSI). By introducing chemical defects in the POE backbone, melting temperature of the copolymer has been considerably lowered leading to conductivities of about 7.10-5 S.cm-1 and a Young’s modulus of 0.3 MPa at 40°C. If interesting properties are obtained thanks to this strategy, the small fraction of conductivity insured by lithium ions (t+=0.15) remains an issue. The low t+ leads to large concentration gradients limiting the performances of the system. In a second approach, TFSI anions have been covalently tethered on the PS backbone, raising the t+ to 1. An important increase of Li+ conductivity was obtained by adding a perfluorinated spacer between PS and TFSI moieties, with an ionophilic phase based on PEO (2.10-5 S.cm-1 @ 60°C). The chemical modification of the PEO block leads to Li+ conductivities of 10-6 S.cm-1 at 40°C. The composition of these different copolymers have been varied and their structural, thermal, mechanical and transport properties have been studied. Finally the best electrolytes of each category have been assessed in a full cell configuration.

"May 2003" / Includes bibliographical references (leaves 261-270) / xvi, 271, [16] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, 2003

This dissertation presents the synthesis of a series of thermo- and pH-sensitive hydrophilic block copolymers and the study of their solution behavior in water. By incorporating a small amount of weak acid or base groups into the thermosensitive block(s) of a hydrophilic block copolymer, the LCST of the thermosensitive block(s) can be modified by changing the solution pH. Accordingly, the critical micellization temperature (CMT) and the sol-gel transition temperature (Tsol-gel) of the block copolymer in water can be tuned. Chapter 1 describes the synthesis of thermo- and pH-sensitive poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid)-b-PEO-bpoly( methoxydi(ethylene glycol) methacrylate co-methacrylic acid) and the study of sol-gel transitions of its aqueous solutions at various pH values. The CMT of the 0.2 wt% solution and the Tsol-gel of the 12.0 wt% solution of this copolymer can be varied over a large temperature range. By judiciously controlling temperature and pH, multiple sol-gel-sol transitions were realized. Chapter 2 presents a systematic study of pH effect on rheological properties of micellar gels formed from 10.0 wt% aqueous solutions of thermo- and pH-sensitive poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid)-b-PEO-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid). With the increase of pH, the sol-gel transition became broader. The plateau moduli (GN) evaluated from frequency sweeps at T/Tsol-gel of 1.025, 1.032, and 1.039 decreased with the increase of pH from 3.00 to 5.40 with the largest drop observed at pH = ~ 4.7. The decrease in GN reflects the reduction of the number of bridging chains. The ionization of carboxylic acid introduced charges onto the thermosensitive blocks and made the polymer more hydrophilic, facilitating the formation of loops and dangling chains. Chapter 3 presents the synthesis of PEO-b-poly(methoxydi(ethylene glycol)methacrylate-co-2-(N-methyl-N-(4-pyridyl)amino)ethyl methacrylate) with the thermosensitive block containing a catalytic 4-N,N-dialkylaminopyridine and the study of the effect of thermo-induced micellization on its activity in the hydrolysis of pnitrophenyl acetate. The CMTs of this copolymer at pH of 7.06 and 7.56 were 40 and 37 °C, respectively. Below CMT, the logarithm of initial hydrolysis rate changed linearly with 1/T. Above CMT, the reaction rate leveled off, which is presumably because it was controlled by mass transport to the core of micelles above CMT.

Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic) well-defined graft polymers having core-shell morphologies, with a hydrophobic core and a hydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded successive generations of arborescent polystyrenes. The anionic polymerization of styrene with sec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a linear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An analogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also obtained by a variation of the same technique, using a bifunctional organolithium initiator containing a hydroxyl functionality protected by a silyl ether group to generate the polystyrene side chains. These were coupled with the linear acetylated polystyrene substrate and subjected to a deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain ends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1 polymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol chain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic shell around the hydrophobic cores, but led to extensive degradation. A click reaction was also developed to synthesize the amphiphilic copolymers and was much more successful. In this case alkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the hydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized polyglycidol side chains.

No description available.

A novel methodology has been developed for the formation of block copolymers that combines ring-opening metathesis polymerization (ROMP) with functional chain-transfer agents (CTAs), functional chain-terminators (CTs) and self-assembly. Telechelic homopolymers of cyclooctene derivatives that are end-functionalized with hydrogen-bonding or metal-coordination sites are formed via the combination of ROMP with a corresponding functional CTA. These telechelic homopolymers are fashioned with a high control over molecular weight and without the need for post-polymerization procedures. The homopolymers undergo fast and efficient self-assembly with their complement homopolymer or small molecule analogues to form block copolymer architectures. The block copolymers have similar association constants to small molecule analogues described in the literature, regardless of size or the nature of the complementary unit or the polymer side-chain. The ROMP of side-chain functionalized norbornene polymers is coupled with functional CTs to produce block copolymer with main- and side-chain self-assembly sites. Combinations of these norbornene polymers with their complement polymer via self-assembly produce non-covalent AB type block copolymers fast and efficiently. ABA type block copolymers are realized by combining the difunctional homopolymer formed via the CTA pathway with the CT synthesized mono-functional polymer. These polymers show similar association constants regardless of the sequence of polymer formation.

A series of immiscible crystalline-crystalline diblock copolymers, poly(ethylene oxide)-b-(£`-caprolactone) (PEO-b-PCL), were synthesized through ring-opening polymerization and then blended with phenolic resin. FT-IR analyses provide that the ether group of PEO is a stronger hydrogen bond acceptor than the carbonyl group of PCL with the hydroxyl group of phenolic. Phenolic after curing with hexamethylenetetramine (HMTA) results in the excluded and confined PCL phase based on differential scanning calorimeter (DSC) analyses. This effect leads to the formation of a variety of composition-dependent nanostructures, including disorder, gyroid and short cylinder. The self-organized mesoporous phenolic resin was only found at 40~60 wt% phenolic content by intriguing balance of the contents of phenolic, PEO, and PCL. In addition, the mesoporous structure was destroyed with the increasing the ratio of PCL to PEO in block copolymers by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses. In addition, the large and long-range order of bicontinuous gyroid-type mesoporous carbon was obtained from mesoporous gyroid phenolic resin calcined at 800 ¢XC under nitrogen.