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This dissertation is aimed at understanding the microstructure evolution in styrene — diene block copolymer — based pressure-sensitive adhesive compositions in melt. The work also focuses on determining the microphase separation mechanism in adhesive melts containing various amounts of low molecular weight resin (tackifiers) blended with styrene — diene block copolymers. To understand the correlation between adhesive morphology and their dynamic mechanical behavior, small angle X-ray scattering (SAXS) and rheological analysis were performed on blends with different compositions. A modified Percus — Yevick model combined with Gaussian functions was used fit the liquid like disordered and bcc — ordered peaks of the SAXS intensity profiles. The morphological parameters derived from SAXS analysis corresponded to features such as the size and extent of ordering of the microphase separated polystyrene domains. The variation in these parameters with respect to temperature and adhesive composition correlated reasonably well with the trends observed in the shear modulus measured using rheological analysis. It was found that the ordering of polystyrene domains was influenced by the tackifier content in the adhesive blends. Polymer chain mobility was determined to be the dominant factor governing ordering kinetics, which depended on both the quench temperature and tackifier content in the blends. The addition of increasing amounts of tackifier eventually leads to a shift from a nucleation and growth type mechanism to a spinodal decomposition mechanism for phase separation and ordering. The compatibility of the tackifier with the polystyrene chains had a significant impact on the morphological transitions and microphase separation in adhesive blends. The blends containing a styrene — incompatible tackifier showed ordering over a broader range of temperatures compared to the blends containing a polystyrene — compatible tackifier. / Ph. D.

Stimuli responsive polymers (SRP) have attracted a lot of attention, due to their potential and promising applications in many fields, as protein-ligand recognition, on-off switches for modulated drug delivery or artificial organs. Poly(N-isopropylacrylamide) (PNIPAM) is one of the most widely studied polymers due to its lower critical solution temperature (LCST) at ~ 32° C in aqueous solution. Additionally, glycopolymers, where free sugar units are present, have potentially interesting applications especially in bio-recognition where sugars play an important role. In this work, our interest was focused on the synthesis of glycomonomers and its block- and random- copolymers with NIPAM. NIPAM homopolymers with an active chain transfer unit at the chain end could be prepared by RAFT. They were used as macro-chain transfer agents to prepare a variety of sugar containing responsive block copolymers from new glycomonomers by the monomer addition concept. The LCSTs of the aqueous solutions of the copolymers are affected strongly by the comonomer content, spacer chain length of the glycomonomer and the chain architecture of the copolymers. These polymers were coated on a solid substrate by spin coating and crosslinked by plasma immobilization. Characterization of the polymers was performed by nuclear magnetic resonance spectroscopy (NMR), ultraviolet (UV), dynamic light scattering (DLS, detection of aggregation behaviour) and gel permeation chromatography (GPC). Polymer films were investigated by ellipsometry, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) regarding their surface properties. Afterwards sulfation of sugar – OH groups was performed in order to obtain heparin like structure, as heparin exhibits numerous important biological activities, like good interaction with diverse proteins. Finally, affinity of the polymers (sulfated and non sulfated form) on a solid support to the endothelial cells was investigated.

Block copolymers have attracted interests for potential application ranging from dynamic photonic sensors to solid-state ion conductors. However, due to nucleation and growth mechanism, block copolymer inherently forms granular microstructure with defects such as grain boundaries. Understanding the microstructure of block copolymer is thus crucial in many applications because the microstructure determines the transport property of functional fillers such as ions in block copolymer template. Previous research has shown that athermal filler segregated to grain boundary of lamellae block copolymer and retards the grain coarsening. However, the kinetics of this grain boundary segregation during thermal annealing has not been revealed. Polystyrene-b-polyisoprene blended with deuterated polystyrene is used for neutron scattering study on studying the kinetics of grain boundary segregation. Deuterated polystyrene will segregate to grain boundaries, therefore, decorate grain boundary. The filler segregation behavior will be studied by comparing neutron scattering of polystyrene-b-polyisoprene/deuterated polystyrene with different annealing times (at T=130 deg C, duration of 0hr, 3hr, 1day, 3day and 7day, respectively). Invariant (Q) analysis along with grain mapping is conducted to quantitatively analyze the kinetics of grain boundary segregation. This kinetic was in good agreement with the McLean’s kinetic model for grain boundary segregation in metals. By applying Langmuir-Mclean’s segregation isotherm equation, we have predicted the equilibrium concentration of filler in grain boundary by calculating the strain energy stored in grain boundary.

Ce travail de thèse propose une nouvelle approche pour la préparation de membranes à matrice mixte basée sur l’utilisation de copolymères à blocs et de nanoparticules inorganiques disposant de propriétés magnétiques. Des aggrégats de copolymères ont été préparés avec une morphologie variée (sphères, cylindres et vésicules) à partir du copolymère poly(acide méthacrylique)-b-poly(méthacrylate de méthyle). Ce dernier a été synthétisé par polymérisation radicalaire contrôlée par transfert de chaîne réversible par addition-fragmentation (RAFT) dans l’éthanol à 70°C. Des particules d’oxyde de fer ont, quant à elles, été préparées en présence de différents stabilisants à température variée pour permettre d’atteindre la charge de surface et les propriétés magnétiques recherchées. La structure des copolymères à bloc a permis d’obtenir à la fois des membranes hydrophobes via le procédé de séparation de phase induite par un non-solvant, ainsi que des membranes hydrophiles lorsque que la technique de spin-coating était appliquée aux aggrégats formés par auto-assemblage induit lors de la polymérisation. Grâce à l’étude détaillée des propriétés de filtration des membranes obtenues, la relation structure-propriété a été discutée sous l’action d’un champ magnétique externe. Enfin, la sensibilité au colmatage a été vérifiée via la filtration de solutions de protéines. Il a ainsi été démontré une diminution notable du colmatage sous champ magnétique, ouvrant de belles perspectives pour ces nouvelles membranes. / This thesis presents a new approach to produce mix matrix membranes using block copolymers and inorganic nanoparticles having magnetic properties. The polymeric nanoparticle with different morphologies (linear, Spheres, worms, and vesicles), from poly (methacrylic acid)-b-(methyl methacrylate) diblock copolymer, were synthesized using Reversible addition−fragmentation chain transfer polymerization (RAFT) in ethanol at 70 ֠C. The inorganic counterpart, iron oxide nanoparticles were prepared using different stabilizers at various temperatures to acquire the necessary surface charge and magnetic properties. The chemistry of the particles leads to form both hydrophobic membranes using non-solvent induced phase separation as well as a hydrophilic membrane by using the simple spin coating technique with the particles from polymerization induced self-assembly. By a detailed experimental study of the membrane filtration, the influence of different parameters on the process performance has been investigated with and without magnetic field. Finally, membrane fouling has been studied using protein solution. Also, the membrane performance was examined under magnetic field revealing the successful reduction in the fouling phenomenon making them new performant membranes in the area of membrane technology.

In recent years, the use of self-associating block copolymer based drug delivery systems have attracted increasing attention as nanoscopic carriers for the encapsulation and the controlled delivery of water insoluble drugs. Currently, most of the drug formulations proceed by trial and error method with no distinct method to predict the right combination of block copolymers and drugs to give all the desired functional properties. This is simply because such drug delivery systems involve complex intermolecular interactions and geometric fitting of molecules of different shapes. So, in the context of block copolymer design process, quantification and prediction of the interactions between potential block copolymers and the target drug are of great importance. Computer simulations that can predict the level and type of interactions encountered in drug/block copolymer pairs will enable researchers to make educated decisions on choosing a particular polymeric carrier for a given drug, avoiding time consuming and expensive trial and error based formulation experiments. In the present thesis, we reported the use of molecular dynamics (MD) simulation to predict the solubility of sets of hydrophobic drug molecules having different spatial distribution of hydrogen bond forming moieties in a series of micelle-forming PEO-b-PCL block copolymers with and without functionalized PCL blocks. The solubility predictions based on the MD results were then compared with those obtained from the solubility experiments and those obtained by the commonly used group contribution method (GCM). MD analysis techniques like radial distribution functions provided useful atomistic details to understand the molecular origin of miscibility and/or immiscibility observed between drugs and di-block copolymers. Based on the evidence of reported work, intermolecular specific interactions, intra-molecular interactions, local molecular packing, and stereochemistry of the hydrophobic block all play important roles in inducing miscibility between drugs and block copolymers. Additionally, not only the architecture of block copolymers but also the molecular characteristics of drug molecules, e.g., spatial distributions of hydrogen bond donors and acceptors on their molecules can affect the miscibility characteristics of binary mixtures. Depending on the groups present on drugs and block copolymers, any of the above factors can play vital role in the process of favouring encapsulation. The understanding of relative contributions of these interactions can help us to customize the performance of drug carriers by engineering the structure of block copolymers. / Chemical Engineering