Organisation and dynamics of an amphiphilic block copolymer at the air/water interface

This thesis describes the techniques of anionic polymerisation and characterisation used in the synthesis of poly(methyl methacrylate)/poly(ethylene oxide) diblock copolymers, the various surface techniques used to examine the interfacial properties of these copolymers spread on water, and the dynamics of these copolymers in solution. The surface techniques used were surface pressure-concentration isotherm studies, neutron reflectivity, surface quasi-elastic light scattering, and ellipsometry. The thermodynamics of micellization and dynamic properties of the copolymer solutions were investigated using light scattering. The diblock copolymers had a target composition of 50:50 mole ratio and M(_W) = 50000. In addition, several copolymers had one or both blocks holly deuterated which was necessary for the neutron reflectivity studies where contrast variation was required to apply the kinematic approximation. Surface pressure isotherms give thermodynamic information about the behaviour of polymer segments at the interface. It has been possible to interpret this behaviour by using neutron reflectivity to obtain information concerning die thickness and distribution of the PMMA and PEO blocks, and water at the interface. The trends in layer thickness have been supported by the ellipsometric measurements and interpretation of the viscoelastic SQELS data has allowed conclusions about the hydrodynamics of the polymer chains at various surface concentrations

Matching structure and bargaining outcomes in buyer–seller networks

We examine the relationship between the matching structure of a bipartite (buyer-seller) network and the (expected) shares of the unit surplus that each connected pair in this network can create. We show that in different bargaining environments, these shares are closely related to the Gallai-Edmonds Structure Theorem. This theorem characterizes the structure of maximum matchings in an undirected graph. We show that the relationship between the (expected) shares and the tructure Theorem is not an artefact of a particular bargaining mechanism or trade centralization. However, this relationship does not necessarily generalize to non-bipartite networks or to networks with heterogeneous link values

The coupling of valence shell and particle-hole degrees of freedom in a partial random phase approximation

It is well known that the random phase approximation breaks down in the absence of a substantial energy gap between occupied and unoccupied single-particle states. Particle-hole excitations are then inevitably accompanied by substantial rearrangements of the particles in the neighbourhood of the Fermi surface. To accommodate this situation, a partial RPA is introduced which corresponds to replacing only the particle-hole degrees of freedom by bosons but leaving the valence space degrees of freedom intact. The PRPA is therefore a mapping of the many-fermion dynamics into the dynamics of a coupled boson-valence space. In application of the PRPA, algebraic methods, of either a fermionic or Lie algebra type, can be introduced, if desired, to facilitate the treatment of the valence space degrees of freedom. Results of applications are presented in which the valence space particles are treated in the rotational and SU(3) models, and are coupled strongly to giant dipole and quadrupole resonances.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26774/1/0000326.pd