Kinetics of microphase separation

MSI) that uses the same time-dependent Ginzburg Landau kinetic equation as CDS, but starts from (arbitrary) bead models for polymer chains. The methods have been summarized elsewhere. Examples of recent applications include LB simulations of viscoelastic effects in complex fluids under oscillatory shear,DPD simulations of microphase separation in block copoly-mers ° and mesophase formation in amphiphiles, and cell dynamics simulations applied to block copolymers under shear. - DPD is able to reproduce many features of analytical mean field theory but in addition it is possible to study effects such as hydrodynamic interactions. The use of cell dynamics simulations to model non-linear rheology (especially the effect of large amplitude oscillatory shear) in block copolymer miscrostructures is currently being investigated. ... 

It has been well established by Cooper and Tobolsky that the unique properties of polyurethanes are strongly linked to its two-phase morphology [21], Characterization of microphase separation is performed using a variety of techniques including dynamic mechanical thermal analysis (DMTA), Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), and atomic force microscopy. Consideration of both the thermodynamic driving forces and the kinetics is needed to elucidate microstructure formation in polyurethanes [60-66],... 

The experimental data shows that the formation of semi-IPN occixrs according to a spinodal mechanism which is realized in spite of the preceding reaction and, consequently, the non-equilibrium conditions of the process. It was also shown that under these conditions the reaction kinetics determine the beginning of microphase separation, i.e., the thermod5mamics of formation of the system and its thermod3uiamic state are determined by the reaction kinetics. 

The effect of fillers on the reaction of polymer formation was discussed in Chapter 4. It is evident that introducing a filler during IPN formation should also lead to its influence on the rates of the IPN formation. This influence should affect the possibility of microphase separation. This question was studied " for simultaneous semi-lPN based on a crosslinked polyurethane and linear PBMA. The ratio PU PBMA was 3 1, the ratio IPN flller was 60 40 and 80 20 by weight. It was established that the onset of auto-acceleration of the butyl methacrylate polymerization increases from 160 min without filler to 220 min in the presence of a filler (talc). After the onset of auto-acceleration, the reaction rate of butyl methacrylate pol5mierization decreases with the increase of amount of filler. The filler influence on the reaction kinetics was explained based on the so-called... 

The development of solid-state structure in semicrystalline block copolymers has been studied extensively over the past decade. Most of the earlier studies are covered in a recent review by Hamley [1999] the present chapter complements this earlier review by highlighting recent advances in this field, with a particular focus on how the processes of microphase separation and crystallization interact. We begin by providing a brief overview of synthetic routes to near-monodisperse semicrystalline block copolymers. We then enumerate the key experimental techniques used to examine the crystallization behavior and morphology of semicrystalline block copolymers. The remainder of the chapter focuses on the solid-state structures that these materials exhibit, the pathways by which these structures develop, and the impact of melt microphase separation on polymer crystallization kinetics. 

It is evident that effects of the mutual influence of constituent networks on the kinetics of their formation will be seen more clearly for simultaneous IPNs. This case is also interesting because it allows us to elucidate simultaneously the role of microphase separation in the reaction kinetics. 

It can therefore be inferred that simultaneously proceeding chemical processes of formation of polymer molecules which constitute the IPNs and physical processes of microphase separation occur under nonequilibrium conditions [103]. In this case the microphase structure of semi-IPNs and the kinetics of their formation become interrelated (see Sect. 4). The effect of the reaction conditions on the morphology of simultaneous PU/PMMA IPNs has also been estabUshed in [294], and for poly(dimethylsiloxane-urethane)/PMMA IPNs in [295]. It was shown that depending on the kinetic conditions, both compatible and incompatible IPNs could be formed with well-matched rates of cross-finking reaction. Incompatible IPNs are formed by a much slower cross-linking reaction producing phase-separated IPNs. We believe that in the present case, because of the method of determination, one should talk not about true compatibility, but about the dependence of apparent compatibility on reaction kinetics. 

Fraaije, J.G.E.M. Dynamic density functional theory for microphase separation kinetics of block copolymer melts. J. Chem. Phys. 99 (1993) 9202-9212. 

Methyl-l,10-undecadiene, ADMET polymerization of, 442 Michaelis-Menten enzymatic kinetics, 84 Microbial hydrolysis, 43 Microcellular elastomers, 204-205 Microphase-separated block copolymers, 6-7... 

The fascinating thermodynamics of block copolymers that results from microphase separation are the subject of the parts 2.2,2.3, and 2.4 of Chapter 2. Part 2.4 is concerned with the complex kinetic processes that accompany phase transitions, and the dynamic processes controlled by the structure of the block copolymer melt. 

---