Heterogeneous percolation-to-cluster transition in phase separation of an off-critical polymer mixture

Abstract

Articles you may be interested inWetting-layer formation mechanisms of surface-directed phase separation under different quench depths with off-critical compositions in polymer binary mixture Crossover of domain-growth behavior from percolation to cluster regime in phase separation of an off-critical polymer mixture Phase separation kinetics of an off-critical polymer mixture involving percolation-to-cluster transition ͑PCT͒ was investigated by time-resolved light scattering and by transmission optical and electron microscopies. The process involving a splitting of a single peak in the light scattering profile into a double peak was observed for the first time after the onset of PCT. Each peak changes with time (t) according to different evolution modes, e.g., the first peak wave number q m,1 evolved according to the power law of percolated structures (q m ϳt Ϫ␣ ; ␣ϭ0.9), while the time evolution of the second peak wave number q m,2 is very slow, which corresponds to the growth of cluster of the droplets after PCT. Furthermore, the real space pictures and the light scattering analysis reveal that a cluster of the small spherical droplets and the locally percolating domains coexist for a very long time. The percolating domains are larger than the small droplets, minor in volume fraction, and formed in bulk and they are developed into sheet-like grains with their surfaces parallel to the glass surface.

Surface energy inducing asymmetric phase distribution in films of a bynary polymeric blend

“…The phase separation evolved by hydrodynamic channels and was driven by the wetting of the stainless steel moulding surface. A similar behavior was reported for a PP/ EPR blend [9] and for films made by a polybuthene/ polyisoprene blend [10]. In particular a percolating phase morphology parallel to the surface was observed in films annealed on glass plates and having a thickness of 0.5 mm [10].…”

Percolation-to-droplets transition during spinodal decomposition in polymer blends, morphology analysis

“…It directly influences physical properties of blends and, so, their applications. The formation and growth of the domain pattern via SD is strongly dependent on the type of the phase diagram ͑symmetric, asymmetric͒, 1,2 polymer melt composition ͑critical, off-critical͒, [3][4][5][6] and temperature quench depth. 6 It is also known that a system quenched to a temperature between the binodal and spinodal lines ͑metastable region͒ shows only the droplet morphology, and the phase separation proceeds via the nucleation and growth mechanism.…”

“…6 It is also known that a system quenched to a temperature between the binodal and spinodal lines ͑metastable region͒ shows only the droplet morphology, and the phase separation proceeds via the nucleation and growth mechanism. 5 Most of the previous studies 1,4,5,7,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] have been concerned with the evaluation of the quantities that have been measured only by the scattering techniques, for example, the average domain size, which is extracted from the structure factor ͑light scattering intensity͒. Less attention has been paid to the quantitative characterization of the interface morphology.…”

Physical properties of PVA/PSSNa blends

“…Levon et al19 pointed out one possible way to make a blend with a conductive polymer content lower than the threshold conductive, that is, to make the conductive polymer percolate in its rich phase while the conductive polymer‐rich phase percolates in its minor phase, and have put forward an equilibrium dynamics equation according to their model, but they did not give applicable factors, which would form the multiple percolation. Takeno et al20 found that it is common for a polymer mixture in off‐critical conditions to form a coexistence structure, with the minority phase forming interconnected droplets in the sheetlike percolating structure of the rich phase, which hints to us that polymer behavior in a metastable state is important for obtaining multiple percolation.…”