Microphase separation in the melts of diblock copolymers composed of linear and amphiphilic blocks

Macro Theory & Simulations

2012

The free volume (voids) distribution in the lamellae of the conventional symmetric and amphiphilic diblock copolymers is studied via Monte–Carlo simulation based on the standard bond fluctuation model. Both in the conventional and amphiphilic block copolymers the voids are found to concentrate on the interfaces between the incompatible units, the magnitude of the effect being unexpectedly significant. A crystalline‐like ordering of voids with increase of the incompatibility between the different repeated units in amphiphilic copolymers is first reported and implications of this peculiarity for the morphology and mechanical properties of the amphiphilic copolymers are discussed.

Section: The Model and Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Void Microstructuring in Lamellar Phase of Amphiphilic Macromolecules

Глаголева

Erukhimovich

Macro Theory & Simulations

2012

“…Some beads, for example, A, form a backbone and other beads, B, are pendants. 34 It was shown that such a model allows to describe the unique conformations adopted by macromolecules with amphiphilic monomer units in dilute and concentrated solutions, 34−39 to reconstruct their specific ordering in the bulk 40,41 and near interface. 42−44 In selective solvent, amphiphilic homopolymers sparsely grafted onto a flat substrate can form an ultrathin coating having the width of about two monomer units.…”

Section: Introductionmentioning

confidence: 99%

Lamellae—Parking Garage Structure—Lamellae Transition in Densely Grafted Layers of Amphiphilic Homopolymers: Impact of Polymerization Degree

Lazutin

2018

ACS Omega

By means of computer modeling, the self-organization of densely grafted macromolecules with amphiphilic monomer units as a function of macromolecular polymerization degree and solvent quality was studied and a diagram of state was constructed. The diagram contains fields of disordered distribution of monomer units and of prolonged aggregates, regions of lamellae with small and big domain spacing, and transition region. Within the transition region, the lamellae with different spacing coexist: the lamellae with big domain spacing are on the top of the grafting layer and the lamellae with small domain spacing are close to the grafting surface. The lamellae are connected with each other and form bicontinuous parking garage structure joining all side groups into a single cluster. The domain spacing of lamellae does not depend on the macromolecular length, but the width of the transition region decreases with the decrease of polymerization degree until total vanishing at relatively short macromolecules. The sharp switch between lamellae and bicontinuous structure opens the perspective for practical applications of densely grafted layers with amphiphilic monomer units.

“…37 The phase diagram for the melt of copolymers with an amphiphilic block can be significantly different from that known for the conventional diblocks. 38,39 In the limit of significant amphiphilicity (surface activity), the resulting morphology corresponds to thin channels and slits of amphiphilic units penetrating through the matrix of a majority non-polar component. The voids are found to concentrate on the interfaces and to perform crystalline-like ordering in case of significant amphiphilicity of units.…”

Section: Introductionmentioning

confidence: 99%

New strategy to create ultra-thin surface layer of grafted amphiphilic macromolecules

Lazutin

Govorun

The Journal of Chemical Physics

et al. 2015

Self Cite

It was found first that macromolecules made of amphiphilic monomer units could form spontaneously an ultra-thin layer on the surface which the macromolecules are grafted to. The width of such layer is about double size of monomer unit consisting of hydrophilic A (repulsive) and hydrophobic (attractive) B beads. The hydrophilic A beads are connected in a polymer chain while hydrophobic B beads are attached to A beads of the backbone as side groups. Three characteristic regimes are distinguished. At low grafting density, the macromolecules form ultra-thin micelles of the shape changing with decrease of distance d between grafting points as following: circular micelles-prolonged micelles-inverse micelles-homogeneous bilayer. Those micelles have approximately constant height and specific top-down A-BB-A structure. At higher grafting density, the micelles start to appear above the single bilayer of amphiphilic macromolecules. The thickness of grafted layer in these cases is different in different regions of grafting surface. Only at rather high density of grafting, the height of macromolecular layer becomes uniform over the whole grafting surface. The study was performed by computer modeling experiments and confirmed in framework of analytical theory.