A variety of morphologies in diblock copolymer/homopolymer blends

1989 ◽  
Vol 47 ◽  
pp. 346-347
Author(s):  
Edwin L. Thomas ◽  
Karen I. Winey
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Diblock Copolymer ◽  
Copolymer Composition ◽  
Molecular Weights ◽  
Copolymer Concentration ◽  
Wide Range ◽  
Homopolymer Blends ◽  
Long Range Ordering ◽  
Double Diamond

A wide range of morphologies and thereby physical properties can be achieved in block copolymer/homopolymer blends by varying the copolymer composition, copolymer concentration and molecular weights. Recently we investigated micelle shape transitions in diblock copolymer with homopolymer blends at low copolymer concentration. In this paper we study the microstructure over a wider concentration range for a polystyrene-polybutadiene (PS/PB) diblock copolymer of molecular weight 20.5 × 103/20.5 × 103 blended with 17.2 × 103 molecular weight homopolystyrene (hPS).Figure 1 shows schematically a possible spectrum of microdomain structures dependent on the copolymer concentration of a lamellar PS/PB and hPS. Below the critical micelle concentration (CMC) the block copolymer is molecularly dispersed in the homopolymer exhibiting a homogeneous phase. As diblock concentration increases the minority (i.e. PB) forms spherical and/or cylindrical micelles randomly dispersed in the hPS. Further increases in diblock concentration induces long range ordering of various microdomains. In addition three biphasic regions are proposed in which two phases coexist: isotropic cylinders with ordered cylinders, ordered cylinders with ordered bicontinuous double diamond (OBDD), and OBDD with swollen lamellae.

Morphologies in Blends of Diblock Copolymer and Homopolymer: Morphology Diagrams and the Intermaterial Dividing Surface

1991 ◽  
Vol 248 ◽  
Author(s):  
Karen I. Winey
Keyword(s):  
Molecular Weight ◽  
Diblock Copolymer ◽  
Mean Curvature ◽  
Morphological Data ◽  
Copolymer Composition ◽  
Binary Blends ◽  
Morphological Transitions ◽  
The Mean ◽  
Dividing Surface ◽  
Double Diamond

AbstractBinary blends of diblock copolymer (AB) and homopolymer (hA) self assemble upon solvent evaporation into a great variety of microphase separated morphologies. The ordered lamellar, bicontinuous double diamond, cylindrical and spherical morphologies were observed by TEM and SAXS in our studies, as well as a range of micellar morphologies.The mean curvature (H) and the area per copolymer junction (σj), which characterize the intermaterial dividing surface, increased with increasing homopolymer concentration in the blend and/or with decreasing homopolymer molecular weight. These trends were generally obeyed both between and within ordered morphology types. The increase in H and σj was related to an increased degree of mixing between the homopolymer and the block of the copolymer.Two types of isothermal morphology diagrams were constructed to consolidate the extensive morphological data and to illustrate the general morphological transitions in AB/hA blends. The constant molecular weight morphology diagrams illustrated the interdependence of the copolymer composition and the homopolymer concentration. The constant copolymer composition diagrams emphasized the importance of the relative homopolymer molecular weight and the overall blend composition.

Structural transitions and organization of micelles in block copolymer/hompolymer blends

1987 ◽  
Vol 45 ◽  
pp. 520-523
Author(s):  
Edwin L. Thomas ◽  
David J. Kinning
Keyword(s):  
Block Copolymer ◽  
Self Assembly ◽  
Radius Of Gyration ◽  
Physical Situation ◽  
Molecular Weights ◽  
Amphiphilic Molecules ◽  
Wide Range ◽  
Homopolymer Blends ◽  
Cylindrical Micelles ◽  
Solvation Forces

Spherical and cylindrical micelles are quite common in lipid/water systems. The self assembly of amphiphilic molecules into well defined geometries has been extensively studied and is explained in terms of geometric and packing properties in addition to electrostatic, van der Waals and solvation forces. While macromolecular self assembly may seem more complex than for such small molecule systems, it is actually a simpler physical situation to model. Much can be learned from the combined study of each type of system.In block copolymer/homopolymer blends the scale of the phase separation is restricted to the radius of gyration of the polymer blocks (typically several hundred A). By varying the composition and the molecular weights of the blocks and of the homopolymer, a wide range of morphologies and therefore physical properties can be achieved.

The Ordered Bicontinuous Double Diamond Structure in Binary Blends of Diblock Copolymer and Homopolymer.

1989 ◽  
Vol 171 ◽  
Author(s):  
Karen I. Winey ◽  
Edwin L. Thomas
Keyword(s):  
Molecular Weight ◽  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Composition Range ◽  
Volume Fraction ◽  
Diamond Structure ◽  
Binary Blends ◽  
Resultant Effect ◽  
Strong Segregation ◽  
Double Diamond

ABSTRACTWe report the observation of the ordered bicontinuous double diamond (OBDD) structure in binary blends of poly(styrene-isoprene) diblock copolymer and homopolystyrene. The overall polystyrene volume fraction range is 64 - 67 PSvol% for the OBDD structure in binary blends of a lamellar diblock (SI 27/22) and a homopolymer (14.0 hPS). This composition range is approximately within the polystyrene volume fraction range established for pure diblock copolymers in the strong segregation regime having the OBDD structure. Ordered lamellae are observed at approximately 65 PSvol% when the homopolystyrene molecular weight is greater than the molecular weight of the polystyrene block of the copolymer. This observation is discussed in terms of the decreased degree of mixing between the homopolymer and the corresponding block and the resultant effect on the interfacial curvature.

Viscoelastic relaxation in poly-1-butenes of low molecular weight

1967 ◽  
Vol 300 (1462) ◽  
pp. 356-372 ◽  
Keyword(s):  
Molecular Weight ◽  
Steady Flow ◽  
Simple Liquid ◽  
Viscoelastic Relaxation ◽  
Low Frequencies ◽  
Chain Polymer ◽  
Molecular Weights ◽  
Wide Range ◽  
Volume Equation ◽  
Rouse Theory

Measurements have been made of the viscoelastic properties of a range of poly-1-butene liquids of different molecular weights under cyclic shearing stress. The five liquids studied range in steady-flow viscosity at 20 °C from 5.5 to 9330 P corresponding to number average molecular weights from 448 to 2700. Measurements over the temperature range – 60 to +90 °C were made at frequencies of alternating shear of 64 kc/s, 6, 18 and 30 Mc/s. The liquid of lowest molecular weight (448) was nominally pure, having eight repeat units, while the remaining four each had a distribution of molecular weights. In all cases, the dependence of steady flow viscosity upon temperature follows the equation In η = A + B /(T - T 0 ), (1) which is derived from the free-volume equation with a linear dependence of density upon temperature. Recent measurements on a wide range of pure liquids which have viscosities described by equation (1) have been interpreted in terms of a simple phenomenological model for viscoelastic relaxation which allows the behaviour to be predicted (Barlow, Erginsav & Lamb 1967 b ). Analysis of the present results on the liquid of lowest molecular weight shows that the measured behaviour can also be described by this model. For the four liquids of higher molecular weight a second relaxation process is found at lower frequencies. This is attributed to the increased chain length of the molecules giving rise to 'quasi-Rouse’ modes of motion. At low frequencies the results for these four liquids show a behaviour intermediate between that of a simple liquid and that exhibited by a long chain polymer which conforms to the extended form of the Rouse theory.

Dependence of the OBDD morphology on diblock copolymer molecular weight in copolymer/homopolymer blends

1993 ◽  
Vol 26 (5) ◽  
pp. 956-962 ◽  
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Molecular Weight ◽  
Diblock Copolymer ◽  
Homopolymer Blends

Equation for osmotic pressure of serum protein (fractions)

2004 ◽  
Vol 96 (2) ◽  
pp. 762-764 ◽  
Author(s):  
Johan Ahlqvist
Keyword(s):  
Molecular Weight ◽  
Regression Analysis ◽  
Osmotic Pressure ◽  
Serum Protein ◽  
Protein Fractions ◽  
Fibrinogen Concentration ◽  
Nonlinear Regression Analysis ◽  
Molecular Weights ◽  
Wide Range ◽  
Better Than

The colloid or protein osmotic pressure (Π) is a function of protein molarity (linear) and of Donnan and other effects. Albumin is the major osmotic protein, but also globulins influence Π. Equations based on concentrations of albumin and nonalbumin (globulin concentration + fibrinogen concentration) protein approximate Π better than albumin alone. Globulins have a wide range of molecular weights, and a 1956 diagram indicated that Π of globulin fractions decreased in the order α1-, α2-, β-, and γ-globulin. The molecular weight of the serum protein fractions had been extrapolated, so van't Hoff's law and nonlinear regression analysis of the curves permitted expression of the diagram as an equation: [Formula: see text], where Πs,Ott,2°C,cmH2O is Π of serum at 2°C (in cmH2O) computed from the 1956 diagram, Ctot is the concentration (g/l) of total protein in serum, and xalb, xα1, xα2, xβ, and xγ are the fractions of albumin, α1-, α2-, β-, and γ-globulin, respectively. At one and the same concentration of fractions, Π“Ott” decreases in the order α1-globulin, albumin, α2-globulin, β-globulin, and γ-globulin.

Effect of homopolymer molecular weight on the morphology of block copolymer/homopolymer blends

1987 ◽  
Vol 20 (6) ◽  
pp. 1431-1434 ◽  
Author(s):  
X. Quan ◽  
I. Gancarz ◽  
J. T. Koberstein ◽  
G. D. Wignall
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Homopolymer Blends
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