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.

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.

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.

scholarly journals Evolution of the first eigenvalue of the Laplace operator and the p-Laplace operator under a forced mean curvature flow

2020 ◽  
Vol 18 (1) ◽  
pp. 1518-1530
Author(s):  
Xuesen Qi ◽  
Ximin Liu
Keyword(s):  
Laplace Operator ◽  
Mean Curvature ◽  
Mean Curvature Flow ◽  
Curvature Flow ◽  
Second Fundamental Form ◽  
Coefficient Function ◽  
First Eigenvalue ◽  
Initial Hypersurface ◽  
The Mean ◽  
The Laplace Operator

Abstract In this paper, we discuss the monotonicity of the first nonzero eigenvalue of the Laplace operator and the p-Laplace operator under a forced mean curvature flow (MCF). By imposing conditions associated with the mean curvature of the initial hypersurface and the coefficient function of the forcing term of a forced MCF, and some special pinching conditions on the second fundamental form of the initial hypersurface, we prove that the first nonzero closed eigenvalues of the Laplace operator and the p-Laplace operator are monotonic under the forced MCF, respectively, which partially generalize Mao and Zhao’s work. Moreover, we give an example to specify applications of conclusions obtained above.

Synthesis of poly(methyl methacrylate)-b-poly(acrylic acid) by DPE method

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Dong Chen ◽  
Ruixue Liu ◽  
Zhifeng Fu ◽  
Yan Shi
Keyword(s):  
Molecular Weight ◽  
Acrylic Acid ◽  
Methyl Methacrylate ◽  
Diblock Copolymer ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Amphiphilic Diblock Copolymer ◽  
Poly Methyl Methacrylate ◽  
Copolymer Poly ◽  
Poly Acrylic Acid

AbstractAmphiphilic diblock copolymer poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) was prepared by 1,1-diphenylethene (DPE) method. Firstly, free radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE-containing PMMA precursor with controlled molecular weight. tert-Butyl acrylate (tBA) was then polymerized in the presence of the PMMA precursor, and PMMA-b-PtBA diblock copolymer with controlled molecular weight was prepared. Finally, amphiphilic diblock copolymer PMMA-b-PAA was obtained by hydrolysis of PMMA-b-PtBA. The formation of PMMA-b-PAA was confirmed by 1H NMR spectrum and gel permeation chromatography. Transmission electron microscopy and dynamic light scattering were used to detect the self-assembly behavior of the amphiphilic diblock polymers in methanol.

Swelling of lamellar diblock copolymer by homopolymer: influences of homopolymer concentration and molecular weight

1991 ◽  
Vol 24 (23) ◽  
pp. 6182-6188 ◽  
Author(s):  
Karen I. Winey ◽  
Edwin L. Thomas ◽  
Lewis J. Fetters
Keyword(s):  
Molecular Weight ◽  
Diblock Copolymer
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