نتایج جستجو برای: Copolymer melts

تعداد نتایج: 17155  

Journal: :physical chemistry and electrochemistry 0
seyyed mostafa hosseini young researchers and elite club, marvdasht branch, islamic azad university,marvdasht, iran abstract

calculate some thermodynamic properties of molten polymers including specific volume and isothermal compressibility (s.m. hoseini, physical chemistry & electrochemistry, 2 (2014) 56-65). this work extended that eos to predict the volumetric properties of some molten ethylene copolymers including ethylene/1-octene, ethylene/1-butene (xethylene equal to 0.8543 and 0.563), ethylene/propene. the ab...

2008
Vijay R. Tirumala Vikram Daga August W. Bosse Alvin Romang Jan Ilavsky Eric K. Lin James J. Watkins

The use of short chain block copolymer melts as nanostructured templates with sub-10 nm domains is often limited by their low segregation strength ( N). Since increasing molar mass to strengthen segregation also increases the interdomain spacing of block copolymer melts, it is more desirable to increase the Flory-Huggins segment-segment interaction parameter, , to produce strong segregation. We...

Journal: :The Journal of chemical physics 2011
Shuang Yang Aleksey Vishnyakov Alexander V Neimark

The self-consistent field theory (SCFT) complemented with the Poisson-Boltzmann equation is employed to explore self-assembly of polyelectrolyte copolymers composed of charged blocks A and neutral blocks B. We have extended SCFT to dissociating triblock copolymers and demonstrated our approach on three characteristic examples: (1) diblock copolymer (AB) melt, (2) symmetric triblock copolymer (A...

Journal: :Physical review letters 2014
Jens Glaser Pavani Medapuram Thomas M Beardsley Mark W Matsen David C Morse

Simulations of five different coarse-grained models of symmetric diblock copolymers are compared to demonstrate a universal (i.e., model-independent) dependence of the free energy and order-disorder transition (ODT) on the invariant degree of polymerization N̄. The actual values of χN at the ODT approach predictions of the Fredrickson-Helfand (FH) theory for N̄ ≳ 10(4) but significantly exceed FH...

2010
Rustum Choksi Xiaofeng Ren

Melts of diblock copolymer / homopolymer blends exhibit multiscale phase separation: (i) macrophase separation into homopolymerand copolymer-rich macrodomains followed by (ii) microphase separation into Aand B-rich microdomains within the copolymer-rich macrodomains (cf. [16, 17, 26]). Following our previous derivation in [6], we derive a density functional theory for blends. This theory has be...

2008
Vijay R. Tirumala Alvin Romang Sumit Agarwal Eric K. Lin James J. Watkins

Microphase segregated block copolymer melts and solids have long garnered significant scientific interest due to their ability to spontaneously form periodic morphologies at controllable length scales. Their utility as stand-alone nanostructured functional materials or as templates for the fabrication of hierarchical solids is well documented. However, their deployment in large scale applicatio...

Journal: :Physical Review Letters 2014

Journal: :NHM 2008
Michael Helmers Barbara Niethammer Xiaofeng Ren

We study the evolution of diblock copolymer melts in which one component has small volume fraction. In this case one observes phase morphologies which consist of small spheres of the minority component embedded in the other component. Based on the Ohta-Kawasaki free energy one can set up an evolution equation which has the interpretation of a gradient flow. We restrict this gradient flow to mor...

Journal: :Physical review letters 2006
David M Hall Turab Lookman Glenn H Fredrickson Sanjoy Banerjee

We introduce a mesoscale technique for simulating the structure and rheology of block-copolymer melts and blends in hydrodynamic flows. The technique couples dynamic self-consistent field theory with continuum hydrodynamics and flow penalization to simulate polymeric fluid flows in channels of arbitrary geometry. We demonstrate the method by studying phase separation of an ABC triblock copolyme...

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