scholarly journals The Influence of Annealing Atmosphere, Blending Ratio, and Molecular Weight on the Phase Behavior of Blend Materials

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1586
Author(s):  
Weichen Liu ◽  
Libin Zhang ◽  
Yayi Wei

In the study of block copolymers, many parameters need to be adjusted to obtain good phase separation results. Based on block copolymer polystyrene-b-polycarbonate and homopolymer polystyrene, the effects of the annealing atmosphere, blending ratio, and molecular weight on phase separation were studied. The results show that annealing in air can inhibit the occurrence of phase separation. In addition, snowflake patterns are formed during phase separation. The blending ratio affects the quality of the pattern. The molecular weight affects the size of the pattern, and the size increases as the molecular weight increases. In this article, the influence of process conditions and materials on phase separation was discussed, which has laid a solid foundation for the development of block copolymer self-assembly in the future.

2021 ◽  
Author(s):  
Maciej Łojkowski ◽  
Adrian Chlanda ◽  
Emilia Choińska ◽  
Wojciech Swieszkowski

<p>The formation of complex structures in thin films is of interest in many fields. Segregation of polymer chains of different molecular weights is a well-known process. However, here, polystyrene with bimodal molecular weight distribution, but no additional chemical modification was used. It was proven that at certain conditions, the phase separation occurred between two fractions of bimodal polystyrene/methyl ethyl ketone solution. The films were prepared by spin-coating, and the segregation between polystyrene phases was investigated by force spectroscopy. Next, water vapour induced secondary phase separation was investigated. The introduction of moist airflow induced the self-assembly of the lower molecular weight into islands and the heavier fraction into a honeycomb. As a result, an easy, fast, and effective method of obtaining island/honeycomb morphologies was demonstrated. The possible mechanisms of the formation of such structures were discussed.</p>


2017 ◽  
Vol 53 (36) ◽  
pp. 5005-5008 ◽  
Author(s):  
Xiao-Li Sun ◽  
Dong-Ming Liu ◽  
Pan Wang ◽  
Jia-Lin Tan ◽  
Kang-Kang Li ◽  
...  

Clews of tubules are reported via block copolymer self-assembly of P4VP-b-PS with both high asymmetry and very high molecular weight.


2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Sungmin Park ◽  
Yeongsik Kim ◽  
Hyungju Ahn ◽  
Jong Hak Kim ◽  
Pil J. Yoo ◽  
...  

2009 ◽  
Vol 42 (15) ◽  
pp. 5442-5445 ◽  
Author(s):  
Osamu Sato ◽  
Yusuke Inagaki ◽  
Sungmin Kang ◽  
Masatoshi Tokita ◽  
Junji Watanabe

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Camila Honorato-Rios ◽  
Jan P. F. Lagerwall

Abstract The helical self-assembly of cholesteric liquid crystals is a powerful motif in nature, enabling exceptional performance in many biological composites. Attempts to mimic these remarkable materials by drying cholesteric colloidal nanorod suspensions often yield films with a non-uniform mosaic-like character, severely degrading optical and mechanical properties. Here we show—using the example of cellulose nanocrystals—that these problems are due to rod length dispersity: uncontrolled phase separation results from a divergence in viscosity for short rods, and variations in pitch can be traced back to a twisting power that scales with rod length. We present a generic, robust and scalable method for fractionating nanorod suspensions, allowing us to interrogate key aspects of cholesteric self-assembly that were previously hidden by colloid dispersity. By controlled drying of fractionated suspensions, we can obtain mosaic-free films that are uniform in colour. Our findings unify conflicting observations and open routes to biomimetic artificial materials with performance that can compete with that of nature’s originals.


2016 ◽  
Vol 7 (18) ◽  
pp. 3076-3089 ◽  
Author(s):  
Yihui Xie ◽  
Nicolas Moreno ◽  
Victor M. Calo ◽  
Hong Cheng ◽  
Pei-Ying Hong ◽  
...  

For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymer membranes used in this method, which were mainly based on polystyrene blocks.


2020 ◽  
Vol 24 (5) ◽  
pp. 46-50
Author(s):  
N.N. Smirnova ◽  
M.S. Savelyeva

The possibility and efficiency of biflocсulation systems, including polymer electrolytes capable of interaction and polyelectrolyte complexes formation, usage in the processes of water treatment for the mineral particles separation, was studied. The influence of the nature, molecular weight of polyelectrolyte components and their ratio in the system on the efficiency and speed of the dispersed phase particles deposition process was considered. Sodium salt of carboxymethylcellulose, poly-N,N-dimethyl-N,N-diallylammonium chloride and polyanions and polycations polyacrylamide-based were used as polyelectrolytes. It was shown that application biflocсulation systems significantly increases the speed of the dispersed phase separation and allows to improve the clarification quality of the dispersion with a much lower (compared to monoflocculation systems) consumption of polymer electrolytes.


1996 ◽  
Vol 461 ◽  
Author(s):  
J. H. Laurer ◽  
J. F. Mulling ◽  
R. Bukovnik ◽  
R. J. Spontak

ABSTRACTAddition of a block-selective homopolymer to a microphase-ordered block copolymer is known to result in preferential swelling of the chemically compatible microdomain. In this work, we examine the miscibility between a triblock copolymer and a relatively low-molecular-weight, chemically dissimilar, midblock-associating homopolymer and demonstrate that the homopolymer molecules residing in the swollen midblock matrix self-assemble to avoid repulsive interactions with neighboring microdomains. We extend this investigation to include systems composed of a very low-molecular-weight, midblock-associating additive (an oil). At high oil concentrations, the glassy copolymer endblocks micellize, resulting in the formation of a thermoplastic elastomer gel.


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