Block Copolymers
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Aggregate ◽  
2021 ◽  
Author(s):  
Hao Li ◽  
Bijin Xiong ◽  
Jiangping Xu ◽  
Jintao Zhu

Author(s):  
Farzad Seidi ◽  
Mohammad Reza Saeb ◽  
Yongcan Jin ◽  
Philippe Zinck ◽  
Huining Xiao

: Controlled polymerization techniques make possible fabrication of polymers with desired molecular weights, narrow dispersity, and also tailor-making of advanced hybrid materials. Thiol-Lactam Initiated Radical Polymerization (TLIRP) was introduced in 2002 and developed during the last two decades. The thiol/lactam combination enables one to generate radicals that can initiate the polymerization of vinyl-based monomers. The study of the mechanism and kinetics of TLIRP revealed the characteristics of living polymerization for TLIRP. Moreover, TLIRP has been used successfully for the synthesis of homopolymers, block copolymers, and statistical copolymers with polydispersity below 2.0. Especially, TLIRP provides a very straightforward method for grafting polymer brushes on the surface of nanoparticles. We review herein the systems developed for TLIRP and their applications for macromolecular engineering, with an emphasis on the surface functionalization of nanoparticles via the grafting-from approach.


2021 ◽  
Author(s):  
Fatimah Algarni ◽  
Valentina Elena Musteata ◽  
Gheorghe Falca ◽  
Stefan Chisca ◽  
Nikos Hadjichristidis ◽  
...  

2021 ◽  
Vol 9 ◽  
Author(s):  
Hélène Pizzala ◽  
Magalie Claeys-Bruno ◽  
Valérie Monnier ◽  
Michelle Sergent ◽  
Laurence Charles

Matrix-assisted laser/desorption ionization (MALDI) has become a very popular ionization technique for mass spectrometry of synthetic polymers because it allows high throughput analysis of low amounts of sample while avoiding the complexity introduced by extensive multiple charging of electrospray ionization. Yet, fundamental mechanisms underlying this ionization process are not fully understood, so development of sample preparation methods remains empirical. Reliable prediction for the optimal matrix/analyte/salt system is indeed still not possible for homopolymers and it becomes even more challenging in the case of amphiphilic block copolymers where conditions dictated by one block are not compatible with MALDI requirements of the second block. In order to perform MALDI of copolymers composed of poly (ethylene oxide) (PEO) and polystyrene (PS) blocks, it was postulated here that experimental conditions suitable for both species would also be successful for PEO-b-PS. Accordingly, designs of experiments based on Quantitative Structure Activity Relationship (QSAR) analysis were first implemented, studying the influence of 19 matrices and 26 salts on the laser fluence requested for successful MALDI. This analysis first permitted to highlight correlations between the investigated 10 descriptors of matrices and salts and the analytical response, and then to construct models that permits reliable predictions of matrix/salt couples to be used for one or the other homopolymer. Selected couples were then used for MALDI of a PEO-b-PS copolymer but no general trend was observed: experimental conditions expected to work often failed whereas ionic adducts of the copolymer were clearly detected with some matrix/salt systems that were shown to badly perform for constituting homopolymers. Overall, this rules out the working assumption stating that the MALDI behavior of chains composed of PEO and PS segments should combine the behavior of the two polymeric species. Yet, although requiring a dedicated design of experiments, MALDI of the amphiphilic PEO-b-PS copolymer was achieved for the first time.


2021 ◽  
Author(s):  
Chappel J. Sharrock ◽  
Ja Eon Cho ◽  
Xin Wang ◽  
Xiuhong Li ◽  
Whitney Loo ◽  
...  

2021 ◽  
Vol 899 ◽  
pp. 67-72
Author(s):  
V.D. Polonik ◽  
A.S. Kukleva ◽  
N.D. Avdeev ◽  
M.D. Shlyaptseva ◽  
Vadim G. Nikol'skii ◽  
...  

This work presents the results of optimization compositions of polymer-modified binder (PMB) by a compromise task. The conducted study of influence two prescription factors – containing styrene-butadiene-styrene and sulfur – on which is a set of indicators of polymer-bitumen binders were carried out. The regularities of these factors of mutual influence were established by such indicators as the Fraas brittleness temperature, penetration, softening point, ductility. The dosages of SBS and sulfur have been determined by ensuring the achievement of the required level of PBB indicators in accordance with GOST R 52056-2003 «Bitumen-polymer road binders are based on styrene-butadiene-styrene block copolymers. Specifications».


Nano Letters ◽  
2021 ◽  
Author(s):  
Yunpeng Feng ◽  
Sean P. Quinnell ◽  
Alison M. Lanzi ◽  
Arturo J. Vegas

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.


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