The physical properties of thermotropic side-chain triblock copolymers ofn-butyl acrylate and a comonomer with azobenzene group

2009 ◽  
Vol 17 (5) ◽  
pp. 313-318 ◽  
Author(s):  
Kyung Sik Dan ◽  
Byoung Chul Kim ◽  
Yang-Kyoo Han
Keyword(s):  
Physical Properties ◽  
Butyl Acrylate ◽  
Triblock Copolymers ◽  
Side Chain ◽  
Azobenzene Group

A study of the relationships of interactions between Asp-201, Na+ or K+, and galactosyl C6 hydroxyl and their effects on binding and reactivity of β-galactosidase

2004 ◽  
Vol 82 (2) ◽  
pp. 275-284 ◽  
Author(s):  
Julia Xu ◽  
Mary A.A McRae ◽  
Scott Harron ◽  
Beatrice Rob ◽  
Reuben E Huber
Keyword(s):  
Physical Properties ◽  
Negative Charge ◽  
Binding Pocket ◽  
Side Chain ◽  
Wild Type ◽  
Sodium Potassium ◽  
The Difference ◽  
Potassium Binding ◽  
Covalent Intermediate ◽  
Catalytic Effects

The interactions between Na+ (and K+) and Asp-201 of β-galactosidase were studied. Analysis of the changes in Km and Vmax showed that the Kd for Na+ of wild type β-galactosidase (0.36 ± 0.09 mM) was about 10× lower than for K+ (3.9 ± 0.6 mM). The difference is probably because of the size and other physical properties of the ions and the binding pocket. Decreases of Km as functions of Na+ and K+ for oNPG and pNPG and decreases of the Ki of both shallow and deep mode inhibitors were similar, whereas the Km and Ki of substrates and inhibitors without C6 hydroxyls remained constant. Thus, Na+ and K+ are important for binding galactosyl moieties via the C6 hydroxyl throughout catalysis. Na+ and K+ had lesser effects on the Vmax. The Vmax of pNPF and pNPA (substrates that lack a C6 hydroxyl) did not change upon addition of Na+ or K+, showing that the catalytic effects are also mediated via the C6 hydroxyl. Arrhenius plots indicated that Na+, but not K+, caused k3 (degalactosylation) to increase. Na+ also caused the k2 (galactosylation) with oNPG, but not with pNPG, to increase. In contrast, K+ caused the k2 values with both oNPG and pNPG to increase. Na+ and K+ mainly altered the entropies of activation of k2 and k3 with only small effects on the enthalpies of activation. This strongly suggests that only the positioning of the substrate, transition states, and covalent intermediate are altered by Na+ and K+. Further evidence that positioning is important was that substitution of Asp-201 with a Glu caused the Km and Ki values to increase significantly. In addition, the Kd values for Na+ or K+ were 5 to 8 fold higher. The negative charge of Asp-201 was shown to be vital for Na+ and K+ binding. Large amounts of Na+ or K+ had no effect on the very large Km and Ki values of D201N-β-galactosidase and the Vmax values changed minimally and in a linear rather than hyperbolic way. D201F-β-galactosidase, with a very bulky hydrophobic side chain in place of Asp, essentially obliterated all binding and catalysis.Key words: β-galactosidase, sodium, potassium, binding, aspartic acid.

scholarly journals Gas-separation and physical properties of ABA triblock copolymers synthesized from polyimide and hydrophilic adamantane derivatives

Polymer ◽  
2020 ◽  
Vol 202 ◽  
pp. 122642
Author(s):  
Tsubasa Ito ◽  
Ryunosuke Shiota ◽  
Naomi Taniguchi ◽  
Richard J. Spontak ◽  
Kazukiyo Nagai
Keyword(s):  
Physical Properties ◽  
Gas Separation ◽  
Triblock Copolymers ◽  
Adamantane Derivatives

Structure and rheology of di- and triblock copolymers of polystyrene and poly(n-butyl acrylate)

2011 ◽  
Vol 55 (2) ◽  
pp. 379-400 ◽  
Author(s):  
Nicolas Jullian ◽  
Laurent Rubatat ◽  
Pierre Gerard ◽  
Jean Peyrelasse ◽  
Christophe Derail
Keyword(s):  
Butyl Acrylate ◽  
Triblock Copolymers

Synthesis and Characterization of Poly(styrene-b-n-butyl acrylate-b-styrene) Triblock Copolymers Using a Dialkoxyamine as Initiator

2002 ◽  
Vol 35 (10) ◽  
pp. 3844-3848 ◽  
Author(s):  
Sophie Robin ◽  
Olivier Guerret ◽  
Jean-Luc Couturier ◽  
Rosangela Pirri ◽  
Yves Gnanou
Keyword(s):  
Butyl Acrylate ◽  
Triblock Copolymers ◽  
Synthesis And Characterization

Synthesis of Polystyrene-b-poly(n-butyl acrylate)-b-Polystyrene Triblock Copolymers as Binder for Pigment Dyeing

2012 ◽  
Vol 441 ◽  
pp. 473-477
Author(s):  
Lei Yang ◽  
Cheng Jie Hu ◽  
Hai Yang ◽  
Dong Ming Qi
Keyword(s):  
Mechanical Properties ◽  
Butyl Acrylate ◽  
Triblock Copolymer ◽  
Chain Transfer ◽  
Triblock Copolymers ◽  
Polymerization Process ◽  
Fastness Properties ◽  
Copolymer Films ◽  
Reversible Addition ◽  
Dyed Fabrics

Well-controlled polystyrene-b-poly (n-butyl acrylate)-b-polystyrene (PSt-b-PnBA-b-PSt) triblock copolymers were prepared by RAFT (reversible addition-fragmentation chain transfer) emulsion polymerization process. The mechanical properties of the triblock copolymers were investigated in comparison to the P(nBA-co-St) statistical copolymers. When the PSt content is 20%, the ultimate tensile strength of triblock copolymer is nearly six times the strength of statistical copolymer, while their modulus are all around 3.0×103 Pa. The triblock copolymer films feel smooth and non-tacky as the PSt content is higher than 20%. It indicates that PSt-b-PnBA-b-PSt triblock copolymers can be used as binders in pigment dyeing, providing the dyed fabrics with soft non-tacky handle and good fastness properties.

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