scholarly journals Polymer for Internal Hydrophobization of Cement-Based Materials: Design, Synthesis, and Properties

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3069
Author(s):  
Xiao Liu ◽  
Xiaofei Song ◽  
Ziming Wang ◽  
Chunlei Xia ◽  
Ting Li ◽  
...  
Keyword(s):  
Hydrophobic Effect ◽  
Gel Permeation Chromatography ◽  
Exothermic Peak ◽  
Side Chain ◽  
Design Synthesis ◽  
Promising Alternative ◽  
1H Nuclear Magnetic Resonance ◽  
Cement Based Materials ◽  
Responsive Behavior ◽  
Chain Lengths

A series of novel comb-like poly(butyl acrylate)-g-poly(dimethylaminoethyl methacrylate) (PBA-g-PDMAEMA) with different side chain lengths were designed and successfully synthesized by the “first main chain then side chain” method. Infrared Spectroscopy (IR), 1H Nuclear Magnetic Resonance (1H NMR), and gel permeation chromatography (GPC) were used for structural confirmation and molecular weight characterization. This polymer exhibited responsive behavior from hydrophilicity to hydrophobicity under the alkaline environment of cement-based materials, with the contact angle of 105.6°, a decreased evaporation rate, and a hydrophile–lipophile balance (HLB) value. A significant internal hydrophobic effect on cement mortar was shown in the water absorption rate, which decreased by 75.2%, and a dry shrinkage-reducing rate of more than 30%. Furthermore, this polymer can effectively slow the exothermic rate, reduce the heat release, and delay the exothermic peak of cement hydration. It was interesting that these properties showed a direct correlation with the side chain length of the comb polymer. The aims of this study are to provide a new avenue to synthesize polymers with the spontaneous hydrophilicity–hydrophobicity transition in the cement system, achieving excellent internal hydrophobicity of cement-based materials, and to offer a promising alternative to resist external erosion for improving the durability and service life of cement-based materials.

Polypeptides Folding: Rules for the Calculation of the Backbone Dihedral Angles φ starting from the Amino Acid Sequence

2020 ◽  
Author(s):  
Michele Larocca
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Theoretical Approach ◽  
Polypeptide Chain ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Dihedral Angles ◽  
Mechanical Forces ◽  
Specific Chemical

<p>Protein folding is strictly related to the determination of the backbone dihedral angles and depends on the information contained in the amino acid sequence as well as on the hydrophobic effect. To date, the type of information embedded in the amino acid sequence has not yet been revealed. The present study deals with these problematics and aims to furnish a possible explanation of the information contained in the amino acid sequence, showing and reporting rules to calculate the backbone dihedral angles φ. The study is based on the development of mechanical forces once specific chemical interactions are established among the side chain of the residues in a polypeptide chain. It aims to furnish a theoretical approach to predict backbone dihedral angles which, in the future, may be applied to computational developments focused on the prediction of polypeptide structures.</p>

Synthesis of azobenzene-containing side chain liquid crystalline diblock copolymers using RAFT polymerization and photo-responsive behavior

2013 ◽  
Vol 130 (3) ◽  
pp. 2165-2175 ◽  
Author(s):  
Wuqiong Sun ◽  
Xiaohua He ◽  
Xiaojuan Liao ◽  
Shaoliang Lin ◽  
Wei Huang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Side Chain ◽  
Responsive Behavior

scholarly journals Novel Steroidal 5α,8α-Endoperoxide Derivatives with Semicarbazone/Thiosemicarbazone Side-chain as Apoptotic Inducers through an Intrinsic Apoptosis Pathway: Design, Synthesis and Biological Studies

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1209 ◽  
Author(s):  
Liwei Ma ◽  
Haijun Wang ◽  
Jing Wang ◽  
Lei Liu ◽  
Song Zhang ◽  
...  
Keyword(s):  
Hepg2 Cells ◽  
Antitumor Agents ◽  
Human Cancer ◽  
Side Chain ◽  
Design Synthesis ◽  
Apoptosis Pathway ◽  
Human Cancer Cell Lines ◽  
Biological Studies ◽  
Intrinsic Apoptosis Pathway

A series of novel steroidal 5α,8α-endoperoxide derivatives bearing semicarbazone (7a–g) or thiosemicarbazone (7h–k) side chain were designed, synthesized and evaluated for their cytotoxicities in four human cancer cell lines (HepG2, HCT-116, MCF-7, and A549) using the MTT assay in vitro. The results showed that compound 7j exhibited significant cytotoxic activity against HepG2 cells (IC50 = 3.52 μM), being more potent than ergosterol peroxide. Further cellular mechanism studies in HepG2 cells indicated that compound 7j triggered the mitochondrial-mediated apoptosis by decreasing mitochondrial membrane potential (MMP), which was associated with up-regulation of Bax, down-regulation of Bcl-2, activation levels of the caspase cascade, and formation of reactive oxygen species (ROS). The above findings indicated that compound 7j may be used as a promising skeleton for antitumor agents with improved efficacy.

scholarly journals Influence of Calcium Binding on Conformations and Motions of Anionic Polyamino Acids. Effect of Side Chain Length

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1279
Author(s):  
Dmitry Tolmachev ◽  
Natalia Lukasheva ◽  
George Mamistvalov ◽  
Mikko Karttunen
Keyword(s):  
Amino Acids ◽  
Chain Length ◽  
Calcium Binding ◽  
Md Simulations ◽  
Side Chain ◽  
Replica Exchange ◽  
Side Chain Length ◽  
Hamiltonian Replica Exchange ◽  
Cacl2 Concentration ◽  
Chain Lengths

Investigation of the effect of CaCl2 salt on conformations of two anionic poly(amino acids) with different side chain lengths, poly-(α-l glutamic acid) (PGA) and poly-(α-l aspartic acid) (PASA), was performed by atomistic molecular dynamics (MD) simulations. The simulations were performed using both unbiased MD and the Hamiltonian replica exchange (HRE) method. The results show that at low CaCl2 concentration adsorption of Ca2+ ions lead to a significant chain size reduction for both PGA and PASA. With the increase in concentration, the chains sizes partially recover due to electrostatic repulsion between the adsorbed Ca2+ ions. Here, the side chain length becomes important. Due to the longer side chain and its ability to distance the charged groups with adsorbed ions from both each other and the backbone, PGA remains longer in the collapsed state as the CaCl2 concentration is increased. The analysis of the distribution of the mineral ions suggests that both poly(amino acids) should induce the formation of mineral with the same structure of the crystal cell.

scholarly journals Packing of apolar side chains enables accurate design of highly stable membrane proteins

Science ◽  
2019 ◽  
Vol 363 (6434) ◽  
pp. 1418-1423 ◽  
Author(s):  
Marco Mravic ◽  
Jessica L. Thomaston ◽  
Maxwell Tucker ◽  
Paige E. Solomon ◽  
Lijun Liu ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Side Chains ◽  
Chain Packing ◽  
Membrane Protein Folding ◽  
Natural Protein ◽  
Accurate Design ◽  
Polar Interactions ◽  
Packing Code

The features that stabilize the structures of membrane proteins remain poorly understood. Polar interactions contribute modestly, and the hydrophobic effect contributes little to the energetics of apolar side-chain packing in membranes. Disruption of steric packing can destabilize the native folds of membrane proteins, but is packing alone sufficient to drive folding in lipids? If so, then membrane proteins stabilized by this feature should be readily designed and structurally characterized—yet this has not been achieved. Through simulation of the natural protein phospholamban and redesign of variants, we define a steric packing code underlying its assembly. Synthetic membrane proteins designed using this code and stabilized entirely by apolar side chains conform to the intended fold. Although highly stable, the steric complementarity required for their folding is surprisingly stringent. Structural informatics shows that the designed packing motif recurs across the proteome, emphasizing a prominent role for precise apolar packing in membrane protein folding, stabilization, and evolution.

Protein structures and complexes: what they reveal about the interactions that stabilize them

1993 ◽  
Vol 345 (1674) ◽  
pp. 113-129 ◽  
Keyword(s):  
Hydrophobic Effect ◽  
Protein Structures ◽  
Three Dimensional ◽  
Side Chain ◽  
Test Bed ◽  
Local Conformation ◽  
High Quality Protein ◽  
Atomic Interactions ◽  
Chain Atom ◽  
Side Chain Atom

The rapid increase in the number of high-quality protein structures provides an expanding knowledge resource about interactions involved in stabilizing protein three-dimensional structures and the complexes they form with other molecules. In this paper we first review the results of some recent analyses of protein structure, including restrictions on local conformation, and a study of the geometry of hydrogen bonds. Then we consider how such empirical data can be used as a test bed for energy calculations, by using the observed spatial distributions of side chain/atom interactions to assess three different methods for modelling atomic interactions in proteins. We have also derived a new empirical solvation potential which aims to reproduce the hydrophobic effect. To conclude we address the problem of molecular recognition and consider what we can deduce about the interactions involved in the binding of peptides to proteins.

Design, synthesis, and phase behaviors of a novel triphenylene-based side chain liquid crystalline diblock copolymer

2018 ◽  
Vol 42 (16) ◽  
pp. 13581-13588
Author(s):  
Jianfeng Ban ◽  
Lulu Pan ◽  
Bo Shi ◽  
Hailiang Zhang
Keyword(s):  
Diblock Copolymer ◽  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Weight Fraction ◽  
Side Chain ◽  
Design Synthesis ◽  
Phase Behaviors

Influence of the weight fraction of PMT6S on the phase behaviors of diblock copolymers.

Synthesis and Photophysical Properties of Side-Chain Polyfluorenes

2017 ◽  
Vol 865 ◽  
pp. 60-63
Author(s):  
Ning Wang ◽  
Xiao Dan Hu
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Photophysical Properties ◽  
Gel Permeation Chromatography ◽  
Blue Shift ◽  
Red Shift ◽  
Side Chain ◽  
Gel Permeation

In this paper, we reported one vinylfluorene derivative 9,9-dihexyl-vinylfluorene and its corresponding polymers. The monomer and polymers were characterized by NMR, UV-Vis, PL and Gel Permeation Chromatography (GPC). Compared with the monomer, the polymers showed blue-shift in UV-Vis spectra but red-shift in PL spedtra. This kind of side-chain polyfluorenes could be candidates of blue OLED, organic solar cells, and so on.

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