scholarly journals Oxygen and carbon dioxide dual gas-responsive homopolymers and diblock copolymers synthesized via RAFT polymerization

2017 ◽  
Vol 8 (7) ◽  
pp. 1163-1176 ◽  
Author(s):  
Xue Jiang ◽  
Feng Chun ◽  
Guolin Lu ◽  
Huang Xiaoyu
Keyword(s):  
Carbon Dioxide ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Repeated Unit ◽  
New Strategy

This article reports a new strategy to prepare homopolymers with CO2 and O2 responsiveness via the installation of CO2- and O2-responsive functionalities in the same repeated unit.

Carbon Dioxide-Mediated C(sp2)–H Arylation of Primary and Secondary Benzylamines

2018 ◽  
Author(s):  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Michael Young
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Bond Activation ◽  
Bond Formation ◽  
Carbon Bond ◽  
Chelate Effect ◽  
Free Amine ◽  
Carbon Carbon Bond ◽  
New Strategy ◽  
Metal Catalyzed

Carbon-carbon bond formation by transition metal-catalyzed C–H activation has become an important strategy to fabricate new bonds in a rapid fashion. Despite the pharmacological importance of <i>ortho</i>-arylbenzylamines, however, effective <i>ortho</i>-C–C bond formation from C–H bond activation of free primary and secondary benzylamines using Pd<sup>II</sup> remains an outstanding challenge. Presented herein is a new strategy for constructing <i>ortho</i>-arylated primary and secondary benzylamines mediated by carbon dioxide (CO<sub>2</sub>). The use of CO<sub>2</sub> is critical to allowing this transformation to proceed under milder conditions than previously reported, and that are necessary to furnish free amine products that can be directly used or elaborated without the need for deprotection. In cases where diarylation is possible, a chelate effect is demonstrated to facilitate selective monoarylation.

scholarly journals Aqueous one-pot synthesis of well-defined zwitterionic diblock copolymers by RAFT polymerization: an efficient and environmentally-friendly route to a useful dispersant for aqueous pigments

2021 ◽  
Vol 23 (3) ◽  
pp. 1248-1258
Author(s):  
Shannon M. North ◽  
Steven P. Armes
Keyword(s):  
Iron Oxide ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Environmentally Friendly ◽  
Iron Oxide Particles ◽  
One Pot ◽  
One Pot Synthesis ◽  
Highly Effective ◽  
Oxide Particles

An atom-efficient, wholly aqueous one-pot synthesis of zwitterionic diblock copolymers has been devised. Such copolymers can serve as highly effective aqueous dispersants for nano-sized transparent yellow iron oxide particles.

Effect of stabilizer concentration and controller structure and composition on polymerization rate and molecular weight development in RAFT polymerization of styrene in supercritical carbon dioxide

Polymer ◽  
2009 ◽  
Vol 50 (21) ◽  
pp. 5024-5030 ◽  
Author(s):  
Gabriel Jaramillo-Soto ◽  
Pedro R. García-Morán ◽  
Francisco J. Enríquez-Medrano ◽  
Hortensia Maldonado-Textle ◽  
Martha E. Albores-Velasco ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Molecular Weight ◽  
Supercritical Carbon Dioxide ◽  
Raft Polymerization ◽  
Polymerization Rate ◽  
Stabilizer Concentration ◽  
Supercritical Carbon

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 Doubly Dynamic Hydrogel Formed by Combining Boronate Ester and Acylhydrazone Bonds

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 487
Author(s):  
Yusheng Liu ◽  
Yigang Liu ◽  
Qiuxia Wang ◽  
Yugui Han ◽  
Hao Chen ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Solid Content ◽  
Self Healing ◽  
Covalent Bonds ◽  
Boronate Ester ◽  
Isopropyl Acrylamide ◽  
Reversible Addition ◽  
The Difference

The incorporation of double dynamic bonds into hydrogels provides an effective strategy to engineer their performance on demand. Herein, novel hydrogels were PREPARED by combining two kinetically distinct dynamic covalent bonds, boronate ester and acylhydrazone bonds, and the synergistic properties of the hydrogels were studied comprehensively. The functional diblock copolymers P(N-isopropyl acrylamide-co-N-acryloyl-3-aminophenylboronic acid)-b-(N-isopropyl acrylamide-co-diacetone acrylamide) (PAD) were prepared via reversible addition−fragmentation chain transfer (RAFT) polymerization. The hydrogel was constructed by exploiting dynamic reaction of phenyboronic acid moieties with polyvinyl alcohol (PVA) and ketone moieties with adipic dihydrazide (ADH) without any catalyst. The active boronate ester linkage endows the hydrogel with fast gelation kinetics and self-healing ability, and the stable acylhydrazone linkage can enhance the mechanical property of the hydrogel. The difference in kinetics endows that the contribution of each linkage to mechanical strength of the hydrogel can be accurately estimated. Moreover, the mechanical property of the hydrogel can be readily engineered by changing the composition and solid content, as well as by controlling the formation or dissociation of the dynamic linkages. Thus, we provide a promising strategy to design and prepare multi-responsive hydrogels with tunable properties.

scholarly journals The Utilization of Carbon Dioxide to Prepare TiCxOy Films with Low Friction and High Anti-Corrosion Properties

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 533
Author(s):  
Kaixiong Gao ◽  
Zhaolong Wang ◽  
Qian Jia ◽  
Bin Zhang ◽  
Zhixing Mou ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Corrosion Resistance ◽  
Greenhouse Effect ◽  
High Hardness ◽  
Corrosion Properties ◽  
Dilute Gas ◽  
New Strategy ◽  
Co2 Recycling ◽  
Carbon Dioxide Co2 ◽  
Outstanding Question

Recycling carbon dioxide (CO2) for weakening the greenhouse effect is still an outstanding question. Although many chemical methods have been designed for CO2 conversion, they is still a need to develop new ways for CO2 recycling. Plasma methods were employed to convert CO2 into energy molecules, with the addition of H2, H2O and so on. Non heavy elements, like Ti, Cr, Si and Mo and so forth, were employed to take part in a reactive process, which might be very interesting for special scientific interest. In this work, magnetron sputtering method was used not only for igniting the plasma but also for providing Ti elements involved in reactions, via the selected Ti target. One can confirm that the TiCxOy films were successfully grew via sputtering a Ti target in CO2 atmosphere with Ar as dilute gas, which proved that CO2 is a key player in the matter of the involvement of excited CO2+, CO+, CO3− and so on, in the growth process reacting with Ti ions. The TiCxOy films exhibit the highest hardness (20.3 GPa), lowest friction coefficient (0.065) and the best corrosion resistance. The growth of the TiCxOy films are not only a new strategy for consuming CO2 but also a good way for reusing it for preparing TiCxOy films with high hardness for anti-corrosion and reducing friction. Moreover, reducing CO2 emissions via energy saving (through reducing friction and corrosion resistance) and recycling existing CO2 are both important for mitigating the greenhouse effect.

scholarly journals Synthesis and characteristics of novel azo-based diblock copolymers and their self-assembly behavior via solvents and thermal annealing

e-Polymers ◽  
2017 ◽  
Vol 17 (6) ◽  
pp. 523-535 ◽  
Author(s):  
Athmen Zenati ◽  
Yang-Kyoo Han
Keyword(s):  
Self Assembly ◽  
Nematic Phase ◽  
Weight Control ◽  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Gel Permeation Chromatography ◽  
Kinetic Studies ◽  
Morphological Properties ◽  
Scanning Calorimetry

AbstractA series of azo-based diblock copolymers (DBCs) with various compositions were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in anisole with PCAEMA-CTA (macro-CTA), DOPAM (new acrylamide monomer) and AIBN (initiator). Kinetic studies on diblock copolymerization manifested a controlled/living manner with good molecular weight control. Structures and properties of monomers and DBCs were determined by 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). Liquid crystalline (LC) phases and morphological properties were investigated using optical polarizing microscope (OPM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS). Experimental results demonstrated that the prepared PCAEMA-CTA and DBCs possessed low polydispersity index (≤1.37). All DBCs revealed sharp endothermic transition peaks corresponding to the smectic-to-nematic phase. DBCs with high azo contents showed batonnet textures of the smectic phase whereas DBCs of low azo segments displayed threaded textures of the nematic phase. DBC with 49 wt% of azo side-chains generated a lamellar compared to DBCs with low azo block (≤41 wt%) or non-azo block (≤38 wt%) which produced hexagonal-type nanostructures. In addition, all DBCs exhibited reversible trans-cis photoisomerization behavior under UV irradiation and dark storage at different intervals of time.

Surface Modification of Multiwalled Carbon Nanotubes with Engineered Self-Assembled RAFT Diblock Coatings

2014 ◽  
Vol 67 (1) ◽  
pp. 151 ◽  
Author(s):  
Yue Liu ◽  
Xiaojuan Hao ◽  
Lynne J. Waddington ◽  
Jieshan Qiu ◽  
Timothy C. Hughes
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Electrostatic Interactions ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Dispersion Stability ◽  
Multiwalled Carbon ◽  
Molecular Weights ◽  
Poly Ethylene ◽  
Positively Charged

A facile method to modify the surface of multiwalled carbon nanotubes (MWCNTs) via electrostatic interactions between polyelectrolytes and oxidized MWCNTs was developed. Diblock copolymers containing poly[2-(methacryloyloxy)ethyltrimethylammonium chloride] (PMETAC), a positively charged block, and poly(ethylene glycol) methacrylate (PEGMA), a neutral block, with tailored molecular weights and low polydispersities were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Acid treated-MWCNTs were coated with the RAFT diblock copolymers to improve their dispersibility in aqueous phosphate buffered saline (PBS) solution. The short positively charged PMETAC block was designed to attach the block copolymers to the surface of MWCNTs via electrostatic interactions, whereas the PEGMA block improved dispersibility of the MWCNTs in aqueous solutions. Extensive screening of the diblock copolymers with different degrees of polymerization (DP) showed that the dispersion stability of the polymer-coated MWCNTs in PBS was greatly improved with increasing chain length of the PEGMA block. In particular, the MWCNTs coated with a diblock copolymer containing PEGMA (DP = 118, the longest block investigated) showed superior dispersion stability in both water and PBS solution.

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