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Abstract Nanocolloids that are cumulatively referred to as nanocarbons, attracted significant attention during the last decade because of facile synthesis methods, water solubility, tunable photoluminescence, easy surface modification, and high biocompatibility. Among the latest development in this reserach area are chiral nanocarbons exemplified by chiral carbon dots (CDots). They are expected to have applications in sensing, catalysis, imaging, and nanomedicine. However, the current methods of CDots synthesis show often contradictory chemical/optical properties and structural information that required a systematic study with careful structural evaluation. Here, we investigate and optimize chiroptical activity and photoluminescence ofL‐andD‐CDots obtained by hydrothermal carbonization ofL‐andD‐cysteine, respectively. Nuclear magnetic resonance spectroscopy demonstrates that they are formed via gradual dehydrogenation and condensation reactions of the starting amino acid leading to particles with a wide spectrum of functional groups including aromatic cycles. We found that the chiroptical activity of CDots has an inverse correlation with the synthesis duration and temperature, whereas the photoluminescence intensity has a direct one, which is associated with degree of carbonization. Also, our studies show that the hydrothermal synthesis of cysteine in the presence of boric acid leads to the formation of CDots rather than boron nitride nanoparticles as was previously proposed in several reports. These results can be used to design chiral carbon‐based nanoparticles with optimal chemical, chiroptical, and photoluminescent properties.
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Poly(ether imide)s with tailored end groups
Abstract Poly(ether imide) (PEI) from polycondensation of 2,2‐bis[4‐(3,4‐dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) andm‐phenylenediamine (mPD) is a type of high‐temperature engineering thermoplastics that have high glass transition temperature and outstanding mechanical properties. Owing to its wide use in many fields including automotive, aircraft, and electronics, the research of PEI has surged in the last few decades. As science and technology continue to progress rapidly, there is a growing demand for PEIs with better properties. Although a few approaches have successfully improved the properties of PEI, it is recognized that these approaches require complex procedures and are uneconomical. Contrastingly, end‐group modification of PEI is highly effective, simple, and economical. Over the last few years, our group has extensively studied the methods for improving the properties of PEI through end‐group modification. The end‐group moieties and polymer blocks introduce multiple hydrogen bonding, electrostatics, and microphase separation to PEI. In this article, we first classify the end groups based on their characteristics. Then, we compare their effects on the properties of PEIs, including thermal, rheological, mechanical, optical, flame‐retardant, and morphological, and discuss the roots of these effects. The in‐depth comparisons and discussion generate principles to guide the synthesis of PEIs with tailored properties by modifying the end groups. This timely article will provide insights into the synthesis of other novel high‐temperature polymers and entice endeavors to develop novel end groups.
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- Award ID(s):
- 1752611
- PAR ID:
- 10364724
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science
- Volume:
- 59
- Issue:
- 21
- ISSN:
- 2642-4150
- Page Range / eLocation ID:
- p. 2365-2377
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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