Tag: polymers

Photoresponsive Photoacid-Macroion Nano-Assemblies

In mother nature, the concept of self-assembly is vital for life, as it generates much of the functionality of living cells. It also bears great synthetic potential for the formation of versatile, switchable, and functional nanostructures.*

Noncovalent interactions can be triggered by external influences, such as the change of pH, light irradiation, thermal activation, introduction of a magnetic field, moisture, or redox response. Of high interest are light-responsive systems, for example in the fields of sensors or therapy, and, thus, it is desirable to explore novel concepts toward light-triggerable self-assembly.*

In the article “Photoresponsive Photoacid-Macroion Nano-Assemblies” Alexander Zika, Sarah Bernhardt and Franziska Gröhn present light-responsive nano-assemblies with light-switchable size based on photoacids.*

Anionic disulfonated napthol derivates and cationic dendrimer macroions are used as building blocks for electrostatic self-assembly. Nanoparticles are already formed under the exclusion of light as a result of electrostatic interactions. Upon photoexcitation, an excited-state dissociation of the photoacidic hydroxyl group takes place, which leads to a more highly charged linker molecule and, subsequently, to a change in size and structure of the nano-assemblies. The effects of the charge ratio and the concentration on the stability have been examined with absorption spectroscopy and -potential measurements.*

The influence of the chemical structure of three isomeric photoacids on the size and shape of the nanoscale aggregates has been studied by dynamic light scattering and atomic force microscopy, revealing a direct correlation of the strength of the photoacid with the changes of the assemblies upon irradiation.*

NanoWorld Ultra-Short AFM Cantilevers of the USC-F0.3-k0.3 type ( typical force constant 0.3 N/m ) were operated in tapping mode for the Atomic Force Microscopy (AFM) images presented in the article.*

Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika et al: Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation. Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika et al: Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation.
Figure 1 a from “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika  et al:
Assembly formation and photoresponse of the dendrimer–photoacid system at a charge ratio of r = 0.25: (a) AFM height images before (right) and after (left) irradiation. Please refer to the full article for the full figure https://www.mdpi.com/2073-4360/12/8/1746

*Alexander Zika, Sarah Bernhardt and Franziska Gröhn
Photoresponsive Photoacid-Macroion Nano-Assemblies
Polymers 2020, 12, 1746
DOI: 10.3390/polym12081746

Please follow this external link to read the full article: https://www.mdpi.com/2073-4360/12/8/1746

Open Access : The article “Photoresponsive Photoacid-Macroion Nano-Assemblies” by Alexander Zika, Sarah Bernhardt and Franziska Gröhn is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer

In the article «Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer» Daniel Garcia-Garcia , José Enrique Crespo-Amorós, Francisco Parres and María Dolores Samper describe how they studied the effect of ultraviolet radiation on styrene-ethylene-butadiene-styrene (SEBS) at different exposure times in order to obtain a better understanding of the mechanism of ageing.*

The results obtained for the SEBS, in relation to the duration of exposure, showed superficial changes that cause a decrease in the surface energy (s) and, therefore, a decrease in surface roughness. This led to a reduction in mechanical performance, decreasing the tensile strength by about 50% for exposure times of around 200 hours.*

NanoWorld Pointprobe® NCH AFM probes were used in the Atomic force microscopy (AFM) applied to determine the surface topography and roughness of the aged samples.

Figure 4 from «Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer» by Daniel Garcia-Garcia et al.: Atomic force microscopy (AFM) surface of SEBS: (a) without exposure (T0), (b) UV exposure T2, (c) UV exposure T7 and (d) UV exposure T9.


Figure 4 from «Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer» by Daniel Garcia-Garcia et al.:
Atomic force microscopy (AFM) surface of SEBS: (a) without exposure (T0), (b) UV exposure T2, (c) UV exposure T7 and (d) UV exposure T9.

*Daniel Garcia-Garcia , José Enrique Crespo-Amorós, Francisco Parres and María Dolores Samper
Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer
Polymers 2020, 12, 862
DOI: https://doi.org/10.3390/polym12040862

Please follow this external link to read the full article: https://www.mdpi.com/2073-4360/12/4/862

Open Access : The article “Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer» byDaniel Garcia-Garcia , José Enrique Crespo-Amorós, Francisco Parres and María Dolores Samper is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly

Ferroelectric memories are endowed with high data storage density by nanostructure designing, while the robustness is also impaired. For organic ferroelectrics favored by flexible memories, low Curie transition temperature limits their thermal stability.*

In their article “Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly “ Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen demonstrate that a ferroelectric random access memory ( FeRAM ) with high thermal stability and data storage density of ≈60 GB inch−2 could be achieved from an array of edge‐on nano‐lamellae by low‐temperature self‐assembly of P(VDF‐TrFE).*

The self‐assembled P(VDF‐TrFE) described in the article exhibits high storage density of 60 GB inch−2 as a prototype of flexible FeRAM. The authors experimentally determine the self‐assembled FeRAM stored data more robustly, with temperature endurance enhanced over 10 °C and reliable thermal cycling ability. The article shows a novel path to address the thermal stability issues in organic FeRAMs and presents a detailed analysis about the origin of enhanced performance in aligned P(VDF‐TrFE). *

NanoWorld Arrow-CONTPt AFM probes with a conducting Pt/Ir coating were used for the Piezoresponse Force Microscopy ( PFM ) measurements described in this article.

Figure 4 from “Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly” by Mengfan Guo et al.:
Enhanced thermal stability in SA P(VDF‐TrFE). a–c) PFM images of data stored in self‐assembled film at a) 25 °C and b) 90 °C, as well as c) numeric figure of residual area of reversal domains as a function of elevated temperature in a SA film (blue) and a NSA film (red). d) Numeric figure of residual area of reversal domains as a function of thermal cycles in a SA film (blue) and a NSA film (red). Scale bars: 200 nm.

*Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan, Yang Shen
Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly
Advanced Science, Volume6, Issue6, March 20, 2019, 1801931
DOI: https://doi.org/10.1002/advs.201801931

Please follow this external link to read the full article: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201801931

Open Access: The article « Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly » by Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.