scholarly journals Chameleon-like elastomers with molecularly encoded strain-adaptive stiffening and coloration

Science ◽  
2018 ◽  
Vol 359 (6383) ◽  
pp. 1509-1513 ◽  
Author(s):  
Mohammad Vatankhah-Varnosfaderani ◽  
Andrew N. Keith ◽  
Yidan Cong ◽  
Heyi Liang ◽  
Martin Rosenthal ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
The Self ◽  
Cross Linking ◽  
Ambient Conditions ◽  
Bodily Fluids ◽  
Synthetic Materials ◽  
Chemical Cross Linking

Active camouflage is widely recognized as a soft-tissue feature, and yet the ability to integrate adaptive coloration and tissuelike mechanical properties into synthetic materials remains elusive. We provide a solution to this problem by uniting these functions in moldable elastomers through the self-assembly of linear-bottlebrush-linear triblock copolymers. Microphase separation of the architecturally distinct blocks results in physically cross-linked networks that display vibrant color, extreme softness, and intense strain stiffening on par with that of skin tissue. Each of these functional properties is regulated by the structure of one macromolecule, without the need for chemical cross-linking or additives. These materials remain stable under conditions characteristic of internal bodily environments and under ambient conditions, neither swelling in bodily fluids nor drying when exposed to air.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

scholarly journals Cellular Orientation on Repeatedly Stretching Gelatin Hydrogels with Supramolecular Cross-Linkers

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2095
Author(s):  
Dae Hoon Lee ◽  
Yoshinori Arisaka ◽  
Asato Tonegawa ◽  
Tae Woong Kang ◽  
Atsushi Tamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cellular Response ◽  
Linear Polymer ◽  
Cross Linking ◽  
Adherent Cells ◽  
Cell Cultivation ◽  
Supramolecular Compound ◽  
Synthetic Materials ◽  
Cyclic Molecules

The cytocompatibility of biological and synthetic materials is an important issue for biomaterials. Gelatin hydrogels are used as biomaterials because of their biodegradability. We have previously reported that the mechanical properties of gelatin hydrogels are improved by cross-linking with polyrotaxanes, a supramolecular compound composed of many cyclic molecules threaded with a linear polymer. In this study, the ability of gelatin hydrogels cross-linked by polyrotaxanes (polyrotaxane–gelatin hydrogels) for cell cultivation was investigated. Because the amount of polyrotaxanes used for gelatin fabrication is very small, the chemical composition was barely altered. The structure and wettability of these hydrogels are also the same as those of conventional hydrogels. Fibroblasts adhered on polyrotaxane–gelatin hydrogels and conventional hydrogels without any reduction or apoptosis of adherent cells. From these results, the polyrotaxane–gelatin hydrogels have the potential to improve the mechanical properties of gelatin without affecting cytocompatibility. Interestingly, when cells were cultured on polyrotaxane–gelatin hydrogels after repeated stress deformation, the cells were spontaneously oriented to the stretching direction. This cellular response was not observed on conventional hydrogels. These results suggest that the use of a polyrotaxane cross-linking agent can not only improve the strength of hydrogels but can also contribute to controlling reorientation of the gelatin.

scholarly journals STM study on the self-assembly of oligothiophene-based organic semiconductors

2011 ◽  
Vol 2 ◽  
pp. 802-808 ◽  
Author(s):  
Elena Mena-Osteritz ◽  
Marta Urdanpilleta ◽  
Erwaa El-Hosseiny ◽  
Berndt Koslowski ◽  
Paul Ziemann ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Self Assembly ◽  
Theoretical Calculations ◽  
The Self ◽  
Scanning Tunneling ◽  
Ambient Conditions ◽  
Tunneling Microscopy ◽  
Substitution Pattern ◽  
Electronic Density ◽  
The Individual

The self-assembly properties of a series of functionalized regioregular oligo(3-alkylthiophenes) were investigated by using scanning tunneling microscopy (STM) at the liquid–solid interface under ambient conditions. The characteristics of the 2-D crystals formed on the (0001) plane of highly ordered pyrolitic graphite (HOPG) strongly depend on the length of the π-conjugated oligomer backbone, on the functional groups attached to it, and on the alkyl substitution pattern on the individual thiophene units. Theoretical calculations were performed to analyze the geometry and electronic density of the molecular orbitals as well as to analyze the intermolecular interactions, in order to obtain models of the 2-D molecular ordering on the substrate.

Z-E isomerization of azobenzene based amphiphilic poly(urethane-urea)s: Influence on the dynamic mechanical properties and the effect of the self-assembly in solution on the isomerization kinetics

2020 ◽  
Vol 127 ◽  
pp. 109583
Author(s):  
Germana Maria Santos Paiva ◽  
Luís Gustavo Teixeira Alves Duarte ◽  
Marcelo Meira Faleiros ◽  
Teresa Dib Zambon Atvars ◽  
Maria Isabel Felisberti
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Dynamic Mechanical Properties ◽  
The Self ◽  
Dynamic Mechanical

The biphasic effect of ABA triblock copolymers on the self-assembly of surfactants: insight from dissipative particle dynamics

2019 ◽  
Vol 4 (4) ◽  
pp. 921-928 ◽  
Author(s):  
Jiawei Li ◽  
Junfeng Wang ◽  
Qiang Yao ◽  
Yan Zhang ◽  
Youguo Yan ◽  
...  
Keyword(s):  
Self Assembly ◽  
Triblock Copolymers ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
The Self ◽  
Biphasic Effect

ABA triblock copolymers have been demonstrated to be able to produce a biphasic effect on the self-assembly of surfactants.

scholarly journals Dynamic cross-linking of an alginate–acrylamide tough hydrogel system: time-resolved in situ mapping of gel self-assembly

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 10710-10726
Author(s):  
Akanksha Pragya ◽  
Suhas Mutalik ◽  
Muhammad Waseem Younas ◽  
Siu-Kwong Pang ◽  
Pui-Kin So ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Formation Process ◽  
Self Assembly ◽  
Cross Linking ◽  
Time Resolved ◽  
System Time ◽  
Dynamic Formation ◽  
Hydrogel System

In situ, time-resolved characterisation of an alginate–acrylamide tough hydrogel dynamic formation process indicate routes to intervention and modification of chemo-physico-mechanical properties.

scholarly journals Influence of nucleobase stoichiometry on the self-assembly of ABC triblock copolymers

2016 ◽  
Vol 52 (48) ◽  
pp. 7564-7567 ◽  
Author(s):  
Keren Zhang ◽  
Samantha J. Talley ◽  
Ya Peng Yu ◽  
Robert B. Moore ◽  
Mitsuhiro Murayama ◽  
...  
Keyword(s):  
Long Range ◽  
Self Assembly ◽  
Triblock Copolymers ◽  
The Self ◽  
Patterned Substrates ◽  
Abc Triblock Copolymers ◽  
Self Assembled

ABC triblock copolymers bearing adenine- and thymine-functionalized external blocks self-assembled into long-range, ordered lamellar microphase-separated morphologies on non-patterned substrates.

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