Ultimate Properties of Polymer Chains

1993 ◽  
Vol 305 ◽  
Author(s):  
W. Wade Adams ◽  
Ruth Pachter ◽  
Peter D. Haaland ◽  
Thomas R. Horn ◽  
Scott G. Wierschke ◽  
...  
Keyword(s):  
Smart Materials ◽  
High Performance ◽  
Mechanical Response ◽  
Alpha Helix ◽  
Polymer Chains ◽  
Single Chain ◽  
Tension And Compression ◽  
Rigid Rod ◽  
Different Response ◽  
Semi Empirical

AbstractNew polymers with exceptional properties are needed for applications in high-performance structures, novel electrical, optical and electro-optical devices, and for multi-functional smart materials. Concurrently, new computational capabilities and methods for properties prediction and analysis have enabled the study of a variety of polymer chain architectures to examine the principles that govern their high-performance properties. By semi-empirical and ab initio computational methods, flexible, stiff-chain, rigid-rod, and biological structures could be analyzed. Single chain molecular stress-strain curves for axial tension and compression were calculated, and the strain dependence of the molecular modulus and vibrational frequencies were compared to measurements of molecular deformation, such as IR and Raman spectroscopy. However, of special interest is the distinctly different response of alpha-helical biopolymer chains to strain. Indeed, in this study we compare on a theoretical basis the ‘spring-like’ microscopic mechanical response of alpha-helical biopolymers having a reinforcing intra-molecular hydrogen bonding network to analogous synthetic extended chain polymers, especially poly(para-phenylene terephthalamide) (PPTA) [KEVLARTM]. The theoretical verification of the absence of compressive buckling in alpha-helical biopolymer chains rationalizes the molecular elasticity and resistance to ‘kinking’ of those strands, manifested by the prevalence in Nature for coiled coils. The understanding of the structure-tofunction relationship in biopolymers explaining the role of the alpha-helix in these systems as a requirement for superior compressive mechanical properties, may enable new guidance for the synthesis of motifs consistent with molecular frameworks optimized by Nature.

Mechanical Response of High Performance Polymers: Abpbo, Abpbi and Abpbt

1992 ◽  
Vol 291 ◽  
Author(s):  
Tahir Çağin
Keyword(s):  
High Performance ◽  
Mechanical Response ◽  
High Strength ◽  
Elastic Stiffness ◽  
Theory Of Elasticity ◽  
High Performance Polymers ◽  
Atomistic Modelling ◽  
Tension And Compression ◽  
Finite Theory ◽  
Stiff Chain

ABSTRACTLight weight, high strength fibers and films produced from stiff chain polymers are good candidates for use as structural materials. Over the last decade, considerable success has been achieved in synthesizing high strength fibers and films. Due to their thermal and oxidative stability aromatic heterocyclic stiff chain polymers such as ABPBO, ABPBT, and ABPBI are especially good candidates. We first describe the finite theory of elasticity as applied in atomistic modelling and simulations of anisotropic solids and then use this description to investigate the mechanical response of these crystalline polymers as a function of applied hydrostatic pressure and uniaxial tension and compression along the chain direction in molecular mechanics simulations. In addition to these finite stress-strain experiments, I will also present the results of the first elastic stiffness matrix calculations performed on these high performance polymers.

scholarly journals The Ductile Behavior of High Performance Concrete in Compression

2010 ◽  
Vol 56 (1) ◽  
pp. 3-18 ◽  
Author(s):  
A. P. Fantilli ◽  
H. Mihashi ◽  
P. Vallini ◽  
B. Chiaia
Keyword(s):  
High Performance ◽  
Mechanical Response ◽  
High Performance Concrete ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Inelastic Displacement ◽  
Confinement Stress ◽  
Relative Stress ◽  
Tension And Compression ◽  
Ductile Behavior

Abstract The ductility of High Performance Concrete (HPC) can develop both in tension and compression. This aspect is evidenced in the present paper by measuring the mechanical response of normal vibrated concrete (NC), self-compacting concrete (SC) and some HPCs cylindrical specimens under uniaxial and triaxial compression. The post-peak behaviour of these specimens is defined by a non-dimensional function that relates the inelastic displacement and the relative stress during softening. Both for NC and SC, the increase of the fracture toughness with the confinement stress is observed. Conversely, all the tested HPCs, even in absence of confinement, show practically the same ductility measured in normal and self-compacting concretes with a confining pressure. Thus, the presence of HPC in compressed columns is itself sufficient to create a sort of active distributed confinement.

scholarly journals Topological changes in telechelic micelles: flowers versus stars

2021 ◽  
Author(s):  
Vladimir Baulin
Keyword(s):  
Smart Materials ◽  
Linear Chain ◽  
Mean Field Theory ◽  
Mean Field ◽  
Polymer Chains ◽  
Linear Polymers ◽  
Stimuli Responsive ◽  
Single Chain ◽  
Low Concentrations ◽  
Effective Attraction

Micellization and morphology of spherical telechelic micelles formed by tri-block copolymers with short solvophobic end blocks at low concentrations is discussed within scaling arguments and Single Chain Mean Field Theory (SCMFT). In ultra-dilute regime, individual telechelic polymer chains can exist in solution in two distinct states: open linear chain conformation with two free ends and closed loop conformation, when two ends are connected by the effective attraction between two solvophobic ends. At concentrations below gelation point, closed loops tend to form micelles comprised mostly of loops in flower-like micelles, while linear polymers in open conformations tend to form star-shaped aggregates with one hydrophobic dangling end. Resulting two kinds of micelles have remarkably different topology and dimensions, while the transition between them can be driven by the entropy, namely conformation changes between domination of the looped and linear conformations. As a result, the transition between two types of micelles lies in a narrow interaction parameters range. Thus, these topological micelles are very sensitive to the changes in external environment and they can serve as a very sensitive stimuli-responsive smart materials.

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

scholarly journals Advances in the Multi-Orthogonal Folding of Single Polymer Chains into Single-Chain Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 293
Author(s):  
Agustín Blazquez-Martín ◽  
Ester Verde-Sesto ◽  
Angel J. Moreno ◽  
Arantxa Arbe ◽  
Juan Colmenero ◽  
...  
Keyword(s):  
Computer Simulations ◽  
Chemical Species ◽  
Synthetic Polymers ◽  
Review Article ◽  
Polymer Chains ◽  
Single Chain ◽  
High Dilution ◽  
Covalent Bonds ◽  
Covalent Interactions ◽  
Individual Polymer

The folding of certain proteins (e.g., enzymes) into perfectly defined 3D conformations via multi-orthogonal interactions is critical to their function. Concerning synthetic polymers chains, the “folding” of individual polymer chains at high dilution via intra-chain interactions leads to so-called single-chain nanoparticles (SCNPs). This review article describes the advances carried out in recent years in the folding of single polymer chains into discrete SCNPs via multi-orthogonal interactions using different reactive chemical species where intra-chain bonding only occurs between groups of the same species. First, we summarize results from computer simulations of multi-orthogonally folded SCNPs. Next, we comprehensively review multi-orthogonally folded SCNPs synthesized via either non-covalent bonds or covalent interactions. Finally, we conclude by summarizing recent research about multi-orthogonally folded SCNPs prepared through both reversible (dynamic) and permanent bonds.

scholarly journals Recent Advances in the Synthesis of Polymer-Grafted Low-K and High-K Nanoparticles for Dielectric and Electronic Applications

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2942
Author(s):  
Bhausaheb V. Tawade ◽  
Ikeoluwa E. Apata ◽  
Nihar Pradhan ◽  
Alamgir Karim ◽  
Dharmaraj Raghavan
Keyword(s):  
Energy Density ◽  
Polymer Nanocomposites ◽  
High Performance ◽  
Breakdown Strength ◽  
Polymer Nanocomposite ◽  
High Energy ◽  
Polymer Chains ◽  
High Energy Density ◽  
Grafted Nanoparticles ◽  
Grafting From

The synthesis of polymer-grafted nanoparticles (PGNPs) or hairy nanoparticles (HNPs) by tethering of polymer chains to the surface of nanoparticles is an important technique to obtain nanostructured hybrid materials that have been widely used in the formulation of advanced polymer nanocomposites. Ceramic-based polymer nanocomposites integrate key attributes of polymer and ceramic nanomaterial to improve the dielectric properties such as breakdown strength, energy density and dielectric loss. This review describes the ”grafting from” and ”grafting to” approaches commonly adopted to graft polymer chains on NPs pertaining to nano-dielectrics. The article also covers various surface initiated controlled radical polymerization techniques, along with templated approaches for grafting of polymer chains onto SiO2, TiO2, BaTiO3, and Al2O3 nanomaterials. As a look towards applications, an outlook on high-performance polymer nanocomposite capacitors for the design of high energy density pulsed power thin-film capacitors is also presented.

Chemiluminescent self-reported unfolding of single-chain nanoparticles

2021 ◽  
Author(s):  
Fabian R. Bloesser ◽  
Sarah L. Walden ◽  
Ishrath M. Irshadeen ◽  
Lewis C. Chambers ◽  
Christopher Barner-Kowollik
Keyword(s):  
Polymer Chains ◽  
Linear Polymer ◽  
Single Chain

We demonstrate the light-induced, crosslinker mediated collapse of linear polymer chains into single-chain nanoparticles (SCNPs) capable of self-reporting their unfolding.

scholarly journals Single Chain Mean-Field Theory Study on Responsive Behavior of Semiflexible Polymer Brush

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 778
Author(s):  
Yingli Niu ◽  
Xiangyu Bu ◽  
Xinghua Zhang
Keyword(s):  
Field Theory ◽  
Message Passing Interface ◽  
Mean Field Theory ◽  
Mean Field ◽  
Algorithmic Complexity ◽  
Ensemble Average ◽  
Single Chain ◽  
Metropolis Monte Carlo ◽  
Rigid Rod ◽  
Chain Conformations

The application of single chain mean-field theory (SCMFT) on semiflexible chain brushes is reviewed. The worm-like chain (WLC) model is the best mode of semiflexible chain that can continuously recover to the rigid rod model and Gaussian chain (GC) model in rigid and flexible limits, respectively. Compared with the commonly used GC model, SCMFT is more applicable to the WLC model because the algorithmic complexity of the WLC model is much higher than that of the GC model in self-consistent field theory (SCFT). On the contrary, the algorithmic complexity of both models in SCMFT are comparable. In SCMFT, the ensemble average of quantities is obtained by sampling the conformations of a single chain or multi-chains in the external auxiliary field instead of solving the modified diffuse equation (MDE) in SCFT. The precision of this calculation is controlled by the number of bonds Nm used to discretize the chain contour length L and the number of conformations M used in the ensemble average. The latter factor can be well controlled by metropolis Monte Carlo simulation. This approach can be easily generalized to solve problems with complex boundary conditions or in high-dimensional systems, which were once nightmares when solving MDEs in SCFT. Moreover, the calculations in SCMFT mainly relate to the assemble averages of chain conformations, for which a portion of conformations can be performed parallel on different computing cores using a message-passing interface (MPI).

scholarly journals Recent advances in skin collagen: functionality and non-medical applications

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Yanting Han ◽  
Jinlian Hu ◽  
Gang Sun
Keyword(s):  
Smart Materials ◽  
High Performance ◽  
Preparation Method ◽  
Chemical Reactivity ◽  
Medical Field ◽  
Recent Advances ◽  
Synthetic Materials ◽  
Skin Collagen ◽  
Promising Area ◽  
Living Organisms

Abstract During nature evolution process, living organisms have gradually adapted to the environment and been adept in synthesizing high performance structural materials at mild conditions by using fairly simple building elements. The skin, as the largest organ of animals, is such a representative example. Conferred by its intricate organization where collagen fibers are arranged in a randomly interwoven network, skin collagen (SC), defined as a biomass derived from skin by removing non-collagen components displays remarkable performance with combinations of mechanical properties, chemical-reactivity and biocompatibility, which far surpasses those of synthetic materials. At present, the application of SC in medical field has been largely studied, and there have been many reviews summarizing these efforts. However, the generalized view on the aspects of SC as smart materials in non-medical fields is still lacking, although SC has shown great potential in terms of its intrinsic properties and functionality. Hence, this review will provide a comprehensive summary that integrated the recent advances in SC, including its preparation method, structure, reactivity, and functionality, as well as applications, particularly in the promising area of smart materials. Graphical abstract

scholarly journals High Performance NbMoTa–Al2O3 Multilayer Composite Structure Manufacturing by Laser Directed Energy Deposition

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1685
Author(s):  
Hang Zhang ◽  
Zihao Chen ◽  
Yaoyao He ◽  
Xin Guo ◽  
Qingyu Li ◽  
...  
Keyword(s):  
Smart Materials ◽  
Composite Structure ◽  
Composite Structures ◽  
High Performance ◽  
Energy Deposition ◽  
Coefficient Of Thermal Expansion ◽  
Multilayer Composite ◽  
Forming Process ◽  
Directed Energy Deposition ◽  
Directed Energy

The conventional method of preparing metal–ceramic composite structures causes delamination and cracking defects due to differences in the composite structures’ properties, such as the coefficient of thermal expansion between metal and ceramic materials. Laser-directed energy deposition (LDED) technology has a unique advantage in that the composition of the materials can be changed during the forming process. This technique can overcome existing problems by forming composite structures. In this study, a multilayer composite structure was prepared using LDED technology, and different materials were deposited with their own appropriate process parameters. A layer of Al2O3 ceramic was deposited first, and then three layers of a NbMoTa multi-principal element alloy (MPEA) were deposited as a single composite structural unit. A specimen of the NbMoTa–Al2O3 multilayer composite structure, composed of multiple composite structural units, was formed on the upper surface of a φ20 mm × 60 mm cylinder. The wear resistance was improved by 55% compared to the NbMoTa. The resistivity was 1.55 × 10−5 Ω × m in the parallel forming direction and 1.29 × 10−7 Ω × m in the vertical forming direction. A new, electrically anisotropic material was successfully obtained, and this study provides experimental methods and data for the preparation of smart materials and new sensors.

Sign in / Sign up

Export Citation Format

Share Document