Decoupling of the Chemical and Mechanical Surface Contributions in a Force Curve Measurement with AFM

2003 ◽  
Vol 778 ◽  
Author(s):  
Olivier Noel ◽  
Maurice Brogly ◽  
Gilles Castelein ◽  
Jacques Schultz
Keyword(s):  
Mechanical Properties ◽  
Surface Properties ◽  
Adhesion Force ◽  
Force Measurement ◽  
Mechanical Energy ◽  
Polymer Network ◽  
Polymer Networks ◽  
Model Systems ◽  
Silicon Substrates ◽  
Contact Mode

AbstractAtomic Force Microscope (AFM) was used to perform surface force measurements in contact mode to investigate surface properties of model systems at the nanoscale. Model systems were considered and compared. The first one was related to systems of controlled chemical surface properties with identical mechanical properties (chemically modified silicon substrates with hydroxyl, amine, methyl and ester functional groups). The second one deals with model polymer networks (Cross-linked polydimethylsiloxane or PDMS) of controlled mechanical properties and identical surface chemistry. The third system consists in a model polymer network, whose surface is chemically controlled with the same groups as before with silicon substrates. The results show that the viscoelastic contribution is dominating in the adhesion force measurement. Finally, we propose a relationship (derived from the Gent and Schultz's one), which expresses the AFM adhesion force as a function of mechanical energy dissipated in the contact and the surface properties of the material.

scholarly journals A Guide through the Dental Dimethacrylate Polymer Network Structural Characterization and Interpretation of Physico-Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4057 ◽  
Author(s):  
Izabela Maria Barszczewska-Rybarek
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Structural Parameters ◽  
Polymer Network ◽  
Polymer Networks ◽  
Impact Resistance ◽  
Organic Matrices ◽  
Dental Restorative

Material characterization by the determination of relationships between structure and properties at different scales is essential for contemporary material engineering. This review article provides a summary of such studies on dimethacrylate polymer networks. These polymers serve as photocuring organic matrices in the composite dental restorative materials. The polymer network structure was discussed from the perspective of the following three aspects: the chemical structure, molecular structure (characterized by the degree of conversion and crosslink density (chemical as well as physical)), and supramolecular structure (characterized by the microgel agglomerate dimensions). Instrumental techniques and methodologies currently used for the determination of particular structural parameters were summarized. The influence of those parameters as well as the role of hydrogen bonding on basic mechanical properties of dimethacrylate polymer networks were finally demonstrated. Mechanical strength, modulus of elasticity, hardness, and impact resistance were discussed. The issue of the relationship between chemical structure and water sorption was also addressed.

scholarly journals Internal and external catalysis in boronic ester networks

2021 ◽  
Author(s):  
Boyeong Kang ◽  
Julia Kalow
Keyword(s):  
Mechanical Properties ◽  
Binding Affinity ◽  
Polymer Networks ◽  
Model Systems ◽  
Self Healing ◽  
Dynamic Materials ◽  
Boronic Ester ◽  
Rate Acceleration ◽  
Exchange Spectroscopy ◽  
Kinetics Of

In dynamic materials, the reversible condensation between boronic acids and diols provides adaptability, self-healing ability, and responsiveness to small molecules and pH. Recent work has shown that the thermodynamics and kinetics of bond exchange determine the mechanical properties of dynamic polymer networks. However, prior studies have focused on how structural and environmental factors influence boronic acid–diol binding affinity, and design rules for tuning the kinetics of this dynamic bond are lacking. In this work, we investigate the effects of diol (or polyol) structure and salt additives on the rate of bond exchange, binding affinity, and the mechanical properties of the corresponding polymer networks. To better mimic the environment of polymer networks in our small-molecule model systems, we incorporated proximal amide groups, which are used to conjugate diols to polymers, and included salts commonly found in buffers. Using one-dimensional selective exchange spectroscopy (1D EXSY), we find that both proximal amides and buffering anions induce significant rate acceleration consistent with internal and external catalysis, respectively. This rate acceleration is reflected in the stress relaxation of gels formed using PEG modified with different alcohols, and in the presence of salts containing acetate or phosphate. These findings contribute to the fundamental understanding of the boronic ester dynamic bond and offer new molecular strategies to tune the macromolecular properties of dynamic materials.

scholarly journals Multiply Interpenetrating Polymer Networks: Preparation, Mechanical Properties, and Applications

Gels ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 36 ◽  
Author(s):  
Panayiota A. Panteli ◽  
Costas S. Patrickios
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Polymer Network ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
Interpenetrating Polymer Network ◽  
Low Friction ◽  
Friction Coefficients ◽  
Polymeric Component ◽  
Work Done

This review summarizes work done on triply, or higher, interpenetrating polymer network materials prepared in order to widen the properties of double polymer network hydrogels (DN), doubly interpenetrating polymer networks with enhanced mechanical properties. The review will show that introduction of a third, or fourth, polymeric component in the DNs would further enhance the mechanical properties of the resulting materials, but may also introduce other useful functionalities, including electrical conductivity, low-friction coefficients, and (bio)degradability.

scholarly journals Challenges and limits of Mechanical Stability in 3D Direct Laser Writing

2021 ◽  
Author(s):  
Elaheh Sedghamiz ◽  
Modan Liu ◽  
Wolfgang Wenzel
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Mechanical Stability ◽  
Polymer Network ◽  
Polymer Networks ◽  
Ultrashort Laser Pulses ◽  
Dynamics Simulation ◽  
Direct Laser Writing ◽  
Laser Writing ◽  
Direct Laser

Abstract Direct laser writing is an effective technique for fabrication of complex polymeric 3D polymer networks using ultrashort laser pulses. Practically, it remains a challenge to design and fabricate high performance materials with different functions that possess a combination of high strength, substantial ductility, and tailored functionality, in particular for small feature sizes. To date, it is difficult to obtain a time-resolved microscopic picture of the printing process in operando. To close this gap, we herewith present a molecular dynamics simulation approach to model direct laser writing and investigate the effect of writing condition and aspect ratio on the mechanical properties of the printed polymer network. We show that writing condition provides a possibility to tune the mechanical properties and an optimum writing condition can be applied to fabricate structures with improved mechanical properties. We reveal that beyond the writing parameters, aspect ratio plays an important role to tune the stiffness of the printed structures.

Study of PDMS Compounds Using the Adhesion Force Determined by AFM Force Distance Curve Measurements

2010 ◽  
Vol 93-94 ◽  
pp. 141-144 ◽  
Author(s):  
S. Vanitparinyakul ◽  
P. Pattamang ◽  
A. Chanhom ◽  
B. Tunhoo ◽  
T. Thiwawong ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Adhesion Force ◽  
Surface Force ◽  
Model Systems ◽  
Force Measurements ◽  
Distance Curve ◽  
Contact Mode ◽  
Force Microscopy ◽  
The Third ◽  
Atomic Force

The atomic force microscope(AFM) was used to perform surface force measurements in contact mode to investigate surface properties of model systems at the nanoscale. Three different Polydimethylsiloxane (PDMS) compounds were observed. The first consisted of pure PDMS, the second of PDMS blend with the nanoparticles Zinc Oxide(PDMS/ZnO) and the third of PDMS blend with the nanoparticles Zinc Oxide and toluene solvent(PDMS/ZnO/toluene), respectively. Surface morphology and the adhesion force were investigated by using atomic force microscopy. Force–distance curve measurement was performed in a contact mode, which used tip as silicon nitride. Moreover, we found a significantly different of the adhesion force when modified by nanoparticles ZnO and toluene solvent.

scholarly journals Protein Hydrogels: The Swiss Army Knife for Enhanced Mechanical and Bioactive Properties of Biomaterials

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1656
Author(s):  
Carla Huerta-López ◽  
Jorge Alegre-Cebollada
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Polymer Networks ◽  
Biological Tissues ◽  
Modern Medicine ◽  
Body Parts ◽  
Biomedical Sciences ◽  
Protein Hydrogels ◽  
Large Water ◽  
Design Options

Biomaterials are dynamic tools with many applications: from the primitive use of bone and wood in the replacement of lost limbs and body parts, to the refined involvement of smart and responsive biomaterials in modern medicine and biomedical sciences. Hydrogels constitute a subtype of biomaterials built from water-swollen polymer networks. Their large water content and soft mechanical properties are highly similar to most biological tissues, making them ideal for tissue engineering and biomedical applications. The mechanical properties of hydrogels and their modulation have attracted a lot of attention from the field of mechanobiology. Protein-based hydrogels are becoming increasingly attractive due to their endless design options and array of functionalities, as well as their responsiveness to stimuli. Furthermore, just like the extracellular matrix, they are inherently viscoelastic in part due to mechanical unfolding/refolding transitions of folded protein domains. This review summarizes different natural and engineered protein hydrogels focusing on different strategies followed to modulate their mechanical properties. Applications of mechanically tunable protein-based hydrogels in drug delivery, tissue engineering and mechanobiology are discussed.

scholarly journals Internal constraints and arrested relaxation in main-chain nematic elastomers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takuya Ohzono ◽  
Kaoru Katoh ◽  
Hiroyuki Minamikawa ◽  
Mohand O. Saed ◽  
Eugene M. Terentjev
Keyword(s):  
Mechanical Properties ◽  
Main Chain ◽  
Polymer Networks ◽  
Nematic Order ◽  
Nematic Elastomers ◽  
Nematic Director ◽  
Highly Nonlinear ◽  
Nonlinear Mechanical ◽  
Liquid Crystal Elastomers ◽  
Memory Applications

AbstractNematic liquid crystal elastomers (N-LCE) exhibit intriguing mechanical properties, such as reversible actuation and soft elasticity, which manifests as a wide plateau of low nearly-constant stress upon stretching. N-LCE also have a characteristically slow stress relaxation, which sometimes prevents their shape recovery. To understand how the inherent nematic order retards and arrests the equilibration, here we examine hysteretic stress-strain characteristics in a series of specifically designed main-chain N-LCE, investigating both macroscopic mechanical properties and the microscopic nematic director distribution under applied strains. The hysteretic features are attributed to the dynamics of thermodynamically unfavoured hairpins, the sharp folds on anisotropic polymer strands, the creation and transition of which are restricted by the nematic order. These findings provide a new avenue for tuning the hysteretic nature of N-LCE at both macro- and microscopic levels via different designs of polymer networks, toward materials with highly nonlinear mechanical properties and shape-memory applications.

Thermal and mechanical properties of simultaneous and sequential full-interpenetrating polymer networks

2004 ◽  
Vol 370 (1-2) ◽  
pp. 288-292 ◽  
Author(s):  
A Bartolotta ◽  
G Di Marco ◽  
M Lanza ◽  
G Carini ◽  
G D’Angelo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
Thermal And Mechanical Properties

Studies on Nanostructured Polyurethane/Clay Interpenetrating Polymer Networks

2005 ◽  
Vol 475-479 ◽  
pp. 1001-1004
Author(s):  
Ninglin Zhou ◽  
Xiao Xian Xia ◽  
Li Li ◽  
Shao Hua Wei ◽  
Jian Shen
Keyword(s):  
Mechanical Properties ◽  
Polymer Networks ◽  
Testing Machine ◽  
Physical And Mechanical Properties ◽  
Interpenetrating Polymer Networks ◽  
Absorption Properties ◽  
Tensile Testing Machine ◽  
Swelling Agent ◽  
Silicate Layers ◽  
Polyurethane Matrix

A novel exfoliated polyurethane (PU)/clay Interpenetrating Polymer Networks (IPNs) nanocomposite has been synthesized with polyurethane and organoclay. MTPAC is used as swelling agent to treat Na-montmorillonite for forming organoclay. The results indicate that there is very good compatibility between organoclay and PU. Nanoscale silicate dispersion was analyzed by XRD. The mechanical properties of the nanocomposites have been measured by tensile testing machine. The nanocomposites show obviously improved physical and mechanical properties when compared with the pure polymer. Additionally, PU /MTPAC- clay shows lower water absorption properties than pure PU do. In addition, the reinforcing and intercalating mechanism of silicate layers in polyurethane matrix are discussed.

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