Enhancing mechanical properties of chitosan/PVA electrospun nanofibers: a comprehensive review

• Nur Areisman Mohd Salleh,
• Amalina Muhammad Afifi,
• Fathiah Mohamed Zuki and
• Hanna Sofia SalehHudin

Beilstein J. Nanotechnol. 2025, 16, 286–307, doi:10.3762/bjnano.16.22

• Viscoelasticity is another property relevant to nanofibers, which combines both elastic and viscous responses to deformation. Viscoelastic properties, including storage modulus and loss modulus, can be tested using dynamic mechanical analysis (DMA) or dynamic mechanical thermal analysis (DMTA). This technique

• of cross-linked and not cross-linked chitosan/PVA nanofibers to investigate the variation in loss factor with temperature, which is obtained from the ratio of loss modulus to storage modulus. The increase in loss factor observed after cross-linking for 48 h indicates high cross-linking density and

• smaller distance between molecular chains, which improves energy dissipation. Saeedi et al. [142] conducted DMTA tests and found that storage modulus and loss modulus of chitosan/PVA improved with the addition of graphene oxide. An improvement of loss modulus indicates resistance of polymer chains against

Modification of graphene oxide and its effect on properties of natural rubber/graphene oxide nanocomposites

• Nghiem Thi Thuong,
• Le Dinh Quang,
• Vu Quoc Cuong,
• Cao Hong Ha,
• Nguyen Ba Lam and
• Seiichi Kawahara

Beilstein J. Nanotechnol. 2024, 15, 168–179, doi:10.3762/bjnano.15.16

• chemical interaction between GO and NR. Dynamic mechanical properties Dynamic mechanical properties of composite samples reveal how much energy is stored or lost during applied cyclic shearing force. Figure 11 shows the dependence of the storage modulus (G'), loss modulus (G''), and loss tangent (tan δ) of

• storage for composite materials. The G' values seemed to depend on the silica content; the higher the silica content, the higher the storage modulus. The dependence of loss modulus (G'') on frequency for DPNR, DPNR/GO, DPNR/GO-VTES(a), and DPNR/GO-VTES(b) exhibited a little difference as shown in Figure

• curve of GO-VTES(a) and GO-VTES(b). FE-SEM images for GO-VTES(a) and GO-VTES(b) at 100k and 50k magnifications. Schematic for modification of GO-VTES. Stress–strain curves of DPNR, DPNR/GO, DPNR/GO-VTES(a), and DPNR/GO-VTEs(b). Dependence of storage modulus (G'), loss modulus (G''), and loss tangent

Elasticity, an often-overseen parameter in the development of nanoscale drug delivery systems

• Agnes-Valencia Weiss and
• Marc Schneider

Beilstein J. Nanotechnol. 2023, 14, 1149–1156, doi:10.3762/bjnano.14.95

• loss modulus E'' have been obtained by performing oscillatory measurements in contact with the sample. If maps are created and the recorded data is evaluated via batch processing, these moduli can be displayed as images and correlated with height images. The best option to determine mechanical

Frequency-dependent nanomechanical profiling for medical diagnosis

• Santiago D. Solares and
• Alexander X. Cartagena-Rivera

Beilstein J. Nanotechnol. 2022, 13, 1483–1489, doi:10.3762/bjnano.13.122

• loss modulus [14][15][16][17]. These quantities are appropriate for characterizing soft viscoelastic materials, such as biological specimens, whose mechanical response depends on the rate of application of stress or strain. Notably, many measurements on complex biological systems are still reported

• than a single scalar quantity such as a modulus of elasticity, and from which traditional viscoelastic quantities can be obtained, such as the storage and loss modulus (which are also frequency dependent). Figure 3 provides an example of storage and loss modulus estimates for cancerous human melanoma

• important features (“biomarkers”) within the data. Finally, the clinician correlates the obtained patient mechanical data with the patient demographics and an aggregate database to make a decision concerning disease stage and therapeutic approaches. Nomenclature: ES – storage modulus, EL – loss modulus, T

A new method for obtaining model-free viscoelastic material properties from atomic force microscopy experiments using discrete integral transform techniques

• Berkin Uluutku,
• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 1063–1077, doi:10.3762/bjnano.12.79

• as loss modulus or loss compliance, respectively. Although directly obtaining the Fourier representation of the source operators is possible with the proposed method when harmonic or bounded inputs are used, this is not the case for the classical force–distance curve approach, which is based on a

Correction: Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 137–138, doi:10.3762/bjnano.12.10

• ). Similarly, it is stated that the loss modulus (E″) and loss compliance (J″) are inverses of one another (Equation 11). However, it is the relaxance (Q) and retardance (U) that are inverses of one another in the Laplace domain (not in the time domain), leading to a more complex relationship between the

On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• help inform dynamic AFM characterization. Keywords: dynamic atomic force microscopy; Generalized Maxwell model; loss modulus; storage modulus; viscoelasticity; Introduction There have been significant methodology developments since the introduction of atomic force microscopy (AFM) in the mid-1980s [1

• frequency of two hypothetical materials, the Generalized Maxwell model parameters of which are provided in Table 1. It is clear from the graphs that both the storage and the loss modulus can vary significantly as a function of the deformation frequency, which has very important implications in the context

• of dynamic force spectroscopy. First, for samples exhibiting such variation in their moduli, it is not possible to assign a single value to the coefficient of viscous dissipation during deformation, since the loss modulus is not constant. The variation in the elastic modulus also precludes the

Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 922–937, doi:10.3762/bjnano.11.77

• parameters such as storage modulus, loss modulus, loss angle, and compliance. These steps constitute a complete guide to leveraging AFM-SFS data to estimate key material parameters, with a series of detailed insights into both the methodology and supporting analytical choices. Keywords: atomic force

• is common to calculate harmonic quantities such as the storage modulus E′, loss modulus E′′, and loss angle δ [23][24][25]. Each has a physical interpretation, representing the elastic and viscous motion of the material and their magnitudes relative to one another. For example, a material that is

• very stiff will have a high storage modulus and a low loss modulus. Such a sample will tend to store a majority of the applied load within its molecular structure and elastically return most or all of that energy when unloaded. Alternately, a medium that is susceptible to large shear forces (such as

Design of a nanostructured mucoadhesive system containing curcumin for buccal application: from physicochemical to biological aspects

• Sabrina Barbosa de Souza Ferreira,
• Gustavo Braga,
• Évelin Lemos Oliveira,
• Jéssica Bassi da Silva,
• Hélen Cássia Rosseto,
• Lidiane Vizioli de Castro Hoshino,
• Mauro Luciano Baesso,
• Wilker Caetano,
• Craig Murdoch,
• Helen Elizabeth Colley and
• Marcos Luciano Bruschi

Beilstein J. Nanotechnol. 2019, 10, 2304–2328, doi:10.3762/bjnano.10.222

High-tolerance crystalline hydrogels formed from self-assembling cyclic dipeptide

• Yongcai You,
• Ruirui Xing,
• Qianli Zou,
• Feng Shi and
• Xuehai Yan

Beilstein J. Nanotechnol. 2019, 10, 1894–1901, doi:10.3762/bjnano.10.184

• , disabled mechanical modulus (storage or loss modulus), and poor environmental tolerance under thermal, acidic, or alkaline conditions [35][36][37]. Hence, new types of peptide hydrogels are highly needed to promote the practical applications of peptide hydrogels. Cyclic dipeptides (CDPs), which are based

Nanoscale spatial mapping of mechanical properties through dynamic atomic force microscopy

• Zahra Abooalizadeh,
• Leszek Josef Sudak and
• Philip Egberts

Beilstein J. Nanotechnol. 2019, 10, 1332–1347, doi:10.3762/bjnano.10.132

• response of the cantilever were simultaneously recorded with the topography and the lateral force signals using a digital lock-in amplifier supplied with the RHK R9 controller. The calibration of the detected variations in amplitude and phase into elastic and loss modulus with high accuracy requires a good

Outstanding chain-extension effect and high UV resistance of polybutylene succinate containing amino-acid-modified layered double hydroxides

• Adam A. Marek,
• Vincent Verney,
• Christine Taviot-Gueho,
• Grazia Totaro,
• Laura Sisti,
• Annamaria Celli and
• Fabrice Leroux

Beilstein J. Nanotechnol. 2019, 10, 684–695, doi:10.3762/bjnano.10.68

• sweeps from 0.1 to 100 rad s−1 and the gap between plates set at 1 mm. In all cases, the oscillatory shear stress amplitude was checked to ensure that measurements were performed inside the linear viscoelastic domain. The storage modulus (G’), loss modulus (G”) and tan δ (ratio of G” and G’) were

• composites were recorded via the storage modulus (E′) and tan δ, which is the ratio of the loss modulus to the storage modulus (Figure 8). With respect to PBS, the composites present moderate enhancement in the storage modulus E’ over almost the entire temperature range, quantifiable as 6–12% and 17–26% from

Graphene–graphite hybrid epoxy composites with controllable workability for thermal management

• Idan Levy,
• Eyal Merary Wormser,
• Maxim Varenik,
• Matat Buzaglo,
• Roey Nadiv and
• Oren Regev

Beilstein J. Nanotechnol. 2019, 10, 95–104, doi:10.3762/bjnano.10.9

• loss modulus (G', open symbols) as functions of the volume fraction of graphite (a) and GNP fillers (b) recorded at an oscillating frequency of 1 Hz and temperature of 25 °C. The dashed lines indicate the G'-G'' crossover volume fraction. Thermal conductivity (a) and viscosity (b) of hybrid composites

• graphite-containing composites to higher volume fractions of the filler compared to those of GNP-loaded composites [41][48][49][50], in line with previously studied silicone rubber systems [41]. The viscoelasticity of a composite may be described by the dynamic moduli, G' (storage modulus) and G'' (loss

• modulus), which strongly depend on the volume fraction of the filler (Figure 3). A modulus ratio G''/G' > 1 reflects a more viscous material, while G''/G' < 1 indicates a more elastic material [50][51]. A crossover volume fraction (indicated by dashed lines in Figure 3) was detected for both the GNP

Layered calcium phenylphosphonate: a hybrid material for a new generation of nanofillers

• Kateřina Kopecká,
• Ludvík Beneš,
• Klára Melánová,
• Vítězslav Zima,
• Petr Knotek and
• Kateřina Zetková

Beilstein J. Nanotechnol. 2018, 9, 2906–2915, doi:10.3762/bjnano.9.269

• higher values compared to the pristine film. While the value of the loss modulus of the composite with unexfoliated CaPhP is roughly the same as for the pristine epoxy film, the loss modulus of the composite with exfoliated CaPhP is higher. Barrier properties The addition of thin but large particles can

Material property analytical relations for the case of an AFM probe tapping a viscoelastic surface containing multiple characteristic times

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2017, 8, 2230–2244, doi:10.3762/bjnano.8.223

• ); the second one is proportional to the loss modulus G″(ω); the third term is related to the transients (associated with the poles of the transfer function); the fourth term relates to the relaxation modulus (G(t)); and the fifth term is related to the adhesion component of the vdW interaction (surface

• energy hysteresis). Interestingly, energy dissipation in this case is not exclusively proportional to the loss modulus as in the case of steady-state harmonic applications (e.g., DMA, see Equation 8). It is evident that substantial complexity is generated in the analytical relations derived when the

• case of DMA (see Equation 11), in which the virial is only proportional to the storage modulus. Here, as for the case of dissipated energy, the virial has contributions that are not only proportional to the storage modulus G′(ω), but also to the loss modulus G″(ω), the relaxation modulus G(t) (4th term

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications

• Bertha T. Pérez-Martínez,
• Lorena Farías-Cepeda,
• Víctor M. Ovando-Medina,
• José M. Asua,
• Lucero Rosales-Marines and
• Radmila Tomovska

Beilstein J. Nanotechnol. 2017, 8, 1328–1337, doi:10.3762/bjnano.8.134

• in an augmentation of the storage modulus (i.e., stiffness) over the entire temperature range. In addition, the loss modulus of the composites was also higher than that of the blank polymer (Figure 4b), namely the energy dissipation as heat was promoted. This may be due to an additional energy

• . Continuous lines are a guide to the eye. SEM images of the fractured surface of films made of MMA/BA/HEMA/MWCNT in situ hybrid latexes at different air-sonicated MWCNT loadings: (a) 0.1 wt % MWCNT; (b) 0.5 wt % MWCNT; (c,d) 1 wt % MWCNT under different magnifications. (a) Storage modulus and (b) loss modulus

Bio-inspired micro-to-nanoporous polymers with tunable stiffness

• Julia Syurik,
• Ruth Schwaiger,
• Prerna Sudera,
• Stephan Weyand,
• Siegbert Johnsen,
• Gabriele Wiegand and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2017, 8, 906–914, doi:10.3762/bjnano.8.92

• -specific characterisation routine yields the complex modulus E* = E' + iE'' as a function of the frequency for a specific indentation, with E' and E'' being the storage modulus and the loss modulus of the material, respectively. The ratio E''/E', also known as the loss factor tan δ = α, represents the

• the geometric mean. However, the overall relation between the values does not change with the statistical model. The values for storage modulus and loss modulus as well as the loss factor, determined from nanoindentation performed in the glassy regime, are shown in Figure 5. The storage modulus of

• neat PMMA measured with nanoindentation is comparable to the bulk elastic modulus provided by the manufacturer (2800 MPa and 3300 MPa, respectively) and with other published values [21][36][37]. Storage modulus and loss modulus clearly depend on the measurement location and they decrease for every

Generalized Hertz model for bimodal nanomechanical mapping

• Aleksander Labuda,
• Marta Kocuń,
• Waiman Meinhold,
• Deron Walters and
• Roger Proksch

Beilstein J. Nanotechnol. 2016, 7, 970–982, doi:10.3762/bjnano.7.89

• and loss moduli, as they cannot be distinguished from changes in indentation depth. In tapping mode, only the ratio of the storage to loss modulus can be measured [10][21][22]. The same limitation applies to many other parametric techniques, such as force modulation [6][7] and other single-frequency

Nanoscale effects in the characterization of viscoelastic materials with atomic force microscopy: coupling of a quasi-three-dimensional standard linear solid model with in-plane surface interactions

• Santiago D. Solares

Beilstein J. Nanotechnol. 2016, 7, 554–571, doi:10.3762/bjnano.7.49

• only in methods such as CR-AFM or FMOD-AFM [2][3][4][5][6][21]. Therefore, neither the use of the complex modulus nor of quantities derived from it (e.g., the loss tangent, which is the ratio of the loss modulus to the storage modulus) are appropriate for analysis of intermittent-contact AFM

• equal to the storage modulus (the loss modulus is zero, so the complex modulus is real), which according to Equation 17 is equal to k1 and is called the rubbery modulus [25]. At infinite frequency the loss modulus also becomes zero and the complex modulus is again real and reduces to the storage modulus

Active multi-point microrheology of cytoskeletal networks

• Tobias Paust,
• Tobias Neckernuss,
• Lina Katinka Mertens,
• Ines Martin,
• Michael Beil,
• Paul Walther,
• Thomas Schimmel and
• Othmar Marti

Beilstein J. Nanotechnol. 2016, 7, 484–491, doi:10.3762/bjnano.7.42

• as active microrheology [8][9][10]. Both the passive and the active method provide an insight into the storage and the loss modulus of the medium. An extension to the single particle active method is achieved by the measurement of two or more particles. It was observed that the movement of two

Mapping of elasticity and damping in an α + β titanium alloy through atomic force acoustic microscopy

• M. Kalyan Phani,
• Anish Kumar,
• T. Jayakumar,
• Walter Arnold and
• Konrad Samwer

Beilstein J. Nanotechnol. 2015, 6, 767–776, doi:10.3762/bjnano.6.79

• -resonance spectra are used to calculate the contact stiffness k* and the local contact damping E″/E′ by employing suitable models for the tip–specimen contact, and in turn enabling one to image and to measure the local elasticity or the storage modulus E′ and the damping or loss modulus E″ of the specimen

Modeling viscoelasticity through spring–dashpot models in intermittent-contact atomic force microscopy

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 2149–2163, doi:10.3762/bjnano.5.224

• related to a glass transition temperature Tg where the loss modulus (which is proportional to dissipation) peaks within that frequency range [27]. Figure 8b confirms the trend in the inset of Figure 8a. It can be seen that from 25 kHz to 75 kHz dissipation increases almost for all the setpoints (except

Controlling mechanical properties of bio-inspired hydrogels by modulating nano-scale, inter-polymeric junctions

• Seonki Hong,
• Hyukjin Lee and
• Haeshin Lee

Beilstein J. Nanotechnol. 2014, 5, 887–894, doi:10.3762/bjnano.5.101

• times each on both 6Arm-PEG-NH-catechol and 6Arm-PEG-catechol hydrogels, after allowing time for complete gelation (10 min). The elastic modulus, G’, and loss modulus, G”, were found to be independent over a wide range of frequencies and strains, demonstrating that the gelation was successfully

• kinetics In rheology, gelation point is defined by the intersection of the elastic modulus (G’) and the loss modulus (G”). We tried to measure the point by a rheometer, but it was found that gelation occurred within a minute in both hydrogels (6Arm-PEG-NH-catechol and 6Arm-PEG-catechol), preventing a

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• principles in nanoindentation, and compares and contrasts these two techniques as they are used for characterization of viscoelastic processes at the nanoscale. Keywords: atomic force microscopy; loss modulus; nanoindentation; storage modulus; viscoelasticity; Review Introduction Understanding and

• strain could be modulated. In this case, stress and strain will exhibit a phase difference designated as angle δ and the modulus can be now expressed as complex modulus E*: Here, E′ is the storage modulus, which measures the energy stored during one oscillation cycle, and E″ is the loss modulus, which

• individual segments and finally to internal rotations and vibrations of the component molecules. Polymers exhibit several phase transitions that can be correlated with the relaxation at characteristic frequencies [66]. The loss modulus will vary over a wide range of frequencies and show peaks at specific

Conducting composite materials from the biopolymer kappa-carrageenan and carbon nanotubes

• Ali Aldalbahi,
• Jin Chu,
• Peter Feng and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2012, 3, 415–427, doi:10.3762/bjnano.3.48

• measurements can be used to determine the sol–gel transition of polymer solutions. A larger loss modulus (G˝) than storage modulus (G΄) in the linear viscoelastic region is indicative of solution-like behaviour. Whereas, the reverse (G΄ > G˝) is indicative of gel-like behaviour [44]. The KC solutions with

• straight line in (c) indicates the rate of increase at the lower concentrations. (a–c) Storage (G΄, diamonds) and loss modulus (G˝, squares) of KC solutions at concentrations of 0.4%, 0.5%, and 0.6% w/v, respectively; (d and e) loss and storage modulus of KC versus solution concentration at 1.47% shear