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Polymers
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Rheology of Bio-Based Polymeric Materials
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Rheology of Bio-Based Polymeric Materials

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 14346

Special Issue Editors

Dr. Sharadwata Pan

E-Mail Website
Guest Editor
TUM School of Life Sciences, Technical University of Munich, Freising, Germany
Interests: materials characterization; rheology; DNA dynamics; complex soft materials; biomaterials; cosmetics; nanotechnology
Dr. Thomas Goudoulas

E-Mail Website
Guest Editor
TUM School of Life Sciences, Technical University of Munich, Freising, Germany
Interests: rheology; nonlinear rheology; Rheo-Particle Image Velocimetry (Rheo-PIV); biopolymers; crosslinking; polysaccharides; bioprocesses; lab-scale prototypes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

A deep, vertical knowledge of the physical interpretations of a wide range of everyday biological processes and phenomena is critical, mainly within the purview of understanding their underlying action mechanisms. In investigating systems such as biologically derived polymeric materials, this is achieved by elucidating their mechanical properties. These properties grossly influence their processability under varying physical operating conditions, as well as their target applications. In this context, rheology stands at the forefront of the vastly efficient physical characterization procedures due to its extraordinary ability to interpret stress tolerance abilities and stress–strain relations. Moreover, it can be used to reveal the entire mechanical spectrum of biopolymers, ranging from negligible, small-scale linear responses at low-stress levels to extraordinarily large-scale nonlinear responses, including yielding, under very high deformation stresses. A sufficient comprehension of the mechanical response lies in an effective explanation and association of the macroscopic, bulk rheological properties with their microstructural characteristics.

The current Special Issue of Polymers is dedicated to the “Rheology of Bio-based Polymeric Materials”. We aim to bring together the contemporary rheological work, documenting state-of-the-art advancements in rheological characterizations of a wide array of polymeric biological systems, focusing particularly on how the microstructure influences the rheological response. Contributions with primarily experimental work are welcome, focusing on three principal deformation characterization modes: oscillatory/steady shear, elongational, and interfacial.

Dr. Sharadwata Pan
Dr. Thomas Goudoulas
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Shear rheology
  • extensional rheology
  • interfacial rheology
  • biopolymers
  • biomaterials
  • sol-gel rheology
  • mechanical stress response
  • linear viscoelasticity
  • nonlinear viscoelasticity
  • microstructural interpretation

Published Papers (5 papers)

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Research

13 pages, 3277 KiB  
Article
Comparative Large Amplitude Oscillatory Shear (LAOS) Study of Ionically and Physically Crosslinked Hydrogels
by Thomas B. Goudoulas, Anna Didonaki, Sharadwata Pan, Ehsan Fattahi and Thomas Becker
Polymers 2023, 15(6), 1558; https://0-doi-org.brum.beds.ac.uk/10.3390/polym15061558 - 21 Mar 2023
Cited by 4 | Viewed by 2423
Abstract
Hydrogels are highly versatile and widely applicable materials within various scientific, technological, and food sectors. Alginate and gelatin hydrogels, along with their crafted variations, are possibly the most common ones. However, the ionic crosslinking of alginate-Ca++ is a different gelation mechanism than [...] Read more.
Hydrogels are highly versatile and widely applicable materials within various scientific, technological, and food sectors. Alginate and gelatin hydrogels, along with their crafted variations, are possibly the most common ones. However, the ionic crosslinking of alginate-Ca++ is a different gelation mechanism than the physical crosslinking of gelatin. In this work, we prepare alginate-Ca++ hydrogels using individual layer gelation and experimentally evaluate LAOS rheological behavior. We apply shear-stress decomposition using the MITlaos software and obtain the elastic and viscous contributions within the nonlinear response of the individual alginate-Ca++ layer. We compare these results with the nonlinear responses of the gelatin-alginate ex situ individual layer. The strain-sweep patterns are similar, with loss modulus overshoot. The applied shear can destroy the larger-scale structural units (agglomerate/aggregates), resulting in analogous patterns. However, the critical strain points are different. Based on the shear-thickening ratio T of the LAOS analysis, it can be assumed that the common feature of ex situ preparation, i.e., gelation as individual layers, provides a matching bulk microstructure, as the hydrogels differ significantly at a molecular-binding level. Full article
(This article belongs to the Special Issue Rheology of Bio-Based Polymeric Materials)
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15 pages, 1421 KiB  
Article
Probing the Stoichiometry Dependence of Enzyme-Catalyzed Junction Zone Network Formation in Aiyu Pectin Gel via a Reaction Kinetics Model
by Fan-Wei Wang, Yun-Ju Chen, Jung-Ren Huang and Yeng-Long Chen
Polymers 2022, 14(21), 4631; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14214631 - 31 Oct 2022
Viewed by 1084
Abstract
We investigate the enzymatic self-catalyzed gelation process in aiyu gel, a natural ion crosslinked polysaccharide gel. The gelation process depends on the concentration ratio (Rmax) of the crosslinking calcium ions and all galacturonic acid binding sites. The physical gel network [...] Read more.
We investigate the enzymatic self-catalyzed gelation process in aiyu gel, a natural ion crosslinked polysaccharide gel. The gelation process depends on the concentration ratio (Rmax) of the crosslinking calcium ions and all galacturonic acid binding sites. The physical gel network formation relies on the assembly of calcium-polysaccharide crosslink bonds. The crosslinks are initially transient and through break-up/rebinding gradually re-organizing into long, stable junction zones. Our previous study formulated a reaction kinetics model to describe enzymatic activation, crosslinker binding, and crosslink microstructural reorganization, in order to model the complex growth of elasticity. In this study, we extend the theory for the time-dependent profile of complex moduli and examine the interplay of enzyme conversion, crosslink formation, and crosslink re-organization. The adjusted model captures how the gelation and structural rearrangement characteristic times vary with the polymer and calcium concentrations. Furthermore, we find that calcium ions act as both crosslinkers and dopants in the excess calcium ion scenario and the binding dynamics is determined by Rmax. This study provides perspectives on the dynamic binding behaviors of aiyu pectin gel system and the theoretical approach can be generalized to enzyme-catalyzed ionic gel systems. Full article
(This article belongs to the Special Issue Rheology of Bio-Based Polymeric Materials)
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13 pages, 3971 KiB  
Article
Flow Behaviors of Polymer Solution in a Lid-Driven Cavity
by Cuong Mai Bui, Anh-Ngoc Tran Ho and Xuan Bao Nguyen
Polymers 2022, 14(12), 2330; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14122330 - 09 Jun 2022
Cited by 2 | Viewed by 1825
Abstract
In this work, a numerical study of polymer flow behaviors in a lid-driven cavity, which is inspired by the coating process, at a broad range of Oldroyd numbers (0≤Od≤50), is carried out. The Reynolds number is height-based [...] Read more.
In this work, a numerical study of polymer flow behaviors in a lid-driven cavity, which is inspired by the coating process, at a broad range of Oldroyd numbers (0≤Od≤50), is carried out. The Reynolds number is height-based and kept at Re=0.001. The fluid investigated is of Carbopol gel possessing yield stress and shear-thinning properties. To express rheological characteristics, the Herschel–Bulkley model cooperated with Papanastasiou’s regularization scheme is utilized. Results show that the polymer flow characteristics, i.e., velocity, viscosity, and vortex distributions, are considerably influenced by viscoplastic behaviors. Additionally, there exist solid-like regions which can be of either moving rigid or static dead types in the flow patterns; they become greater and tend to merge together to construct larger ones when Od increases. Furthermore, various polymer flow aspects in different cavity configurations are discussed and analyzed; the cavity width/aspect ratio and skewed angle are found to have significant impacts on the vortex structures and the formation of solid-like regions. Moreover, results for the critical aspect ratio at which the static dead zone is broken into two parts and the characteristic height of this zone are also reported in detail. Full article
(This article belongs to the Special Issue Rheology of Bio-Based Polymeric Materials)
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Graphical abstract

18 pages, 3707 KiB  
Article
Polyurea Thickened Lubricating Grease—The Effect of Degree of Polymerization on Rheological and Tribological Properties
by Max Jopen, Patrick Degen, Stephan Henzler, Bastian Grabe, Wolf Hiller and Ralf Weberskirch
Polymers 2022, 14(4), 795; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14040795 - 18 Feb 2022
Cited by 7 | Viewed by 3143
Abstract
Lubricating greases based on urea thickeners are frequently used in high-performance applications since their invention in 1954. One property that has so far been neglected in the further development of these systems due to their low solubility and the resulting difficulty of analysis, [...] Read more.
Lubricating greases based on urea thickeners are frequently used in high-performance applications since their invention in 1954. One property that has so far been neglected in the further development of these systems due to their low solubility and the resulting difficulty of analysis, is to better understand how the degree of polymerization affect such polyurea lubricating systems. In this work, we prepared three different oligo- or polyurea systemswith different degrees of polymerization (DP) and investigated the influence of DP on rheological and tribological properties. The results showed that the DP has an influence on the flow limit in rheology as well as on the extreme pressure (EP) and anti-wear (AW) properties as examined by tribology measurements. By optimizing the DP for a thickener system, comparable EP and AW properties can be achieved through the use of additives. The DP showed an increasing influence on the flow limit. This could reduce damage to rolling bearings due to lateral loading at rest. Therefore, modifying the DP of the polyurea systems shows similar effects as the addition of external additives. Overall, this would reduce the use of additives in industrial applications. Full article
(This article belongs to the Special Issue Rheology of Bio-Based Polymeric Materials)
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15 pages, 2080 KiB  
Article
Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin
by Kai-Hung Yang, Gabriella Lindberg, Bram Soliman, Khoon Lim, Tim Woodfield and Roger J. Narayan
Polymers 2021, 13(11), 1877; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13111877 - 05 Jun 2021
Cited by 21 | Viewed by 4244
Abstract
Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling [...] Read more.
Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern. Full article
(This article belongs to the Special Issue Rheology of Bio-Based Polymeric Materials)
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