Numerous mechanically strong and tough soft materials comprising of polymer networks have been developed over the last two decades, motivated by new high-tech applications in engineering and bio-related fields. These materials are characterized by their dynamic complexities and large deformation behaviors. In this Review, we focus on how chain dynamics affects the large deformation and fracture behaviors of soft materials. To favor readers without a rheology background, first we review the linear rheology behaviors of several simple networks. We show that, by playing with the physical entanglement, chemical cross-linking, and physical association of the building polymers, a very rich panel of dynamic responses can be obtained. Then, we show examples of how chain dynamics affects the deformation and fracture behaviors of dually cross-linked hydrogels having chemical cross-linkers and physical bonds. We also provide examples on the unique deformation behavior of physical double-network gels made from triblock polymers. Thereafter, examples of the influence of chain dynamics on the crack initiation and growth behaviors are presented. We show that even for chemically cross-linked double-network hydrogels that exhibit elastic behaviors in a common deformation window, the chain dynamics influences the damage zone size at the crack tip. Finally, we conclude this Review by proposing several directions for future research.
{"title":"How double dynamics affects the large deformation and fracture behaviors of soft materials","authors":"Kunpeng Cui, J. Gong","doi":"10.1122/8.0000438","DOIUrl":"https://doi.org/10.1122/8.0000438","url":null,"abstract":"Numerous mechanically strong and tough soft materials comprising of polymer networks have been developed over the last two decades, motivated by new high-tech applications in engineering and bio-related fields. These materials are characterized by their dynamic complexities and large deformation behaviors. In this Review, we focus on how chain dynamics affects the large deformation and fracture behaviors of soft materials. To favor readers without a rheology background, first we review the linear rheology behaviors of several simple networks. We show that, by playing with the physical entanglement, chemical cross-linking, and physical association of the building polymers, a very rich panel of dynamic responses can be obtained. Then, we show examples of how chain dynamics affects the deformation and fracture behaviors of dually cross-linked hydrogels having chemical cross-linkers and physical bonds. We also provide examples on the unique deformation behavior of physical double-network gels made from triblock polymers. Thereafter, examples of the influence of chain dynamics on the crack initiation and growth behaviors are presented. We show that even for chemically cross-linked double-network hydrogels that exhibit elastic behaviors in a common deformation window, the chain dynamics influences the damage zone size at the crack tip. Finally, we conclude this Review by proposing several directions for future research.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44327206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Existing single-chain models for unentangled associating polymers account for the association by assigning the sticky junctions a large value of the monomeric friction coefficient, which prevents them from moving in space unless stickers effectively dissociate. With such an assumption, comparison of model predictions with linear viscoelastic data is not fully successful in the intermediate range of frequency. In this work, we improve agreement with data by developing a single-chain model where sticky junctions are allowed to quickly move in space without dissociating. We also account for a random distribution of the stickers but differently from the recent model by Jiang et al. [Macromolecules 53, 3438–3451 (2020)]. Predictions of the model are successfully compared with unentangled melt data for two different copolymer chemistries and different sticker concentrations. Particularly significant are the data by Cui et al. [J. Rheol., 62, 1155–1174 (2018)] of melts of polymers with only two stickers per chain, revealing that sticky junctions are in fact also endowed with fast mobility.
{"title":"A single-chain model for the linear viscoelasticity of unentangled melts of associating polymers","authors":"Hongwei Liu, G. Ianniruberto, G. Marrucci","doi":"10.1122/8.0000409","DOIUrl":"https://doi.org/10.1122/8.0000409","url":null,"abstract":"Existing single-chain models for unentangled associating polymers account for the association by assigning the sticky junctions a large value of the monomeric friction coefficient, which prevents them from moving in space unless stickers effectively dissociate. With such an assumption, comparison of model predictions with linear viscoelastic data is not fully successful in the intermediate range of frequency. In this work, we improve agreement with data by developing a single-chain model where sticky junctions are allowed to quickly move in space without dissociating. We also account for a random distribution of the stickers but differently from the recent model by Jiang et al. [Macromolecules 53, 3438–3451 (2020)]. Predictions of the model are successfully compared with unentangled melt data for two different copolymer chemistries and different sticker concentrations. Particularly significant are the data by Cui et al. [J. Rheol., 62, 1155–1174 (2018)] of melts of polymers with only two stickers per chain, revealing that sticky junctions are in fact also endowed with fast mobility.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45554504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Clément Coutouly, E. van Ruymbeke, L. Ramos, Philippe Dieudonné-George, C. Fustin
This work focuses on the temperature-dependent structural and rheological characterization of polystyrene- b-poly( n-butyl acrylate)- b-polystyrene triblock copolymers (PS- b-P nBA- b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature (LDOT). To this aim, copolymers of varying block lengths, but keeping the P nBA block as a major component, were synthesized. Small-angle x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature, these copolymers exhibit higher moduli compared to a P nBA homopolymer due to the reinforcing effect of the PS but are flowing at temperatures above the glass transition of the PS. Increasing the PS and P nBA block length, to keep the same PS fraction, induces more profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures.
{"title":"Coutouly et al.: Exploiting the lower disorder-to-order temperature in polystyrene-b-poly(n-butyl acrylate)-b-polystyrene triblock copolymers to increase their flow resistance at high temperature","authors":"Clément Coutouly, E. van Ruymbeke, L. Ramos, Philippe Dieudonné-George, C. Fustin","doi":"10.1122/8.0000565","DOIUrl":"https://doi.org/10.1122/8.0000565","url":null,"abstract":"This work focuses on the temperature-dependent structural and rheological characterization of polystyrene- b-poly( n-butyl acrylate)- b-polystyrene triblock copolymers (PS- b-P nBA- b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature (LDOT). To this aim, copolymers of varying block lengths, but keeping the P nBA block as a major component, were synthesized. Small-angle x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature, these copolymers exhibit higher moduli compared to a P nBA homopolymer due to the reinforcing effect of the PS but are flowing at temperatures above the glass transition of the PS. Increasing the PS and P nBA block length, to keep the same PS fraction, induces more profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47327853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Christina Pyromali, Yanzhao Li, Flanco Zhuge, C. Fustin, E. van Ruymbeke, D. Vlassopoulos
We present a systematic experimental study of the shear rheology of metallosupramolecular assemblies based on entangled telechelic star polymers comprising one (single dynamic network) or two (double dynamics network) types of physical bonds with the aim to unravel the role of concentration and strength of these bonds on the nonlinear response. Model dynamic networks functionalized with terpyridine ligands were formed by adding different metal ions with increasing bonding strength, zinc, copper, and cobalt. The dynamics are driven by entanglement/disentanglement processes and a ligand exchange mechanism. Steady-state viscosities of single and double dynamics networks collapse onto a universal curve over a wide range of Weissenberg numbers based on terminal time (up to about 300 for single and 1000 for double), exhibiting stronger shear thinning (with an exponent of −0.76) compared to entangled neutral star polymers. Double dynamics networks consisting of two different metal ions (with different lifetimes) exhibit stronger mechanical coherence (rate-dependent fractional viscosity overshoot) and accumulate larger strain at steady-state flow compared to single-ion counterparts. The shear stress growth function signals exhibit weak, albeit unambiguous shear strain hardening, which becomes more pronounced for stronger associations. They also exhibit double overshoot, which reflects the interplay of association strength and chain deformation. Increasing the strength of associations leads to the failure of the Cox–Merz rule, which is more severe for single dynamic networks. The markedly different behavior of double dynamics networks is attributed to the fact that at sufficiently high ion content, the weaker bond acts as a sacrificial component, which provides local energy dissipation and enhances the overall deformability. This bears analogies with their linear viscoelastic response, which has revealed that the arm disentanglement (delayed due to the reversible bonds) effectively interpolates between the two single dynamic network components, depending on composition. Our results suggest ways to tailor the mechanical properties of this class of materials by judicious choice of the type and content of the ion.
{"title":"Pyromali et al.: Nonlinear shear rheology of single and double dynamics metal-ligand networks","authors":"Christina Pyromali, Yanzhao Li, Flanco Zhuge, C. Fustin, E. van Ruymbeke, D. Vlassopoulos","doi":"10.1122/8.0000573","DOIUrl":"https://doi.org/10.1122/8.0000573","url":null,"abstract":"We present a systematic experimental study of the shear rheology of metallosupramolecular assemblies based on entangled telechelic star polymers comprising one (single dynamic network) or two (double dynamics network) types of physical bonds with the aim to unravel the role of concentration and strength of these bonds on the nonlinear response. Model dynamic networks functionalized with terpyridine ligands were formed by adding different metal ions with increasing bonding strength, zinc, copper, and cobalt. The dynamics are driven by entanglement/disentanglement processes and a ligand exchange mechanism. Steady-state viscosities of single and double dynamics networks collapse onto a universal curve over a wide range of Weissenberg numbers based on terminal time (up to about 300 for single and 1000 for double), exhibiting stronger shear thinning (with an exponent of −0.76) compared to entangled neutral star polymers. Double dynamics networks consisting of two different metal ions (with different lifetimes) exhibit stronger mechanical coherence (rate-dependent fractional viscosity overshoot) and accumulate larger strain at steady-state flow compared to single-ion counterparts. The shear stress growth function signals exhibit weak, albeit unambiguous shear strain hardening, which becomes more pronounced for stronger associations. They also exhibit double overshoot, which reflects the interplay of association strength and chain deformation. Increasing the strength of associations leads to the failure of the Cox–Merz rule, which is more severe for single dynamic networks. The markedly different behavior of double dynamics networks is attributed to the fact that at sufficiently high ion content, the weaker bond acts as a sacrificial component, which provides local energy dissipation and enhances the overall deformability. This bears analogies with their linear viscoelastic response, which has revealed that the arm disentanglement (delayed due to the reversible bonds) effectively interpolates between the two single dynamic network components, depending on composition. Our results suggest ways to tailor the mechanical properties of this class of materials by judicious choice of the type and content of the ion.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44993293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Parisi et al.: Rheological investigation on the associative properties of poly(vinyl alcohol) solutions","authors":"","doi":"10.1122/8.0000572","DOIUrl":"https://doi.org/10.1122/8.0000572","url":null,"abstract":"","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41915565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Preface: Special Issue on Double Dynamics Networks","authors":"E. van Ruymbeke, T. Narita","doi":"10.1122/8.0000582","DOIUrl":"https://doi.org/10.1122/8.0000582","url":null,"abstract":"","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43309824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The linear rheological properties of supramolecular polymer networks formed by mixtures of two different bis-Pd(II) cross-linkers with poly(4-vinylpyridine) in dimethyl sulfoxide are examined. The changes in storage and loss moduli of the networks with mixed cross-linkers are compared to those of samples with a single type of cross-linkers. While the plateau moduli, and presumably network topology, of the networks remain equal regardless of the cross-link distribution, the relaxation time contributed by the faster cross-linkers is increased (by a factor of about 1.5 for the specific samples used in this work) by the presence of the slower cross-linkers, while the reverse influences are not significant. This effect can be explained by the fact that a certain fraction of the elastically effective strands cross-linked with fast cross-linkers is pinned on one end by slow cross-linkers, reducing by half the rate of fast chain relaxation. This effect is anticipated to be general for gels with two well-separated relaxation times.
{"title":"Relaxation dynamics of supramolecular polymer networks with mixed cross-linkers","authors":"Donghua Xu, B. Olsen, S. Craig","doi":"10.1122/8.0000421","DOIUrl":"https://doi.org/10.1122/8.0000421","url":null,"abstract":"The linear rheological properties of supramolecular polymer networks formed by mixtures of two different bis-Pd(II) cross-linkers with poly(4-vinylpyridine) in dimethyl sulfoxide are examined. The changes in storage and loss moduli of the networks with mixed cross-linkers are compared to those of samples with a single type of cross-linkers. While the plateau moduli, and presumably network topology, of the networks remain equal regardless of the cross-link distribution, the relaxation time contributed by the faster cross-linkers is increased (by a factor of about 1.5 for the specific samples used in this work) by the presence of the slower cross-linkers, while the reverse influences are not significant. This effect can be explained by the fact that a certain fraction of the elastically effective strands cross-linked with fast cross-linkers is pinned on one end by slow cross-linkers, reducing by half the rate of fast chain relaxation. This effect is anticipated to be general for gels with two well-separated relaxation times.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45928394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rowanne Lyons, L. Hammer, Alexis André, C. Fustin, Renaud Nicolaÿ, E. van Ruymbeke
We investigate the viscoelastic properties of double dynamic networks (DDNs) based on side-functionalized P nBA chains. One of these networks is highly crosslinked by metal-ligand junctions characterized by a fast association/dissociation dynamics, while the other network is sparsely crosslinked with slow dynamic covalent networks (DCNs). We first show that modulating the dynamics of the metallosupramolecular networks, by playing with the temperature, the density of reversible junctions, or the stress applied, has direct consequences on the local equilibration of the DCN. The latter takes place by a constraint release Rouse process at the rhythm of the association/dissociation of the metal-ligand junctions. Then, based on creep-recovery experiments, we investigate the ability of the DDNs to recover their initial shape after a creep test and show again the important role played by the metallosupramolecular network. In particular, the sample recovery strongly depends on the network connectivity, which is enhanced if a denser metallosupramolecular network is used as it reduces the possible creep of the double dynamic network and increases its elastic memory. The sample recovery also depends on the association-dissociation dynamics of the metallosupramolecular bonds as it fixes how fast the stretched DCN can come back to its equilibrium conformation and can recover its initial shape after a large deformation has been applied. Adjusting the dynamics of the weak network is thus a key process to govern the viscoelastic response of the slow network.
{"title":"Equilibration dynamics of a dynamic covalent network diluted in a metallosupramolecular polymer matrix","authors":"Rowanne Lyons, L. Hammer, Alexis André, C. Fustin, Renaud Nicolaÿ, E. van Ruymbeke","doi":"10.1122/8.0000473","DOIUrl":"https://doi.org/10.1122/8.0000473","url":null,"abstract":"We investigate the viscoelastic properties of double dynamic networks (DDNs) based on side-functionalized P nBA chains. One of these networks is highly crosslinked by metal-ligand junctions characterized by a fast association/dissociation dynamics, while the other network is sparsely crosslinked with slow dynamic covalent networks (DCNs). We first show that modulating the dynamics of the metallosupramolecular networks, by playing with the temperature, the density of reversible junctions, or the stress applied, has direct consequences on the local equilibration of the DCN. The latter takes place by a constraint release Rouse process at the rhythm of the association/dissociation of the metal-ligand junctions. Then, based on creep-recovery experiments, we investigate the ability of the DDNs to recover their initial shape after a creep test and show again the important role played by the metallosupramolecular network. In particular, the sample recovery strongly depends on the network connectivity, which is enhanced if a denser metallosupramolecular network is used as it reduces the possible creep of the double dynamic network and increases its elastic memory. The sample recovery also depends on the association-dissociation dynamics of the metallosupramolecular bonds as it fixes how fast the stretched DCN can come back to its equilibrium conformation and can recover its initial shape after a large deformation has been applied. Adjusting the dynamics of the weak network is thus a key process to govern the viscoelastic response of the slow network.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41791719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Yavitt, T. Tomkovic, D. Gilmour, Z. Zhang, N. Kuanr, E. van Ruymbeke, L. Schafer, S. G. Hatzikiriakos
The rheological and self-healing behavior of a class of catalytically synthesized amine-functionalized polyolefins is investigated. We demonstrate that these materials possess tunable rheological properties according to the molecular weight and display autonomous self-healing. The linear viscoelastic properties are modeled using a tube-based model developed by Hawke et al. [J. Rheol., 60, 297–310, (2016)] to calculate several model parameters that describe the individual chain dynamics. The self-healing response is described by findings from the reptation model as well as recent theory on associating polymer networks with reversible bonds. The cooperation between experiments, modeling, and theory provide insight into designing new materials with programmable rheological properties and superior self-healing ability.
{"title":"Rheology and self-healing of amine functionalized polyolefins","authors":"B. Yavitt, T. Tomkovic, D. Gilmour, Z. Zhang, N. Kuanr, E. van Ruymbeke, L. Schafer, S. G. Hatzikiriakos","doi":"10.1122/8.0000364","DOIUrl":"https://doi.org/10.1122/8.0000364","url":null,"abstract":"The rheological and self-healing behavior of a class of catalytically synthesized amine-functionalized polyolefins is investigated. We demonstrate that these materials possess tunable rheological properties according to the molecular weight and display autonomous self-healing. The linear viscoelastic properties are modeled using a tube-based model developed by Hawke et al. [J. Rheol., 60, 297–310, (2016)] to calculate several model parameters that describe the individual chain dynamics. The self-healing response is described by findings from the reptation model as well as recent theory on associating polymer networks with reversible bonds. The cooperation between experiments, modeling, and theory provide insight into designing new materials with programmable rheological properties and superior self-healing ability.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42872932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogels are polymer networks swollen in water and, therefore, suitable for biomedical applications. For this purpose, hydrogels have to mimic the functionality and mechanics of natural tissues. In drug delivery, for example, the diffusion is crucial and can be controlled through targeted variation of the network mesh-size. In tissue engineering, on the other side, the mechanics plays a fundamental role and can be strengthened through the use of two interpenetrated polymer networks, realizing a double network, or with two dynamic motifs anchored in one common network, realizing a dual dynamic network (DDN). However, current knowledge encompasses mainly nonlinear rheological characterization of these networks. We intend to fill this gap and provide a systematic linear rheological study. To realize this strategy, we combine two supramolecular motifs in a common network, thereby realizing a comblike DDN with the ability to change the building blocks on demand. In our DDN, a tetra-poly(ethylene) glycol (pEG) (the first building block) is functionalized on each arm with two dynamic motifs: terpyridine capable of undergoing metal-complexation with different divalent metal ions, and a thermo-responsive unit consisting of poly( N-isopropylacrylamide) (pNIPAAm) (the second building block) that is capable of undergoing temperature-dependent nano-phase-separation. In particular, we change the molar mass of the tetra-pEG-terpyridine and the pNIPAAm grafted chains. In addition, we investigate two different metal ions that form complexes with the terpyridine. With this platform, we tune the elastic properties on demand, and we systematically study the structure–property relationships with oscillatory shear rheology in the linear regime.
{"title":"Mechanical switching of a comblike dual dynamic polymer network","authors":"P. Nicolella, S. Seiffert","doi":"10.1122/8.0000388","DOIUrl":"https://doi.org/10.1122/8.0000388","url":null,"abstract":"Hydrogels are polymer networks swollen in water and, therefore, suitable for biomedical applications. For this purpose, hydrogels have to mimic the functionality and mechanics of natural tissues. In drug delivery, for example, the diffusion is crucial and can be controlled through targeted variation of the network mesh-size. In tissue engineering, on the other side, the mechanics plays a fundamental role and can be strengthened through the use of two interpenetrated polymer networks, realizing a double network, or with two dynamic motifs anchored in one common network, realizing a dual dynamic network (DDN). However, current knowledge encompasses mainly nonlinear rheological characterization of these networks. We intend to fill this gap and provide a systematic linear rheological study. To realize this strategy, we combine two supramolecular motifs in a common network, thereby realizing a comblike DDN with the ability to change the building blocks on demand. In our DDN, a tetra-poly(ethylene) glycol (pEG) (the first building block) is functionalized on each arm with two dynamic motifs: terpyridine capable of undergoing metal-complexation with different divalent metal ions, and a thermo-responsive unit consisting of poly( N-isopropylacrylamide) (pNIPAAm) (the second building block) that is capable of undergoing temperature-dependent nano-phase-separation. In particular, we change the molar mass of the tetra-pEG-terpyridine and the pNIPAAm grafted chains. In addition, we investigate two different metal ions that form complexes with the terpyridine. With this platform, we tune the elastic properties on demand, and we systematically study the structure–property relationships with oscillatory shear rheology in the linear regime.","PeriodicalId":16991,"journal":{"name":"Journal of Rheology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41875813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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