Double‐networks based on interconnected amphiphilic “in–out” star first polymer conetworks prepared by RAFT polymerization

Kitiri, Elina N.; Varnava, Constantina K.; Patrickios, Costas S.; Voutouri, Chrysovalantis; Stylianopoulos, Triantafyllos; Gradzielski, Michael; Hoffmann, Ingo

doi:10.1002/pola.29176

Cited by 17 publications

(11 citation statements)

References 36 publications

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“…The multiple network hydrogels of this study were prepared via successive aqueous photopolymerizations of monomer and cross-linker within the previous network hydrogel having the immediately lower multiplicity, as is schematically illustrated in Figure . Unlike many previous studies on double-network hydrogels, − the present system comprised only nonionic components, thereby avoiding any possibly undesired effects arising from electrostatic interactions. Thus, DMAAm and MBAAm were used as the hydrophilic nonionic monomer and cross-linker, respectively, whereas OXG served as the photoinitiator.…”

Section: Results and Discussionmentioning

confidence: 99%

Complex Hydrogels Based on Multiply Interpenetrated Polymer Networks: Enhancement of Mechanical Properties via Network Multiplicity and Monomer Concentration

Panteli

Patrickios

2018

Macromolecules

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We present the preparation and study of the compressive mechanical and swelling properties of multiply interpenetrated, from double to quintuple (5-fold), polymeric hydrogels based on N,N-dimethylacrylamide (DMAAm) crosslinked with N,N′-methylenebis(acrylamide) (MBAAm), using five different monomer concentrations, from 1 to 5 M. Our results showed enhancement of the fracture stress, fracture energy density, and Young's modulus with network multiplicity and DMAAm monomer concentration. Fracture strain was found to substantially improve only when increasing the monomer concentration from 1 to 3 M and network multiplicity from 1 to 2. The best-performing multiple polymer hydrogel was the quintuple network prepared at 5 M DMAAm concentrations, which exhibited a record fracture stress of 51 MPa, a fracture strain of 88%, a fracture energy density of 5.5 MJ m −3 , and a Young's modulus of 2.1 MPa. Normalized values of the fracture stress and fracture energy density calculated by multiplication of the corresponding original values by the aqueous swelling degrees also increased with network multiplicity and monomer concentration, suggesting a net gain in mechanical property enhancement, primarily originating from network multiplicity. Combined analysis of the swelling and Young's modulus measurements on the multiply interpenetrated polymeric hydrogels allowed the calculation of the concentration of the elastically ef fective polymer chains in the bulk, which was independent of monomer concentration but increased linearly with network multiplicity, suggesting a corresponding increase in the concentration of trapped entanglements and/or strain hardening.

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Section: Results and Discussionmentioning

confidence: 99%

Complex Hydrogels Based on Multiply Interpenetrated Polymer Networks: Enhancement of Mechanical Properties via Network Multiplicity and Monomer Concentration

Panteli

Patrickios

2018

Macromolecules

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“…Despite its elegance, the above‐described DN recipe requires the presence of a first polyelectrolyte network hydrogel, accompanied by the introduction of ionic charges in the system. However, these electrical charges in the polymers may be undesired for certain applications involving, for example, biomacromolecules, such as proteins, DNA, RNA, or polysaccharides, which are usually also charged and may interact electrostatically with the DN hydrogel.…”

Section: Introductionmentioning

confidence: 99%

Multiple Network Hydrogels: A Study of Their Nanoindentation Hardness

Panteli¹,

Patrickios²,

Constantinou³

et al. 2019

Macromolecular Symposia

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Nanoindentation is employed to investigate at the nanoscale the mechanical properties of multiply‐interpenetrated N,N‐dimethylacrylamide hydrogels cross‐linked using N,N′‐methylenebis(acrylamide). The main result from these measurements is the determination of the hardness of the materials, that is, their resistance to penetration by the nanoindenter, which increases with network multiplicity, arising from the increase in network compactness with multiplicity. In addition to hardness, the nanoindentation elastic modulus and the percentage of recoverable energy are also determined, and both are found to increase with network multiplicity as well. A general conclusion from this study is that nanoindentation is a facile and fast method for the characterization of a number of mechanical properties of hydrogels, with the important advantage of small amount of sample required for the measurements.

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“…[19] Thus, star polymers are useful building blocks for functionalization of hydrogels. For gel synthesis, star polymers are often used for a reaction involved in end-linking of arm chains, [20][21][22][23][24][25][26][27][28] being incorporated into the network. By contrast, connecting star polymers by utilizing the vinyl groups in the cores allows a gel design consisting of numerous free-end chains around crosslinking points.…”

Section: Doi: 101002/marc202000558mentioning

confidence: 99%

Multiarm Star‐Crosslinked Hydrogel: Polymer Network with Thermoresponsive Free‐End Chains Densely Connected to Crosslinking Points

Ida

Toda

Oyama³

et al. 2020

Macromol. Rapid Commun.

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Soft tissue in biological system is a hydrogel with elaborate structure exhibiting repeatable dynamic function. In order to approach such sophisticated system, precise construction of a designed network with multi‐components is desired. This communication presents a novel hydrogel having highly dense stimuli‐responsive free‐end chains around crosslinking structure. A key molecule is a core‐crosslinked star‐shaped polymer with multiple thermoresponsive arms, which can be prepared by reversible addition–fragmentation chain transfer polymerization of divinyl crosslinker with poly(N‐isopropylacrylamide) (PNIPAAm) macro‐chain transfer agent and have a number of unreacted carbon–carbon double bonds in the core. These unreacted double bonds can be utilized as a crosslinker for poly(acrylamide) (PAAm) gel synthesis by free radical polymerization. The obtained gel contains homogeneously dispersed star PNIPAAms as crosslinking points and exhibits thermoresponsive swelling behavior in water depending on the star contents. In particular, the gel with low content of the star crosslinker shows localized responsive behavior with expansion and shrinkage of the star in one molecule. The mechanical properties of the star‐crosslinked gel are significantly high compared to the conventional PAAm gels particularly in compressive strength (≈9 MPa). Moreover, the star‐crosslinked gel has thermoresponsive mechanical toughening property.

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Double‐networks based on interconnected amphiphilic “in–out” star first polymer conetworks prepared by RAFT polymerization

Cited by 17 publications

References 36 publications

Complex Hydrogels Based on Multiply Interpenetrated Polymer Networks: Enhancement of Mechanical Properties via Network Multiplicity and Monomer Concentration

Complex Hydrogels Based on Multiply Interpenetrated Polymer Networks: Enhancement of Mechanical Properties via Network Multiplicity and Monomer Concentration

Multiple Network Hydrogels: A Study of Their Nanoindentation Hardness

Multiarm Star‐Crosslinked Hydrogel: Polymer Network with Thermoresponsive Free‐End Chains Densely Connected to Crosslinking Points

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