Hydrogel formation by photocrosslinking of dimethylmaleimide functionalized polyacrylamide

Seiffert, Sebastian; Oppermann, Wilhelm; Saalwächter, Kay

doi:10.1016/j.polymer.2007.07.013

Cited by 65 publications

(107 citation statements)

References 76 publications

(40 reference statements)

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“…The related dipolar coupling constant, D res , is a microscopic observable that reflects the local crosslinking density; it can also serve to assess the crosslink density heterogeneity by its distribution. 40,53,54 In our previous publication, 41 the inhomogeneity of a larger set of microgel samples was related to the relative width of this distribution, w C , which exhibits a higher value for the microgel sample prepared by free-radical copolymerization at elevated temperature (T prep 5 28 8C, w C 5 1.09) compared to the samples prepared at T prep 5 10 8C (w C 5 0.68) and T prep 5 20 8C (w C 5 0.57), as compiled in Table 1(a). The microgel batch synthesized by polymeranalogous photogelation exhibits a distribution width comparable to the latter sample (w C 5 0.57), as listed in Table 1(b).…”

Section: Resultsmentioning

confidence: 99%

Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

Habicht

Schmolke

Goerigk

et al. 2015

J Polym Sci B Polym Phys

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Thermoresponsive polymer gels exhibit pronounced swelling and deswelling upon changes in temperature, accompanied by dynamic concentration fluctuations that have been interpreted as critical opalescence. These fluctuations span lengthscales similar to that of static structures in the gels, such as the gel polymer-network meshsize (1-10 nm) and static polymer-network crosslinking inhomogeneities (10-1000 nm). To systematically investigate this overlay, we use droplet-based microfluidics and fabricate submillimeter-sized gel particles with varying static heterogeneity, as revealed on a molecular scale by proton NMR. When these microgels are probed by small-angle neutron scattering, the detection of dynamic fluctuations during the volume phase transitions is strongly perturbed by the co-existing static inhomogeneity. Depending of the type of data analysis employed, the temperature-dependent evolution of the correlation length associated to the dynamic fluctuations does or does not agree with predictions by the critical scaling theory. Only the most homogeneous sample of this study, prepared by controlled polymer crosslinking in droplet microfluidics, shows a diverging correlation length in agreement to the critical scaling theory independent of the specific approach of data analysis. These findings suggest that care must be taken about polymernetwork heterogeneity when gel volume phase transitions are evaluated as critical phenomena.

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Section: Resultsmentioning

confidence: 99%

Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

Habicht

Schmolke

Goerigk

et al. 2015

J Polym Sci B Polym Phys

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“…G 0 ) G 00 which shows the elastic component dominates over the viscous component and indicates that a true gel forms. The evolution of G 0 has previously been correlated with reaction progression in photopolymerised hydrogels 42 and rheometry alone is often used to monitor gelation kinetics. 41 Martens et al 43 demonstrated using near infrared spectroscopy (NIR) that PVA-acrylate photopolymerised hydrogels react to near 100% conversion, and the gelation kinetics observed with NIR correlate well with the results from rheometry for the current study.…”

Section: -8mentioning

confidence: 99%

Poly(vinyl alcohol)-heparin biosynthetic microspheres produced by microfluidics and ultraviolet photopolymerisation

et al. 2013

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Biosynthetic microspheres have the potential to address some of the limitations in cell microencapsulation; however, the generation of biosynthetic hydrogel microspheres has not been investigated or applied to cell encapsulation. Droplet microfluidics has the potential to produce more uniform microspheres under conditions compatible with cell encapsulation. Therefore, the aim of this study was to understand the effect of process parameters on biosynthetic microsphere formation, size, and morphology with a co-flow microfluidic method. Poly(vinyl alcohol) (PVA), a synthetic hydrogel and heparin, a glycosaminoglycan were chosen as the hydrogels for this study. A capillary-based microfluidic droplet generation device was used, and by varying the flow rates of both the polymer and oil phases, the viscosity of the continuous oil phase, and the interfacial surface tension, monodisperse spheres were produced from $200 to 800 lm. The size and morphology were unaffected by the addition of heparin. The modulus of spheres was 397 and 335 kPa for PVA and PVA/heparin, respectively, and this was not different from the bulk gel modulus (312 and 365 for PVA and PVA/heparin, respectively). Mammalian cells encapsulated in the spheres had over 90% viability after 24 h in both PVA and PVA/heparin microspheres. After 28 days, viability was still over 90% for PVA-heparin spheres and was significantly higher than in PVA only spheres. The use of biosynthetic hydrogels with microfluidic and UV polymerisation methods offers an improved approach to long-term cell encapsulation. V C 2013 AIP Publishing LLC. [http://dx

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“…For the softer A8-B.10 gel at an exposure time of 300 s, the highest modulus was achieved at the lowest 15 mW/cm 2 UV light intensity; there was a 37% drop in modulus between gels made at 15 mW/cm 2 versus 131 mW/cm 2 intensity. An increase in photopolymerized hydrogel modulus with increased light intensity was an anticipated result and can be explained by an improved crosslinking reaction and a greater number of functional crosslinks formed [20]. The second trend, which showed no further increase in modulus above a certain threshold UV light intensity, is not as well documented.…”

Section: Effect Of Uv Intensitymentioning

confidence: 96%

UV Dose Governs UV-Polymerized Polyacrylamide Hydrogel Modulus

Sheth

Jain

Karadaghy

et al. 2017

International Journal of Polymer Science

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Polyacrylamide (PAA) hydrogels have become a widely used tool whose easily tunable mechanical properties, biocompatibility, thermostability, and chemical inertness make them invaluable in many biological applications, such as cell mechanosensitivity studies. Currently, preparation of PAA gels involves mixtures of acrylamide, bisacrylamide, a source of free radicals, and a chemical stabilizer. This method, while generally well accepted, has its drawbacks: long polymerization times, unstable and toxic reagents, and tedious preparation. Alternatively, PAA gels could be made by free radical polymerization (FRP) using ultraviolet (UV) photopolymerization, a method which is quicker, less tedious, and less toxic. Here, we describe a simple strategy based on total UV energy for determining the optimal UV crosslinking conditions that lead to optimal hydrogel modulus.

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Hydrogel formation by photocrosslinking of dimethylmaleimide functionalized polyacrylamide

Cited by 65 publications

References 76 publications

Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

Poly(vinyl alcohol)-heparin biosynthetic microspheres produced by microfluidics and ultraviolet photopolymerisation

UV Dose Governs UV-Polymerized Polyacrylamide Hydrogel Modulus

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