Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels

Zhang, Zhenfang; Li, Qian; Yesildag, Cigdem; Bartsch, Christoph; Zhang, Xiaoyuan; Liu, Wei; Loebus, Axel; Su, Zhiqiang; Lensen, Marga C.

doi:10.3390/polym10090970

Open AccessArticle

Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels

by

Zhenfang Zhang

^1,2,3,

Qian Li

^1,2,

Cigdem Yesildag

³,

Christoph Bartsch

³

,

Xiaoyuan Zhang

^1,2,

Wei Liu

^1,2,

Axel Loebus

³,

Zhiqiang Su

^1,2,* and

Marga C. Lensen

^3,*

¹

State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China

²

Beijing Key Laboratory of Advanced Functional Polymer Composites, Beijing University of Chemical Technology, Beijing 100029, China

³

Technische Universität Berlin, Institut für Chemie, Nanostrukturierte Biomaterialien, Sekr. TC 1, Straße des 17. Juni 124, 10623 Berlin, Germany

^*

Authors to whom correspondence should be addressed.

Polymers 2018, 10(9), 970; https://doi.org/10.3390/polym10090970

Submission received: 18 July 2018 / Revised: 17 August 2018 / Accepted: 21 August 2018 / Published: 1 September 2018

(This article belongs to the Special Issue Hydrophilic Polymers)

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Abstract

The network structure of hydrogels is a vital factor to determine their physical properties. Two network structures within hydrogels based on eight-arm star-shaped poly(ethylene glycol)(8PEG) have been obtained; the distinction between the two depends on the way in which the macromonomers were crosslinked: either by (i) commonly-used photo-initiated chain-growth polymerization (8PEG–UV), or (ii) Michael addition step-growth polymerization (8PEG–NH₃). The crystallization of hydrogels is facilitated by a solvent drying process to obtain a thin hydrogel film. Polarized optical microscopy (POM) results reveal that, while in the 8PEG–UV hydrogels only nano-scaled crystallites are apparent, the 8PEG–NH₃ hydrogels exhibit an assembly of giant crystalline domains with spherulite sizes ranging from 100 to 400 µm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses further confirm these results. A model has been proposed to elucidate the correlations between the polymer network structures and the crystallization behavior of PEG-based hydrogels.

Keywords: crystallization; PEG-based hydrogels; network structure; step-growth polymerization

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MDPI and ACS Style

Zhang, Z.; Li, Q.; Yesildag, C.; Bartsch, C.; Zhang, X.; Liu, W.; Loebus, A.; Su, Z.; Lensen, M.C. Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels. Polymers 2018, 10, 970. https://doi.org/10.3390/polym10090970

AMA Style

Zhang Z, Li Q, Yesildag C, Bartsch C, Zhang X, Liu W, Loebus A, Su Z, Lensen MC. Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels. Polymers. 2018; 10(9):970. https://doi.org/10.3390/polym10090970

Chicago/Turabian Style

Zhang, Zhenfang, Qian Li, Cigdem Yesildag, Christoph Bartsch, Xiaoyuan Zhang, Wei Liu, Axel Loebus, Zhiqiang Su, and Marga C. Lensen. 2018. "Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels" Polymers 10, no. 9: 970. https://doi.org/10.3390/polym10090970

APA Style

Zhang, Z., Li, Q., Yesildag, C., Bartsch, C., Zhang, X., Liu, W., Loebus, A., Su, Z., & Lensen, M. C. (2018). Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels. Polymers, 10(9), 970. https://doi.org/10.3390/polym10090970

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Influence of Network Structure on the Crystallization Behavior in Chemically Crosslinked Hydrogels

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