Multiarm Star‐Crosslinked Hydrogel: Polymer Network with Thermoresponsive Free‐End Chains Densely Connected to Crosslinking Points. Issue 8 (26th November 2020)

• Record Type: Journal Article
• Authors: Ida, Shohei; Toda, Shogo; Oyama, Masatoshi; Takeshita, Hiroki; Kanaoka, Shokyoku
• Other Names: Besenius Pol guestEditor.; Schacher Felix H. guestEditor.; Terashima Takaya guestEditor.
• Is Part Of: Macromolecular rapid communications. Volume 42:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-26
• Subjects: hydrogels -- mechanical properties -- reversible addition–fragmentation chain transfer -- star polymers -- stimuli‐sensitive polymers; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202000558
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: 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. Abstract : In order to approach a sophisticated system of biological soft tissue, precise construction of a network with multi‐components is desired. In this work, a novel hydrogel having highly dense thermoresponsive free‐end chains around crosslinking structure is designed utilizing core‐crosslinked star polymers as crosslinking points. The obtained gel exhibits unique mechanical properties and thermoresponsive behavior.