Smart and Covalently Cross‐Linked: Hybrid Shape Memory Materials Reinforced through Covalent Bonds by Zirconium Oxoclusters. Issue 3 (13th January 2016)

• Record Type: Journal Article
• Authors: Gibin, Giacomo; Lorenzetti, Alessandra; Callone, Emanuela; Dirè, Sandra; Dolcet, Paolo; Venzo, Alfonso; Causin, Valerio; Marigo, Antonio; Modesti, Michele; Gross, Silvia
• Is Part Of: ChemPlusChem. Volume 81:Issue 3(2016)
• Page Start: 338
• Page End: 350
• Publication Date: 2016-01-13
• Subjects: organic–inorganic hybrid composites -- polymers -- shape memory properties -- structure–activity relationships -- zirconium; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.201500339
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: The first examples of organic–inorganic hybrid materials reinforced by transition‐metal oxoclusters that exhibit shape memory properties, based on the covalent incorporation of zirconium‐based inorganic building blocks, are reported. Methacrylate‐functionalized zirconium oxoclusters Zr4 O2 (OMc)12 and [Zr6 O4 (OH)4 (OOCCH2 CH3 )3 {OOCC(CH3 )=CH2 }9 ]2, with the covalent incorporation in a butyl acrylate (BA)/polycaprolactone dimethacrylate (PCLDMA) copolymer and the noncovalent incorporation of [Zr6 O4 (OH)4 (OOCCH2 CH3 )12 ]2 are focused upon herein. Shape recovery and fixity rates are studied to observe if the shape memory properties are preserved upon going from a simple copolymer to noncovalent or covalent‐based hybrids. These rates display values higher than 90 %, which provides evidence that the oxocluster does not hinder the shape memory properties in the hybrid materials. The introduction of an inorganic phase and the progressively more stable interactions between organic and inorganic parts lead to an enhancement of the thermomechanical properties. The materials are characterized through FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and swelling tests. Dynamic–mechanical analyses are used to investigate whether the hybrid materials display thermally activated shape memory properties. The stability of the hybrid materials are evaluated by a combined spectroscopic approach based on FTIR, solid‐state NMR, and X‐ray absorption spectroscopy. Abstract : Snapping back : The first example of smart hybrid shape memory materials reinforced by zirconium oxoclusters through covalent bonds is described. The observed increase in the shape recovery rate represents a proof of concept that the adopted strategy could be implemented for the preparation of shape memory hybrid materials based on covalent bonds (see figure; BA=butyl acrylate, PCLDMA=polycaprolactone dimethacrylate).