Thermomechanical properties and shape-memory behavior of bisphenol a diacrylate-based shape-memory polymers

A series of acrylate-based shape-memory materials are synthesized from bisphenol A diacrylate monomers as crosslinking agents. Networks are synthesized by keeping constant the content of bisphenol A-based crosslinking agent and systematically varying the content ratio of different monofunctional chain builder monomers. The implications of the structure of bisphenol A-based monomers and the chemical structure and content of monofunctional monomers on thermomechanical properties are discussed. Thermomechanical properties are analyzed using dynamic mechanical analyses and mechanical properties are studied at room temperature and at the onset of the glass transition temperature. Shape-memory performances under isothermal and transient temperature conditions are also carried out. Tensile tests show excellent values of stress at break up to 45 and 15 MPa at room and high temperature, respectively. The measurements show excellent shape recovery and shape fixity ratios, ˜95% and 97%, respectively. These materials also show very high recovery velocities under transient temperature conditions, up to 24% min-1, and very short recovery times, up to 1.5 s, under isothermal conditions in a water bath. The results confirm that networks synthesized from bisphenol A crosslinkers are promising shape-memory materials.Postprint (author's final draft

PEG−peptide conjugates

The remarkable diversity of the self-assembly behavior of PEG−peptides is reviewed, including self-assemblies formed by PEG−peptides with β-sheet and α-helical (coiled-coil) peptide sequences. The modes of self-assembly in solution and in the solid state are discussed. Additionally, applications in bionanotechnology and synthetic materials science are summarized

Supramolecular Gelatin Networks Based on Inclusion Complexes

Hydrogel forming physical networks based on gelatin are an attractive approach toward multifunctional biomaterials with the option of reshaping, self-healing, and stimuli-sensitivity. However, it is challenging to design such gelatin-based hydrogels to be stable at body temperature. Here, gelatin functionalized with desaminotyrosine (DAT) or desaminotyrosyl tyrosine (DATT) side chains is crosslinked with cyclodextrin (CD) dimers under formation of inclusions complexes. The supramolecular networks displayed at room temperature decreased water uptake (200–600 wt% for DAT-based systems, 200 wt% for DATT based systems), and increased storage moduli up to 25.6 kPa determined by rheology compared to DAT(T) gelatin. The gel–sol transition temperature increased from 33 up to 42 °C. The presented system that is completely based on natural building blocks may form the basis for materials that may potentially respond by dissolution or changes of properties to changes in environmental conditions or to the presence of CD guest molecules