Physically crosslinked polyacrylates by quadruple hydrogen bonding side chains.

Dynamic polymer materials can be obtained by introducing supramolecular interactions between the polymer chains. Here we report on the preparation and mechanical properties of poly(methyl acrylate) (PMA) and poly(-butyl acrylate) (PBA) funcionalized with ureidopyrimidinone (UPy) in the side chains. In contrast to the traditional UPy with a methyl group, the selected UPy motif contained a branched alkyl side chain, which enhances solubility, compatibility with the polymer matrix and potentially prevents stacking of UPy dimers.

Degradable Cell-Adhesive Hybrid Hydrogels by Cross-Linking of Gelatin with Poly(2-isopropenyl-2-oxazoline).

This study focused on the cross-linking of poly(2-isopropenyl-2-oxazoline) (PiPOx) with gelatin to obtain strong, degradable hybrid hydrogels with good cell adhesion. The molecular weight and concentration of PiPOx and the PiPOx-to-gelatin ratio were varied to adjust the mechanical and swelling properties of the hybrid hydrogels. The swelling degree of PiPOx-gelatin hydrogels in water ranged between 1260 and 810%, with the corresponding Young's compressive moduli ranging from 77 to 215 kPa.

Engineering of an electrically charged hydrogel implanted into a traumatic brain injury model for stepwise neuronal tissue reconstruction.

Neural regeneration is extremely difficult to achieve. In traumatic brain injuries, the loss of brain parenchyma volume hinders neural regeneration. In this study, neuronal tissue engineering was performed by using electrically charged hydrogels composed of cationic and anionic monomers in a 1:1 ratio (C1A1 hydrogel), which served as an effective scaffold for the attachment of neural stem cells (NSCs).

Poly(-allyl acrylamide) as a Reactive Platform toward Functional Hydrogels.

The synthesis of poly(-allyl acrylamide) (PNAllAm) as a platform for the preparation of functional hydrogels is described. The PNAllAm was synthesized via organocatalyzed amidation of poly(methyl acrylate) (PMA) with allylamine and characterized by H NMR spectroscopy, size exclusion chromatography (SEC), and turbidimetry, which allowed an estimation of the lower critical solution temperature of ∼26 °C in water. The PNAllAm was then used to make functional hydrogels via photoinitiated thiol-ene chemistry, where dithiothreitol (DTT) was used to cross-link the polymer chains.

Nanoscale TEM Imaging of Hydrogel Network Architecture.

In this work, the authors succeed in direct visualization of the network structure of synthetic hydrogels with transmission electron microscopy (TEM) by developing a novel staining and network fixation method. Such a direct visualization is not carried out because sample preparation and obtaining sufficient contrast are challenging for these soft materials. TEM images reveal robust heterogeneous network architectures at mesh size scale and defects at micro-scale.