Macromol, Volume 1, Issue 1 (March 2021) – 5 articles

In this work, polymer nanocomposite films based on poly(L-lactic acid) (PLLA) were reinforced with mesoporous silica nanoparticles, mesoporous cellular foam (MCF) and Santa Barbara amorphous-15 (SBA). PLLA is a biobased aliphatic polyester, that possesses excellent thermomechanical properties, and has already been commercialized for packaging applications. The aim was to utilize nanoparticles that have already been established as nanocarriers to enhance the mechanical and thermal properties of PLLA. Since the introduction of antibacterial properties has become an emerging trend in packaging applications, to achieve an effective antimicrobial activity, micro/nano 3D micropillars decorated with cone- and needle-shaped nanostructures were implemented on the surface of the films by means of thermal nanoimprint lithography (t-NIL), a novel and feasible fabrication technique with multiple industrial applications. The materials were characterized regarding their composition and crystallinity using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively, and their thermal properties using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Their mechanical properties were examined by the nanoindentation technique, while the films’ antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus strains was tested in vitro. The results demonstrated the successful production of nanocomposite PLLA films, which exhibited improved mechanical and thermal properties compared to the pristine material, as well as notable antibacterial activity, setting new groundwork for the potential development of biobased smart packaging materials. Full article

Crosslinking of polyethylene oxide (PEO) using a peroxide in the melt is employed to synthesize soft hydrogels with the ability of controlled release of proteins. The viscoelastic properties of the swollen networks confirm the elastic nature of the synthesized material and they are in agreement with swelling characteristics. The hydrogels have mesh sizes at the nm scale as it is estimated by swelling measurements and measured by small angle neutron scattering (SANS). Diffusion of bovine serum albumin (BSA) and lysozyme (LYZ) out of the hydrogels is restricted by the presence of the network. The diffusion coefficient in the hydrogels is lower for BSA in comparison to LYZ, while in both cases it drops as the mesh size of the network becomes smaller. This study introduces the use of peroxide-crosslinked PEO networks in the investigation of protein transport within hydrogels, the development of hydrogel-based protein delivery patches and polymeric constructs. Full article

Self-healing coatings or materials have received significant importance in paint, coating, and other industries, as well as in academia, because of their capability to extend materials service life, improving protection, and ensuring sustainability. This review article emphasizes significant advances accomplished in the preparation and properties of intrinsic self-healing materials exclusively based on hydrogen bonding interactions, with possible applications in coatings and adhesives. The main topic of discussion in this review article is the preparation, healing conditions, healing efficiency, and mechanical property recovery after healing. The last part of the review discusses the conclusions and outlook of self-healing materials. Full article

A diverse range of linear polysiloxane-based ionic polymers that are hydrophobic and highly flexible can be obtained by substituting the polymers with varying amounts of ionic centers. The materials can be highly crystalline solids, amorphous soft solids, poly(ionic) liquids or viscous polymer liquids. A key to understanding how structural variations can lead to these different materials is the establishment of correlations between the physical (dynamic and static) properties and the structures of the polymers at different distance scales. This short review provides such correlations by examining the influence of structural properties (such as molecular weights, ion pair contents, and ion types) on key bulk properties of the materials. Full article