Adhesion Engineering in Polymer-Metal Comolded Joints with Biomimetic Polydopamine.

Joints that connect thermoplastic polymer matrices (TPMs) and metals, which are obtained by comolding, are of growing importance in numerous applications. The overall performance of these constructs is strongly impacted by the TPM-metal interfacial strength, which can be tuned by tailoring the surface chemistry of the metal prior to the comolding process. In the present work, a model TPM-metal system consisting of poly(methyl methacrylate) (PMMA) and titanium is used to prepare comolded joints.

Collapse from the top: brushes of poly(N-isopropylacrylamide) in co-nonsolvent mixtures.

Using a combination of ellipsometry and friction force microscopy, we study the reversible swelling, collapse and variation in friction properties of covalently bound poly(N-isopropylacrylamide) (PNIPAM) layers on silicon with different grafting densities in response to exposure to good solvents and co-nonsolvent mixtures. Changes in the thickness and segment density distribution of grafted films are investigated by in situ ellipsometry. Based on quantitative modelling of the ellipsometry spectra, we postulate a structural model, which assumes that collapse takes place in the contacting layer between the brush and the co-nonsolvent and the top-collapsed brushes remain hydrated in the film interior.

Molecular "chaperones" guide the spontaneous formation of a 15-component hydrogen-bonded assembly.

Chaperones are small molecules that assist in the folding of naturally occurring peptides. There are no examples of small molecules acting as chaperones in the self-assembly of synthetic noncovalent assemblies. In this communication we describe an unprecedented example of the "chaperone effect" in the noncovalent synthesis of organic nanostructures.