Current strategies to limit macrophage adhesion, fusion and fibrous capsule formation in the foreign body response have focused on modulating material surface properties. We hypothesize that topography close to biological scale, in the micron and nanometric range, provides a passive approach without bioactive agents to modulate macrophage behavior. In our study, topography-induced changes in macrophage behavior was examined using parallel gratings (250 nm-2 μm line width) imprinted on poly(s-caprolactone) (PCL), poly(lactic acid) (PLA) and poly(dimethyl siloxane) (PDMS). RAW 264.7 cell adhesion and elongation occurred maximally on 500 nm gratings compared to planar controls over 48 hr. TNF-α and VEGF secretion levels by RAW 264.7 cells showed greatest sensitivity to topographical effects, with reduced levels observed on larger grating sizes at 48 hr. In vivo studies at 21 days showed reduced macrophage adhesion density and degree of high cell fusion on 2 μm gratings compared to planar controls. It was concluded that topography affects macrophage behavior in the foreign body response on all polymer surfaces examined. Topography-induced changes, independent of surface chemistry, did not reveal distinctive patterns but do affect cell morphology and cytokine secretion in vitro, and cell adhesion in vivo particularly on larger size topography compared to planar controls.

Benzoxazine-based phenolic resin has recently attracted a great deal of attention due to its versatile properties. This paper explores yet another interesting property shown by this class of phenolic resin:  volumetric expansion upon polymerization. It is proposed that the volumetric expansion of the benzoxazine resin is mostly due to the consequence of molecular packing influenced by inter- and intramolecular hydrogen bonding. The role of hydrogen bonding on the volumetric expansion has been studied by systematically changing the primary amine used in the benzoxazine monomer synthesis. In comparison to the other known expanding monomer, spiroortho compounds, this resin has been shown to have a high potential for structural/engineering applications. The homopolymers of this resin have a high glass transition temperature (T g).

A mono- to multilayer thick MoS₂ film has been grown by using the atomic layer deposition (ALD) technique at 300 °C on a sapphire wafer. ALD provides precise control of the MoS₂ film thickness due to pulsed introduction of the reactants and self-limiting reactions of MoCl₅ and H₂S. A post-deposition annealing of the ALD-deposited monolayer film improves the crystallinity of the film, which is evident from the presence of triangle-shaped crystals that exhibit strong photoluminescence in the visible range.

A combination of solid-state 1H NMR techniques, namely MAS, CRAMPS, and DQ MAS spectroscopy, is used to investigate the hydrogen-bonding properties of a range of alkyl-substituted benzoxazine dimers in the solid state. These dimers are of interest because they serve as model compounds for a class of recently synthesized polymers, the polybenzoxazines, whose unusual properties, in particular a near-zero shrinkage or volumetric expansion upon curing, have been rationalized in terms of favorable hydrogen-bonding interactions. The enhanced resolution achievable at the only recently available very-fast MAS rotation frequency of 35 kHz coupled with the sensitivity of the 1H chemical shift to the hydrogen-bonding arrangement means that much useful information can be obtained by simple MAS alone. In addition, spectra obtained by using a recently introduced CRAMPS approach, suitable for fast MAS and requiring no special experimental setup, are presented. Comparing the methyl- and ethyl- (and n-propyl-) substituted dimers, the significant shifts to low field of the chemical shifts of the hydrogen-bonded protons, as well as the observation of a second aromatic peak only in the latter case, suggest different packing arrangements for the different dimers. On the basis of the additional information about proton proximities provided by the presence or absence of peaks in two-dimensional DQ MAS spectra, it is shown that, while for the methyl dimer, as previously proposed, pairs of hydrogen-bonded dimers are present, for the ethyl and n-propyl dimer, an alternative linear arrangement of hydrogen-bonded dimers predominates.