Poly(methyl methacrylate) (PMMA) was melt mixed 30:70 into polystyrene (PS) with and without symmetric P(S-b-MMA) diblock copolymers. The molecular weight of the components was varied. After 5 min of shear mixing, the PMMA was dispersed into roughly spherical, submicron particles. Particle size was measured by light scattering and transmission electron microscopy. As little as 1% copolymer led to a significant reduction in PMMA particle size, although larger amounts were needed to make the particles stable to annealing (180 °C for 15 min). The principle role of block copolymers in controlling morphology appears to be in preventing coalescence. Preventing dynamic coalescence leads to size reduction, while preventing static coalescence results in stability or compatibilization. We estimate that less than 5% of the interface needs to be covered to prevent dynamic coalescence while ∼20% is necessary to impart static stability. Mobility, critical micelle concentration, and molecular weight of the block copolymer also appear to be important. Lowering the molecular weight of the PMMA phase from 43 000 to 11 000 resulted in dramatically lower particle size (700 vs 60 nm). These variables are discussed in terms of a qualitative balance between rate of diffusion and rate of area generation during blending.
C.S. were involved in experimental design. C.R. and C.S. realized most experiments, compiled the data and contributed equally to this work. P.M., C.Ru. and J.S. were involved in (bone marrow-derived) dendritic cell-related experiments. M.T. and S.L.J. were involved in experiments aiming at detecting and inhibiting NETs. C.V., F.P., N.R. and D.C. contributed to experiments involving ozone exposure and invasive measurements of airway function. T.M. analysed single cell RNA sequencing data with the help of the GIGA Genomics Platform. C.R. and T.M. prepared the figures, and T.M. wrote the manuscript. All authors provided feedback on the manuscript.
The origin of the β transition in poly(vinylidene fluoride) (PVDF) is still a pending question. This transition has been studied by dynamic mechanical analysis (d.m.a.) and differential scanning calorimetry (d.s.c.) in dependence on sample annealing and dilution with e-caprolactam (CPL). The β transition temperature is increased upon annealing and thus influenced by the polymer crystallization. Upon addition of CPL, there is no systematic shift in the β transition temperature, in contrast to the PVDF crystallinity that increases steadily. A shoulder on the low temperature side of the β transition peak is also observed as a result of annealing. It is shifted to lower temperatures when CPL is added, consistently with a glass transition. It thus appears that the so-called β-transition is sensitive to the amorphous material, but in a close relationship with the polymer crystallization. Comparison of the observations by d.s.c, and d.m.a, shows that the broad transition observed for the unannealed samples would result from the overlap of two transitions: the glass transition of the unconstrained amorphous phase and the glass transition of chains constrained by the crystalline phase. This situation can account for the complex dependence of the β transition on the polymer history.
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