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Introduction. Considering its potential relevance for prevention and intervention with victims of childhood maltreatment, different studies have attempted to analyze the role of adult attachment in the relationship between child abuse and depressive symptoms. The aim of this study is to carry out a systematic review of the empirical literature with a robust methodology on the mediating role of attachment in the association between childhood maltreatment and depressive symptoms in the adulthood. Methodology. From the database and citation search, 13 articles were identified that met the inclusion and exclusion criteria. Results. Overall, the evidence confirms the mediating role of insecure attachment, although discrepancies are observed between the studies regarding the specific attachment dimensions that would act as mediators. Discussion. The type of childhood victimization experienced and the figure to whom the attachment evaluation is directed may be two determining variables in the effect of attachment on the association. Further studies are necessary to confirm the conclusions raised and serve as a basis for the design of more complete intervention programs for victims of child maltreatment., Introducción. Atendiendo a su relevancia potencial para la prevención y la intervención con víctimas de violencia infantil, distintos estudios han intentado analizar el papel del apego adulto en la relación entre el maltrato infantil y la sintomatología depresiva. El objetivo de este estudio es llevar a cabo una revisión sistemática de la literatura empírica con una metodología robusta sobre el rol mediador del apego en la asociación entre el maltrato infantil y los síntomas de depresión en la edad adulta. Metodología. A partir de la búsqueda en bases de datos y citas, se identificaron 13 artículos que cumplían con los criterios de inclusión y exclusión. Resultados. En conjunto, las evidencias confirman el papel mediador del apego inseguro, si bien se observan discrepancias entre los estudios en lo que se refiere a las dimensiones de apego específicas que actuarían como mediadoras. Discusión. El tipo de victimización infantil experimentada y la figura a la que se dirige la evaluación del apego pueden ser dos variables determinantes en el efecto del apego sobre la asociación. Son necesarios estudios adicionales que confirmen las conclusiones planteadas y sirvan de base para el diseño de programas de intervención más completos para víctimas de maltrato infantil.

Cross-linked poly(tetrahydrofuran) (PTHF) networks are useful as organic solvent/oil sorbents with high swelling capacity and mechanically robust solid polymer electrolyte membranes for lithium-ion batteries, as well as solid-state calcium ion batteries. Recently, the control of intra-vs intermolecular interactions has attracted significant interest to modulate the properties of dynamic networks involving non-covalent and dynamic covalent bonds. However, to the best of our knowledge, a comparison of the segmental dynamics in polymeric materials prepared exactly from the same precursor polymer through intra-vs intermolecular covalent bonds is still lacking. In this work, we report the dissimilar dynamic properties of PTHF-based materials prepared through intra-vs intermolecular click chemistry (i.e., films of PTHF-based single-chain nanoparticles (SCNPs) vs cross-linked networks). Particularly we observed remarkable similarities in the segmental relaxation time and glass transition temperature value but evident differences in the dynamic heterogeneities. These differences are attributed to the peculiar morphology of the intra-chain collapsed polymer chains (i.e., SCNPs).

The conformation of poly(methyl methacrylate) (PMMA)-based single-chain nanoparticles (SCNPs) and their corresponding linear precursors in the presence of deuterated linear PMMA in deuterated dimethylformamide (DMF) solutions has been studied by small-angle neutron scattering (SANS). The SANS profiles were analyzed in terms of a three-component random phase approximation (RPA) model. The RPA approach described well the scattering profiles in dilute and crowded solutions. Considering all the contributions of the RPA leads to an accurate estimation of the single chain form factor parameters and the Flory–Huggins interaction parameter between PMMA and DMF. The value of the latter in the dilute regime indicates that the precursors and the SCNPs are in good solvent conditions, while in crowding conditions, the polymer becomes less soluble.

[EN] Single-chain nanoparticles (SCNPs) result from the folding of isolated polymer chains via intramolecular interactions. Currently, there is no theory able to rationalize the astonishing conformational behaviour of SCNPs under severe crowding conditions (e.g., highly concentrated solutions, all-polymer nanocomposites) and, specifically, the significant size reduction observed in highly crowded solutions of covalent-bonded SCNPs and all-polymer nanocomposites containing SCNPs. Herein, we propose a valuable method to estimate the size of SCNPs under crowding. The method - which is based on combining MD simulations results with scaling concepts - is also useful for ring polymers and nanostructured Janus-shaped SCNPs.

[EN] We have investigated an all-polymer nanocomposite (NC) consisting of single-chain nanoparticles (SCNPs) immersed in a matrix of linear chains of their precursors (25/75% composition in weight). The SCNPs were previously synthesized via "click" chemistry, which induces intramolecular cross-links in the individual macromolecules accompanied by a slight shift (5-8 K) of the glass transition temperature toward higher values and a broadening of the dynamic response with respect to the raw precursor material. The selective investigation of the dynamics of the NC components has been possible by using properly isotopically labeled materials and applying quasielastic neutron scattering techniques. Results have been analyzed in the momentum transfer range where the coherent scattering contribution is minimal, as determined by complementary neutron diffraction experiments with polarization analysis. We observe the development of dynamic heterogeneity in the intermediate scattering function of the NC components, which grows with increasing time. Local motions in the precursor matrix of the NC are accelerated with respect to the reference bulk behavior, while the displacements of SCNPs' hydrogens show enhanced deviations from Gaussian and exponential behavior compared with the pure melt of SCNPs. The resulting averaged behavior in the NC coincides with that of the pure precursor, in accordance with the macroscopic observations by differential scanning calorimetry (DSC) experiments.

The molecular dynamics of a copolymer composed of methyl methacrylate (MMA) and (2-acetoacetoxy)ethyl methacrylate (AEMA) monomers and the influence on it of intra-to intermolecular cross-links of AEMA units with ethylenediamine (EDA) was studied by combining dielectric relaxation experiments and thermal investigations. The dielectric spectra of the non-cross-linked copolymer show three dynamical processes: a slow relaxation (alpha) and a faster (beta), both dominated by the MMA dynamics, and an even faster secondary relaxation (gamma) reflecting the AEMA dynamics. Already for low cross-linking densities, the gamma process is very much affected and eventually disappears, increasing the cross-linking density. The secondary beta relaxation however was nearly unaffected by cross-linking. The effect of cross-linking on the alpha relaxation was very pronounced with an important increasing of the glass transition temperature Tg. There was also an increase of the dynamic heterogeneity and the relaxation intensity when increasing the cross-linking density (up to the maximum explored, 9 mol % EDA). The quality of the average time scale and Tg value have similarities in behavior for intra-and intermolecular cross linking, but clear differences in the dynamic heterogeneities where observed. These differences can be interpreted in connection with the sparse internal structure of the collapsed single chains obtained by intramolecular cross-linking.

We present a combined study by quasielastic neutron scattering (QENS), differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS) on poly(tetrahydrofuran-co-epichlorohydrin) copolymers, to see how their composition can be used to tune their crystallizability and to elucidate the impact of this factor on the dynamical properties. QENS reveals a strong effect on the local dynamics upon cooling down, where the local motions of a sample that remains in the supercooled state at lower temperatures are less Gaussian and slower than those in a sample that crystallizes a few degrees below. This can be attributed to the enhancement of local heterogeneities in the former, which could be a determining factor preventing crystallization.

Single-chain nanoparticles (SCNPs) result from the folding of isolated polymer chains via intramolecular interactions. Currently, there is no theory able to rationalize the astonishing conformational behaviour of SCNPs under severe crowding conditions (e.g., highly concentrated solutions, all-polymer nanocomposites) and, specifically, the significant size reduction observed in highly crowded solutions of covalent-bonded SCNPs and all-polymer nanocomposites containing SCNPs. Herein, we propose a valuable method to estimate the size of SCNPs under crowding. The method – which is based on combining MD simulations results with scaling concepts – is also useful for ring polymers and nanostructured Janus-shaped SCNPs.

We have investigated an all-polymer nanocomposite (NC) consisting of single-chain nanoparticles (SCNPs) immersed in a matrix of linear chains of their precursors (25/75% composition in weight). The SCNPs were previously synthesized via “click” chemistry, which induces intramolecular cross-links in the individual macromolecules accompanied by a slight shift (5–8 K) of the glass transition temperature toward higher values and a broadening of the dynamic response with respect to the raw precursor material. The selective investigation of the dynamics of the NC components has been possible by using properly isotopically labeled materials and applying quasielastic neutron scattering techniques. Results have been analyzed in the momentum transfer range where the coherent scattering contribution is minimal, as determined by complementary neutron diffraction experiments with polarization analysis. We observe the development of dynamic heterogeneity in the intermediate scattering function of the NC components, which grows with increasing time. Local motions in the precursor matrix of the NC are accelerated with respect to the reference bulk behavior, while the displacements of SCNPs’ hydrogens show enhanced deviations from Gaussian and exponential behavior compared with the pure melt of SCNPs. The resulting averaged behavior in the NC coincides with that of the pure precursor, in accordance with the macroscopic observations by differential scanning calorimetry (DSC) experiments.