113 research outputs found
Mechanochemistry of Spiropyran under Internal Stresses of a Glassy Polymer
No full textMechanophores are powerful molecular tools used to track bond rupture and characterize mechanical damage in polymers. The majority of mechanophores are known to respond to external stresses, and we report in this study the first precedent of a mechanochemical response to internal, residual stresses that accumulate during polymer vitrification. While internal stress is intrinsic to polymers that can form solids, we demonstrate that it can dramatically affect the mechanochemistry of spiropyran probes and alter their intramolecular isomerization barriers by up to 70 kJ mol-1. This new behavior of spiropyrans (SPs) enables their application for analysis of internal stresses distribution and their mechanochemical characterization on the molecular level. Spectroscopy and imaging based on SP mechanochemistry showed high topological sensitivity and allowed us to discern different levels of internal stress impacting various locations along the polymer chain. The nature of the developed technique allows for wide-field imaging of stress heterogeneities in polymer samples of irregular shapes and dimensions, making it feasible to directly observe molecular-level manifestations of mechanical stresses that accompany the formation of a vast number of solid polymers. BN/BionanoscienceBN/Cees Dekker LabTeam Georgy Filonenk
CCDC 1849321: Experimental Crystal Structure Determination
No full textRelated Article: Georgy A. Filonenko, Jody A. M. Lugger, Chong Liu, Ellen P. A. van Heeswijk, Marco M. R. M. Hendrix, Manuela Weber, Christian Müller, Emiel J. M. Hensen, Rint P. Sijbesma, Evgeny A. Pidko|2018|Angew.Chem.,Int.Ed.|57|16385|doi:10.1002/anie.20180910
Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics, and Their Molecular Weight Dependence in a Polymer Glass
No full textPolymer glasses have an irregular structure. Among the causes for such complexity are the chemically distinct chain end groups that are the most abundant irregularities in any linear polymer. In this work, we demonstrate that chain end induced defects allow polymer glasses to create confined environments capable of hosting small emissive molecules. Using environmentally sensitive luminescent complexes, we show that the size of these confinements depends on molecular weight and can dramatically affect the photoluminescence of free or covalently bound emissive complexes. We confirm the impact of chain end confinement on the bulk glass transition in poly(methyl acrylate) (pMA) and show that commonly observed Tg changes induced by the chain ends should have a structural origin. Finally, we demonstrate that the size and placement of luminescent molecular probes in pMA can dramatically affect the probe luminescence and its temperature dependence, suggesting that polymer glass is a highly irregular and complex environment, marking its difference with conventional small molecule solvents. Considering the ubiquity of luminescent glassy materials, our work lays down a blueprint for designing them with structural considerations in mind, ones where packing density and chain end size are key factors.ChemE/Advanced Soft MatterChemE/Inorganic Systems Engineerin
The contours of the eucharistic anthropology of Alexandr Filonenko
No full textТемою даною публікації є проект євхарістийної антропології українського
філософа і богослова Олександра Філоненко. Ми ставимо дослідницьке
завдання - окреслити контури нового напряму у філософській та
богословській антропології, показати евристичні можливості цієї
оригінальної інтелектуальної пропозиції. Євхаристійна антропологія
представляє форму філософії та богослов’я свідчення в українському
контексті, в якому формується нова богословська дисциплінарна матриця
після тривалого періоду домінування філософії підозри.Тема данной публикации – проект евхаристической антропологии
украинского философа и богослова Александра Филоненко. Мы ставим
перед собой исследовательскую задачу – очертить контуры нового
направления философской и богословской антропологии, показать
эвристические возможности этого оригинального интеллектуального
предложения. Евхаристическая антропологии представляет собой
форму философии и богословия свидетельства в украинском контексте,
в котором формируется новая богословская дисциплинарная матрица
после долгого периода доминирования философии подозрения.The project of the Eucharistic anthropology that was proposed by Alexandr
Filonenko, for the first time on a national scale in theological and philosophical studies,presents eucharistic anthropology as a new branch of
philosophical and theological anthropology, which studies practices of
gratitude as recognition of the Other and paths of human dignity after
dehumanizing practices of the XXth century anthropological catastrophe.
The urgency of eucharistic anthropology is defined by the context of the return
of Reality, Subject and the Sacred after their elimination from the philosophical
field of modern and postmodern thought; this return is described as the presence
of the Other. The main task of our paper is to investigate original theoretical
proposition of the well-known Ukrainian scholar, heuristic capabilities and
cognitive potential of the new trend of communicative anthropology. Alexandr
Filonenko describes the interaction between the philosophical and the
theological contexts of eucharistic anthropology from point of view of the
contemporary culture of presence outside modern and postmodern languages.
He opens new horizon of the theoasethetics, theodrama and theologics, which
have been developed in the theological proposal of H. U. von Balthasar. The
author develops an anthropological language sensitive towards theology
and pedagogics, which lets one describe ways of overcoming the
postideological crisis through practices of gratitude. As A. Filonenko stressed,
Eucharistic anthropology offers one to consider philosophy and theology of
witnessing in the Ukrainian context, in which the theological disciplinary
matrix is currently taking shape after a long period of the philosophy of
suspicion domination
Performance of homogeneous catalysts viewed in dynamics
No full textEffective assessment of catalytic performance is the foundation for the rational design and development of new catalysts with superior performance. The ubiquitous screening/optimization studies use reaction yields as the sole performance metric in an approach that often neglects the complexity of the catalytic system and intrinsic reactivities of the catalysts. Using an example of hydrogenation catalysis, we examine the transient behavior of catalysts that are often encountered in activation, deactivation and catalytic turnover processes. Each of these processes and the reaction environment in which they take place are gradually shown to determine the real-time catalyst speciation and the resulting kinetics of the overall catalytic reaction. As a result, the catalyst performance becomes a complex and time-dependent metric defined by multiple descriptors apart from the reaction yield. This behaviour is not limited to hydrogenation catalysis and affects various catalytic transformations. In this feature article, we discuss these catalytically relevant descriptors in an attempt to arrive at a comprehensive depiction of catalytic performance. ChemE/Inorganic Systems EngineeringTeam Georgy Filonenk
Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics, and Their Molecular Weight Dependence in a Polymer Glass
No full textPolymer glasses have
an irregular structure. Among the causes for
such complexity are the chemically distinct chain end groups that
are the most abundant irregularities in any linear polymer. In this
work, we demonstrate that chain end induced defects allow polymer
glasses to create confined environments capable of hosting small emissive
molecules. Using environmentally sensitive luminescent complexes,
we show that the size of these confinements depends on molecular weight
and can dramatically affect the photoluminescence of free or covalently
bound emissive complexes. We confirm the impact of chain end confinement
on the bulk glass transition in poly(methyl acrylate) (pMA) and show
that commonly observed Tg changes induced
by the chain ends should have a structural origin. Finally, we demonstrate
that the size and placement of luminescent molecular probes in pMA
can dramatically affect the probe luminescence and its temperature
dependence, suggesting that polymer glass is a highly irregular and
complex environment, marking its difference with conventional small
molecule solvents. Considering the ubiquity of luminescent glassy
materials, our work lays down a blueprint for designing them with
structural considerations in mind, ones where packing density and
chain end size are key factors
Mechanochemistry of Spiropyran under Internal Stresses of a Glassy Polymer
No full textMechanophores are
powerful molecular tools used to track
bond rupture
and characterize mechanical damage in polymers. The majority of mechanophores
are known to respond to external stresses, and we report in this study
the first precedent of a mechanochemical response to internal, residual
stresses that accumulate during polymer vitrification. While internal
stress is intrinsic to polymers that can form solids, we demonstrate
that it can dramatically affect the mechanochemistry of spiropyran
probes and alter their intramolecular isomerization barriers by up
to 70 kJ mol–1. This new behavior of spiropyrans
(SPs) enables their application for analysis of internal stresses
distribution and their mechanochemical characterization on the molecular
level. Spectroscopy and imaging based on SP mechanochemistry showed
high topological sensitivity and allowed us to discern different levels
of internal stress impacting various locations along the polymer chain.
The nature of the developed technique allows for wide-field imaging
of stress heterogeneities in polymer samples of irregular shapes and
dimensions, making it feasible to directly observe molecular-level
manifestations of mechanical stresses that accompany the formation
of a vast number of solid polymers
Mechanochemistry of Spiropyran under Internal Stresses of a Glassy Polymer
No full textMechanophores are
powerful molecular tools used to track
bond rupture
and characterize mechanical damage in polymers. The majority of mechanophores
are known to respond to external stresses, and we report in this study
the first precedent of a mechanochemical response to internal, residual
stresses that accumulate during polymer vitrification. While internal
stress is intrinsic to polymers that can form solids, we demonstrate
that it can dramatically affect the mechanochemistry of spiropyran
probes and alter their intramolecular isomerization barriers by up
to 70 kJ mol–1. This new behavior of spiropyrans
(SPs) enables their application for analysis of internal stresses
distribution and their mechanochemical characterization on the molecular
level. Spectroscopy and imaging based on SP mechanochemistry showed
high topological sensitivity and allowed us to discern different levels
of internal stress impacting various locations along the polymer chain.
The nature of the developed technique allows for wide-field imaging
of stress heterogeneities in polymer samples of irregular shapes and
dimensions, making it feasible to directly observe molecular-level
manifestations of mechanical stresses that accompany the formation
of a vast number of solid polymers
Mechanochemistry of Spiropyran under Internal Stresses of a Glassy Polymer
No full textMechanophores are
powerful molecular tools used to track
bond rupture
and characterize mechanical damage in polymers. The majority of mechanophores
are known to respond to external stresses, and we report in this study
the first precedent of a mechanochemical response to internal, residual
stresses that accumulate during polymer vitrification. While internal
stress is intrinsic to polymers that can form solids, we demonstrate
that it can dramatically affect the mechanochemistry of spiropyran
probes and alter their intramolecular isomerization barriers by up
to 70 kJ mol–1. This new behavior of spiropyrans
(SPs) enables their application for analysis of internal stresses
distribution and their mechanochemical characterization on the molecular
level. Spectroscopy and imaging based on SP mechanochemistry showed
high topological sensitivity and allowed us to discern different levels
of internal stress impacting various locations along the polymer chain.
The nature of the developed technique allows for wide-field imaging
of stress heterogeneities in polymer samples of irregular shapes and
dimensions, making it feasible to directly observe molecular-level
manifestations of mechanical stresses that accompany the formation
of a vast number of solid polymers
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