Structure–Property Relationships in Sterically Congested Proton-Conducting Poly(phenylene)s: the Impact of Biphenyl Linearity

The ability to predict macroscopic properties using a compound's chemical structure is an essential idea for chemistry as well as other disciplines such as biology. In this study we investigate how different levels of interventions impact the components of students’ explanations (claims, evidence, and reasoning) of structure–property relationships, particularly related to boiling point trends. These interventions, aligned with Three-Dimensional Learning (3DL), were investigated with four different cohorts of students: Cohort 1 – a control group of students enrolled in an active learning general chemistry course; Cohort 2 – students enrolled in the same active learning general chemistry course but given Intervention 1 (a 3DL worksheet administered during class time); Cohort 3 – students enrolled in the same active learning general chemistry course but given Intervention 1 and Intervention 2 (a 3DL course exam question administered after instruction); and Cohort 4 – a reference group of students enrolled in a transformed active learning general chemistry curriculum in which 3DL is an essential feature and includes Intervention 1 and Intervention 2 as part of the curriculum. We found that Cohort 2 students (with the 3DL worksheet intervention) were more likely than the control group (Cohort 1) to correctly predict the compound with a higher boiling point as well as incorporate ideas of strength of intermolecular forces into their explanations of boiling point differences. When a 3DL exam question was given as a follow up to the 3DL worksheet, students in Cohort 3 were more likely than Cohorts 1 and 2 to correctly identify the claim. Further comparison showed that Cohort 4 (transformed general chemistry curriculum) were more likely than Cohorts 1–3 to also include the ideas of energy needed to overcome stronger forces for a more sophisticated explanation (50% of Cohort 4 students compared to 17–33% for Cohorts 1–3). In addition, 80% of Cohort 4 students were able to construct a correct representation of hydrogen bonding as a non-covalent interaction compared to 13–57% for the other three cohorts.

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Dynamic transformation of cubic copper catalysts during CO2 electroreduction and its impact on catalytic selectivity

Nature Communications ◽

10.1038/s41467-021-26743-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Philipp Grosse ◽

Aram Yoon ◽

Clara Rettenmaier ◽

Antonia Herzog ◽

See Wee Chee ◽

...

Keyword(s):

Electron Microscopy ◽

Copper Catalysts ◽

Underlying Structure ◽

Structure Property ◽

Product Analysis ◽

Time Resolved ◽

Catalytic Selectivity ◽

Structure Property Relationships ◽

Co2 Electroreduction ◽

The Impact

AbstractTo rationally design effective and stable catalysts for energy conversion applications, we need to understand how they transform under reaction conditions and reveal their underlying structure-property relationships. This is especially important for catalysts used in the electroreduction of carbon dioxide where product selectivity is sensitive to catalyst structure. Here, we present real-time electrochemical liquid cell transmission electron microscopy studies showing the restructuring of copper(I) oxide cubes during reaction. Fragmentation of the solid cubes, re-deposition of new nanoparticles, catalyst detachment and catalyst aggregation are observed as a function of the applied potential and time. Using cubes with different initial sizes and loading, we further correlate this dynamic morphology with the catalytic selectivity through time-resolved scanning electron microscopy measurements and product analysis. These comparative studies reveal the impact of nanoparticle re-deposition and detachment on the catalyst reactivity, and how the increased surface metal loading created by re-deposited nanoparticles can lead to enhanced C2+ selectivity and stability.

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Synthesis and Physicochemical Evaluation of Bees’ Chitosan-Based Hydrogels Modified with Yellow Tea Extract

Materials ◽

10.3390/ma14123379 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3379

Author(s):

Sonia Kudłacik-Kramarczyk ◽

Anna Drabczyk ◽

Magdalena Głąb ◽

Paweł Gajda ◽

Anna Jaromin ◽

...

Keyword(s):

Contact Angles ◽

Structure Property ◽

Swelling Properties ◽

Structure Property Relationships ◽

Physicochemical Evaluation ◽

Measurement Methodology ◽

Ft Ir ◽

Tea Extract ◽

The Impact ◽

Dressing Materials

The novelty of the research involves designing the measurement methodology aimed at determining the structure–property relationships in the chitosan-based hydrogels containing yellow tea extract. Performed investigations allowed us to determine the swelling properties of hydrogels in selected time intervals, evaluate the mutual interactions between the hydrogels and simulated physiological liquids via pH measurements and directly assess the impact of such interactions on the chemical structure of hydrogels using Fourier transform infrared (FT-IR) spectroscopy and their wettability by the measurements of the flatness of the drop on the surface of the tested samples via the static drop method. Next, the surface morphology of hydrogels was characterized by the Scanning Electron Miscorcopy (SEM) and their elasticity under the tension applied was also verified. It was proved that incubation in simulated physiological liquids resulted in a decrease in contact angles of hydrogels, even by 60%. This also caused their certain degradation which was reflected in lower intensities of bands on FT-IR spectra. Further, 23% v/v yellow tea extract in hydrogel matrices caused the decrease of their tensile strength. An increase in the amount of the crosslinker resulted in a decrease in the sorption capacity of hydrogels wherein their modification caused greater swelling ability. In general, the investigations performed provided much information on the tested materials which may be meaningful considering their application, e.g., as dressing materials.

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Synthesis and structure–property relationships of phthalimide and naphthalimide based organic π-conjugated small molecules

Physical Chemistry Chemical Physics ◽

10.1039/c6cp01596d ◽

2016 ◽

Vol 18 (21) ◽

pp. 14709-14719 ◽

Cited By ~ 20

Author(s):

Abby-Jo Payne ◽

Arthur D. Hendsbee ◽

Seth M. McAfee ◽

Devproshad K. Paul ◽

Kunal Karan ◽

...

Keyword(s):

Thin Films ◽

Small Molecules ◽

Chain Length ◽

Side Chain ◽

Structure Property ◽

Side Chain Length ◽

Materials Properties ◽

Structure Property Relationships ◽

And Topology ◽

The Impact

Six organic π-conjugated small molecules with a bithiophene core and aryl imide terminal units are reported. The impact of alky side chain length and topology, and aryl imide size on materials properties in solution and as thin-films was investigated.

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Structure-property relationships of PE/PP sandwiched films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126998 ◽

1987 ◽

Vol 45 ◽

pp. 454-455

Author(s):

J. Petermann ◽

G. Broza ◽

U. Rieck ◽

A. Jaballah ◽

A. Kawaguchi

Keyword(s):

Mechanical Tests ◽

Polymer Materials ◽

Ionic Crystals ◽

Structure Property ◽

Polymer Systems ◽

Structure Property Relationships ◽

Oriented Films ◽

Materials Used ◽

Polymer Laminates ◽

Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

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Approaches for TEM imaging of cavitation in toughened nylon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153737 ◽

1989 ◽

Vol 47 ◽

pp. 352-353

Author(s):

Barbara A. Wood

Keyword(s):

Morphological Characteristics ◽

Structure Property ◽

Polymer Systems ◽

Selective Staining ◽

Structure Property Relationships ◽

Rubber Toughened ◽

Shear Yield ◽

Controversial Topic ◽

Selection Of ◽

Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

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Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

10.26434/chemrxiv.12588965 ◽

2020 ◽

Author(s):

Alex Stafford ◽

Dowon Ahn ◽

Emily Raulerson ◽

Kun-You Chung ◽

Kaihong Sun ◽

...

Keyword(s):

Near Infrared ◽

Transient Absorption ◽

Reaction Times ◽

Infrared Light ◽

Structure Property ◽

Light Emitting ◽

Structure Property Relationships ◽

Nir Light ◽

Light Intensities ◽

Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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