Hydrogen bonding in acrylamide and its role in the scattering behavior of acrylamide-based block copolymers

Hydrogen bonding plays a role in the microphase separation behavior of many block copolymers, such as those used in lithography, where the stronger interactions due to H-bonding can lead to a smaller period for the self-assembled structures, allowing the production of higher resolution templates. However, current statistical thermodynamic models used in descriptions of microphase separation, such as the Flory-Huggins approach, do not take into account some important properties of hydrogen bonding, such as site specificity and cooperativity. In this combined theoretical and experimental study, a step is taken toward the development of a more complete theory of hydrogen bonding in polymers, using polyacrylamide as a model system. We begin by developing a set of association models to describe hydrogen bonding in amides. Both models with one association constant and two association constants are considered. This theory is used to fit IR spectroscopy data from acrylamide solutions in chloroform, thereby determining the model parameters. These parameters are then employed to calculate the scattering function of the disordered state of a diblock copolymer with one polyacrylamide block and one non-hydrogen-bonding block in the random phase approximation. It is then shown that the expression for the inverse scattering function with hydrogen bonding is the same as that without hydrogen bonding, but with the Flory-Huggins parameter χ replaced by an effective value χeff=χ+δχHB(f), where the hydrogen-bonding contribution δχHB depends on the volume fraction f of the hydrogen-bonding block. We find that models with two constants give better predictions of bond energy in the acrylamide dimer and more realistic asymptotic behavior of the association constants and δχHB in the limit of high temperatures

Interaction and engagement with an anxiety management app: Analysis using large-Scale behavioral data

© Paul Matthews, Phil Topham, Praminda Caleb-Solly. Background: SAM (Self-help for Anxiety Management) is a mobile phone app that provides self-help for anxiety management. Launched in 2013, the app has achieved over one million downloads on the iOS and Android platform app stores. Key features of the app are anxiety monitoring, self-help techniques, and social support via a mobile forum (“the Social Cloud”). This paper presents unique insights into eMental health app usage patterns and explores user behaviors and usage of self-help techniques. Objective: The objective of our study was to investigate behavioral engagement and to establish discernible usage patterns of the app linked to the features of anxiety monitoring, ratings of self-help techniques, and social participation. Methods: We use data mining techniques on aggregate data obtained from 105,380 registered users of the app’s cloud services. Results: Engagement generally conformed to common mobile participation patterns with an inverted pyramid or “funnel” of engagement of increasing intensity. We further identified 4 distinct groups of behavioral engagement differentiated by levels of activity in anxiety monitoring and social feature usage. Anxiety levels among all monitoring users were markedly reduced in the first few days of usage with some bounce back effect thereafter. A small group of users demonstrated long-term anxiety reduction (using a robust measure), typically monitored for 12-110 days, with 10-30 discrete updates and showed low levels of social participation. Conclusions: The data supported our expectation of different usage patterns, given flexible user journeys, and varying commitment in an unstructured mobile phone usage setting. We nevertheless show an aggregate trend of reduction in self-reported anxiety across all minimally-engaged users, while noting that due to the anonymized dataset, we did not have information on users also enrolled in therapy or other intervention while using the app. We find several commonalities between these app-based behavioral patterns and traditional therapy engagement

In Situ Small-Angle X-ray Scattering Studies During Reversible Addition–Fragmentation Chain Transfer Aqueous Emulsion Polymerization

Polymerization-induced self-assembly (PISA) is a powerful platform technology for the rational and efficient synthesis of a wide range of block copolymer nano-objects (e.g., spheres, worms or vesicles) in various media. In situ small-angle X-ray scattering (SAXS) studies of reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization have previously provided detailed structural information during self-assembly (see M. J. Derry et al., Chem. Sci. 2016, 7, 5078–5090). However, conducting the analogous in situ SAXS studies during RAFT aqueous emulsion polymerizations poses a formidable technical challenge because the inherently heterogeneous nature of such PISA formulations requires efficient stirring to generate sufficiently small monomer droplets. In the present study, the RAFT aqueous emulsion polymerization of 2-methoxyethyl methacrylate (MOEMA) has been explored for the first time. Chain extension of a relatively short non-ionic poly(glycerol monomethacrylate) (PGMA) precursor block leads to the formation of sterically-stabilized PGMA-PMOEMA spheres, worms or vesicles, depending on the precise reaction conditions. Construction of a suitable phase diagram enables each of these three morphologies to be reproducibly targeted at copolymer concentrations ranging from 10 to 30% w/w solids. High MOEMA conversions are achieved within 2 h at 70 °C, which makes this new PISA formulation well-suited for in situ SAXS studies using a new reaction cell. This bespoke cell enables efficient stirring and hence allows in situ monitoring during RAFT emulsion polymerization for the first time. For example, the onset of micellization and subsequent evolution in particle size can be studied when preparing PGMA29-PMOEMA30 spheres at 10% w/w solids. When targeting PGMA29-PMOEMA70 vesicles under the same conditions, both the micellar nucleation event and the subsequent evolution in the diblock copolymer morphology from spheres to worms to vesicles are observed. These new insights significantly enhance our understanding of the PISA mechanism during RAFT aqueous emulsion polymerization

An acoustic on-chip goniometer for room temperature macromolecular crystallography

This paper describes the design, development and succesful use of an on-chip goniometer for room-temperature macromolecular crystallography via acoustically induced rotations. We present for the first time a low cost, rate-tunable, acoustic actuator for randomised in-fluid sample orientation and its utilisation for protein structure determination on a synchrotron beamline. The device enables the efficient collection of diffraction data via a rotation method from a sample within a surface confined droplet. This method facillitates efficient macromolecular structural data acquisition in fluid environments for dynamical studies

Personal health technologies, micropolitics and resistance: A new materialist analysis

Personal health technologies (PHTs) are near-body devices or applications designed for use by a single individual, principally outside healthcare facilities. They enable users to monitor physiological processes or body activity, are frequently communication-enabled, and sometimes also intervene therapeutically. This paper explores a range of PHTs, from blood pressure or blood glucose monitors purchased in pharmacies, fitness monitors such as FitBit and Nike+ Fuelband, through to drug pumps and implantable medical devices. It applies a new materialist analysis, first reverse engineering a range of PHTs to explore their micropolitics, and then forward-engineering PHTs to meet, variously, public health, corporate, patient and resisting-citizen agendas. The paper concludes with a critical discussion of PHTs, and the possibilities of designing devices and apps that might foster a subversive micropolitics and encourage collective and resisting ‘citizen-health’

Papery Graveyards: Sense and Silence With Archives

This article seeks to explore the problematics of engaging with archives. In exploring how nonexperts may come to a new topic and area to ask pertinent questions, this article seeks to put to work the author’s own reflexive engagements with an archive. The archives drew the author in both material and bodily senses and invited thinking about how we might reuse data or at least reengage with materials. The article challenges notions that reflexivity is circular or upholds sameness and proposes that the movement is iterative and one which seeks critical engagement with difference

Facile synthesis and proposed mechanism of α,ω‐oxetanyl-telechelic poly(3-nitratomethyl-3-methyl oxetane) by an SN2(i) nitrato displacement method in basic media

The synthesis of a novel heterocyclic–telechelic polymer, α,ω-oxetanyl-telechelic poly(3-nitratomethyl-3-methyl oxetane), is described. Infrared spectroscopy (IR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) spectroscopy have been used to confirm the successful synthesis, demonstrating the presence of the telechelic-oxetanyl moieties. Synthesis of the terminal functionalities has been achieved via displacement of nitrato groups, in a manner similar to that employed with other leaving groups such as azido, bromo, and nitro, initiated by nucleophiles. In the present case, displacement occurs on the ends of a nitrato-functionalized polymer driven by the formation of sodium nitrate, which is supported by the polar aprotic solvent N,N-dimethyl formamide. The formation of an alkoxide at the polymer chain ends is favored and allows internal back-biting to the nearest carbon bearing the nitrato group, intrinsically in an SN2(i) reaction, leading to α,ω-oxetanyl functionalization. The telechelic-oxetanyl moieties have the potential to be cross-linked by chemical (e.g., acidic) or radiative (e.g., ultraviolet) curing methods without the use of high temperatures, usually below 100°C. This type of material was designed for future use as a contraband simulant, whereby it would form the predominant constituent of elastomeric composites comprising rubbery polymer with small quantities of solids, typically crystals of contraband substances, such as explosives or narcotics. This method also provides an alternative approach to ring closure and synthesis of heterocycles