From Block Copolymers to Functional Nanostructured Materials

Selbstassemblierung von Blockcopolymeren (BCPs) stellt ein mächtiges Werkzeug in der Herstellung nanostrukturierter Materialien mit Domänen unter 50 nm dar. Die Bestückung derartiger Materialien mit reaktiven Oberflächenelementen macht sie hochattraktiv für die Bereiche kontrollierter Immobilisierung, Nanostrukturierung und Fabrikation von Mikro-/Nanoarrays. Die vorliegende Dissertation präsentiert eine neuartige Strategie zur Darstellung reaktiver nanostrukturierter Materialien mit Nanodomänen in einer Größenordnung von weniger als 20 nm unter Verwendung funktionalisierter Blockcopolymere. Zu diesem Zweck wurden Bibliotheken bifunktionaler BCPs, basierend auf poly(Methylmethacrylat–stat-Pentafluorophenylmethacrylat)-block-(Polystyrol-stat-Pentafluorostyrol) (P(MMA-r-PFPMA)-b-P(S-r-PFS)) mittels Postpolymerisationsmodifikation hergestellt. Die BCPs wurden mithilfe reversibler Additions-Fragmentierungs Polymerisation (RAFT) synthetisiert. Funktionalisierung erfolgte durch Modifikation der PFPMA-Einheiten mit Aminen und PFS-Einheiten mit Thiolen. Im Zuge dessen wurde die Orthogonalität zwischen der para-Fluoro-Thiol Reaktion (PFTR) und der Amidierung von PFP-Aktivestern etabliert, sowie ein weiterer Reaktionsweg zwischen PFPMA und Thiolen aufgedeckt. Die Darstellung nanostrukturierter Nanopartikel und Membranen wurde durch Selbstassemblierung funktioneller BCPs in Angriff genommen. Gemusterte Nanopartikel wurden mittels selbstorganisierender Fällung von Chloro-, Azido- und PFP-funktionalen PS-b-PI BCPs hergestellt. Die Gegenwart funktionaler lateraler und Seitengruppen im BCP, sowie die genutzten Herstellungsbedingungen beeinflussten die Ausbildung gepunkteter, zwiebelartiger oder gestapelt lamellarer Morphologien. Modellthiole konnten selektiv auf den PS Domänen gestapelt lamellarer Nanopartikel immobilisiert werden, was das außerordentliche Potential solcher Nanopartikel für selektive Modifikationen demonstriert. Des Weiteren wurde eine Strategie entwickelt, um nanoporöse Membranen unter Ausnutzung der Selbstassemblierung amphiphiler BCPs mit spaltbarer PFP-basierter Verknüpfung zu gewinnen. Darüber hinaus wurden ideale PFTR Bedingungen zur Darstellung amphiphiler BCPs aus PS und wasserlöslichen Einheiten aufgezeigt. Zuletzt wurden funktionelle Copolymere mit neuartigen Photosäure- und Photobasegeneratoren synthetisiert, mithilfe derer der grundlegende Einfluss von pH-Wert auf Entzündungsreaktionen anhand bestrahlungsgesteuerter pH-Sprünge untersucht werden kann

Effect of a behaviour-change intervention on handwashing with soap in India (SuperAmma): a cluster-randomised trial.

BACKGROUND: Diarrhoea and respiratory infections are the two biggest causes of child death globally. Handwashing with soap could substantially reduce diarrhoea and respiratory infections, but prevalence of adequate handwashing is low. We tested whether a scalable village-level intervention based on emotional drivers of behaviour, rather than knowledge, could improve handwashing behaviour in rural India. METHODS: The study was done in Chittoor district in southern Andhra Pradesh, India, between May 24, 2011, and Sept 10, 2012. Eligible villages had a population of 700-2000 people, a state-run primary school for children aged 8-13 years, and a preschool for children younger than 5 years. 14 villages (clusters) were selected, stratified by population size (1200), and randomly assigned in a 1:1 ratio to intervention or control (no intervention). Clusters were enrolled by the study manager. Random allocation was done by the study statistician using a random number generator. The intervention included community and school-based events incorporating an animated film, skits, and public pledging ceremonies. Outcomes were measured by direct observation in 20-25 households per village at baseline and at three follow-up visits (6 weeks, 6 months, and 12 months after the intervention). Observers had no connection with the intervention and observers and participant households were told that the study was about domestic water use to reduce the risk of bias. No other masking was possible. The primary outcome was the proportion of handwashing with soap at key events (after defecation, after cleaning a child's bottom, before food preparation, and before eating) at all follow-up visits. The control villages received a shortened version of the intervention before the final follow-up round. Outcome data are presented as village-level means. FINDINGS: Handwashing with soap at key events was rare at baseline in both the intervention and control groups (1% [SD 1] vs 2% [1]). At 6 weeks' follow-up, handwashing with soap at key events was more common in the intervention group than in the control group (19% [SD 21] vs 4% [2]; difference 15%, p=0·005). At the 6-month follow-up visit, the proportion handwashing with soap was 37% (SD 7) in the intervention group versus 6% (3) in the control group (difference 31%; p=0·02). At the 12-month follow-up visit, after the control villages had received the shortened intervention, the proportion handwashing with soap was 29% (SD 9) in the intervention group and 29% (13) in the control group. INTERPRETATION: This study shows that substantial increases in handwashing with soap can be achieved using a scalable intervention based on emotional drivers. FUNDING: Wellcome Trust, SHARE

Design Strategies for Structurally Controlled Polymer Surfaces via Cyclophane‐Based CVD Polymerization and Post‐CVD Fabrication

Molecular structuring of soft matter with precise arrangements over multiple hierarchical levels, especially on polymer surfaces, and enabling their post-synthetic modulation has tremendous potential for application in molecular engineering and interfacial science. Here, recent research and developments in design strategies for structurally controlled polymer surfaces via cyclophane-based chemical vapor deposition (CVD) polymerization with precise control over chemical functionalities and post-CVD fabrication via orthogonal surface functionalization that facilitates the formation of designable biointerfaces are summarized. Particular discussion about innovative approaches for the templated synthesis of shape-controlled CVD polymers, ranging from 1D to 3D architecture, including inside confined nanochannels, nanofibers/nanowires synthesis into an anisotropic media such as liquid crystals, and CVD polymer nanohelices via hierarchical chirality transfer across multiple length scales is provided. Aiming at multifunctional polymer surfaces via CVD copolymerization of multiple precursors, the structural and functional design of the fundamental [2.2]paracyclophane (PCP) precursor molecules, that is, functional CVD monomer chemistry is also described. Technologically advanced and innovative surface deposition techniques toward topological micro- and nanostructuring, including microcontact printing, photopatterning, photomask, and lithographic techniques such as dip-pen nanolithography, showcasing research from the authors’ laboratories as well as other\u27s relevant important findings in this evolving field are highlighted that have introduced new programmable CVD polymerization capabilities. Perspectives, current limitations, and future considerations are provided

Novel UCST block copolymers

Solutions of thermoresponsive polymers exhibit a drastic and discontinuous change in their properties with temperature. A thermoresponsive polymer that is soluble at low temperatures but undergoes reversible phase transition in a solvent with rising temperature resulting in precipitation or cloud formation is said to exhibit Lower Critical Solution Temperature (LCST)-type behaviour. On the other hand, polymers that exhibit Upper Critical Solution Temperature (UCST)-type behaviour are soluble in water at temperatures above UCST and become reversible insoluble when temperature decreases below upper critical solution temperature. This work deals with the synthesis of novel upper critical solution temperature block copolymers and the effect of pH and electrolyte on their cloud point temperatures. The polymers poly(N-acryloylglycinamide) (PNAGA), poly(ethyleneoxide)-b-poly(N-acryloylglycinamide) (PEO-b-PNAGA), poly(N-isopropyl acrylamide)-b-poly(N-acryloylglycinamide) (PNIPAAm-b-PNAGA) and poly(ethyleneoxide)-b-poly(N-acryloylglycinamide)-b-poly(N-isopropyl acrylamide) (PEO-b-PNAGA-b-PNIPAAm) were synthesized by Reversible Addition-Fragmentation chain-Transfer polymerization in dimethyl sulphoxide. PEO-b-PNAGA and PEO-b-PNAGA-b-PNIPAAm exhibited UCST-type behaviour both in pure water (studied by NMR) and 0.1M NaCl solutions (studied by turbidimetry). Poly (ethyleneoxide) (PEO) block played an important role in enhancing the UCST behaviour of PNAGA by improving the polymers solubility. Yet, higher cloud points in 0.1M NaCl were observed than for PNAGA due to the presence of hydrophobic dodecyl end group. Measuring the particle size between 10-50 °C by dynamic light scattering proved that the polymers phase separated on cooling below the UCST. PEO-b-PNAGA-b-PNIPAAm showed multiresponsive behaviour both in pure water and electrolyte solution exhibiting both LCST and UCST. Change in pH had a dramatic effect on the UCST of PNAGA owing to the carboxylic acid end group shifting the cloud points to higher temperatures with increase in pH. The cloud points were lower for the PNAGA block copolymers in pH 4 buffer solutions compared to that of PNAGA itself due to high solubility of poly (ethylene oxide) block in aqueous solutions

Anisotropic Nanomaterials: Surface‐Reactive Patchy Nanoparticles and Nanodiscs Prepared by Tandem Nanoprecipitation and Internal Phase Separation (Adv. Funct. Mater. 39/2018)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146376/1/adfm201870282.pd

Sharing of Strain Between Nanofiber Forests and Liquid Crystals Leads to Programmable Responses to Electric Fields

Fibers embedded in soft matrices are widely encountered in biological systems, with the fibers providing mechanical reinforcement or encoding of instructions for shape changes. Here, the mechanical coupling of end-attached polymeric nanofiber forests and liquid crystals (LCs) is explored, where the nanofibers are templated into prescribed shapes by the chemical vapor polymerization of paracyclophane-based monomers in supported films of the LCs. It is shown that the elastic energies of the nanofibers and LCs are comparable in magnitude, leading to reversible straining of nanofibers via the application of an electric field to the LC. This coupling is shown to encode complex electrooptical responses in the LC (e.g., optical vortices), thus illustrating how LC-templated nanofiber forests offer the basis of fresh approaches for programming configurational changes in soft materials.Polymeric end-attached nanofibers are synthesized by chemical vapor polymerization within liquid crystalline films and are shown to encode complex mechanical and optical responses upon the application of an electric field. The responses arise from a sharing of elastic strain between the nanofibers and liquid crystal, and they appear promising for programming soft actuators and optical devices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/173026/1/adfm202200830-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/173026/2/adfm202200830.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/173026/3/adfm202200830_am.pd

Formation and Self-assembly of Polymeric Nanofibers by LC Templated CVD Polymerization

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Implementing effective hygiene promotion: lessons from the process evaluation of an intervention to promote handwashing with soap in rural India

Background: An intervention trial of the ‘SuperAmma’ village-level intervention to promote handwashing with soap (HWWS) in rural India demonstrated substantial increases in HWWS amongst the target population. We carried out a process evaluation to assess the implementation of the intervention and the evidence that it had changed the perceived benefits and social norms associated with HWWS. The evaluation also aimed to inform the design of a streamlined shorter intervention and estimate scale up costs. Methods: Intervention implementation was observed in 7 villages. Semi-structured interviews were conducted with the implementation team, village leaders and representatives of the target population. A questionnaire survey was administered in 174 households in intervention villages and 171 households in control villages to assess exposure to intervention activities, recall of intervention components and evidence that the intervention had produced changes in perceptions that were consistent with the intervention core messages. Costs were estimated for the intervention as delivered, as well as for a hypothetical scale-up to 1,000 villages. Results: We found that the intervention was largely acceptable to the target population, maintained high fidelity (after some starting problems), and resulted in a high level of exposure to most components. There was a high recall of most intervention activities. Subjects in the intervention villages were more likely than those in control villages to cite reasons for HWWS that were in line with intervention messaging and to believe that HWWS was a social norm. There were no major differences between socio-economic and caste groups in exposure to intervention activities. Reducing the intervention from 4 to 2 contact days, in a scale up scenario, cut the estimated implementation cost from $2,293 to$1,097 per village. Conclusions: The SuperAmma intervention is capable of achieving good reach across men and women of varied social and economic status, is affordable, and has the potential to be effective at scale, provided that sufficient attention is given to ensuring the quality of intervention delivery. Keywords: Handwashing with soap, Hygiene promotion, Process evaluation, Community-based interventio

Effect of a behaviour-change intervention on handwashing with soap in India (SuperAmma): a cluster-randomised trial

Background: Diarrhoea and respiratory infections are the two biggest causes of child death globally. Handwashing with soap could substantially reduce diarrhoea and respiratory infections, but prevalence of adequate handwashing is low. We tested whether a scalable village-level intervention based on emotional drivers of behaviour, rather than knowledge, could improve handwashing behaviour in rural India. Methods: The study was done in Chittoor district in southern Andhra Pradesh, India, between May 24, 2011, and Sept 10, 2012. Eligible villages had a population of 700–2000 people, a state-run primary school for children aged 8–13 years, and a preschool for children younger than 5 years. 14 villages (clusters) were selected, stratified by population size (1200), and randomly assigned in a 1:1 ratio to intervention or control (no intervention). Clusters were enrolled by the study manager. Random allocation was done by the study statistician using a random number generator. The intervention included community and school-based events incorporating an animated film, skits, and public pledging ceremonies. Outcomes were measured by direct observation in 20–25 households per village at baseline and at three follow-up visits (6 weeks, 6 months, and 12 months after the intervention). Observers had no connection with the intervention and observers and participant households were told that the study was about domestic water use to reduce the risk of bias. No other masking was possible. The primary outcome was the proportion of handwashing with soap at key events (after defecation, after cleaning a child's bottom, before food preparation, and before eating) at all follow-up visits. The control villages received a shortened version of the intervention before the final follow-up round. Outcome data are presented as village-level means. Findings: Handwashing with soap at key events was rare at baseline in both the intervention and control groups (1% [SD 1] vs 2% [1]). At 6 weeks' follow-up, handwashing with soap at key events was more common in the intervention group than in the control group (19% [SD 21] vs 4% [2]; difference 15%, p=0·005). At the 6-month follow-up visit, the proportion handwashing with soap was 37% (SD 7) in the intervention group versus 6% (3) in the control group (difference 31%; p=0·02). At the 12-month follow-up visit, after the control villages had received the shortened intervention, the proportion handwashing with soap was 29% (SD 9) in the intervention group and 29% (13) in the control group. Interpretation: This study shows that substantial increases in handwashing with soap can be achieved using a scalable intervention based on emotional drivers. Funding: Wellcome Trust, SHARE