Self-repairing composites for corrosion protection: A review on recent strategies and evaluation methods

The use of self-healing coatings to protect metal substrates, such as aluminum alloys, stainless steel, carbon steel, and Mg alloys from corrosion is an important aspect for protecting metals and for the economy. During the past decade, extensive transformations on self-healing strategies were introduced in protective coatings, including the use of green components. Scientists used extracts of henna leaves, aloe vera, tobacco, etc. as corrosion inhibitors, and cellulose nanofibers, hallyosite nanotubes, etc. as healing agent containers. This review gives a concise description on the need for self-healing protective coatings for metal parts, the latest extrinsic self-healing strategies, and the techniques used to follow-up the self-healing process to control the corrosion of metal substrates. Common techniques, such as accelerated salt immersion test and electrochemical impedance spectroscopy (EIS), for evaluating the self-healing process in protective coatings are explained. We also show recent advancements procedures, such as scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy (SECM), as successful techniques in evaluating the self-healing process in protective coatings.Qatar UniversityScopu

Challenges for Higher Education in Crisis Stricken Times – The Effects of Covid-19 in Preparing Universities for Future

تحلل وجهة النظر هاته وضعيةَ وتحولات مؤسسات التعليم العالي خلال الأزمات غير المتوقعة من قبيل جائحة كوفيد-19 الحالية، التي أدت إلى اضطراب غالبية اقتصادات العالم. إن التغيرات التي تواجه التعليم العالي ليست جديدة؛ إذ إنها حصلت في كل المجالات، لكن المتوقع أن النقلات ستكون أعمق، وأسرع بعد الجائحة. يُظهِر البحث كيف يمكن لمؤسسات التعليم العالي أن تتكيف وتتحول خلال الجائحة، كما تناقش كيف لتلك المؤسسات أن تخرج من الأزمة أقوى وتصبح قادرة على تحقيق الاستدامة طويلة الأمد، التي يمكن من خلالها، الإسهام في المجتمع بنظام أكثر رشاقة وفاعلية، تحركه سياسات مرنة ومهام محددة تسدي خدمة للمجتمع، مدفوعة برسالتها في الوقت نفسه. يجب على الجامعات أن تتسم ببعد نظر، ولا تفوت فرصة إعادة تقييم فائدتها للمجتمع، وإعادة تركيز المعنى في الحاجة إليها. نرى أن مؤسسات التعليم العالي تلعب دورًا بارزًا في تحقيق جدول أعمال 2030 للتنمية المستدامة، وتسهم بشكل فاعل في أهداف التنمية المستدامة (SDGs)، كما نعتقد أن الاتجاه الاستراتيجي للجامعات يجب أن يرتكز على مبادئ مسؤوليات شركاء المصلحة، المعروفة بالحوكمة البيئية والاجتماعية وحوكمة الشركات (ESG). أخيرًا، نجادل في أن بُعد الحوكمة - تحديدًا - أساسيٌ لمؤسسات التعليم العالي؛ لتحقيق الكفاءة والاستدامة والأهداف طويلة الأمد.This viewpoint analyses the status and transformation of Higher Education institutions during unpredicted great challenges such as the current Covid-19, which disrupted most of the economies on the planet. The changes facing Higher Education are not new, transformation has been seen in different areas, but shifts are expected to be deeper and faster after the pandemic. We show how the Higher Education institutions can resist and transform during the pandemic and we also discuss how these institutions can come out of the recession stronger and become capable of achieving long-term sustainability. For that aim, a leaner and more effective institution system with modified flexible policies that contribute to society and, at the same time, are mission-driven, is expected to be achieved. Universities in their recovery efforts must look far ahead and should not miss the opportunity to reassess their usefulness to society, nor to refocus their sense of purpose. We suggest that institutions of Higher Education play a more important role in achieving the 2030 Agenda for Sustainable Development and contribute decisively to the several SDGs. In addition, we argue that the strategic direction of universities must be focused on stakeholder responsibility principles known as Environmental, Social, and Governance – ESG. Finally, we argue that the governance dimension is particularly critical for Higher Education institutions if they want to achieve long-term efficiency, sustainability and purpose

Center for Advanced Materials, Contribution to "Research for the Future" Rd Map at Qatar University The Journey from 2008 to 2015

"Research for the future" is the roadmap of research at Qatar University for 2014-2019 [i]. It identifies the research priority themes based on Qatar's needs and on National Development Strategy 2011-2016. The following themes are the research priorities of Qatar University 1) Energy, Environment and Resource Sustainability, 2) Social Change and Identity, 3) Population, Health and Wellness and 4) Information and Communication Technologies. This strategy is also aligned with the Qatar National Research Strategy 2012 with a vision for Qatar to be a leading center for research and development excellence and innovation [ii]. Materials Science is the heart of economic growth as it is related to all areas of energy, environment and sustainability. This presentation will show the Center for Advanced Material (CAM) as a leading model for theme number one "Energy, Environment and Resource Sustainability". CAM has grown from a small unit with five people in 2008 to a state-of-the-art center that has more than fifty-five members in 2015 working in various leading projects, this includes a high contribution of female scientists. This number does not include the students, short period visitors and daily visiting QU members. Examples of current research projects in the Materials Science and Nanotechnology subtheme will be presented. This will include research done in collaboration with the industry, mainly local oil and gas industries, and international institutes around the world. Projects such as corrosion protections, energy conservations techniques, medical application and sustainable materials are some examples. Emphasis will be made on emerging trends in technology to manipulate the atoms at the nano level for various technology applications. These improvements in this small scale can lead to improvement in the performance of traditional materials to reduce the energy consumption and cost. The state-of-the-art equipment and high quality accredited labs will also be shown. The presentation will explain a wide range of equipment in synthesis, processing and characterization stages. Graduate and undergraduate students' involvement in the activities as part of their courses, thesis dissertations or working as RAs in projects will be shown. Scientific trips to external institutes and industry as well as continuous exposure of the students to the local industry improved their learning abilities. The presentation will also show selected projects contributing to the other themes, especially in the Health and Wellness. This will include new synthesized nanoparticles that can fight the diseases such as cancer and new biomedical nanofibres for medical applications. Social Change and Identity is another priority that CAM is contributing through many leading projects such as the WISE 2015 wining project AlBairaq and the archeology studies in collaboration with the Qatar Museum Authorities.qscienc

TiO2 nanotubes and mesoporous silica as containers in self-healing epoxy coatings

The potential of inorganic nanomaterials as reservoirs for healing agents is presented here. Mesoporous silica (SBA-15) and TiO2 nanotubes (TNTs) were synthesized. Both epoxy-encapsulated TiO2 nanotubes and amine-immobilized mesoporous silica were incorporated into epoxy and subsequently coated on a carbon steel substrate. The encapsulated TiO2 nanotubes was quantitatively estimated using a ‘dead pore ratio’ calculation. The morphology of the composite coating was studied in detail using transmission electron microscopic (TEM) analysis. The self-healing ability of the coating was monitored using electrochemical impedance spectroscopy (EIS); the coating recovered 57% of its anticorrosive property in 5 days. The self-healing of the scratch on the coating was monitored using Scanning Electron Microscopy (SEM). The results confirmed that the epoxy pre-polymer was slowly released into the crack. The released epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch.This paper was made possible by PDRA grant # PDRA1-1216-13014 from the Qatar National Research Fund (a member of Qatar Foundation)

Impact of Innovative Learning Environment Based on Research Activities on Secondary School Student's Attitude Towards Research and Their Self-Efficacy.

Advanced and free learning environment coupled with the creative learning activities is assumed to be a motivational variable. In the present study, we applied an innovative learning strategy involving students in order to achieve positive impact on their attitude towards science, desire to learn science and future career choices. The study experiment was focused on enhancing the research skills of the students; apply knowledge for solving real world problems, positively changing the students’ attitude towards science, raising students’ self-efficacy and enhance positivism toward science related subjects. This research assumes that if the attitude and perception of post-secondary students is changed and made positive about science, then they might choose to study related science subjects forexample, mathematics, engineering and science at university level studies. Therefore, it will also impact students’ career choices after university studies and they might enter scientific careers. Our study focused on evaluating various changes in the attitude, desire and self-efficacy of participating students when traditional instruction is replaced through the innovative learning environment. A total of 120 students participated in our experiment where researchers assisted students to experience hands on different research activities. Pre and posttest were used to evaluate the change in students’ attitude and desire towards science, knowledge and self-efficacy. The study results have shown that significant changes in the performance of students’ for-example, student noticed positive attitude towards their own research abilities, desire to learn science, self-efficacy, learning and career choices. However, results did not show any differences based on gender as such.Qatar Universit

Cytocompatibility and Dielectric Properties of Sr2+ Substituted Nano-Hydroxyapatite for Triggered Drug Release

Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramics material used in medical applications because of its ability to form direct chemical bonds with living tissues. In this context, we investigate the biocompatibility and dielectric properties of Sr2+-substituted hydroxyapatite nanoparticles were synthesized by sol-gel method. The influence of strontium on the crystal structure, functional group, morphological, electrical properties, and biocompatibility of as-synthesized nano-hydroxyapatite samples was analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM). Dielectrical properties of the bioactive Sr-HA sample were investigated by a dielectric impedance spectroscopy method. The observed results illustrate the incorporation of Sr2+ ions in the apatite lattice could influence the pure HA properties, by reducing the crystallite size and crystallinity quite consistent with the morphology variation. The ac conductivity (σac) increased with an increasing applied frequency confirmed that prepared HA sample exhibited the universal power law nature. Further, the in vitro drug loading and release studies using doxycycline as a model drug demonstrate that the Sr2+ -HA nanoparticles show high drug adsorption capacity and sustained drug release. Thus, the improved bioceramics system could be a promising candidate for future biomedical applications

Inorganic Porous Materials Based Epoxy Self-Healing Coatings

The long-term stability of protective coating for metal is critically important for structural applications [1, 2]. Self-healing ability extend the service life of protective coatings leading to a significant reduction in maintenance cost for oil and gas pipe lines and structural parts in civil and construction industry. Recently, the self-healing technology based on healing agent loaded containers has been receiving attention [3, 4]. The incorporation of self- healing agent loaded containers into polymer matrix can be carried out using existing blending techniques. Hence, this technology facilitate large-scale application of self-healing materials [5]. Different micro or nano containers has been used for the storage and release of self-healing agents upon specific corrosion triggering conditions (e.g. on pH change) or upon mechanical damage [6]. Polymer capsules, polymer nanofibers, hollow glass bubbles, hollow glass fibers etc. were used by the researchers to load the healing agent inside their cavity. The inorganic particles with nano cavity offers large surface area, high pore volume and good stability favorable for the storage of the healing agents. Moreover, the usage of inorganic nanomaterials as reservoirs for healing agent can eliminate the tedious encapsulation process. The present study aims to use inorganic nanotubes and mesoporous silica as containers for healing agents in epoxy coating. The ability of Halloysite nanotubes (HNT), titanium dioxide (TiO2) nanotube and mesoporous silica to load and release the healing agents are investigated and compared their performance. Among them, Halloysite nanotubes are naturally occurring clay mineral. Meanwhile, TiO2 nanotube and mesoporous silica are synthesised in laboratory and characterised using scanning electron microscopic (SEM), transmission electron microscopic (TEM) techniques and Brunauer-Emmett-Teller (BET) surface area analysis. The morphology of the nanotubes and mesoporous silica are shown in Fig. 1 (in supporting file). In this study, the epoxy pre-polymer and hardener are used as healing agents. Containers loaded with epoxy and hardener can provide a repair system with matching chemical entity with host epoxy coating. Both epoxy encapsulated nanotubes (either Halloysite or TiO2 nanotubes) and amine immobilized mesoporous silica are incorporated into epoxy, followed by the addition of diethylenetriamine curing agent. The mixture is coated on the metal with an average thickness of 300 ?m. The controlled epoxy coatings are also prepared without nanotube and mesoporous silica. Epoxy coating loaded with encapsulated Halloysite nanotubes and immobilized mesoporous silica is abbreviated as 'EP/HNT/SiO2' and the one loaded with encapsulated TiO2 nanotubes and immobilized mesoporous silica is abbreviated as 'EP/ TiO2/SiO2'. The self-healing ability of the scratched coatings is monitored by electrochemical impedance spectroscopy (EIS) in definite time intervals for 5 days. Both EIS bode plots and tafel polarization curves are analysed to observe the self-healing ability of the coatings. For the scratched controlled epoxy coating, after an immersion time of 24 hours, the impedance curve drop to its minimum value over the entire frequency range and on further immersion period the impedance curve remains its minimum value. However, in the case of self-healing coatings, the initially declined impedance value recovers in successive days. The recovery in low frequency impedance values (at 0.01 Hz), which is a direct reflection of the recovery of corrosion resistance of the coating are evaluated. While EP/TiO2/SiO2 coating recovered 57% of its anticorrosive property, the EP/HNT/SiO2 coating recovered only 0.026%. This results suggest that the nature of the nanotubes affect the amount and rate of healing agent released into the scratched area from the tube lumen which itself affect the self-healing ability of the coating. SEM is also used to observe the healed scratches on the coatings. After 96 hours of immersion in 3.5 wt% NaCl solution, the scratches in EP/TiO2/SiO2 self-healing coatings are found to be almost covered. The results confirm the effective self-healing ability of the EP/TiO2/SiO2 coating in which the released epoxy pre-polymer from nanotube lumen get contact with the amine hardener immobilized in mesoporous silica and cross-link to cover the scratch. Acknowledgment: This abstract was made possible by PDRA grant # PDRA1-1216-13014 from the Qatar national research fund (a member of Qatar foundation).qscienc

Advanced Thermal Energy Systems Based On Paraffin Waxes Applicable In Building Industry

Thermal energy storage systems are crucial for reducing dependency on fossil fuels and minimizing CO2 emissions. The building sector is a major sector responsible for producing high levels of CO2 in most countries (including Qatar). Thermal energy storage can be accomplished either by using sensible heat storage or latent heat storage components. Latent heat storage is more attractive than sensible heat storage because of its high storage density with smaller temperature fluctuations.[1] The materials able to utilize latent heat which can undergo phase changes (usually solid to liquid changes) at relatively low temperatures, while absorbing or releasing high amounts of energy are called phase change materials (PCMs).[2] Most promising PCMs are paraffin waxes which contain saturated hydrocarbon mixtures. They are frequently used due to their numerous advantages such as high latent heat of fusion, negligible super-cooling, and chemical inertness.[3,4] In this contribution, thermal properties of the PCMs based on linear low density polyethylene (LLDPE), different types of paraffin waxes with melting points, 25 oC and 42 oC, and expanded graphite (EG) were characterized by unique transient guarded hot plate technique (TGHPT), which allow to identified thermal properties of large sized samples[5] in comparison with commonly used ifferential scanning calorimetry (DSC). It was confirmed that all prepared PCMs were able to store and release huge amount of thermal energy. The 25 % increase of capacity to store and release a thermal energy was observed by PCMs contains paraffin wax with melting point 25 oC in comparison with paraffin wax with melting point 42 oC. Also reproducibility of storage and release heat of the PCMs by repeating of heating and cooling process has been demonstrated. Moreover, the increase of the EG content in the PCMs led to the increase of thermal conductivity from 0.24 W/mK for PCMs without EG to 1.3 W/mK for PCMs contain 15 wt.% of EG. Additionally, life cycle assessment of prepared PCMs has been demonstrated to identify the effects of these new materials on the Qatar environment. Our results indicate that using of PCMs in building industry can reduce emission of CO2 up to 10%.qscienc

Antimicrobial Modification of LDPE Using Non-thermal Plasma

Low-density polyethylene (LDPE) represents polymer having good chemical and physical characteristics for which it is widely used in many applications, such as biomedical and food packaging industry. This polymer excels by good transparency, flexibility, low weight and cost which makes it suitable material compared to non-polymer packaging materials. However, its hydrophobicity cause many limitations for antimicrobial activity which can result in absence of some characteristics required in food packaging applications. For that purpose, some researches have done experiments to modify the polymer surface to increase the surface free energy (hydrophilicity). This can be done by introducing some polar functional groups into the LDPE surface which will permit an increment of its surface free energy and so its wettability or adhesion without any disruption in its bulk properties [1]. One of the most preferable modification techniques is known as non-thermal radio-frequency discharge plasma, and it is preferred technique due to the ability to modify only thin surface layer leading to noticable improvement of the surface properties [2].Moreover, it represents environmentally friendly technique since it does not require the use of any hazardous chemicals or dangerous radiations and therefore non-thermal plasma is highly recommended for food packaging applications [1]. In addition, the surface modification of LDPE can lead to the enhancement of the antimicrobial activity, which was the main purpose of this research. Food packaging materials requires preventing any growth of bacteria, fungal, or any other microbial organisms for health and food safety. Some approved preservatives are commonly used directly in foods to preserve them form microorganisms growth and spoilage. Nowadays, some innovative ways are applied to graft acrylic acid on polymers surfaces [3] for biomedical applications to create an effective layer for an immobilization of antibacterial agents and this results in bacteria prevention on the LDPE surface. In this research, we focused on grafting of sorbic acid as one of the most commonly used preservatives in food and beverage for being safe, and effective in bacteria inhibition (whether pathogenic strains or spoilage kinds), molds, and yeasts [4]. It is also used in cosmetic industries since it has good compatibility with skin and it is easily usable [5]. For the potential enhancement of the antimicrobial efficiency, chitosan representing antimicrobial agent was used for the immobilization on sorbic acid created layer. Chitosan (a derivative of chitin polysaccharide) was chosen as a natural occurring antimicrobial agent (from crabs shrimps, and other sea shells [5]) that has strong and effective antimicrobial activity along with its nontoxicity, biofunctionality, biodegradability, and biocompatibility [6]. In this study, the LDPE surface was modified by several modification steps. The first step involved the modification of the LDPE surface by non-thermal radio-frequency discharge plasma as a radical graft initiator for the subsequently polymerization of sorbic acid containing double bonds. In the next step, grafting of sorbic acid was carried out immediately after plasma treatment allowing the interaction of plasma created radicals on LDPE surface with sorbic acid. Final step was focused on the immobilization of chitosan on grafted sorbic acid platform. Each modification step was analyzed by different analytical techniques and methods to obtain detailed information about the modification process. The surface parameters changes after modification of the LDPE surface, such as surface free energy (contact angles measurements), graft yield (gravimetric measurements) surface morphology (scanning electron microscopy and atomic force microscopy) and chemistry (Fourier transform infrared spectroscopy with attenuated total reflectance) were obtained allowing understanding the modification process.Qscienc

Curing enhancement and network effects in multi-walled carbon nanotube-filled vulcanized natural rubber: evidence for solvent sensing

Electrically and thermally conductive polymer composites offer great possibilities in various electronic fields because of their low weight and ease of processing. This paper addresses the curing behaviour and network properties of conducting multi-walled carbon nanotube (MWCNT)-reinforced natural rubber (NR) nanocomposites, emphasizing the sensing and diffusion performances. NR/MWCNT composites were prepared following a special master batch technique which allows the appropriate distribution of nanotubes within the elastomer. The sensing responses of the composites towards solvents were observed as variations in electrical resistance. Thermal resistance and glass transition behaviour were examined and correlated with the swelling measurements as evidence for solvent sensing. An optimum level of 3 phr of MWCNTs is understood to lead to the best properties for the NR/MWCNT composites. Finally, the structural morphology and interfacial interactions were found to have correlations with cure reactions, glass transition temperatures and sensing responses of all compositions.This work has been supported by the University Grants Commission-Department of Atomic Energy (UGC-DAE) Consortium for Scientific Research (project no. CRS-K-01/16), Government of India. The authors are also grateful to NPRP grant 6-282-2-119 from the Qatar National Research Fund (QNRF, a member of Qatar Foundation).Scopu