Correlation between Nanoscale Elasticity, Semiconductivity, and Structural Order in Functionalized Polyaniline Thin Films

ІННОВАЦІЙНИЙ МЕТОД ЗАКРІПЛЕННЯ АЛМАЗНИХ ЗЕРЕН ДЛЯ УДОСКОНАЛЕННЯ ВИРОБНИЦТВА АЛМАЗНО-АБРАЗИВНИХ ІНСТРУМЕНТІВ

Вступ. За поєднанням високої точності обробки, продуктивності та можливості керування формою ріжучого профілю інструменту одношаровий абразивний інструмент має потенційну перевагу над іншими типами абразивних інструментів.Проблематика. Інструменти для прецизійного формоутворення деталей з високолегованих та жароміцних сталей є найбільш складними у виготовленні, економічно привабливими та критично важливими у сегменті інструментального виробництва. Виготовлення таких інструментів шляхом електрохімічного зарощування зерен алмазу металомна електропровідному корпусі відоме давно. Проте їх виготовлення за найкращими традиційними технологіями стикається із значними складнощами і потенціал таких алмазних виробів реалізується лише на 15—20 %.Мета. Удосконалення виробництва високоточного абразивного інструменту для обробки високолегованих та жароміцних сталей на сучасних оброблювальних центрах з числовим програмним керуванням.Матеріали й методи. Електрохімічне осадження покриттів проводили за оригінальною методикою. Мікроструктуру одержаних покриттів вивчали за допомогою скануючої електронної мікроскопії та рентгенівської дифрактометрії. Міцність утримання алмазних зерен у зв’язці вимірювали на розробленому пристрої.Результати. Запропоновано технологію виготовлення високоточних одношарових шліфувальних інструментів шляхом електрохімічного осадження металу. Показано, що між сталевим корпусом та шаром металу, що утримує алмазні зерна, створюється тонкий шар електропровідного полімеру з високою адгезією як до корпусу, так і до металу. Це зебезпечує міцне утримання абразивних зерен та високий ступінь рівномірності їх розміщення, що наразі є недосяжним для традиційних технологій, а також посилює стійкість гострих кромок профілю як найбільш вразливих ділянок інструменту.Висновки. Вперше створено та апробовано новий клас високоточного профільного інструменту, який дає можливість імпортозаміщення на машинобудівних підприємствах України, а також виходу на зовнішні ринки.

Polyaniline/Biopolymer Composite Systems for Humidity Sensor Applications: A Review

The development of polyaniline (PANI)/biomaterial composites as humidity sensor materials represents an emerging area of advanced materials with promising applications. The increasing attention to biopolymer materials as desiccants for humidity sensor components can be explained by their sustainability and propensity to absorb water. This review represents a literature survey, covering the last decade, which is focused on the interrelationship between the core properties and moisture responsiveness of multicomponent polymer/biomaterial composites. This contribution provides an overview of humidity-sensing materials and the corresponding sensors that emphasize the resistive (impedance) type of PANI devices. The key physicochemical properties that affect moisture sensitivity include the following: swelling, water vapor adsorption capacity, porosity, electrical conductivity, and enthalpies of adsorption and vaporization. Some key features of humidity-sensing materials involve the response time, recovery time, and hysteresis error. This work presents a discussion on various types of humidity-responsive composite materials that contain PANI and biopolymers, such as cellulose, chitosan and structurally related systems, along with a brief overview of carbonaceous and ceramic materials. The effect of additive components, such as polyvinyl alcohol (PVA), for film fabrication and their adsorption properties are also discussed. The mechanisms of hydration and proton transfer, as well as the relationship with conductivity is discussed. The literature survey on hydration reveals that the textural properties (surface area and pore structure) of a material, along with the hydrophile-lipophile balance (HLB) play a crucial role. The role of HLB is important in PANI/biopolymer materials for understanding hydration phenomena and hydrophobic effects. Fundamental aspects of hydration studies that are relevant to humidity sensor materials are reviewed. The experimental design of humidity sensor materials is described, and their relevant physicochemical characterization methods are covered, along with some perspectives on future directions in research on PANI-based humidity sensors.

Conducting polymers: a comprehensive review on recent advances in synthesis, properties and applications

Conducting polymers are extensively studied due to their outstanding properties, including tunable electrical property, optical and high mechanical properties, easy synthesis and effortless fabrication and high environmental stability over conventional inorganic materials. Although conducting polymers have a lot of limitations in their pristine form, hybridization with other materials overcomes these limitations. The synergetic effects of conducting polymer composites give them wide applications in electrical, electronics and optoelectronic fields. An in-depth analysis of composites of conducting polymers with carbonaceous materials, metal oxides, transition metals and transition metal dichalcogenides etc. is used to study them effectively. Here in this review we seek to describe the transport models which help to explain the conduction mechanism, relevant synthesis approaches, and physical properties, including electrical, optical and mechanical properties. Recent developments in their applications in the fields of energy storage, photocatalysis, anti-corrosion coatings, biomedical applications and sensing applications are also explained. Structural properties play an important role in the performance of the composites.

Revealing the Surface Effect on Gas Transport and Mechanical Properties in Nonporous Polymeric Membranes in Terms of Surface Free Energy

The contribution of surface roughness of nonporous polymeric membranes to their gas separation and mechanical properties was studied in terms of surface free energy. The membranes samples were prepared based on glassy polymers with different chain rigidity, namely polysulfone (PSU), cellulose triacetate (CTA), and poly(vinyl alcohol) (PVA). The results were obtained by atomic force and scanning electron microscopy (AFM and SEM) with individual gas permeation, wettability, and mechanical testing. The specific surface free energy (as well as its polar and dispersive components) for the polymers was calculated by the Owens-Wendt method. It was proven that the surface roughness of the polymer membranes affects both energy components; however, the degree of this influence depends on the chemical nature of the corresponding polymer. Moreover, it was assumed that the dispersive energy component is inversely correlated with any gases' total permeability. In contrast, the polar one is inversely correlated with the permeability by gases with the ability for site-specific interactions. The gas separation results confirmed this assumption. It was also shown that the mechanical properties of the polymer membranes are also influenced by the surface energy, namely, its dispersive component.

Solution-State Long-Range Molecular Ordering in Poly(3-hexylthiophene)

A blend of poly(3-hexylthiophene) (P3HT) and poly(n-hexyl isocyanate-block-2-vinylpyridine) (PHIC-b-P2VP) in a common solvent shows the formation of long-range (micrometer-scale) nanowires of P3HT through hydrophobic interactions between the hexyl arms of P3HT and PHIC in a parallel way, which increase the planarity that leads to the generation of vibration bands with a lower free exciton bandwidth (W = 67 meV) in the solution state, which is further decreased to 9 meV after 48 h annealing of the blend film. The resulting nanowires of the P3HT show a 100-fold increase in current in comparison to pristine P3HT.

Recognizing conductive islands in polymeric redox surfaces using electrochemical-coupled vibrational spectromicroscopy

We introduce a set up by coupling multiplex FTIR microscopy to electrochemistry through a home-made spectroelectrochemical cell to observe real time changes in the electronic states of polymeric islands by monitoring the oxidation states of polyaniline (PANI). The resultant technique, called electrochemical-coupled vibrational spectromicroscopy (EVSM), enables the measurement of structural changes in the conductive islands of PANI with the spatial resolution as high as 2.5 μm. Unique 2D and 3D chemical maps obtained by the integration of the spectral bands in the subtractively normalized interfacial infrared (SNIFTIR) spectra reveal electrochemical heterogeneity, showing promising topological properties control for conducting polymer-based electronic devices.