Smart Polymeric Nanocomposites: Synthesis and Applications

Smart polymer nanocomposites have gained a wide range of applications in diverse fields of science and technology as they confer the material's great processability and sensitivity to a wide range of environmental stimuli, including magnetic fields, light, temperature, pH, and electrolyte concentration. Incorporating functional or pristine nanoparticles/nanofillers into polymer matrices significantly modifies the properties of smart polymers, including their shape memory ability, selfhealing ability, pH sensitivity, thermal responsiveness, electro responsiveness, etc. These smart polymer nanocomposites find applicability in a wide range of applications such as sensors and actuators, drug delivery, self-healing structural material, smart textiles, smart electronics, aerospace applications, etc. This chapter seeks to address the importance, synthetic strategies, characterization techniques, and application of smart polymeric nanocomposites, summarizing an overview of the range of these materials.

Shape-memory polymer nanocomposites (SMPCs) are considered an advanced type of smart material, in which a specific stimulus influences the structure and thus memorizes their unique shape. SMPCs are widely used in high-performance water–vapor permeability materials, sensors and actuators, intelligent medical devices, morphing applications, and self-deployable structures in spacecraft. Modification of SMPCs overcomes the limitations of the pristine polymer and classical composites and can be counted among the main groups of smart materials. The performance of SMPCs under thermal, electric, optical, magnetic, and solvent stimuli can be improved further, potentially giving them a new range of uses. The most extensively researched SMPCs are those based on polyurethane, epoxy, polycaprolactam, polylactic acid, and polyvinyl alcohol; these also include those nanofillers based on carbon like CNTs, carbon black, graphene oxide, graphene nanoplatelets, graphene quantum dots, etc; metal oxides like Fe3O4 and TiO2 ; cellulose like cellulose nanocrystals and nanocellulose gel; and other nanomaterials such as nano-clay, TiN, AuNRs, organic nanoparticles, silica, sepiolite, silsesquioxane, and hydroxyapatite nanofillers. 

A drug delivery system (DDS) is the mode by which a drug is incorporated inside the body to produce therapeutic effects at the desired pathological site. Common DDSs include capsules and tablets (through the oral route), intravenous injections, nasal and ocular drops, transdermal patches, ointments, gels, etc. The important criteria for an active pharmaceutical ingredient (API) to be effective are that it should be precise and specific for the site of interest, with minimal side effects. This is where the formulation of the drug becomes very important. Regulating the entry of the drug into the body, followed by excellent distribution is necessary to elucidate a quick reaction. Hence, substantial consideration has to be given to the absorption, distribution, metabolism, and excretion (ADME) of the drug. Polymers have been integrated with APIs mostly as inert drug carriers to facilitate ADME, with the pre-requisites that the incorporated polymers must be biocompatible, have the ability to improve the drug stability and release kinetics, and avoid accumulation in the bloodstream. To further improve their efficacy, smart polymers have also come into play. They react to environmental stimuli like temperature, light, magnetic and electric fields, etc. Polymeric magnetic nanocomposites have shown great promise due to their quick response to magnetic cues and remote-control capabilities. The functionalization of both natural and synthetic biodegradable polymers with superparamagnetic iron oxide nanoparticles (SPIONs) results in DDSs where drugs can be remotely released in a controlled manner.

The growing population and depletion of fossil fuels not only hamper industrial system, but also affect everyday life. Rapid urbanization, change in human lifestyle and continuous production of toxic chemicals are directly increasing the amount of chemical waste, air/water polluting substances, which are causing hazardous affect to human health for which no adequate solution is available. Thus, developing new technologies has been a priority for researchers to resolve such issues. Currently available conventional technologies need further development or replacement with newer technologies. Substantial research efforts put forward different methods among which the use of smart polymer materials to reduce environmental problems is observed to be one of the best. Intelligent polymer materials which are strategically designed to conquer multiple properties in diverse conditions such as pH, temperature, stress or electric field made their presence necessary. The response rate of these materials against different environmental stimuli can be regulated by simple functionalization, leading to significant industrial and domestic applications. In this chapter, the readers will get an overview of the using smart materials for environmental issues, and possibilities of exploring further contributions for solving environmental challenges. 

Over the course of several decades, an interest in stimuli-responsive polymers has grown significantly, leading to extensive research in the development of environmentally responsive macromolecules, which can be exhibited as smart novel polymers. They have emerged as a promising platform for the advancement of drug delivery systems, enhancing the efficiency of therapeutic interventions, decreasing dosage frequency, minimizing possible adverse reactions and enhancing patient receptivity. In particular, these materials are responsive to very subtle changes in their environment. The environmental triggers for such transformations can include temperature change, shift in pH, variations of ionic strength, alterations in magnetic or electric fields, exposure to light, etc. They are said to be stimuli-responsive or intelligent polymers. Smart polymeric materials provide a versatile platform for drug delivery, enabling the controlled release of drugs in a stable and bioactive form. Additionally, the incorporation of nanocomposites contributes to increased drug bioavailability, enables targeted delivery through surface modification, and facilitates sustained release profiles. This chapter mainly provides detailed progress of smart polymeric composites or nanocomposites in the advancement of drug delivery applications. It also thoroughly covers several characteristics of these polymers categorized into different groups based on the stimulus type. The chapter aims to shed light on the evolving landscape of stimuli-responsive polymers and their pivotal role in shaping the future of drug delivery systems.

The process of water treatment is aimed at reducing or removing contaminants either chemical or biological in water for its utilization in safe drinking or any other essential purposes. Polymer nanocomposites that show responsiveness to external stimulants play a vital role in this process and purify water by actuating stimuli and by reviving the polymers successively. In response to environmental changes, these polymer nanocomposites can firmly undergo physical as well as chemical characteristic changes like shrinkage, and expansion, or show alterations in optical and electrical features on the basis of the induced stimulants. So far, numerous polymeric compounds that are sensitive to light, heat, CO2, etc. including prefabricated nano polymers, nanoparticles, etc. have been employed in water treatment. This book chapter emphasizes the efficacy of different smart polymeric nanocomposites in removing harmful pollutants including toxic ions, water-soluble ions, and harmful organic colorants in the water treatment process.

As technology globally embraces “smart” features, the polymer industry has acquired some advanced creations, including the development of polymer nanocomposites (PNCs) characterized by smart or intelligent properties. These smart features originate from the ability of these materials to respond to external cues such as pH, temperature, stress, light, electricity, magnetism, chemical environments, etc., facilitating their end use as flexible electronic or motion sensors, shape recognizable polymers, and self-healable materials. The sensitivity of the materials can be hierarchical within the polymer matrix or can be adventitiously introduced by the nanomaterials resulting in a combined system that reflects some additional characteristics. This chapter aims to highlight the various aspects of stimuli-responsive smart PNCs; including a brief overview of the fabrication methods of PNCs using different polymer matrices such as polyurethanes, polyesters, epoxy resins, hydrogels, etc., and various advanced metal- or carbon-based nanomaterials. The authentication methods as well as various sophisticated attributes of these materials are highlighted in the chapter. In turn, the numerous applications of these PNCs in real-world scenarios are also discussed briefly. Thus, the chapter represents an attempt to illustrate the fabrication methods of PNCs and their frontline applications that help in understanding their future possibilities in the area of material sciences.

Self-healing materials can autonomously repair damage or cracks through dynamic mechanisms. These are designed in such a way that they are associated with a self-repairing mechanism supported by grafted functional groups on the backbone of the polymer. Among the self-healable polymer materials, polymer nanocomposites have drawn much attention in recent years in the growing field of materials science. This chapter is based on the methods of synthesis of self-healing polymer nanocomposites and provides a comprehensive discussion of the applications of selfhealing polymer nanocomposites. Owing to their long-term stability and self-healing ability, self-healing polymer nanocomposites are considered one of the best composite materials among the emerging smart materials. Polymer nanocomposites are widely used in electronics, textiles, protective paint and coatings, biomedical, structural materials, etc. This chapter is based on the methods of synthesis of self-healing polymer nanocomposites and provides a comprehensive discussion of the applications of self-healing polymer nanocomposites.

Over the last few decades, polymers have gained lots of importance in everyday life due to their unique properties and wide range of applications. In recent years, biopolymers have received attention due to their features like biodegradability, biocompatibility, renewability, and inexpensiveness. They are also used as smart and active materials in medicine, the food industry, etc., as they exhibit responsiveness to factors like temperature, pH, humidity, light, electrical and magnetic fields, etc. Therefore, this chapter emphasizes an in-depth analysis of various techniques and methodologies employed in the preparation of smart biopolymers, their characterization, applications, and the challenges associated with their development and utilization.

The use of smart electronic devices incorporated with sensors has become an indispensable part of the modern lifestyle. Such devices utilize the concept of flexible electronic sensing. The growing demand for flexible sensors is understandable because of their versatile application in wearable devices and other fields like robotics in the health sector. Continuous healthcare monitoring and personalized health concerns necessitate the development of flexible wearable devices. Flexible sensors play a crucial role in fabricating such wearable devices. In the realm of this, polymer nanocomposites (PNCs) have emerged as primary materials in flexible sensor design owing to their unique combination of electrical and mechanical properties viz. conductivity, mechanical properties, and chemical resistance. This book chapter explores the role of polymer nanocomposites in flexible sensor development. Additionally, various fabrication methods for sensor design with PNCs have been discussed. Moreover, recent advancements in utilizing PNCs for various sensor types are highlighted, paving the way for a new generation of comfortable and reliable wearable health monitoring devices.