Reactive and Functional Polymers Volume Three

Reactive and functional polymers have allowed the development of advanced materials such as active and intelligent polymers, electroactive polymers, multi-response polymers, shape memory polymers, stimuli responsive polymers, etc. for different applications. With this chapter, we open these main topics, which will be analyzed in this volume.

Nowadays, the use of polymer films for flexible packaging has gained a widespread importance because of their easy processing, good final properties, light weight and low relative cost. In order to fulfill the needs of increasingly demanding consumers with respect to the quality of packaged products, additional capabilities must be incorporated into packaging. In this sense, academic and industrial efforts have focused on new technologies that provide a complementary functionality to the packaging performance. These emerging developments involve active and intelligent packaging, which can attract to consumers, improve product quality and/or balance any detrimental effect. In this context, the use of nanoparticle (NP)-modified polyolefins, either in bulk (nanocomposites) or on the surface, allows the inclusion of specific functionalities. These new capabilities enable obtaining active packaging according to the requirements of the product. The aim of this chapter was to analyze the aforementioned approaches for the development of active films by incorporating antibacterial, antifungal and/or repellent functionalities. Currently, several sustainable developments of this type of active films are based on commodity thermoplastics such as poly(ethylene) and poly(propylene). These materials, modified by the incorporation of organic and inorganic NPs, are promising candidates, since their final properties can be tailored for packaging application.

Shape memory polyurethanes (PUs) have the ability to response to external stimuli such as electricity, heat, light, moisture, pH, etc. Among PUs, segmented PU possesses high recoverable strain, tunable physical properties, wide range of glass transition temperature and an easily controllable softening phenomenon. Shape memory nanocomposites have been synthesized from PU containing carbon nanoparticles (C NPs) such as fullerene, graphene, multi-walled carbon nanotube, nanodiamond, etc. The surface modification of C NPs can improve the mechanical, shape memory, strength and thermal properties of the nanocomposite. Shape memory PU and nanocomposite have recently been aroused by research interest due their versatile applications. This chapter basically highlights the design of shape memory PU and their C NP-loaded nanocomposites, the principle of shape memory behavior of these polymers and their applications with future directions.

Molecularly imprinted polymers (MIP) have attracted considerable attention as smart materials so far. They are known to be capable of imitating the recognition event that happens biologically in living organisms and, in this light, they have noteworthy been used as substitutes of natural receptors. Traditionally, imprinted polymers have been developed by bulk free radical polymerization (FRP), obtaining rigid polymers, which are lately ground to get fine particles. Bulk synthesis of imprinted polymers was substituted by other polymerization approaches in order to overcome typical drawbacks associated with bulk MIPs. Recently, new polymer syntheses have emerged such as solid phase imprinting which have allowed for obtaining smart materials with higher affinity for the target ligand, achieving binding affinities similar or even higher than natural receptors. Materials obtained this way are known as plastic antibodies. This chapter focuses on recent advances on imprinted polymers as potential substitutes of natural receptors, emphasizing on new synthesis strategies and novel imprinted nanomaterials.

Circularly polarized luminescence (CPL) reflects the chiroptical properties at the lowest excited state of the emitter. Thus, a wide range of applicability of these materials is in order, e.g. optical sensing. Polymeric systems possess complex vibronic states in ground states and excited states, which presents a challenge to carefully design and amplify the CPL signals from functional polymers. In this chapter, the fundamentals of CPL are briefly introduced followed by a review of several π-conjugated and coordination polymers exhibiting CPL signals. In addition, the chiroptical properties will be discussed based on the CPL signals of the polymer materials.

The use of polymeric materials in biomedical fields, especially in dentistry, has increased due to their improved biological and mechanical properties, ease in processing, low production cost and wide applicability. The additive processing technology, allows to obtain complex shapes with a high accuracy by manufacturing the final 3D object, based on a computer-aided design (CAD) file and layer-by-layer (L-b-L) deposition, with the use of liquid- or solid-based polymers, become of great interest in prosthetic dentistry and bone replacement. The aim of this chapter was to present an overview of the best polymeric three-dimensional (3D) printed materials used in oral and maxillofacial surgery, orthodontics, restorative dentistry, as well as to foresee future trends for the development of new composite materials and technologies for mimicking clinical environment.

Polymers offer several appealing features, mainly because of their adjustable architecture, but they suffer from low thermal stability and high flammability. Reactive and functional polymers are known for superior properties compared to the corresponding pure polymers, but their thermal stability and decomposition mechanisms have not systematically been addressed in the literature. Typically, different macromolecular natures in these polymer families give rise to a dissimilar degradation behavior, especially for biodegradable polymers. The additional reactivity resulting from additives or the second polymer in blends and nanocomposites should also be considered in the stability of the polymers. Taking into account such complexities, this chapter describes the state of fire behavior of reactive polymers.