Smart Polymer Research Articles

Nano-Superfine Polymer Fibers by Electrospinning and Their Thermal-Switching Function

Intelligent or smart polymer materials are those which are either “active” or responsive to a variety of environmental stimuli, such as changes in pH, temperature, ionic strength or electric field, or the presence of a specific chemical substrate. A thermally sensitive polymer, poly(N-isopropylacrylamide) (PNIPAAm), has been of great interest because aqueous solutions of PNIPAAm undergo fast, reversible switching of hydrophilicity/hydrophobicity around 32 °C at their lower critical solution temperature (LCST) of about 29–38 °C (different with variations in their structure). PNIPAAm chains show an expanded conformation in water below the LCST because of strong hydration and change to the compact forms above the LCST by sudden dehydration; this is the reversible switching effect of hydrophilic to hydrophobic. These switchable materials may have wide applications in functional textiles, controllable drug release and special fibers. Electrospinning is a simple, convenient, and versatile technique for generating fibers with diameters that range from several micrometers to tens of nanometers. Herein, we report an electrospinning method to prepare nano PNIPAAm fiber and their thermal response was characterized. Based on the results, the diameters of the PNIPAAm nanofibers within the respective system were around 200 nm and beads-less; they were successfully prepared by an electrospinning method in all cases and the reversible switching with LCST (32 °C) feature was observed clearly in the fibers.

Synthesis and Characterization of Polymer Based Materials for Biomedical Applications

This study summarizes the many biomedical and biomechanical applications of polymer-based materials. The use of polymer-based materials in medical implants and equipment allows for the restoration or enhancement of function of damaged or disconnected tissues or organs, thereby benefiting patients. Appropriateness to the body is the most important factor to consider while choosing the biomaterial. For materials made of polymers to be useful over the long haul, they need to meet certain criteria. Polymers with shape memory and shape-changing capabilities are examples of this class of materials that can perform active movements triggered by external inputs. In the recent two decades, these materials have garnered a lot of attention in the biomedical field, particularly for use in minimally invasive procedures. This is why polymeric biomaterials have been and will continue to be crucial to the development of innovative antibacterial technologies for use in biologic applications. Topics covered in this study include biomolecule conjugates of smart polymers on surfaces, various forms of smart polymeric biomaterials, and the characteristics and applications of smart polymers. This page provides a synopsis of the three main categories of polymeric-based materials, outlining their respective areas of use.

Poly(N‐isopropylacrylamide)‐Based Polymers: Recent Overview for the Development of Temperature‐Responsive Drug Delivery and Biomedical Applications

AbstractTemperature is a widely incorporated stimulus in pharmaceutical applications because of its efficiency as a therapeutic medium; thus, substantial evidence on temperature‐responsive polymer applications is reported. Poly(N‐isopropylacrylamide) (PNIPAAm) is a well‐established, temperature‐responsive polymer that exhibits a low critical solution temperature (LCST) at ≈ 32°C, which is close to physiological temperature. Hence, they are widely used in various pharmaceutical applications, such as drug delivery with nanocarriers and thermogels. Varying the LCST for different applications can be achieved by copolymerization with other hydrophobic or hydrophilic molecules, making it a favorable smart polymer. PNIPAAm is reported to enhance drug delivery by incorporation with nanocarriers and to facilitate prolonged drug delivery, thereby avoiding the burst release of drugs in temperature‐responsive hydrogels. The application of PNIPAAm is not limited to drug delivery, and it is also applied in biomedical applications such as chromatography systems and cell culture applications, where its incorporation in cell culture media enhances cell production. The unique and versatile properties of PNIPAAm render it a promising smart polymer for various functional applications. Hence, this review focuses on the diverse applications of PNIPAAm.

Smart Polymers for Soft Materials: From Solution Processing to Organic Solids.

Polymeric materials are ubiquitous in our everyday life, where they find a broad range of uses-spanning across common household items to advanced materials for modern technologies. In the context of the latter, so called "smart polymers" have received a lot of attention. These systems are soluble in water below their lower critical solution temperature Tℓ and often exhibit counterintuitive solvation behavior in mixed solvents. A polymer is known as smart-responsive when a slight change in external stimuli can significantly change its structure, functionm and stability. The interplay of different interactions, especially hydrogen bonds, can also be used for the design of lightweight high-performance organic solids with tunable properties. Here, a general scheme for establishing a structure-property relationship is a challenge using the conventional simulation techniques and also in standard experiments. From the theoretical side, a broad range of all-atom, multiscale, generic, and analytical techniques have been developed linking monomer level interaction details with macroscopic material properties. In this review, we briefly summarize the recent developments in the field of smart polymers, together with complementary experiments. For this purpose, we will specifically discuss the following: (1) the solution processing of responsive polymers and (2) their use in organic solids, with a goal to provide a microscopic understanding that may be used as a guiding tool for future experiments and/or simulations regarding designing advanced functional materials.

H-bond-type thermo-responsive schizophrenic copolymers: The phase transition correlation with their parent polymers and the improved protein co-assembly ability

Schizophrenic copolymers are one type of the popular smart polymers that show invertible colloidal structures in response to temperature stimulus. However, the lack of principles to predict the phase transition temperature of a schizophrenic copolymer from its corresponding parent thermo-responsive polymers limits their development. Additionally, studies on their applications remain scarce. Herein, a series of schizophrenic copolymers were synthesized by polymerization of a RAFT-made polymer precursor poly(acrylamide-co-N-acryloxysuccinimide-co-acrylic acid) (P(AAm-co-NAS-co-AAc)) with the mixture of N-isopropylmethacrylamide (NIPAm) and acrylamide (AAm) in varying molar ratios. In aqueous solution, the block P(AAm-co-NAS-co-AAc) and the block poly(NIPAm-co-AAm) exhibited upper and lower critical solution temperature (UCST and LCST) behavior, respectively. The schizophrenic copolymers featured either UCST-LCST, LCST-UCST, or only LCST thermo-responsive transition. A preliminary correlation of phase transition between the schizophrenic copolymers and their parent polymers was summarized. Furthermore, the co-assembly of the schizophrenic copolymers and proteins were conducted and the kinetics of protein loading and protein activity were investigated, which showed that the schizophrenic copolymers were efficient platforms for protein co-assembly with ultra-high protein loading while preserving the protein bioactivities. Additionally, all the materials were non-toxic towards NIH 3T3 and MCF-7 cells. This work offers the prospects of the schizophrenic polymers in soft colloidal and assembly systems, particularly in guiding the design of new materials and their use in biomedical applications.

Advances in Material Modification with Smart Functional Polymers for Combating Biofilms in Biomedical Applications.

Biofilms as living microorganism communities are found anywhere, and for the healthcare sector, these constitute a threat and allied mechanism for health-associated or nosocomial infections. This review states the basis of biofilms and their formation. It focuses on their relevance for the biomedical sector, generalities, and the major advances in modified or new synthesized materials to prevent or control biofilm formation in biomedicine. Biofilm is conceptualized as an aggregate of cells highly communicated in an extracellular matrix, which the formation obeys to molecular and genetic basis. The biofilm offers protection to microorganisms from unfavorable environmental conditions. The most frequent genera of microorganisms forming biofilms and reported in infections are Staphylococcus spp., Escherichia spp., and Candida spp. in implants, heart valves, catheters, medical devices, and prostheses. During the last decade, biofilms have been most commonly related to health-associated infections and deaths in Europe, the United States, and Mexico. Smart, functional polymers are materials capable of responding to diverse stimuli. These represent a strategy to fight against biofilms through the modification or synthesis of new materials. Polypropylene and poly-N-isopropyl acrylamide were used enough in the literature analysis performed. Even smart polymers serve as delivery systems for other substances, such as antibiotics, for biofilm control.

Effectiveness of Mesoporous Silica Nanoparticles Functionalized with Benzoyl Chloride in pH-Responsive Anticorrosion Polymer Coatings.

Smart polymer coatings embedding stimuli-responsive corrosion inhibitor nanocarriers are commonly exploited, in the literature, for the development of high-performance active coatings. In this work, high-surface-area amino-functionalized mesoporous silica nanoparticles (MSN-NH2) were developed with a one-step synthesis process and then functionalized with benzoyl chloride (MSN-BC) through a reaction with amino groups. MSN-BC are able to release benzoic acid (BA) in acid and alkaline conditions as a result of the hydrolysis of the pH-sensitive amide bond. MSN-BC were embedded in polymer coatings to exploit the pH-dependent release of corrosion-inhibiting BA. After an in-depth characterization of the developed functional nanoparticles and of their pH-dependent release kinetics of BA, MSN-BC were embedded in an acrylic matrix, realizing coatings for the corrosion protection of aluminum AA2024 alloys. Results demonstrate the effectiveness of the nanoparticles' porous structure for a high loading of the anticorrosive active agent BA and the long-lasting efficiency of the coating for the corrosion protection of aluminum alloys, as validated by morphological and electrochemical impedance spectroscopy (EIS) measurements. EIS experiments were carried out with up to 21 days of exposure to a corrosive environment, revealing the potentialities of the acrylic coatings embedding MSN-BC for the protection of aluminum alloys.

Elastocaloric effect of shape memory polymers in elastic response regime

Solid-state cooling/heating technology based on the elastocaloric effect is one of the promising alternatives to vapor compression systems. Large elastocaloric temperature modulation is often generated through the non-linear strain-induced structural transition by applying large strain and/or stress to ferroelastic materials. Recently, an unconventional approach to expand the application possibilities of the elastocaloric effect was demonstrated by processing elastocaloric materials into kirigami structures, which was inspired by the art of paper cutting. Using this approach, only a small stretch of processed conventional plastics can locally provide more efficient performance of elastocaloric temperature modulation than that of ferroelastic materials. To further improve such a unique functionality, it is necessary to find plastic or polymeric materials showing large elastocaloric effects in the linear elastic response regime that can be driven by a MPa-order weak stress application, where the non-linear structural transition is irrelevant. In this work, by means of a recently developed measurement technique for the elastocaloric effect based on the lock-in thermography, we found that shape memory polymers (SMPs) show prominent performance for elastocaloric temperature modulation that is larger than conventional plastics. SMPs enable the control of crystallinity by changing the cross-linking agents, melting temperature by changing the degree of polymerization, and orientation of the polymer chain segment by the shape memory effect. By utilizing the unique properties of SMPs, we manipulated their elastocaloric performance. The experimental results reported here will highlight the potential of smart polymers for flexible and durable elastocaloric applications.

Recent trends in thermo‐responsive elastomeric shape memory polymer nanocomposites

AbstractShape memory polymers (SMPs) are polymeric smart materials, a class of stimuli‐responsive polymers that can return to their initial shape from a programmed temporary shape under the application of external stimuli, such as light, heat, magnetism, and electricity. Because of these unique features, SMPs can find applications in many fields, like aerospace, biomedical devices, flexible electronics, soft robotics, shape memory arrays, and 4D printing. The comparatively low density, low cost, easy biodegradability, and biocompatibility make SMPs a better candidate for shape memory applications. Among them, thermo‐responsive SMPs can revert to their permanent shape depending on a temperature greater than their polymer transition temperature. Thermo‐responsive SMPs combine semi‐crystalline or elastomeric polymers with improved mechanical and electrical properties. Integrating nanofillers into the polymer elastomer matrices can further enhance these properties, forming shape‐memory polymer nanocomposites (SMPNCs). This review focuses on the basics, design, and classifications of thermo‐responsive SMPs and the characteristics of elastomers and blends of polymers used. Incorporating various nanofillers to get SMPNCs to have improved properties over SMPs is also presented. The importance of Tg (glass transition temperature) and Tm (melting temperature) based SMPs and SMPNCs, various elastomers used, and the methods for preparation like solution casting, melt compounding, in situ polymerization, and their possible future applications are also discussed.

Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

AbstractAggregation‐induced emission (AIE) luminogens are attractive dyes to probe polymer properties that depend on changes in chain mobility and free volume. When embedded in polymers the restriction of intramolecular motion (RIM) can lead to their photoluminescence quantum yield (PLQY) strong enhancement if local microviscosity increases (lowering of chain mobility and free volume). Nonetheless, measuring PLQY during stimuli, i.e. heat or mechanical stress, is technically challenging; thus, emission intensity is commonly used instead, assuming its direct correlation with the PLQY. Here, by using fluorescence lifetime as an absolute fluorescence parameter, it is demonstrated that this assumption can be invalid in many commonly encountered conditions. To this aim, different polymers are loaded with tetraphenylenethylene (TPE) and characterized during the application of thermal and mechanical stress and physical aging. Under these conditions, polymer matrix transparency variation is observed, possibly due to local changes in refractive index and to the formation of microfractures. By combining different characterization techniques, it is proved that scattering can affect the apparent emission intensity, while lifetime measurements can be used to ascertain whether the observed phenomenon is due to modifications of the photophysical properties of AIE dyes (RIM effect) or to alterations in the matrix optical properties.

High‐performance piezoelectric yarns for artificial intelligence‐enabled wearable sensing and classification

AbstractPiezoelectric polymer fibers offer a fundamental element in intelligent fabrics with their shape adaptability and energy‐conversion capability for wearable activity and health monitoring applications. Nonetheless, realizing high‐performance smart polymer fibers faces a technical challenge due to the relatively low piezoelectric performance. Here, we demonstrate high‐performance piezoelectric yarns simultaneously equipped with structural robustness and mechanical flexibility. The key to substantially enhanced piezoelectric performance is promoting the electroactive β‐phase formation during electrospinning via adding an adequate amount of barium titanate (BaTiO3) nanoparticles into the poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)). When transformed into a yarn structure by twisting the electrospun mats, the BaTiO3‐doped P(VDF‐TrFE) fibers become mechanically strengthened with significantly improved elastic modulus and ductility. Owing to the tailored convolution neural network algorithms architected for classification, the as‐developed BaTiO3‐doped piezo‐yarn device woven into a cotton fabric exhibits monitoring and identifying capabilities for body signals during seven human motion activities with a high accuracy of 99.6%.image

Nano Drug Delivery Systems: A Mini-review

Abstract: Medical nanotechnology is surfacing as a challenging arena covering new biomedical applications, such as drug delivery, treatment, nano diagnosis, controlled drug release, regenerative medicine, and disease prevention. The recent developments in the field of Nanotechnology have enabled the nanostructures to overcome the problems associated with drug delivery making them the promising agents for site-specific drug delivery with reduced side effects and the best treatment outcome. These nanodrug delivery systems are designed in such a way that they can breach the biological barrier and deliver the drug in a site-specific manner. They enhance the effectiveness of drugs by increasing the stability and water solubility of drugs and by increasing the rate at which these nano drug complexes are taken up by the cells and tissues. Dendrimers, nanocrystals, nano-polymer NPs, and liposomes are futuristic nano-based drug delivery systems. Smart polymers are future drug-delivery systems with cutting-edge precise technology that are employed in effective cellular targeting based on temperature, pH, photoresponsive, conductive and magnetic responsive smart polymers. This review provides a comprehensive view of various nanostructures and their application in drug delivery.

Multimaterial 3D printing of self-assembling smart thermo-responsive polymers into 4D printed objects: A review

Multimaterial 3D printing of self-assembling smart thermo-responsive polymers into 4D printed objects: A review

Reproducible, self-healable polyurethane composite networks with high toughness, florescence and water-insensitivity

For self-healing polymers, the poor elastic properties and low self-healing efficiency have limited their applications, smart polymer systems adaptable to complex environment have became a hot topic. To address this issue, in this study, a series of polyurethane composite networks were developed, using poly(ɛ-caprolactone) (PCL) and polytetramethylene ether glycol (PTMG) as the soft segment, isophorone diisocyanate (IPDI) as the hard segment, with the incorporation of florescent SrAl2O4: Eu2+, Dy3+ phosphors. The chemically crosslinked networks were investigated by differential scanning calorimetry (DSC), X-ray scattering (XRD), and dynamic mechanical analysis (DMA) on their crystalline properties. Atomic force microscopy (AFM) confirmed the micro-phase separation structures, where soft segments facilitated self-healing and the hard segments enhanced rigidity. Scanning electron microscopy (SEM) and optical microscopy presented highly efficient and rapid healing could be achieved. The materials emitted an intense green light in UV without significant fluorescent intensity reduction in water emersion. Additionally, the synergistic effect of transesterification provided the composite networks reproducibility for recycling use.

Multiple stimuli-switchable electrocatalysis and logic gates of l-cysteine based on P(DEA–co-VPBA) hydrogel films

In this work, poly(N',N-diethylacrylamide-co-4-vinylphenylboronic acid) (P(DEA-co-VPBA)) hydrogel films were successfully assembled on the pyrolytic graphite (PG) electrode by a simple radical polymerization. Reversible thermal, glucose and pH-triggered electrochemical reactions were obtained in the presence of 1,1′-ferrocene dicarboxylic acid (FDA) with electro-redox properties. The thermal response performances of the thin-film electrode were attributed to the PDEA component, the sensitive behaviors of glucose were ascribed to the VPBA component, and the sensitive behaviors of pH were affected by PDEA and VPBA. The electrocatalytic oxidation of l-cysteine by FDA on the hydrogel film electrodes significantly enhanced the difference between the on and off states of the multi-response cyclic voltammetry (CV) signals. This smart polymer hydrogel film electrode with amplified signals could be further used to realize a 4-input/9-output binary logic circuit, which was constructed with temperature, glucose, pH, and cysteine as inputs and different levels of Ipa and Ipc responses as outputs. Furthermore, a 2-to-4 decoder, a 4-to-2 encoder, and a 4-input keypad lock were built on the same platform. This polymer electrocatalysis system provides a novel idea for constructing complex biological computing systems.

Smart Materials with Dual Functionality: Repeatable Damage-Detection and Self-Healing.

Polymer materials are extensively used because of their excellent performance; however, when used for a long time, they break and eventually lose their original properties. Thus, smart polymer materials that can repeatedly detect and repair damage must be urgently developed to increase their durability and lifespan. In this study, a smart material with dual functionality (damage-detection and self-healing) is developed via a facile method of incorporating spiropyran (SP) beads, which exhibit changes in color and fluorescence when damaged, into a Diels-Alder (DA)-based self-healing matrix. When polyurethane (PU) is added to the DA-based matrix, the dual functionality exhibits a strong dependence on the proportion of PU. Because the PU ratio affects two opposing factors (damaged area and load-bearing capacity), the damage-detecting ability exhibits the best performance at 40 wt % PU, where both factors are optimized. A high healing efficiency of 96% is achieved via a dynamic DA reaction. In particular, the repeatability of the dual-functionality is successfully attained through the reversibility of the SP beads and DA networks, where the detection and healing efficiencies are reduced by 15 and 23%, respectively, after 10 cycles. Furthermore, the reprocessed fractured specimens exhibit excellent recyclability.

Hollow microgels and their hybrids: classification, synthesis, characterization, properties and applications

Abstract Hollow microgels and their hybrids have gained much attention in modern-day research because of their fascinating properties and potential applications. This article gives classification, preparation methods, properties and applications of hollow microgels and their hybrids in modern research. Some of the hollow microgels and their hybrids respond to change in specific environmental stimuli like pH, ionic strength and temperature of the medium. They are called smart polymer hollow microgels and smart hybrid microgels, respectively. This peculiar behaviour makes them a suitable candidate for their use in drug delivery, sensing, catalysis and many other fields. This review represents the current advancement along with future perspectives and suggestions for further research in this particular area.

Smart, sustainable and controllable bio-based shape memory polymer composite fabrication

Smart, sustainable and controllable bio-based shape memory polymer composite fabrication

A smart coating with integrated physical antimicrobial and strain-mapping functionalities for orthopedic implants.

The prevalence of orthopedic implants is increasing with an aging population. These patients are vulnerable to risks from periprosthetic infections and instrument failures. Here, we present a dual-functional smart polymer foil coating compatible with commercial orthopedic implants to address both septic and aseptic failures. Its outer surface features optimum bioinspired mechano-bactericidal nanostructures, capable of killing a wide spectrum of attached pathogens through a physical process to reduce the risk of bacterial infection, without directly releasing any chemicals or harming mammalian cells. On its inner surface in contact with the implant, an array of strain gauges with multiplexing transistors, built on single-crystalline silicon nanomembranes, is incorporated to map the strain experienced by the implant with high sensitivity and spatial resolution, providing information about bone-implant biomechanics for early diagnosis to minimize the probability of catastrophic instrument failures. Their multimodal functionalities, performance, biocompatibility, and stability are authenticated in sheep posterolateral fusion model and rodent implant infection model.

APPLİCATİON OF THE SİLK SMART MATERİALS İN BİOMEDİCAL

The development of natural polymers into intelligent materials with exceptional functions and properties always involves the integration of both organic and inorganic components. Scientists would use ideas from nature to create the newest biomedical technology. Scientists have become more interested in the improvement of composite materials during the past few decades . A family of polymers known as "smart polymer materials" react to their surroundings and change their. Therefore, stimulus responsive polymers are those with specific physical or chemical properties. Depending on the physical state of polymer chains, the stimuli may include pH, salt, temperature, electric, magnetic, or optical field. These factors might cause a macroscopic response in materials. For tissue engineering, drug administration, gene therapy, and diagnostics, these intelligent biomaterial polymers serve as a "on-off" switch. This chapter's goal is to introduce readers to the fascinating world of silk-based smart polymers by outlining the present state of research in the subject as well as its potential for use in medical applications. Keywords: smart materials, biomedical technology, natural polymers