Over the last decade, 3D bioprinting has received immense attention from research communities for developing functional tissues. Thanks to the complexity of tissues, various bioprinting methods are exploited to figure...

In this study, the authors present a promising structure of shape-stabilized phase change materials (PCMs) with remarkable thermal energy storage capacity as core/shell phase change nanofibers. In this regard, solutions of polyethylene glycol (PEG) (as an important category of PCMs) and cellulose acetate (CA) were used as core and shell solutions, respectively. Electrospinning with a coaxial spinneret was performed, and nanofibers with the mean diameter of 545 nm under the controlled condition were produced. The formation of the core/shell structure was verified by scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, and transmission electron microscopy analyses. Moreover, thermogravimetric analysis results not only revealed the thermal stability improvement of PCM but also confirmed the presence of the core/shell structure too. Differential scanning calorimetry analysis was also performed to measure the thermal energy storage capacity of the core/shell phase change nanofibers before and after a thermal cyclic test. A major finding in the present study is that the thermal energy storage capacity of core/shell nanofibers after the thermal cyclic test is significantly higher (41.23 J/g) than initial one (14.77 J/g). Ultimately, it can be summarized that the special core/shell configuration provides desirable thermal stability and durability concurrently along with high thermal energy storage capacity. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2016, 35, 21534; View this article online at wileyonlinelibrary.com.

The main aim of the present study is to fabricate a high performance chitosan (CS)/polyvinyl alcohol (PVA) electrospun nanofibrous mat having a high content of CS, a desirable morphology (defect‐free structure) and a superfine diameter (approx. 100 nm). As electrospinning of constructions containing CS is known as a complex process, it is necessary to employ systematic control and optimisation of processes. In this regard, the controlling and optimisation of the processes were followed by two subsequent stages. In the first stage, morphology controlling parameters were investigated with respect to CS/PVA solution characteristics including CS concentration, solvent concentration and the content of the partner polymer (PVA). In the second stage, in order to attain the finest possible diameter, process modelling was carried out in terms of processing parameters (applied voltage, nozzle‐collector distance and feed rate) by using response surface methodology (RSM). According to the experimental results of the first stage, the best morphological structure containing the highest content of CS was obtained under 3% (w/v) of CS, concentrated acetic acid (90%) and 20% weight ratio of PVA. The significance of the applied model was confirmed by statistical approaches and the effect of the selected parameters on the diameter was studied. Experimentally, the finest diameter of 104 ± 18 nm was obtained under optimised processing parameters determined from the RSM technique. The experimental value of the nanofibre diameter was in close agreement with the predicted value in which the prediction error of the model was only 1.92% confirming the high reliability of the applied model.

Nature's materials have evolved over time to be able to respond to environmental stimuli by generating complex structures that can change their functions in response to distance, time, and direction of stimuli. A number of technical efforts are currently being made to improve printing resolution, shape fidelity, and printing speed to mimic the structural design of natural materials with three-dimensional (3D) printing. Unfortunately, this technology is limited by the fact that printed objects are static and cannot be reshaped dynamically in response to stimuli. In recent years, several smart materials have been developed that can undergo dynamic morphing in response to a stimulus, thus resolving this issue. Four-dimensional (4D) printing refers to a manufacturing process involving additive manufacturing, smart materials, and specific geometries. It has become an essential technology for biomedical engineering and has the potential to create a wide range of useful biomedical products. This paper will discuss the concept of 4D bioprinting and the recent developments in smart matrials, which can be actuated by different stimuli and be exploited to develop biomimetic materials and structures, with significant implications for pharmaceutics and biomedical research, as well as prospects for the future.

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