Micro- and Nano-Fabrication Approaches for Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Analysis and Characterization".

Deadline for manuscript submissions: closed (30 April 2020) | Viewed by 26348

Special Issue Editors

Department of Materials, Loughborough University, Loughborough, UK
Interests: biocompatible and natural polymers for regenerative medicine; nanofibrous wound dressings with antimicrobial activity and enhanced cell proliferation; functional nanocomposites with controlled surface and mechanical properties; microfluidic devices for biological assays and food safety; nanofabrication approaches for polymers
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Guest Editor
Department of Materials, Loughborough University, LE11 Loughborough, UK
Interests: polymer self-assembly; polymer colloids; stimuli-reponsive polymers; biopolymers; bio-based nanocomposite materials

Special Issue Information

Dear Colleagues,

Techniques to process polymers at micro- and nano-scale have a great impact on a wide variety of sectors, including electronic, food, energy, pharmaceutical and biomedical industry. The main advantage of using micro- and nano-structured materials, instead of their macroscale counterparts, is their high exposed surface area, which enhances the interaction with the surrounding environment and hence make them more efficient. Manipulation of polymer structures on the micro- and nano- scale allows for tailoring of material properties for advanced applications.
This Special Issue focuses on new advances on micro- and nano-fabrication technologies for natural and synthetic polymers. Topics of interest are, but not limited to: (i) Lithographic procedures to structure surfaces for guiding cell attachment, proliferation and differentiation; (ii) Patterning methods to mimic the complex hierarchical architecture of natural systems and achieve self-cleaning, water/oil repellent, anti-icing, antifouling/antibacterial surfaces; (iii) Fabrication approaches for miniaturised optoelectronic and energy devices, wearable electronics, lab-on-chip systems and biosensors; (iv) Electrospinning and electrospraying of fibrous membranes to be applied in filtration and thermal insulation, sensors, scaffolds for tissue engineering, drug delivery systems, protective clothing, conducting and energy storage devices; (v) Chemical and physical methods to produce nano- and micro-particles, nanowires, nanotubes, quantum dots, etc. for cosmetics, food science, batteries, paints, inks, biotechnology, optoelectronics, composites;  (vi) Porous polymers, with controlled porosity on the nano- or micro-scale, i.e. micro-, meso- or macro-pores, for gas sorption, separation, water treatment, catalysis, energy and biomedical applications; (vii) Self-assembly of polymers to fabricate nano- or micro-particles, including hierarchical organisation of polymer structure.

Dr. Elisa Mele
Dr. Fiona Hatton
Guest Editors

Manuscript Submission Information

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Keywords

  • Surface patterning
  • Soft lithography
  • Electrospinning and electrospraying
  • Hot embossing
  • Micro- and nano-fluidics
  • Phase separation methods
  • Self-assembly
  • Rapid prototyping at micro/nanoscale
  • Colloidal chemistry
  • Porous polymers
  • Hierarchical polymer assembly

Published Papers (6 papers)

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Research

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20 pages, 5104 KiB  
Article
Graphene Nanoplatelets for the Development of Reinforced PLA–PCL Electrospun Fibers as the Next-Generation of Biomedical Mats
by Enrica Chiesa, Rossella Dorati, Silvia Pisani, Giovanna Bruni, Laura G. Rizzi, Bice Conti, Tiziana Modena and Ida Genta
Polymers 2020, 12(6), 1390; https://doi.org/10.3390/polym12061390 - 21 Jun 2020
Cited by 21 | Viewed by 3124
Abstract
Electrospun scaffolds made of nano- and micro-fibrous non-woven mats from biodegradable polymers have been intensely investigated in recent years. In this field, polymer-based materials are broadly used for biomedical applications since they can be managed in high scale, easily shaped, and chemically changed [...] Read more.
Electrospun scaffolds made of nano- and micro-fibrous non-woven mats from biodegradable polymers have been intensely investigated in recent years. In this field, polymer-based materials are broadly used for biomedical applications since they can be managed in high scale, easily shaped, and chemically changed to tailor their specific biologic properties. Nonetheless polymeric materials can be reinforced with inorganic materials to produce a next-generation composite with improved properties. Herein, the role of graphene nanoplatelets (GNPs) on electrospun poly-l-lactide-co-poly-ε-caprolactone (PLA–PCL, 70:30 molar ratio) fibers was investigated. Microfibers of neat PLA–PCL and with different amounts of GNPs were produced by electrospinning and they were characterized for their physicochemical and biologic properties. Results showed that GNPs concentration notably affected the fibers morphology and diameters distribution, influenced PLA–PCL chain mobility in the crystallization process and tuned the mechanical and thermal properties of the electrospun matrices. GNPs were also liable of slowing down copolymer degradation rate in simulated physiological environment. However, no toxic impurities and degradation products were pointed out up to 60 d incubation. Furthermore, preliminary biologic tests proved the ability of the matrices to enhance fibroblast cells attachment and proliferation probably due to their unique 3D-interconnected structure. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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15 pages, 7468 KiB  
Article
Efficient and Precise Micro-Injection Molding of Micro-Structured Polymer Parts Using Micro-Machined Mold Core by WEDM
by Qianghua Liao, Chaolan Zhou, Yanjun Lu, Xiaoyu Wu, Fumin Chen and Yan Lou
Polymers 2019, 11(10), 1591; https://doi.org/10.3390/polym11101591 - 29 Sep 2019
Cited by 14 | Viewed by 3012
Abstract
In this paper, micro-structured polymer parts were efficiently and accurately fabricated by micro-injection molding using a micro-structured mold core machined by wire electrical discharge machining (WEDM). The objective was to realize low-cost mass production and manufacturing of micro-structured polymer products. The regular micro-structured [...] Read more.
In this paper, micro-structured polymer parts were efficiently and accurately fabricated by micro-injection molding using a micro-structured mold core machined by wire electrical discharge machining (WEDM). The objective was to realize low-cost mass production and manufacturing of micro-structured polymer products. The regular micro-structured mold core was manufactured by precise WEDM. The micro-structured polymer workpieces were rapidly fabricated by micro-injection molding and the effects of the micro-injection molding process parameters on replication rate and surface roughness of micro-structured polymers were systematically investigated and analyzed. It is shown that the micro-structured polymer can be rapidly and precisely fabricated by the proposed method. The experimental results show the minimum size machining error of the micro-structured mold core and the maximum replication rate of micro-formed polymer were 0.394% and 99.12%, respectively. Meanwhile, the optimal micro-injection molding parameters, namely, jet temperature, melt temperature, injection velocity, holding pressure and holding time were 195 °C, 210 °C, 40 mm/min, 7 Mpa and 5 s, respectively. The surface roughness Ra at the groove bottom and top of the micro-structured polymer workpieces achieved minimum values of 0.805 µm and 0.972 µm, respectively. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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17 pages, 18217 KiB  
Article
Preparation and Properties of Self-Healing and Self-Lubricating Epoxy Coatings with Polyurethane Microcapsules Containing Bifunctional Linseed Oil
by Haijuan Yang, Qiufeng Mo, Weizhou Li and Fengmei Gu
Polymers 2019, 11(10), 1578; https://doi.org/10.3390/polym11101578 - 27 Sep 2019
Cited by 48 | Viewed by 4589
Abstract
An organic coating is commonly used to protect metal from corrosion, but it is prone to failure due to microcracks generated by internal stress and external mechanical action. The self-healing and self-lubricating achieved in the coating is novel, which allows an extension of [...] Read more.
An organic coating is commonly used to protect metal from corrosion, but it is prone to failure due to microcracks generated by internal stress and external mechanical action. The self-healing and self-lubricating achieved in the coating is novel, which allows an extension of life by providing resistance to damage and repair after damage. In this study, a new approach to microencapsulating bifunctional linseed oil with polyurethane shell by interfacial polymerization. Moreover, the self-healing and self-lubricating coatings with different concentrations of microcapsules were developed. The well-dispersed microcapsules showed a regular spherical morphology with an average diameter of ~64.9 μm and a core content of 74.0 wt.%. The results of the salt spray test demonstrated that coatings containing microcapsules still possess anticorrosion, which is improved with the increase of microcapsules content, after being scratched. The results of electrochemical impedance spectroscopy showed a |Z|f=0.01Hz value of 104 Ω·cm2 for pure epoxy coating after being immersed for 3 days, whereas the coating with 20 wt.% microcapsules was the highest, 1010 Ω·cm2. The results of friction wear showed that the tribological performance of the coating was enhanced greatly as microcapsule concentration reached 10 wt.% or more, which showed a 86.8% or more reduction in the friction coefficient compared to the pure epoxy coating. These results indicated that the coatings containing microcapsules exhibited excellent self-healing and self-lubricating properties, which are positively correlated with microcapsules content. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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10 pages, 2080 KiB  
Communication
Controlled Shape and Porosity of Polymeric Colloids by Photo-Induced Phase Separation
by Elad Hadad, Eitan Edri and Hagay Shpaisman
Polymers 2019, 11(7), 1225; https://doi.org/10.3390/polym11071225 - 23 Jul 2019
Viewed by 4281
Abstract
The shape and porosity of polymeric colloids are two properties that highly influence their ability to accomplish specific tasks. For micro-sized colloids, the control of both properties was demonstrated by the photo-induced phase separation of droplets of NOA81—a thiol-ene based UV-curable adhesive—mixed with [...] Read more.
The shape and porosity of polymeric colloids are two properties that highly influence their ability to accomplish specific tasks. For micro-sized colloids, the control of both properties was demonstrated by the photo-induced phase separation of droplets of NOA81—a thiol-ene based UV-curable adhesive—mixed with acetone, water, and polyethylene glycol. The continuous phase was perfluoromethyldecalin, which does not promote phase separation prior to UV activation. A profound influence of the polymer concentration on the particle shape was observed. As the photo-induced phase separation is triggered by UV radiation, polymerization drives the extracted solution out of the polymeric matrix. The droplets of the extracted solution coalesce until they form a dimple correlated to the polymer concentration, significantly changing the shape of the formed solid colloids. Moreover, control could be gained over the porosity by varying the UV intensity, which governs the kinetics of the reaction, without changing the chemical composition; the number of nanopores was found to increase significantly at higher intensities. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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17 pages, 4710 KiB  
Article
Piezoelectric Response in Hybrid Micropillar Arrays of Poly(Vinylidene Fluoride) and Reduced Graphene Oxide
by Igor O. Pariy, Anna A. Ivanova, Vladimir V. Shvartsman, Doru C. Lupascu, Gleb B. Sukhorukov, Tim Ludwig, Ausrine Bartasyte, Sanjay Mathur, Maria A. Surmeneva and Roman A. Surmenev
Polymers 2019, 11(6), 1065; https://doi.org/10.3390/polym11061065 - 20 Jun 2019
Cited by 30 | Viewed by 4785
Abstract
This study was dedicated to the investigation of poly(vinylidene fluoride) (PVDF) micropillar arrays obtained by soft lithography followed by phase inversion at a low temperature. Reduced graphene oxide (rGO) was incorporated into the PVDF as a nucleating filler. The piezoelectric properties of the [...] Read more.
This study was dedicated to the investigation of poly(vinylidene fluoride) (PVDF) micropillar arrays obtained by soft lithography followed by phase inversion at a low temperature. Reduced graphene oxide (rGO) was incorporated into the PVDF as a nucleating filler. The piezoelectric properties of the PVDF-rGO composite micropillars were explored via piezo-response force microscopy (PFM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that α, β, and γ phases co-existed in all studied samples, with a predominance of the γ phase. The piezoresponse force microscopy (PFM) data provided the local piezoelectric response of the PVDF micropillars, which exhibited a temperature-induced downward dipole orientation in the pristine PVDF micropillars. The addition of rGO into the PVDF matrix resulted in a change in the preferred polarization direction, and the piezo-response phase angle changed from −120° to 20°–40°. The pristine PVDF and PVDF loaded with 0.1 wt % of rGO after low-temperature quenching were found to possess a piezoelectric response of 86 and 87 pm/V respectively, which are significantly higher than the |d33eff| in the case of imprinted PVDF 64 pm/V. Thus, the addition of rGO significantly affected the domain orientation (polarization) while quenching increased the piezoelectric response. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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Review

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16 pages, 2469 KiB  
Review
Electrospinning of Essential Oils
by Elisa Mele
Polymers 2020, 12(4), 908; https://doi.org/10.3390/polym12040908 - 14 Apr 2020
Cited by 51 | Viewed by 5899
Abstract
The extensive and sometimes unregulated use of synthetic chemicals, such as drugs, preservatives, and pesticides, is posing big threats to global health, the environment, and food security. This has stimulated the research of new strategies to deal with bacterial infections in animals and [...] Read more.
The extensive and sometimes unregulated use of synthetic chemicals, such as drugs, preservatives, and pesticides, is posing big threats to global health, the environment, and food security. This has stimulated the research of new strategies to deal with bacterial infections in animals and humans and to eradicate pests. Plant extracts, particularly essential oils, have recently emerged as valid alternatives to synthetic drugs, due to their properties which include antibacterial, antifungal, anti-inflammatory, antioxidant, and insecticidal activity. This review discusses the current research on the use of electrospinning to encapsulate essential oils into polymeric nanofibres and achieve controlled release of these bioactive compounds, while protecting them from degradation. The works here analysed demonstrate that the electrospinning process is an effective strategy to preserve the properties of essential oils and create bioactive membranes for biomedical, pharmaceutical, and food packaging applications. Full article
(This article belongs to the Special Issue Micro- and Nano-Fabrication Approaches for Polymers)
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