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International Journal of Bioprinting 3D-printed nanocomposites: Synthesis & applications

of concentric cylinders. Fluid should be sheared At present, studies on the addition of non-rubber
between cylinders, and the torque exerted on the inner, polymer/clay composites in FDM that has demonstrated
stationary cylinder by the outer, rotating cylinder greater attributes remain scarce. Weng et al. used melt
is measured. Non-Newtonian fluids are those that intercalation method to prepare acrylonitrile butadiene
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follow this relationship and can be further classified as styrene (ABS) containing modified montmorillonite.
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either pseudoplastic (n = 1) or dilatant (n > 2) fluids. Adding 5 wt% of the modified montmorillonite
Pseudoplastic fluids (sometimes called shear-thinning enhanced the tensile strength of 3D-printed and
fluids) have high viscosities at low shear strengths but molded ABS samples by 43% and 28.9%, respectively. It
lower values as the shear force is increased. On the was discovered that the incorporation of the modified
other hand, a dilatant (also known as a shear-thickening montmorillonite resulted in a significant rise in elastic
fluid) acts in the opposite way. A shear pressure versus strength, toughness, and dynamic mechanical modulus,
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shear rate diagram is used to compare and contrast while simultaneously leading to a reduction in thermal
Newtonian and non-Newtonian liquids. Some non- expansion ratio and weight loss. The developed ABS
Newtonian fluids also behave like solids when they are nanocomposites with improved mechanical and
moved. This is considered a factor of time because flow thermal characteristics are therefore good candidates
causes the rearrangement of fluid molecules, a reaction for FDM 3D printing. Additionally, the large and highly
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defining the characteristic of viscoelasticity, which can charged plane surface of montmorillonite is beneficial
happen to both solids and liquids. Viscoelastic materials for the adsorption of bioactive molecules. In addition
are polymers and predominantly biological materials, to being biocompatible, it promotes cell proliferation
manifesting qualities in the zone between those of an and attachment, and induces osteogenesis of the
elastic material and a viscous material. encapsulated stem cells. Poly (lactic acid) (PLA) is
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another widely used material in filament compounding,
4. Different types of AF-based 3D prints ranking among the top five in terms of both market
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In spite of its widespread adoption and user-friendliness, value and volume, alongside ABS. Paspali et al.
microextrusion-based 3D printing technique has prepared PLA/clay nanocomposite strands to determine
numerous drawbacks that prevent it from fulfilling how the composition affects the physical properties
its potential as an environment-friendly alternative to of the printed specimens and delineate the effect of
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conventional production techniques. For example, the clay intercalation level on the physical properties.
mechanical property of 3D-printed parts is commonly In another research, the production of biocompatible
poorer than that of samples fabricated via traditional polymer nanocomposite was revealed. Using a single
methods. It is anticipated that polymer/nanofillers would screw extruder nanomixer, the ink was manufactured
display enhanced characteristics, particularly at low by mechanically combining polycaprolactone (PCL),
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weight percentage of filler under which the influence of montmorillonite, and hydroxyapatite.
mechanical reinforcing will be the most obvious. 4.2. Graphene/polymer nanocomposites
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4.1. Clay/polymer nanocomposites Hierarchically coordinated pattern engineering has
Due to its layered structure, thermal stability, rheology, been made possible by the attention paid to carbon-
mechanical strength, and absorption and adsorption based nanomaterials during the past two decades. These
capacity, clay, such as phyllosilicate, laponite, and nanomaterials include fullerene, carbon nanotubes
montmorillonite, has great potential in tissue (CNT), graphene and its derivatives, nanodiamonds, and
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engineering. 60-63 However, the incorporation of nanoclays carbon dots reinforcements. Its unusual atomic structure
into the polymer feedstock filament is still challenging and electron distribution provide graphene exceptional
due to the high viscosity of the raw material melt, which specific surface areas, thermal and electrical conductivity,
is detrimental to the processability of the material and mechanical properties, optoelectronic behaviors, carrier
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the establishment of printed objects. For example, when mobility, and chemical stability.
laponite is dispersed in water, sodium ions dissociate Recent research has discovered that graphenic filler
from individual platelets, resulting in negatively increases polymeric mechanical properties because a
charged face, while the hydroxide ions dissociate at the single graphene layer’s Young’s modulus is 1 TPa, which
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8
rim, leaving the rim slightly positively charged. The is 200 times the breaking strength of steel. In order
charge distribution drives the self-assembly of laponite to generate graphene-based polymer nanocomposites,
platelets via electrostatic interactions to form gel, various manufacturing procedures, such as melt mixing,
which shows typical characteristics of “thixotropic” and solvent-aided casting/coating methods, electrospinning,
“shear-thinning” behavior. 8 and so on, are utilized. Moreover, the basic dispersion

Volume 10 Issue 2 (2024) 85 doi: 10.36922/ijb.1637