Processing parameters for electrospinning poly ( methyl methacrylate ) ( PMMA ) / titanium isopropoxide composite in a pump-free setup [ version 1 ; peer review : 2 approved with reservations ]

Background: Electrospinning is a technique for producing nanofibers, useful in many fields of nanotechnology. The size and morphology of the nanofibers obtained depends on the polymer solution properties, the parameters of the equipment and the conditions of the surrounding. In almost all reported electrospinning set ups, a pump ,which regulates the flow of the polymer solution, has been included as one of the requirements. In this study, the effects of solution concentration, viscosity, voltage and the distance from the tip of the syringe to the aluminum collector on the morphology and diameters of poly(methyl methacrylate)(PMMA) fibers were investigated, using a pump-free electrospinning set up. Methods: Varied PMMA concentration (50 -120 mg/mL), voltage (10-18 kV) and distance (5 – 18 cm) of electrospinning were studied and the optimum electrospinning conditions identified.  PMMA/ titanium isopropoxide solution of ratio 1:2 was prepared, electrospun at optimized conditions (15 kV, 18 cm, Dichloromethane/Dimethylformamide 60:40) and the fibers obtained analyzed using a scanning electron microscope. Results: Solutions of PMMA whose concentrations were less than 50 mg/mL, produced beads on fibers, whereas those at ~ 100 mg/mL formed the best bead-free fibers of diameter 350±50 nm. The results showed a direct dependence of fiber diameter on the solution viscosity. Fibers of larger diameters were obtained when the distance from the tip of the syringe to the aluminum collector and voltage were increased but at higher distances (>18 kV) fewer fibers were collected. When the voltage was steadily increased, the fibers broadened and the diameters were non-uniform due to splaying and splitting. Increasing the distance between the pipette-tip and the collector from 10 to 18 cm resulted in reduced electric field which in turn yielded fewer fibers. Conclusions: The results obtained in a pump free set-up were comparable to those eletrospun in the presence of a pump.


Introduction
The technique of electrospinning was first described in a 1930 patent by Formhals Anton.It is a non-mechanized, electrostatic process that produces fibers that range from nanometers to micrometers from electrically driven jets of polymer solution or melt.In this process, a high electric field is created between the polymer fluid and an electrically conducting collector screen, as shown in Figure 1.
At a critical electrical potential, a thin jet is produced from the charged polymer fluid at the tip of a pipette or syringe needle.The jet undergoes "electrostatically driven bending instabilities" that cause it to split and spray (Doshi & Reneker, 1995).The solvent evaporates rapidly as the jet travels to the collector screen where dry fibers accumulate producing a mat of nanofibers.The diameter and morphology of the fibers can be influenced by process variables and solution properties (Anton, 1934;Deitzel et al., 2001).
The parameters affecting electrospinning and the morphology of spun fibers can be classified as polymer solution parameters, process parameters and ambient conditions.The solution parameters include: molecular weight of the polymer, surface tension, solution viscosity, solution conductivity and dielectric effect of the solvent.The process parameters include: applied voltage, distance between tip and collector, and diameter of the spinneret orifice.The ambient parameters include: humidity, temperature and pressure.By understanding these parameters, it is possible to design electrospinning set-ups that can influence the morphology, dimensions and arrangements/alignments of the resultant fibers.Table 1 summarizes the effects of different parameters on fiber morphology.

Electrospinning mechanism
Previously, nanofiber formation was attributed to the splitting or spraying of the electrified jet because of repulsion between the surface charges.Shin et al. (2001) attributed the thinning of the electrospinning jet to bending instabilities associated with an electrified jet.This was done by real-time observation of the Taylor cone (conical envelope), which confirmed that it consisted of only one rapidly bending or whipping thread.Hohman et al. (2001) formulated a mathematical model to enhance the understanding of the electrostatic spinning process.Their findings indicated that the spinning phenomenon only involved a whipping of a liquid jet.The interactions between the surface charges on the jet results into a thrashing flux as the fluid is stretched and accelerated resulting in fiber formation (Dong et al., 2006).

Polymers for electrospinning
One of the requirements of electrospinning is that the polymers used should be completely soluble in the solvent of choice and the resulting solution should be able to conduct current.With these two conditions fulfilled, both natural and synthetic polymers can be electro spun.For much better results, the polymer should be dissolved in a solvent(s) that results in a solution with an overall high dielectric constant.Controlling the amount of polymer and solvent used influences the viscosity and surface tension of the resulting solution.In cases     et al., 2007) where the polymer solution is non-conductive, an inorganic salt can be added to the polymer solutions to form a composite and conducting solution.Two polymers of different properties and structures can also be mixed to improve the properties of the resulting solutions.The polymer solutions can also be functionalized to suit the field of application for the fibers obtained (Meneghetti & Qutubuddin, 2004).
A variety of nanofibers from organic polymers, mixture of polymers, and polymers blended with inorganic materials have been obtained through electrospinning (Li et al., 2003).
Examples of organic nanofibers that have been fabricated through electrospinning include: polycarbonate, Poly-L-lactide (PLA), polyacrylonitrile (PAN), polystyrene (Kenawy et al., 2002), blends of PAN and acrylic acid, poly sulfone (Kenawy et al.), polyvinyl pyridine (PVP) and poly(methyl methacrylate) (PMMA) (Huang et al., 2003).The selection criteria of polymers used in electrospinning is based on polymer properties and above all, the field of application of the fibers being synthesized.

Properties of poly(methyl methacrylate)
Poly(methyl methacrylate) (PMMA) is a linear thermoplastic polymer of methyl methacrylate, with the chemical formula (C 5 H 8 O 2 )n (Figure 2).
Several factors favor the choice of PMMA over the wide range of polymers available, including: high mechanical strength, low moisture and water absorbing capacity, good dielectric properties, thermal stability, non-toxicity, and solubility in most solutions.The low moisture and water absorbing ability help prevent titanium isopropoxide (TIP) hydrolysis during preparation of PMMA-TIP polymer solution before electrospinning.The high dielectric property improves the conductivity of the polymer solution obtained making it easy to electro spin.The thermal stability makes it suitable for making of fibers that are thermally stable and can in turn be used in applications that work at high temperatures.It's solubility in a variety of solvents adds to the many advantages (Ali et al., 2015).
Concerning environmental conservation, PMMA is a biodegradable polymer that decomposes naturally.All the abovementioned properties give PMMA an advantage over other polymers.In addition to the above reasons, PMMA and its derivatives have found use in a wide range of applications in the field of nanotechnology (Sill & von Recum, 2008).

Electrospinning of PMMA
Earlier studies have shown that a wide range of parameters affect the morphology of the final fibers obtained from electrospinning (Casper et al., 2004;Chen et al., 2008;Huang et al., 2003;Jacobs et al., 2010) In this study a simple electrospinning set-up that excluded a pump was used to successfully produce PMMA and PMMA/ TIP nanofibers.Locally available copper wire was used as an electrode and glass pipette as a syringe.

Instrumentation
The morphologies of the PMMA and PMMA/TIP nanofibers were observed using a scanning electron microscope (Carl Zeiss Ultra Plus) at an accelerated voltage of less than 8 kV to prevent perturbations of nanofibers Ostwald viscometer (PSL tube viscometer, Bs /U type with 4 mm capillarity) was used to measure the viscosity of the different polymer solutions prepared.The viscometer was calibrated using glycerol from Sigma and Aldrich.The experiments were carried out in triplicate at room temperature.
The electrospinning apparatus consisted of a high voltage supply equipment (capable of up to 30 kV voltage), which was used to apply a potential difference between the spinneret (improvised as 146 mm Corning™ Disposable Glass Pasteur Pipets) and the grounded collector plate (aluminum foil).The power supply was from the table top electrospinning equipment (Model Holmarc's HO-NFES-040) manufactured in India.It delivers a maximum of 30 kV at 5 mA, via an adjustable knob on a scale of one to ten, with increments of 1/100th.A copper wire inserted into the polymer solution acted as the positive electrode and the squared aluminum foil (30 cm dimension), which was electrically grounded, acted as the collector (Figure 3).The pipette containing the polymer solution was mounted horizontally on a laboratory tripod stand.
Preparation of polymer solution of different solvents 2 mg of PMMA was added to 5 mL of each of the selected solvents and the mixture stirred magnetically for 6h to 12h (depending on the time a homogenous solution is formed) at room temperature.The solvents tested included Hexane, DCM, DMF, CHCl 3 , and EtOH.The dissolution was done under continuous magnetic stirring at 600 rpm, the resultant solution electrospun and any fibers obtained observed under a SEM.

Optimizing different electrospinning parameters
In optimization tests, every consequent test was based on the results of the preceding experiment.To optimize distance and voltage, the distances between the tip of the syringe and the collector as well as the voltage were varied as the electrospinning was carried out.
To optimize polymer concentration, 50, 100 and 120 mg of PMMA (Av mw 996,000) were separately dissolved in 1mL of a binary solvent system of 40/60 DMF/DCM (based on the optimum electrospinning conditions achieved in earlier experiments) in clean glass vials with lids.The solution was magnetically stirred at 600 rpm until a homogenous clear solution was obtained.
To optimize voltage, 100 mg of PMMA (Av mw 996,000 from Sigma and Aldrich) was dissolved in 1mL solution of DCM/DMF (60:40).Solutions obtained were electrospun at room temperature at ~10 kV, 15 kV and 18kV.
To optimize distance, 100 mg of PMMA (Av mw 996,000 from Sigma and Aldrich) was dissolved in 1mL solution of DCM/DMF (60:40).Solutions obtained were electrospun at room temperature at ~15 kV and variable distance of 5, 10 and 18 cm.The fibers obtained were observed under SEM.

Preparation of PMMA/TIP composite polymer solution
To prepare PMMA/TIP polymer solution, a similar procedure for preparing PMMA/TIP polymer solution was followed.After obtaining a PMMA/TIP homogenous solution, Titanium isopropoxide (TiP) (MW 284.22; density 0.96 g/mL; assay 97%, Sigma and Aldrich), was added to the polymer solution in the w/w ratio of 1:2 (PMMA: TIP).The mixture was stirred until a homogenous solution was obtained.PMMA solutions of concentration 50, 100 and 120 mg/mL were prepared.
Electrospinning at optimized conditions PMMA and PMMA/TIP solutions were prepared and separately placed in a 146 mm Corning™ Disposable Glass Pasteur Pipets and the solution allowed to flow freely from the pipette as controlled by its own viscosity.The optimum electrospinning voltage and distance obtained in earlier experiments (15 kV and 18 cm, respectively) were set.The electrospinning process was performed in an improvised fume hood at room temperature.The electrospun nanofibers were then allowed to stand for 2h at room temperature to dry off the solvent and to allow complete hydrolysis of titanium (IV) hydroxide, Ti(OH) 4 .

Results and discussion
Dissolving PMMA in different solvents Trial experiments using common solvents such as DCM, DMF, Toluene and EtOH showed that all the solutions dissolved PMMA sufficiently well but at different rates.Clear solutions were obtained after stirring for approximately 3-6h.No significant fibers were obtained when ethanol, CHCl 3 and hexane were used as solvents.Based on these observations, DCM and DMF were taken as solvent for preparing polymer solutions for electrospinning (Obuya et al., 2011).The properties of the two solvents (summarized in Table 2) that favor electrospinning mechanism.The boiling points, dipole moments, density and dielectric constants of DMF and DCM all played a role in making it possible to spin fibers of PMMA.
When DCM/DMF 75/25 was used, beads of different sizes were formed on the fibers.Bead formation could be due to the low surface tension and high viscosity of the solution which in turn provided less resistance to formation of continuous and orderly fibers (Figure 4a).At 50/50 DCM/DMF the beads on the fibers appeared flattened (Figure 4b).Further addition of DCM to 40/60, homogenous fibers without beads were obtained (Figure 4c).Increasing the amount of DCM in the solution also increased the charge density due to its lower conductivity than that of DMF, leading to a trend of stable jets and larger diameters fiber formation.The different evaporation rates of DCM and DMF could result in direct accumulation rates of fibers.At 100% DCM, beads were observed (Figure 4e).(2006) reported that the success of the electrospinning process depends on complete solubility of polymers in a solvent of moderate boiling point.
Volatile solvents are preferred because a high evaporation rate promotes faster evaporation of the solvent from the nanofiber as the jet travels from the needle tip to the collector.Low boiling point solvents evaporate quickly causing the jet to dry at the tip and in turn block the needle tip.Less volatile solvents dry slowly during jet flight and the deposition of solvents-containing nanofibers on the collector will cause the formation of fibers with beads (Gupta et al., 2005;Hohman et al., 2001;Huang et al., 2003;Piperno et al., 2006).
Sill & von Recum (2008) showed that the solvent also plays a vital role in the fabrication of highly porous nanofibers when the polymer is dissolved in two different solvents -one acting as a solvent and the other one acting as a non-solvent.The different evaporation rates of the two solvents lead to phase separation and result in the fabrication of highly porous electrospun nanofibers.Megelski et al. (2002) prepared porous nanofibers by varying the ratio of tetrahydrofuran (THF) and DMF and showed that, in addition to the volatile nature of the solvent, conductivity and dipole-moment are also very important.From the results of the experiments carried out in this study, it can be concluded that PMMA fibers with parallel strand morphology can be manufactured using DCM/DMF solvent ratio of 60/40.

Effect of viscosity and concentration
The concentrations examined in this study were 50, 100 and 120 mg/mL PMMA in a DMF/DCM solvent mixture.
A solution's viscosity has considerable influence in the electrospinning process and the resultant fiber morphology.Generally, the polymer molecular weight (which has an impact on concentration) directly determines the viscosity of the polymer solution.For electrospinning to occur, the solution must consist of a polymer of high molecular weight to achieve critical viscosity.Combined with electrical properties, the viscosity of the solution also determines the extent of elongation of the solution, the smoothness and the diameter of the resultant fibers.
The viscosity decreased as the amount of DCM in solution decreased.This was due to less entanglement and diffusion of solvent molecules.At a low viscosity, polymer solution was less spinnable because the electrified jet breaks up into droplets or drains freely from the pipette because of high electrostatic repulsion experienced at low surface tension.At moderate viscosity,   surface tension predominates along the electrospinning jet resulting in formation of beads on the fiber (Figure 4b, Table 3 Entry 2).On the other hand, with increased viscosity, the diameter of the fibers has been found to increase (and bead free (Figure 4c, Table 3 Entry 4).This is probably due to the greater resistance of the solution to be stretched by the charges on the electrospinning jet (Dong et al., 2004).The trend of viscosity obtained in this study is similar to the one reported in a number of publications (Ki et al., 2005;Koski et al., 2004).

Influence of concentration of polymer
The SEM images of the fibers obtained from solutions of different concentrations are as shown in Figure 5. From the SEM images, fibers with some defect fibers as well as smooth ones were observed.At low concentration, few beads and droplets were formed (Figure 5a, 50 mg/mL).This could have been due to low density, and low solvent volatility causing the jet to reach the collector in a short while before drying.Bead free fibers were collected as the polymer concentration increased from 50 to 100 mg/mL.fiber diameters also increased with an increase in polymer solution concentration.The average fiber diameters of the fibers spun from 50, 100 and 120 mg/mL PMMA solution was 350±50 nm, 604 ±50 nm and 994 ±50 nm, respectively.

Influence of tip-to collector distance
A series of electrospinning experiments were carried out at 10, 15 and 18 cm.The results of the fiber diameter sizes obtained were as shown in Table 4.
When 50 mg/mL PMMA concentration was used at 10 cm, narrow fibers with beads were formed, and as the distance increased, fewer fibers reached the collector and those that reached the collector were broken.When distances were small and the electric field increased; the jet became unstable and, in some cases, multiple jets resulted forming fibers with beads.
When the distances were increased to 15 and 18 cm, broken fibers were obtained but the diameter decreased, respectively.This was comparable to the results obtained by Matabola et al. (2011).When a solution of 100 mg/mL was electrospun, the fibers were of a larger diameter than those of 50 mg/mL but continuous in nature and defect free.This implied that at longer distance, the polymer had to travel for a longer time allowing the fiber to stretch maximally before settling on the collector.Much further distances >18 kV resulted in broken fibers too due to weak electric field.Yuan et al. (2004) obtained comparable results when studying the morphology of electrospun ultrafine polysulfone fibers.At low distances, the fibers reached the collector when still wet and their morphologies could change shape during settling and solvent evaporation time.

Effect of varied voltage
The results in this study revealed that an increase in voltage resulted in increased diameters of the fibers (Table 5).
Low voltage of 10 kV at 10 cm yielded beaded fibers of about 248 ±57 nm.As both the voltage and the distance were increased, the size of the fibers increased too as the beads decreased.Similarly, increase in electric field strength and distance resulted into smaller diameter fibers and vice versa.
Increasing the electric field, increased the surface charges and in turn the jet was stabilized producing fibers on nanoscale.
When the voltage was increased, more polymer solutions were ejected causing breaks and blocking of the tip.Such ejections of high velocity resulted into larger diameter fibers.The bead-free fibers started to form only at threshold voltage (12 kV).High voltage also improved the stretching and hence drying of the fibers as the solvent evaporated.However, very high voltage leads to the formation of several jets producing fibers with large diameters (Demir et al., 2002).
Comparing the results obtained in this study with those reported by Deitzel et al. (2001), there is a slight difference as during their study a pump was used to regulate the flow rate of the polymer while in this study, a pump free system was used.
The results of this are comparable to those obtained in pumpcontrolled experiments.Bedi et al. (2013), electrospun PMMA in a pump free process and obtained larger diameter fibers at high voltage and morphologies having cups and rings at low voltage.
Morphology of PMMA and PMMA/TIP nanofibers On mixing Ti(OiPr) 4 with DCM/DMF solvent, it was observed that upon exposure to air Ti(OiPr) 4 fumes.The solution of PMMA/TIP/DCM/DMF instantly turned to light yellow on stirring for 1h.Upon exposure to air, it solidifies; this happened many times at the end of the Pasteur pipette causing pressure build up which resulted in unstable bursts of liquid jets, which ruined many samples.Precipitation also occurred at many instances while the sample was on the stir plate in a closed container.Oddly enough there was no set pattern to this behavior.Sometimes the solution precipitated in a closed jar after a few hours, and other times after a few days.This may be due to the humidity in the air and hydrolysis of TIP that occurs in the solution reactions.
Despite the challenge of solidification and precipitation, continuous fibers of PMMA and PMMA/TIP were successfully produced at 18 kV voltage and 15 cm distance from the spinneret tip to the collector.Calcination was performed between 400°C to 800°C for ~3h. Figure 6 shows the SEM images of the different fibers obtained.The fibers of PMMA had a large diameter (Figure 6a).PMMA/ TIP appeared rough on hydrolyzing in air.Heat treatment resulted in shrinking of the fibers (Figure 6b) from 350±50 to 150±56 nm.
Comparing the weight of the fibers, there was noticeable weight loss on calcination of fibers, since PMMA was selectively removed resulting in TiO 2 nanofibers.

Conclusion
SEM images revealed that the electrospun PMMA/TIP nanofibers at high-voltage source (15 kV), low flow rate, concentration of 100 mg/mL, a tip-to-collector distance of ~18 cm and a DCM/DMF solvent ratio of 60/40 had cylindrical, beaded fibers with junctions.Spinning distance and voltage did have a significant effect on the structure and size of the fiber but a decrease in viscosity resulted in increased fiber diameters. 1.

Open Peer Review
Current Peer Review Status: The paper reports on the optimization of experiments for the electrospinning of PMMA/TIP using a pump free set-up.It is a useful study to demonstrate that electrospinning can be conducted without using a pump.Furthermore, it helps with further understanding of practical aspects of optimizing electrospinning to obtain bead free nanofibers followed by post electrospinning modification using heat treatment.
However, it should be noted that it is not the first time that a pump free set-up is being used for electrospinning.For example, Ajao et al 2010 reported a similar set-up on PEO.It is also not the first time for PMMA to be electrospun using a pump free set-up, for example, Moloto et al 2018 who reported a similar set-up for PMMA.To improve the presentation of the work, there are some suggestions below that the authors could take into consideration; Page 1 affiliation 2 "Africa" not "Afria" Page 1 line 4 under results "longer" not "higher" Page 3 paragraph 2 line 4.The result of bending instability is jet thinning due to extensive stretching due to tensile forces that are brought about by like charge repulsion on the polymer surface.I suggest the author rephrase the claim by Reneker that splitting and splaying results as it conflicts with paragraph 4. In order to further explain the fundamental process of electrospinning in terms of like charges, the authors could also refer to the work by Kowalewski 2009 who explains very well the view of an electrospinning jet as a string of charge elements connected by a viscoelastic medium.Any electrospinning set-up consists of three basic components (i) source of polymer solution (ii) source of high voltage (iii) collector.I suggest the authors provide a more descriptive caption for Check space between "6" and "h" and be consistent right through the manuscript with spacing

21.
Check space between "6" and "h" and be consistent right through the manuscript with spacing between numbers and units.Page 5 last paragraph line 2 replace "solutions" with "solvents" Figure 3 needs to be replaced with a better picture that clearly shows the power supply, the polymer solution source and the collector all in one picture and not the current pictures.Page 6 paragraph 2 line 1 rephrase the first statement to replace "The SEM appearance.." with probably "As observed from the SEM image…."Page 6 last paragraph rephrase the statement about droplets forming due to high electrostatic repulsion on low surface tension solutions, low surface tension favours stretching but short polymer chains reduces entanglements which can also be related to low viscosity and concentration that favour droplet formation.So, the authors need to clarify this aspect to avoid confusing the readers.
It is also necessary for the authors to bring out the aspect of viscoelasticity because it is not all viscous solutions that are spannable but those of optimal viscoelasticity.Page 8 paragraph 4 line 7 distance should be in "cm" not "kV" Page 8 paragraph 4 line 10 "short" not "low" In all the reported experimental approach, the authors did not state the deposition time.This should come out clearly for anyone to reproduce what is reported in the paper.In all the reported work, the authors did not state the humidity and temperature which are important for anyone to reproduce what they reported in the paper.Page 9 paragraphs 4 and 5 the authors seem not to have optimized the step of handling the PMMA/TIP/DCM/DMF as they appear not to have control of the observed solidification.From their description, it would be difficult for a reader to reproduce as that part if not clearly what exactly they did.Probably this could be further work on having total control of the solidification part.For example, they mentioned humidity as a possible cause but there was no discussion on a study of the effect of humidity.
For demonstration of the most basic set-up of electrospinning it is necessary to use the Pasteur pipette set-up.However, it is necessary to clearly show the significance of the study going forward, that is, how does the demonstration that using a pump free electrospinning achieves comparable results to a pump-based set-up add value to the developments in electrospinning?This component did not come out clearly in the manuscript and it is important for this aspect to be made clear.
In conclusion, the authors used appropriate experimental techniques that are appropriate with an electrospinning study which is satisfactory.Furthermore, they generally followed a systematic experimental approach to reach meaningful conclusions as is expected of a scientific study.However, there are some areas that require the authors to revisit to add clarity to the manuscript as stated in points 1-20.If all these points are addressed, definitely they will add to the improvement of the presentation.Therefore, I recommend that the authors consider these suggestions,

AAS Open Research
Yes Is the study design appropriate and is the work technically sound?Yes Are sufficient details of methods and analysis provided to allow replication by others?Yes If applicable, is the statistical analysis and its interpretation appropriate?

Not applicable
Are all the source data underlying the results available to ensure full reproducibility?Yes

Are the conclusions drawn adequately supported by the results? Yes
No competing interests were disclosed.

Competing Interests:
Reviewer Expertise: Electrospinning, Analytical Chemistry, Water Filtration, Material Science I have read this submission.I believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
Any advantages should be inserted within the introduction section with evidence as well as in the conclusions.
The references are in order.

Is the work clearly and accurately presented and does it cite the current literature? Yes
Is the study design appropriate and is the work technically sound?Yes

Are sufficient details of methods and analysis provided to allow replication by others? Yes
If applicable, is the statistical analysis and its interpretation appropriate?Not applicable Are all the source data underlying the results available to ensure full reproducibility?Yes

Are the conclusions drawn adequately supported by the results? Yes
No competing interests were disclosed.

Competing Interests:
Reviewer Expertise: I am an inorganic chemist, an organometallic specialist and nanomaterial chemist with biological applications I have read this submission.I believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Figure 3 .
Figure 3. Image of electrospinning equipment set up.
/doi.org/10.21956/aasopenres.13979.r26655© 2018 Chigome S. This is an open access peer review report distributed under the terms of the Creative Commons , which permits unrestricted use, distribution, and reproduction in any medium, provided the original Attribution Licence work is properly cited.Samuel Chigome Nanomaterials Department, Botswana Institute of Technology Research and Innovation, Gaborone, Botswana

Fig 1
to describe the three components in their set-up.Page 4 paragraph 4 line 5 last word should be "solvents" and not "solutions" Page 5 paragraph 4 line 2 delete "equipment" after "supply" Rephrase paragraph 5 first and third sentence to avoid repeating the step of stirring.

. Electrospinning parameters and their assumed effects on fiber morphology. Effect on morphology Reference
Tip-to-collector distance BeadsLess or no fibers collected (Macossay