Why temperature and relative humidity are important in the electrospinning

Nanofiber Generation: Electrospinning versus Meltblown

Electrospinning nanofibers is the newest breakthrough technique for scientists and engineers because of it’s flexibility to use different materials and the ability to precisely control conditions previously not achievable with other techniques. For applications such as tissue engineering and drug delivery, meltblown techniques do not allow for temperature sensitive ingredients to be incorporated in the spinning process. While meltblown processes utilize 100% of the polymer solution, the high temperatures of the process make it prohibitive for the wide variety of materials that can be used with electrospinning.  The electrospinning technique has room-temperature processing capabilities enabling a wider selection including materials that are unstable or are deactivated at high temperatures.

Additionally, electrospinning offers highly controllable fiber and particle diameter (typically 20 nm to 10 µm), ability to encapsulate active ingredients, targeted orientation, controlled porosity and scalability. Advantages like surface area to volume ratio, ease of active pharmaceutical ingredient (API) encapsulation, operation at room temperature, among others, make this technique ideal for multiple applications from R&D to field applications with batch-to-batch consistency.

Generating reproducible results with precision controls

The electrospinning process involves a polymer and solvent based solution which is strongly influenced by temperature and relative humidity. Depending on the region where the electrospinning process is occurring the temperature and humidity can vary, the tight controls of the environmental chamber available in Nanoscience Analytical’s laboratory overcomes this challenge.

In the example shown below demonstrates how solvent evaporation is affected without tightly controlled environmental conditions. The polymer and solvent solution dries inconsisitenly during processing creating undesired secondary jetting. Evaluating the sample’s microstrucutre the defects become clearly recognizable, in the case of a sample that needs consistent fiber diameter and fiber orientation, such as drug delivery, this structure would inhibit the release of the active ingredients.

However, when temperature and relative humidity are tightly controlled the process becomes independent of location and the generates consistent product that is uniform and defect free that as is demonstrated in the second microstructure.

Figure 1: Electrospinning behavior and microstructure with and without temperature and relative humidity conditioning

Controlled environmental conditions for electrospinning is also important for the elimination of sample imperfections such as beading, fiber bundles, fiber-fiber bonding. Generating defect free microstruture assure performance and reproducible results.

Figure 2: Typical electrospinning sample defects when temperature and relative humidity are not controlled affecting overall sample properties

Controlling relative humidity and temperature may require trial and error and may need to be adjust on a daily basis to control the morphology of a final product and obtain reproducible results. Nanoscience Analytical provides this process and formulation development services for our clients to expedite your nanofiber development, remove unknowns and get you to launch in a more efficiently. Our comprehensive consultation focuses on fully understanding  the goal of the materials, consultation on material and solvents and recommending formula optimization.

Analytical capabilities include morphological analysis, microstructure characteristics, chemical analysis, surface chemistry analysis, residual solvent analysis, and mechanical testing. An example of the offered analytical services includes but not limited to:

• Fiber Morphology| SEM
• Fiber Diameter| Specialized automated image analysis software
• Pore Size| Porometry and mathematical modeling
• Porosity| Porosity and mathematical modeling
• Surface Wettability| Contact angle

Examples of polymers and materials the scientists from Nanoscience Analyitcal can process with the electrospinning Process.

Synthetic Polymers:

• Nylon
• Poly(e-caprolactone) (PCL)
• Poly(lactic-co-glycolic acid) (PLGA)
• Polyacrylonitrile (PAN)
• Poly(ethylene terephthalate) (PET)
• Polyglycolic acid (PGA)
• Polylactic acid (PLA)
• Polystyrene (PS)
• Polysulfone (PES)
• Polyurethanes (PU)
• Polyvinyl alcohol (PVA, PVOH)
• Polyvinylidene fluoride (PVDF)
• Polyvinylpyrrolidone (PVP)

Natural Polymers:

• Cellulose
• Chitosan
• Collagen
• Gelatin
• Levan
• Starch

Additives (metals, ceramics, bioactives, and other small molecules):

• Aluminum
• Gallium nitrate hydrate (Ga(NO3)3)
• Platinum
• Titanium
• Zinc
• Zirconium hydride
• Hydroxyapatite (HA)
• Asphaltene
• Hyaluronic Acid
• Lecithin
• Myoglobin
• Hemoglobin

*Other materials available upon request. Please contact us for more polymer materials.