The presence of resistance to diffusion is an important factor when assessing the movement of molecules and substances within a system. There are several different factors that can affect the resistance to diffusion, and this article will offer a comprehensive overview of which of those factors provide the least resistance.
The simplest and most common factor that affects diffusion is the presence of diffusion barriers. Diffusion barriers are impermeable physical or chemical barriers that restrict the movement of molecules, thus slowing down the diffusion process. In general, diffusion barriers such as cell walls, membranes, and even smaller molecules can provide the least resistance to diffusion. These types of barriers are often present in biological systems and can often be bypassed by using specialized techniques such as permeabilization.
In addition to physical diffusion barriers, chemical diffusion barriers can also play a role in restricting the rate of diffusion. These include polar and non-polar molecules, solvents, and other substances such as salts. Polar molecules, which have a positive and negative charge, tend to reduce the rate of diffusion due to their higher resistance to diffusion. In contrast, non-polar molecules tend to provide the least resistance to diffusion due to their lower resistance.
Finally, surface diffusion can also affect the rate of diffusion. Surface diffusion occurs when molecules are blocked from moving across the surface of a substance. The presence of surface diffusion can lead to a slower rate of diffusion, as molecules are restricted from freely moving across the surface. Contribution of surface diffusion to diffusion flux within the macropores was found to be quite significant, thus it can be said that surface diffusion provides the most resistance to diffusion.
In summary, there are several factors that can affect the rate of diffusion, and thus an accurate assessment of the type of factor providing the least resistance to diffusion is needed. Physical barriers, such as those found in biological systems, are often the most restrictive and provide the most resistance to diffusion. Chemical barriers, such as polar and non-polar molecules, also provide a certain degree of resistance. Finally, surface diffusion is found to be the most restrictive of all factors, as it acts as a physical barrier to the movement of molecules.