Imaging of Nanofibrils by Atomic Force Microscopy by Ryan Lena & Dr. Doug Bousfield

The process of making nanofibrils is well-established today. Many groups around the world have found methods, but unfortunately none of these are very high-yield processes, and they are expensive. The challenge, then, is finding a way to get a high yield of nanofibrils, and doing so in such a way as to reduce the time it takes to produce the fibrils, as well as reducing the cost and the energy consumption.

Not only must the process be cheap and efficient, but the fibrils produced must be able to be utilized. To be useful in industry, these fibrils must have high aspect ratios (the ratio of fibril length to diameter). The problem with measuring the fibril’s aspect ratio is that the fibrils often entangle in the pulp-water suspension due to hydrogen bonding between the fibers. Thus, the technique for creating the fibrils must also have a method of separation that is not deleterious to the fibrils themselves. Furthermore, only fibrils of a certain diameter are useful—ideal nanofibrils have diameters less than 100 nanometers.

Many groups have researched this process in a water-based medium, without pre-treating the sample with enzymes. The aim of this project is to determine which enzymes have the greatest effect on nanofibril production, as well as the most effective method of production. The two machines that are used are the Kady mill, which is an industrial mixer and applies an extremely high shear force to the sample in a short period of time, and the homogenizer, which forces the sample through a series of tubes at 45,000 psi and breaks the sample down into smaller pieces, making the sample more uniform. The Kady mill and homogenizer are used in this experiment to break down the larger microfibrils (which have diameters in the micron range) into smaller nanofibrils. The experiment varies how many passes through the homogenizer produce the greatest number of nanofibrils, how long the sample should be put in a Kady mill and how it should be filtered afterward, and so on. There are many different combinations of methods that involve high-shearing forces that can be tested.

My focus in this project will pertain to the use of Atomic Force Microscopy in this research project. I will gain expertise in using the AFM, and analyze different samples given to me. Different methods of sample preparation will be used, i.e. scanning a dry sample vs. scanning the sample in an aqueous solution. My findings will provide support on the nanoscale for observations made through optical and electron microscopes. I will determine which method of production gives the best nanofibrils.

The results of this project could have many different applications. Many people have thought of uses for nanofibrils were they to become readily available. Nanofibrils can be used to strengthen other materials, such as polymers, without altering the overall appearance. They also have potential to be used in the medical field, such as in dressings or drug delivery systems. These are just a few examples of the applications, but there are many more out there, and certainly more to come.

REU Interview 07/11/07

http://efolio.umeedu.maine.edu/~tvassiliev/FBRI/2007FBRI/ryan.m4a