The unexpected challenges of marketing a new membrane technology


What is the molecular weight cut off of your pervaporation membranes? I have been asked this question more times than I can count over the past year. Explaining that our pervaporation membranes do not have a molecular weight cut off (MWCO) has been a challenge that no one at CMS anticipated.


CMS makes a variety of membranes for tough chemical separation applications. Using custom amorphous fluoropolymers, we produce ultrathin, durable membranes for separations that are difficult or impossible to achieve with current technology. Our pervaporation membranes are commercially available and have been found to be particularly useful in drying pharmaceutical and industrial chemicals.


Professionals who use membrane separation technologies may be familiar with the concept of the nanofiltration; hence the questions about a molecular weight cut off. The solution diffusion mechanism for nanofiltration membranes is based on the size of the pores. These membranes generally have intentionally manufactured pores with uniform pore distribution. The separation is driven by applying pressure to the feed side of the membrane.


What makes CMS pervaporation membranes unique is that both the membrane structure is different. The membrane is comprised of a fluoropolymer that is chemically and thermally durable even in a thin membrane. Unlike traditional nanofiltration membranes, CMS membranes are nonporous. Rather than pores, the polymer matrix contains free volume that is sufficient to allow small molecules like water vapor and dissolved gases to move through the polymer matrix. This mechanism is called solution-diffusion.


Our pervaporation membranes have a few key advantages because of the solution diffusion mechanism. There are more process conditions that can be adjusted to increase the efficiency of the desired separation. The temperature, permeate pressure, and initial water loading all affect the driving force across the membrane. This allows us to adjust the design parameters of our systems to minimize the required membrane area.


The terminology used to describe the separation mechanism is slightly less important than the fact that CMS membranes have been proven to perform tough chemical separation. So, whether you think of it as nanofiltration with added chemical barriers or solution diffusion through a nonporous membrane, CMS membranes can perform tough chemical separations because of their unique fluoropolymer structure. At the end of the day, that’s all that matters.