(495a) From Chemical Engineering Fundamentals to the Commercialization of Vapor Deposited Polymers

Authors: 
Gleason, K. K., Massachusetts Institute of Technology
Fundamental considerations enabled the invention of mechanistically-driven processes for chemically vapor deposited (CVD) polymers. Utilizing selective chemistry allows CVD polymer growth to proceed rapidly on room temperature surfaces with full retention of the polymer’s organic functional groups. The initiated CVD (iCVD) and oxidative CVD (oCVD) methods mimic chain-growth and step-growth polymerization, respectively. Adsorption of the vapor phase reactants is often rate-limiting and follows the Brunauer Emmett Teller (BET) adsorption isotherm. With this knowledge, iCVD and oCVD homopolymer and copolymer thin films has been demonstrated for nearly 100 monomers.

CVD can be the only viable single-step film forming method for polymers which are incompatible with solution or melt processing. The absence of solvent-based dewetting effects leads to pinhole-free, low roughness (<1 nm rms) ultrathin polymeric layers (<10 nm thin). Additionally, CVD can provide fully uniform conformal coverage, even over complex geometric features. Fabrication of devices on breathable textiles for wearable electronics and surface modification of porous membranes for improved separations processes are just two of many applications for conformal films.

As a result of dimensionless analysis and computation fluid dynamics, CVD polymer reactors have been scaled up to widths >1 m and from batch to semi-continuous roll-to-roll processing. These capabilities led to the founding of GVD Corporation, which currently manufactures robust CVD polymer coatings for an array of industrial applications. For example, GVD applies conformal low-surface energy CVD polymers to tire molds, allowing for the ready release of rubber from complex tread patterns during tire manufacture. More recently, DropWise Technologies Corporation was founded to commercialize robust ultrathin hydrophobic modification layers for improved condensation heat transfer.