Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018)
    Plasma Processing Thursday Sessions
       Session PS-ThM

Paper PS-ThM3
Super-reactive Haloester Surface Initiator for ARGET ATRP Readily Prepared by RF Glow Discharge Plasma

Thursday, December 6, 2018, 8:40 am, Room Naupaka Salon 5

Session: Plasma Processing
Presenter: Marvin Mecwan, University of Washington
Authors: M. Mecwan, University of Washington
B.D. Ratner, University of Washington
Correspondent: Click to Email
Introduction: Surface initiated activators regenerated by electron transfer atomic transfer radical polymerization or SI ARGET ATRP is a technique that has become a powerful tool for the preparation of functional surfaces and interfaces to match the desired needs of a specific biomedical application. Glow discharge plasma polymerization has historically been used to create uniform thin polymer films that are strongly bond to surfaces. In this research, we explore ARGET ATRP surface initiators that were prepared using a novel, robust and easy synthesis method using plasma polymerization of haloesters, specifically: methyl-3-bromopropionate (M3BP), methyl-2-chloropropionate (M2CP), and ethyl-2-fluoropropionate (E2FP). Once prepared, we used the plasma polymerized haloester surface as a surface initiator for SI ARGET ATRP synthesis of HEMA as proof of concept.

Methods: Cleaned glass discs were Ar etched (40W for 10 min), followed by a CH4 layer (80W for 5 min). The monomer of choice—M3BP, M2CP or E2FP—was introduced into the reactor and plasma deposition was carried out at 150mT pressure; 80W for 1 min (adhesion), 10W for 10 mins (deposition). Plasma-treated samples were washed in methanol and ESCA was used to assess coating composition before and after washing. To grow HEMA brushes on plasma polymerized haloester surfaces, a solution prepared from HEMA, methanol, CuBr2/TPMA, and L-ascorbic acid was pipetted onto the plasma polymerized substrates and allowed to polymerize for 5, 15, 30, 60 and 120mins. ESCA, TofSIMS and ellipsometry were used to analyze the surfaces after ARGET ATRP of HEMA. Clean glass discs were used as negative controls.

Results and Conclusions: RF glow discharge plasma is a robust technique that is able to create a surface coatings that is rich in halogen species and does not delaminates; hence it can be used as a surface initiator for ARGET ATRP. Of all plasma polymerized surface coatings, M3BP showed the highest halogen content and was able to grow HEMA polymer brushes on its surface via ARGET ATRP in as fast as 15 mins. Surprisingly, E2FP, a fluoroester, was also able to grow HEMA polymer brushes despite fluorine being a poor leaving group for ARGET ATRP. The versatility of RF glow discharge plasma offers a clear advantage over other techniques previously used to deposit ARGET ATRP surface initiators.