Anti-protein and anti-bacterial behavior of amphiphilic silicones.

Silicones with improved water-driven surface hydrophilicity and anti-biofouling behavior were achieved when bulk-modified with poly(ethylene oxide) (PEO) -silane amphiphiles of varying siloxane tether length: α-(EtO)Si-(CH)-oligodimethylsiloxane --poly(ethylene oxide)-OCH ( = 0, 4, 13, 17, 24, and 30). A PEO-silane [α-(EtO)Si-(CH)-PEO-OCH] served as a conventional PEO-silane control. To examine anti-biofouling behavior in the absence versus presence of water-driven surface restructuring, the amphiphiles and control were surface-grafted onto silicon wafers and used to bulk-modify a medical-grade silicone, respectively.

Antifouling silicones based on surface-modifying additive amphiphiles.

Surface modifying additives (SMAs), which may be readily blended into silicones to improve anti-fouling behavior, must have excellent surface migration potential and must not leach into the aqueous environment. In this work, we evaluated the efficacy of a series of poly(ethylene oxide) (PEO)-based SMA amphiphiles which varied in terms of crosslinkability, siloxane tether length (m) and diblock versus triblock architectures. Specifically, crosslinkable, diblock PEO-silane amphiphiles with two oligodimethylsiloxane (ODMS) tether lengths [(EtO)Si-(CH)-ODMS -PEO, = 13 and 30] were compared to analogous non-crosslinkable, diblock (H-Si-ODMS -PEO) and triblock (PEO-ODMS -PEO) SMAs.

Protein resistance efficacy of PEO-silane amphiphiles: Dependence on PEO-segment length and concentration.

Unlabelled: In contrast to modification with conventional PEO-silanes (i.e. no siloxane tether), silicones with dramatically enhanced protein resistance have been previously achieved via bulk-modification with poly(ethylene oxide) (PEO)-silane amphiphiles α-(EtO)3Si(CH2)2-oligodimethylsiloxane13-block-PEOn-OCH3 when n=8 and 16 but not when n=3.

Direct observation of the nanocomplex surface reorganization of antifouling silicones containing a highly mobile PEO-silane amphiphile.

While nanocomplexity derived from surface reorganization in aqueous biofouling environments is known to give rise to antifouling behavior, quantification of this process is limited. In this work, the surface of an antifouling polymer matrix - a silicone modified with a highly mobile PEO-silane amphiphile - was characterized while undergoing dynamic surface reorganization in aqueous solution via off-resonance tapping mode atomic force microscopy (AFM) and while monitoring surface changes at a rate >25 μm min. Utilizing multimodal analysis during incubation in aqueous solution and surface force spectroscopic mapping before and after incubation, we directly observed the nanoscopically complex surface of the matrix and its five distinct stages of surface reorganization.

Bacteria and diatom resistance of silicones modified with PEO-silane amphiphiles.

Silicone coatings with enhanced antifouling behavior towards bacteria, diatoms, and a diatom dominated slime were prepared by incorporating PEO-silane amphiphiles with varied siloxane tether lengths (a-c): α-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-poly(ethylene oxide)8-OCH3 [n = 0 (a), 4 (b), and 13 (c)]. Three modified silicone coatings (A-C) were prepared by the acid-catalyzed sol-gel cross-linking of a-c, respectively, each with a stoichiometric 2:3 M ratio of α, ω-bis(Si-OH)polydimethylsiloxane (Mn = 3,000 g mol(-1)). The coatings were exposed to the marine bacterium Bacillus sp.