POSS for Surface Modification and and Corrosion Prevention

Transcription

1 PSS for Surface Modification and and Corrosion Prevention Bill einerth Presented at the Nanostructured Chemicals Workshop September 7 th - 8 th, Mount Baldy Circle Fountain Valley, CA

2 General Types of Surface Treatment lanes Surfactants Polymers Fatty Acids Titanates Zirconates Phosphate Esters Inorganic All filler treatments in commercial use are chosen to bond an organic molecule to molecule to a filler surface. Monofunctional coatings aid filler incorporation and dispersion. Bifunctional coatings are known as Coupling Agents because of their ability to ability to chemically couple the filler to the polymer.

3 lane Treatment of Surfaces Substrates Y Y = rganic functional group (vinyl, methacryl, epoxy, amine, thiol, etc.) = Cl,, Et, acetoxy,etc. Excellent Good Slight Poor lica Quartz Glass Aluminum Copper Alumino-licates (clays) Mica Talc Inorganic xides Steel, Iron Asbestos Nickel Zinc Lead CaC 3 CaS 4 BaS 4 Graphite Carbon Black

4 Why use lanes? Surface Modifiers (hydrophobicity, low surface free energy, oleophobicity, etc.) Dispersion Agents (Improve wetting and dispersion of filler) Coupling Agents (Change a non-reinforcing filler into a reinforcing material) Crosslinking Agents Adhesion Promoters Co-monomers Moisture Scavengers Corrosion Protection

5 Benefits of lanes in Polymer Composites Increased strength and toughness (tensile, tear, abrasion, impact) Better filler wet-out and dispersion Water repellant filler/polymer interphase region Lower viscosity of filled resin Protection of composite properties against hydrous attack educe cure inhibition of filler Improve electrical properties of filled polymers verall Cost eduction- lane treatment enables polymer composites to composites to be used in new ways.

6 Mode of lane Action Step-by-Step Hydrolysis Catalyst Y () 3 Y (H) + 3 H 3 2 / - 3 H Bonding by Condensation Y (H) 3 + H Y - x H 2 Inorganic Substrate Covalent Bonding Coupling by Interaction Y Polymer Hydrogen Bonding Electrostatic Interaction Interpenetrating Polymer Network Modification of Polymer Crystallinity

7 Mode of lane Action-The eal World Interphase IPN Interface H H H H H H H ligomerization vs. Condensation Catalyst, ph, water, time, temperature Multiple (>8) ill-defined layers of silane form IPN with polymer matrix.

8 lanes vs. PSS -lanols () 3 H H Moisture sensitive Volatile liquid (Fp = 27 C) Water required for complete silane hydrolysis (365 g water/kg lane) Volatile organic by-product released released (648 g H/kg lane) Moisture stable Non-volatile solid or oil No activation required No VCs released

9 PSS -lanol Surface Modifiers H H H H H H = Cyclopentyl, i-butyl, i-ctyl, Ethyl, Cyclohexyl H H (CF 2 ) 5 CF 3 H

10 PSS -lanol Coupling Agents H H H H H H PSS cages can be tailored with virtually any reactive functionality for interaction interaction with a polymer matrix. Surface modification can be accomplished before or after polymerization.

11 lanes vs. PSS: Monolayer Comparison 17.2 Å 17.2 Å 8.1 Å 5.5 Å 12.5 Å 14.4 Å The well-defined polyhedral structure leads to a more well-ordered, regular regular surface. PSS cages provide increased surface coverage leading to a more hydrophobic surface.

12 PSS: The Hydrophobic Umbrella PSS H H H H PSS acts a hydrophobic umbrella covering surface H groups (Approx. (Approx H groups/pss nanostructure) The surface coverage provided by a single PSS cage is approximately that provided by a typical silane. (2.32 nm 2 vs nm 2 )

13 Multiscale einforcement Interphase egion IPN Polymer PSS Polymer PSS Polymer PSS Polymer PSS PSS Macroscopic Filler PSS can stabilized and reinforce interphase region. PSS cages could provide nanoscopic reinforcement of polymer chains which chains which may complement the filler s macroscopic reinforcement. PSS surface treatment can provide added value to traditional fillers.

14 Traditional PSS Surface Modifiers 1 or 2 1 or 2 1 or 2 = Cl,, Et

15 Traditional PSS Crosslinkers = Cl,, Et () 3 () 3 () 3 Compare with: Crosslinker Moisture Scavenger

16 PSS for Corrosion Prevention H H H H H H H H (H 1.5 ) x x = 8, 10, 12, 14 Hydrosilsesquioxane cages form corrosion resistant coating on a variety of metal surfaces by interacting with metal oxides on the surface. Coating can be applied by a number of methods but CVD is preferred. The nanoscopic size and hydrophobic nature of the PSS coating very effectively prevents the diffusion of water and ions to the surface. esidual H groups allow coating to function as a primer layer. Banaszak Holl,et al US Patent 5,858,544

17 AIS of H on Chromium xide 1: chromium oxide 2: H on chromium oxide Chromium xide Banaszak Holl et al. University of Michigan Appl. rganomet. Chem. 1999, 13,

18 STM Image of a H Cluster Chemisorbed on (100)-2x1 Line Scan 1 Line Scan 2 Banaszak Holl et al. University of Michigan Phys. ev. Lett. 2000, 85, 602.

19 H on (100)-2x1 University of Michigan Phys. ev. Lett. 2000, 85, 602.

20 Monovertex Binding Geometry Three Geometrical Constraints: 1) Position of features with respect to dimer rows 2) Pattern of features 3) elative height of features within pattern cracked-cluster monovertex cluster Cracked Cluster Bonding Geometry Consistent with No Constraints Monovertex Geometry Bonding Geometry Consistent with All Constraints University of Michigan Phys. ev. Lett. 2000, 85, 602.

21 PSS for Corrosion Prevention H 2 H 2 2 H 2 H H 2 H 2 2 H 2 H ctalane-pss SH1310 ctalane-pss has a more hydrophobic nature than (H 1.5 ) x which should result in even less surface corrosion. Spraying would likely be the preferred coating method. esidual H groups allow coating to function as a primer layer. ctalane-pss is approximately one tenth the cost of (H 1.5 ) x.

22 Why use lanes? Surface Modifiers PSS provides a more well-defined surface. Dispersion Agents PSS provides a more hydrophobic surface. Coupling Agents PSS changes a filler into a multiscale reinforcement. Crosslinking Agents PSS increases 4 (8 groups vs. 2) Adhesion Promoters PSS -lanols No activation/no VCs Co-monomers PSS can be tailored with virtually any polymerizable group. Moisture Scavengers PSS increases 8 (24 hydrolyzable groups vs. 3) Corrosion Protection PSS provides a tailorable surface.