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Reversible addition-fragmentation chain transfer (RAFT) polymerization techniques were used to copolymerize an F-POSS macromere with methyl methacrylate (MMA) to produce novel copolymers that possess excellent wetting-resistant behaviour and are the first examples of covalently bound F-POSS nanocomposites for improved surface robustness. These F-POSS/MMA copolymers have also been used to coat cotton fabrics, resulting in both superhydrophobic and oleophobic behaviour., Published in the Polymer Chemistry, DOI: 10.1039/c3py00018d, February 2013. Prepared in collaboration with ERC Inc, Edwards AFB, CA and Department of Chemistry, United States Air Force Academy, Colorado Springs, CO. The original document contains color images.

A new polycyanurate network exhibiting extremely low moisture uptake has been produced via the treatment of perfluoroyclobutane-containing Bisphenol T with cyanogen bromide and subsequent thermal cyclotrimerization. The water uptake, at 0.56 + or - 0.10% after immersion in water at 85 degrees C for 96 hours, represents some of the most promising moisture resistance observed to date in polycyanurate networks. This excellent performance derives from a near optimal value of the glass transition at 190 degrees C at full cure. Superior dielectric loss characteristics compared to commercial polycyanurate networks based on Bisphenol E were also observed. Polycyanurate networks derived from this new monomer appear particularly well-suited for applications such as radomes and spacecraft where polycyanurates are already widely recognized as providing outstanding properties., Journal article submitted to ACS Macro Letters. The original document contains color images.

Perfluorocyclobutane (PFCB) polymer solutions were subjected to pulsed ultrasound, leading to mechanically induced chain scission and molecular weight degradation. 19F NMRrevealed that the new, mechanically generated end groups are trifluorovinyl ethers formed by cycloreversion of the PFCB groups, a process that differs from thermal degradation pathways. One consequence of the mechanochemical process is that the trifluorovinyl ether end groups can be remended simply by subjecting the polymer solution to the original polymerization conditions, that is, heating to 150 C. Stereochemical changes in the PFCBs, in combination with radical trapping experiments, indicate that PFCB scission proceeds via a stepwise mechanismwith a 1,4-diradical intermediate, offering a potential mechanismfor localized functionalization and cross-linking in regions of high stress., Pub. in Journal of the American Chemical Society, v133, p17882 17888, 2011.

Acrylonitrile/1-vinylimidazole (AN/VIM) copolymers containing various mol% of VIM were synthesized by free radical solution polymerization. The copolymers were characterized by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, 1H NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Char yields of the copolymers were 40-48% as determined by thermogravimetric analysis (TGA) while gel fractions were found to be 90-99% depending upon the composition, temperature and time. The complex viscosity of the precursor copolymers was measured as a function of composition and temperature. 82/18 mol% of AN/VIM copolymer based carbon fiber precursor was successfully processed by solvent-free melt spinning at 192 deg C and the melt-spun fiber was characterized by DSC, ATR-IR, and X-ray Diffraction (XRD)., Published in Polymer, v52 p622-628, 2011. Prepared in cooperation with the Department of Chemistry, Clemson University, Clemson, SC, Advanced Fiber Engineering, LLC, Westfield, NJ, and the Department of Chemistry and Macromolecules and Interfaces Institute, Virginia Tech, Blacksburg. Sponsored in part by DoE.

Composite fluoropolymers were prepared by solvent blending fluorinated POSS (F-POSS) with perfluorocyclobutyl (PFCB) aryl ether polymers. The semifluorinated PFCB aryl ether polymers were shown to be hydrophobic, but demonstrated complete wetting by hydrocarbon-based liquids. Upon the incorporation of F-POSS as a drop-in modifier at low weight percent loadings, the composite fluoropolymer spin cast films exhibited increased water in addition to hydrocarbon repellency as determined by contact angle analysis. Composite film surface characterization included SEM and AFM analysis which showed excellent F-POSS dispersion and increased surface roughness. Thermal properties of the blended films were performed using DSC and demonstrated the incorporation of F-POSS did not affect the bulk matrix properties inherent of PFCB aryl ether polymers. This work demonstred that optimized F-POSS PFCB aryl ether polymer blend formulations have potential use as hydro- and oleophobic materials for seals, fibers, and coatings

The wetting of surfaces by water often leads to corrosion and degradation. Data provided by the military services indicate that corrosion is the number one cost driver in lifecycle costs. The total cost incurred by the DoD for corrosion related issues has been estimated to be as high as $20 billion per year. The wetting of materials by hydrocarbons in automotive and aerospace applications often leads to decreased performance, shorter life-span, and increased cost. Fluorinated polyhedral oligomeric silsesquioxane (F-POSS) compounds have been created and examined to potentially help address these issues. Displaying water contact angles higher than that of PTFE, Fluorodecyl POSS is believed to possess the lowest surface energy of any known solid. The combination of this low surface energy with surface roughness and curvature, similar to that of the Lotus leaf, can lead to the creation of superoleophobic materials. The properties of these materials, as well as their polymer composites, will be discussed, For presentation at SAMPE 2010, held in Seattle, WA, on 17-20 May 2010. Prepared in cooperation with Patrick AFB, and Clemson University.

Water-repellent materials, possessing a high degree of hydrophobicity are currently under a spotlight. Preparative approaches are often inspired by naturally evolved biological systems. Specifically, a leaf of the lotus plant exhibits an inherent self-cleaning mechanism resulting from micron-sized waxy nodes protruding from its surface such that water is naturally repelled, removing any foreign debris. This cleansing mechanism, commonly referred to as the "lotus effect," has been artificially reproduced in order to prepare materials with pronounced hydrophobicity. Utilized techniques include surface patterning, molecular self-assembly, deposition, and etching. However, these examples often require aggressive chemical surface treatments, high temperature post-surface modification, or elaborate patterning. For such reasons, there exists a demand to engineer hydrophobic materials that are easy to prepare on a large scale., Published in the journal Angewandte Chemie, International Edition, v47 p4137-4140, 2008. Prepared in cooperation with Clemson University.

A new class of perfluorocyclobutyl (PFCB) polymers covalently functionalized with polyhedral oligomeric silsesquioxnes (POSS) is presented. Three discreetly functionalized POSS monomers possessing thermally reactive trifluorovinyl aryl ethers (TFVE) were prepared in good yields. The POSS TFVE monomers were prepared by initial corner capping of cyclopentyl (-C5H9), iso-butyl (-CH2CH(CH3)2), or trifluoropropyl (-CH2CH2CF3) functionalized POSS trisilanols with acetoxyethyltrichlorsilane followed by sequential acid-catalyzed deprotection and coupling with 4-(trifluorovinyloxy)benzoic acid. TFVE functionalized POSS monomers were thermally polymerized with 4,4'-bis(4-trifluorovinyloxy)biphenyl or 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomers via a condensate-free, [2+2] step-growth polymerization. The polymerization afforded solution processable PFCB polymers with POSS macromers installed on the polymer chain ends. POSS monomers and their corresponding copolymers were characterized by 1H, 13C, 19F, and 29Si NMR, GPC, ATR-FTIR, and elemental combustion analysis. GPC trace analysis showed agreeable number-average molecular weight for various weight percent of iso-butyl and trifluoropropyl chain terminated POSS PFCB copolymers. DSC analysis showed the introduction of increasing POSS weight percent in the endcapped PFCB copolymers lowers glass transition temperatures as high as 31 deg C. On the other hand, the trifluoropropyl POSS endcapped PFCB polymer glass transition temperature was unaffected when copolymerized with the more fluorinated 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomer., Published in Polymer Journal, v48 p4637-4645, 2007. Sponsored in part by AFOSR, DOE and NSF.

A new class of perfluorocyclobutyl (PFCB) polymers covalently functionalized with polyhedral oligomeric silsesquioxnes (POSS) is presented. Three discreetly functionalized POSS monomers possessing thermally reactive trifluorovinyl aryl ethers (TFVE) were prepared in good yields. The POSS TFVE monomers were prepared by initial corner capping of cyclopentyl (-C5H9), iso-butyl (-CH2CH(CH3)2), or trifluoropropyl (-CH2CH2CF3) functionalized POSS trisilanols with acetoxyethyltrichlorsilane followed by sequential acid-catalyzed deprotection and coupling with 4-(trifluorovinyloxy)benzoic acid. TFVE functionalized POSS monomers were thermally polymerized with 4,4'-bis(4-trifluorovinyloxy)biphenyl or 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomers via a condensate-free, [2+2] step-growth polymerization. The polymerization afforded solution processable PFCB polymers with POSS macromers installed on the polymer chain ends. POSS monomers and their corresponding copolymers were characterized by 1H, 13C, 19F, and 29Si NMR, GPC, ATR-FTIR, and elemental combustion analysis. GPC trace analysis showed agreeable number-average molecular weight for various weight percent of iso-butyl and trifluoropropyl chain terminated POSS PFCB copolymers. DSC analysis showed the introduction of increasing POSS weight percent in the endcapped PFCB copolymers lowers glass transition temperatures as high as 31C. On the other hand, the trifluoropropyl POSS endcapped PFCB polymer glass transition temperature was unaffected when copolymerized with the more fluorinated 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomer., Pub. in Polymer Journal, p1-23, 2007.

The first preparation of processable, semi-fluorinated PFCB aryl ether polymers possessing covalently bound pendant POSS cages is reported. Theses copolymers exhibit increased hydrophobicity attributed to the surface migration of the nanometer-sized POSS aggregates, producing nanoroughness that mimics surface features of the lotus leaf.

Perfluorocyclobutyl (PFCB) aryl ether polymers are semi-fluorinated polymers that produce processable, optically transparent materials for a multitude of materials applications. Incorporating low surface energy polyhedral oligomeric silsesquioxanes (POSS) into the PFCB polymer matrix produced enhanced hydro- and oleo-phobicity. PFCB polymers functionalized with POSS nanostructures include blends, copolymers, and block copolymers. For copolymers, trifluorovinyl aryl ether (TFVE) POSS monomers were prepared in good yields using an operationally simple corner capping methodology from commercial POSS trisilanols. The surface analysis of POSS functionalized PFCB polymer blends and copolymers using microscopy and optical profilometry showed the POSS structures produced sub-micron to nano-meter roughness that contributes to enhanced water and hexadecane repellency., Prepared in collaboration with Clemson University, Clemson, SC. For publication in the American Chemical Society Series Book Chapter, "Silicones and Silicone-Modified Materials". The original document contains color images.

New fluorinated polyhedral oligomeric silsesquioxane (F-POSS) structures possessing a high degree of hydrophobicity have been prepared via facile corner-capping methodology., Pub. in Chemical Communication, p4992-4994, 2007.

Recently, significant attention has been drawn to preparing low surface energy materials inspired by naturally evolved biological systems possessing a high degree of ultrahydrophobicity. Specifically, the lotus leaf exhibits an inherent self-cleaning mechanism resulting from micron-sized waxy nodes protruding from its surface so that water is naturally repelled removing any foreign debris. This remarkable cleansing mechanism, coined the "lotus effect," has been artificially mimicked to produce materials with pronounced ultrahydrophobicity. Notable examples include surface patterning, molecular self-assembly, deposition, and etching. However, these examples require aggressive chemical surface treatments, high temperature post-surface modification, elaborate patterning, or necessitate the need for limitedly accessible deposition equipment. For such reasons, there exists a demand to construct ultrahydrophobic materials inspired by nature that are easy to prepare on a large scale., To be published in Angewante Chemie.

Co-monomera A and B were the focus of this investigation because they demonstrate accelerated cure times at lower temperatures compared with monomer precursors 1-3. We have demonstrated bis-ortho-diynylarene (BODA) monomers undergo Bergman cyclopolymerizations to form hyper-branched, rigid naphthalene networks that can be further carbonized at 1000 C to form glassy carbon in high yield (>80%).