The effect of cross-contamination in the sequential interfacial polymerization on the RO performance of polyamide bilayer membranes

International audienceIn this study, hexafluoroalcohol-containing polyamide layer (HFAPA) was prepared on top of a conventional polyamide under-layer (REFPA) via sequential interfacial polymerization (SIP) to improve RO separation behavior, and the performance of the resulting bilayer membrane was thoroughly optimized by investigating the effect of cross-contamination in the SIP process. When several coupons of the polyamide bilayer membrane were prepared by SIP of MPD(aq), TMC(hx) and hexafluoroalcohol-containing diamine (HFAMDA)(aq) in the manner of subsequent membrane dipping, unreacted MPD monomer (mostly captured in the porous PSF support) carried over from the 1st interfacial reaction dissolved and accumulated in the 2nd aqueous solution as verified by UV spectroscopic analysis. The MPD contaminant then participated in the 2nd interfacial reaction, forming copolyamide with HFAMDA monomer onto the REFPA. Depending on the amount of MPD contaminant accumulated in the 2nd aqueous solution, the composition of the resulting co-polyamide in the top-layer varied, causing a significant variation of RO performance; the flux was gradually decreased with the increase of MPD contaminants while the salt rejection slightly increased (from 1st coupon toward 4th coupon). This result indicated that a trace amount of MPD contaminant may be necessary to maximize RO separation behavior. Through in-depth performance evaluation of polyamide bilayer membranes prepared by adding various known-amount of MPD into 2nd HFAMDA solution, and also by applying a frame process (2nd amine solution was applied only top surface of membrane) to eliminate uncontrollable MPD contamination, we have successfully demonstrated consistent RO performance, and identified an optimum material composition to provide superior separation performance. The bilayer membrane prepared by adding 1.2 mol% of MPD to the total amount of HFAMDA in the 2nd aqueous solution showed 99.8% NaCl rejection with the water flux of 45 LMH under the cross-flow filtration performed with 2000 ppm NaCl solution at 400 psi, 25 °C

Post-porosity Plasma protection (P4): a promising strategy against v-UV damage in porous, low-k materials

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Carbon-Bridge Incorporation in Organosilicate Coatings Using Oxidative Atmospheric Plasma Deposition

Carbon-bridges were successfully incorporated into the molecular structure of inorganic silicate films deposited onto polymer substrates using an oxidative atmospheric plasma deposition process. Key process parameters that include the precursor chemistry and delivery rate are discussed in the context of a deposition model. The resulting coating exhibited significantly improved adhesion and a 4-fold increase in moisture resistance as determined from the threshold for debonding in humid air compared to dense silica or commercial sol–gel polysiloxane coatings. Other important parameters for obtaining highly adhesive coating deposition on oxidation-sensitive polymer substrates using atmospheric plasma were also investigated to fully activate but not overoxidize the substrate. The resulting carbon molecular bridged adhesive coating showed enhanced moisture resistance, important for functional membrane applications

Heterogeneous Solution Deposition of High-Performance Adhesive Hybrid Films

Interfaces between organic and inorganic materials are of critical importance to the lifetime of devices found in microelectronic chips, organic electronics, photovoltaics, and high-performance laminates. Hybrid organic/inorganic materials synthesized through sol–gel processing are best suited to address these challenges because of the intimate mixing of both components. We demonstrate that deposition from <i>heterogeneous</i> sol–gel solutions leads to the unique nanolength-scale control of the through-thickness film composition and therefore the independent optimization of both the bulk and interfacial film properties. Consequently, an outstanding 3-fold improvement in the adhesive/cohesive properties of these hybrid films can be obtained from otherwise identical precursors

Independent Control of Adhesive and Bulk Properties of Hybrid Silica Coatings on Polycarbonate

International audienceTransparent polymers are widely used in many 9 applications ranging from automotive windows to micro-10 electronics packaging. However, their intrinsic characteristics, 11 in particular their mechanical properties, are significantly 12 degraded with exposure to different weather conditions. For 13 instance, under humid environment or UV-irradiation, 14 polycarbonate (PC) undergoes depolymerization, leading to 15 the release of Bisphenol A, a molecule presumed to be a 16 hormonal disruptor, potentially causing health problems. This 17 is a serious concern and the new REACH (Registration, 18 Evaluation, Authorization and Restriction of Chemical 19 substances) program dictates that materials releasing Bisphenol A should be removed from the market by January 1st, 2015 20 (2012-1442 law). Manufacturers have tried to satisfy this new regulation by depositing atop the PC a dense oxide-like protective 21 coating that would act as a barrier layer. While high hardness, modulus, and density can be achieved by this approach, these 22 coatings suffer from poor adhesion to the PC as evidenced by the numerous delamination events occurring under low scratch 23 constraints. Here, we show that the combination of a N 2 /H 2-plasma treatment of PC before depositing a hybrid organic-24 inorganic solution leads to a coating displaying elevated hardness, modulus, and density, along with a very high adherence to PC 25 (> 20 J/m 2 as measured by double cantilever beam test). In this study, the sol-gel coatings were composed of hybrid O/I silica 26 (based on organoalkoxysilanes and colloidal silica) and designed to favor covalent bonding between the hybrid network and the 27 surface treated PC, hence increasing the contribution of the plastic deformation from the substrate. Interestingly, double-28 cantilever beam (DCB) tests showed that the coating's adhesion to PC was the same irrespective of the organoalkoxysilanes/ 29 colloidal silica ratio. The versatility of the sol-gel deposition techniques (dip-coating, spray-coating, etc.), together with the 30 excellent mechanical properties and exceptional adherence of this hybrid material to PC should lead to interesting new 31 applications in diverse fields: optical eyeglasses , medical materials, packaging, and so forth. 3

Scratch-resistant sol-gel coatings on pristine polycarbonate

International audienceThe deposition of protective transparent coatings on polycarbonate (PC) with higher scratch resistance than that of the polymeric substrate is performed using an original sol-gel system. Our strategy relies on the preparation of hybrid organic-inorganic (HOI) films using sol-gel based on 3-glycidoxypropyltri-methoxysilane (GPTMS), tetraethoxysilane (TEOS) and zirconium(IV) propoxide (ZTP). We demonstrate that despite a low coating-to-PC adhesion (<2 J m(-2)), it is possible to maintain the coating integrity under high applied scratch forces when the organic domains of the film are highly connected. In this case, the increase in organic network connectivity was achieved through the reaction of epoxide rings in the presence of ZTP, as evidenced by FTIR. The subsequent additional plasticity of the coating led to an increase in scratch-test delamination force by more than twofold: from 1.7 N for the hybrid film without ZTP to 3.8 N with the highest degree of ZTP content. In regard to the inorganic network, an increasing number of Si-O-Zr and Zr-O-Zr bonds with increasing ZTP content were evidenced by FTIR and O-17 MAS NMR, allowing improved hydrolysis resistance, and therefore more durable coatings. Altogether, these results demonstrate the key role played by ZTP in tuning the mechanical properties and durability of HOI coating without requiring adhesion-promoting treatments

Plasma Damage of Porous Low-k Materials

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Molecular-Controlled Fracture and Release of Templated Nanoporous Organosilicate Thin Films

Molecular interactions between templating porogen particles and the underlying substrate can be exploited to create a controlled release mechanism while maintaining the bulk properties of the matrix material. Furthermore, these interactions can be reversed by priming the substrate with a hydrophobic layer to produce a strong interface with a nanoporous layer