title: Rendering Titanium Superhydrophobic

authors: Pachal, Sam Rewi

abstract: Two methods are reported herein to render titanium metal superhydrophobic. A superhydrophobic surface by definition is one that shows a water contact angle of equal to or greater than 150˚,(1) while in contrast bare titanium metal is hydrophilic and exhibits a water contact angle of 73±3˚.(2) Titanium metal is extremely reactive in air and rapidly forms a self-repairing oxide layer, which makes the necessary surface modification of the material to render it superhydrophobic challenging.
The first method employed in this work consists of a cold compression procedure whereby copper powder that has been previously rendered superhydrophobic by galvanic deposition of silver followed by treatment with 1-dodecanethiol is compressed onto titanium powder. The resulting compact consists of a superhydrophobic copper layer on a titanium substrate. The superhydrophobic copper layer is robust in that if it is damaged, the damaged layer can be abraded away to expose a new, fresh superhydrophobic copper layer beneath. Each successive layer exposed after abrasion throughout the superhydrophobic copper portion of the material is shown to exhibit the same wetting characteristics with regards to water roll-off angle.
The superhydrophobic titanium material prepared by this method exhibited a static water contact angle of 157±1º and water roll-off angles of 3.8±0.9º. The method was also successfully applied to aluminium powder, which showed a water roll-off angle of 4.2±0.4˚.
An additional superhydrophobic titanium material was prepared using this method which had a polyfluoroalkylthiol surface modifier, 1H,1H,2H,2H-perfluorodecanethiol, used in place of the 1-dodecanethiol. This material showed no statistically significant difference in wetting behaviour from its alkylthiol treated counterpart, with a water roll-off angle of 3.4±0.5˚ and a static water contact angle of 159±3˚.
The second method employed in this work was applicable to a foil form of titanium. It involves the deposition of copper onto a titanium foil, followed by galvanic reduction of silver onto the copper plate and adsorption of 1H,1H,2H,2H-perfluorodecanethiol in a self-assembled monolayer. Difficulty was encountered in getting a reproducibly adherent copper plate onto the titanium foil, and two methods were experimented with to find optimum conditions for an adherent copper deposit.
The first strategy used to deposit copper onto titanium involved a high voltage capacitor discharge across a titanium electrode in an acidic copper sulfate solution to destroy the native oxide layer present on titanium. A copper electroplate immediately followed this step, though unfortunately none of the deposits prepared in this manner passed adherence tests. The second method involved an anodic etching step before deposition of copper and showed much improved adherence over the first method, but was inconsistent and the copper coatings were non-uniform.
The superhydrophobic titanium materials prepared on titanium foils using both methods of copper deposition showed the same roll-off angles for an applied glycerol droplet as a purely superhydrophobic copper foil. A previous publication1 has quoted superhydrophobic copper foil prepared by the same method as having a water contact angle of 173±1˚ and a water roll-off angle of 0.64±0.04˚. Extrapolating from the materials sharing the same glycerol roll-off angles gives some confirmation that a superhydrophobic surface has successfully been applied to titanium foil in this work.

text: Rendering Titanium Superhydrophobic Two methods are reported herein to render titanium metal superhydrophobic. A superhydrophobic surface by definition is one that shows a water contact angle of equal to or greater than 150˚,(1) while in contrast bare titanium metal is hydrophilic and exhibits a water contact angle of 73±3˚.(2) Titanium metal is extremely reactive in air and rapidly forms a self-repairing oxide layer, which makes the necessary surface modification of the material to render it superhydrophobic challenging.
The first method employed in this work consists of a cold compression procedure whereby copper powder that has been previously rendered superhydrophobic by galvanic deposition of silver followed by treatment with 1-dodecanethiol is compressed onto titanium powder. The resulting compact consists of a superhydrophobic copper layer on a titanium substrate. The superhydrophobic copper layer is robust in that if it is damaged, the damaged layer can be abraded away to expose a new, fresh superhydrophobic copper layer beneath. Each successive layer exposed after abrasion throughout the superhydrophobic copper portion of the material is shown to exhibit the same wetting characteristics with regards to water roll-off angle.
The superhydrophobic titanium material prepared by this method exhibited a static water contact angle of 157±1º and water roll-off angles of 3.8±0.9º. The method was also successfully applied to aluminium powder, which showed a water roll-off angle of 4.2±0.4˚.
An additional superhydrophobic titanium material was prepared using this method which had a polyfluoroalkylthiol surface modifier, 1H,1H,2H,2H-perfluorodecanethiol, used in place of the 1-dodecanethiol. This material showed no statistically significant difference in wetting behaviour from its alkylthiol treated counterpart, with a water roll-off angle of 3.4±0.5˚ and a static water contact angle of 159±3˚.
The second method employed in this work was applicable to a foil form of titanium. It involves the deposition of copper onto a titanium foil, followed by galvanic reduction of silver onto the copper plate and adsorption of 1H,1H,2H,2H-perfluorodecanethiol in a self-assembled monolayer. Difficulty was encountered in getting a reproducibly adherent copper plate onto the titanium foil, and two methods were experimented with to find optimum conditions for an adherent copper deposit.
The first strategy used to deposit copper onto titanium involved a high voltage capacitor discharge across a titanium electrode in an acidic copper sulfate solution to destroy the native oxide layer present on titanium. A copper electroplate immediately followed this step, though unfortunately none of the deposits prepared in this manner passed adherence tests. The second method involved an anodic etching step before deposition of copper and showed much improved adherence over the first method, but was inconsistent and the copper coatings were non-uniform.
The superhydrophobic titanium materials prepared on titanium foils using both methods of copper deposition showed the same roll-off angles for an applied glycerol droplet as a purely superhydrophobic copper foil. A previous publication1 has quoted superhydrophobic copper foil prepared by the same method as having a water contact angle of 173±1˚ and a water roll-off angle of 0.64±0.04˚. Extrapolating from the materials sharing the same glycerol roll-off angles gives some confirmation that a superhydrophobic surface has successfully been applied to titanium foil in this work.

year: 2012

title: Do research assessment exercises raise the returns to publication quality? Evidence from the New Zealand market for academic economists

authors: Gibson, John

subjects: research assessment

abstract: Many countries have introduced research assessment exercises to help measure and raise the quality of research in their university sector. But there is little empirical evidence on how these exercises, such as the Quality Evaluation of the Performance Based Research Fund (PBRF) in New Zealand and the recently aborted Research Quality Framework (RQF) in Australia, affect the signals that researchers observe in the academic labour market. Since these assessments aim to raise research quality, individual academics should perceive rising returns to publication quality at the expense of the returns to quantity. Data we collected on the rank and publication records of New Zealand academic economists prior to the introduction of the PBRF and just after the second assessment round are used to estimate the changing returns to the quantity and quality of journal articles.

text: Do research assessment exercises raise the returns to publication quality? Evidence from the New Zealand market for academic economists Many countries have introduced research assessment exercises to help measure and raise the quality of research in their university sector. But there is little empirical evidence on how these exercises, such as the Quality Evaluation of the Performance Based Research Fund (PBRF) in New Zealand and the recently aborted Research Quality Framework (RQF) in Australia, affect the signals that researchers observe in the academic labour market. Since these assessments aim to raise research quality, individual academics should perceive rising returns to publication quality at the expense of the returns to quantity. Data we collected on the rank and publication records of New Zealand academic economists prior to the introduction of the PBRF and just after the second assessment round are used to estimate the changing returns to the quantity and quality of journal articles.

year: 2008-08

title: Tikanga Tainui: Tikanga Whare Wananga

authors: Roa, Tom

subjects: Tainui protocols

abstract: This paper is a preliminary report on an ongoing research project begun in 1999. The project involves consultation with Waikato-Tainui, the tangata whenua of the Waikato region, about the construction of guidelines for University of Waikato staff (both Māori and non-Māori) who are involved in gatherings that call for adherence to Tainui protocols. Here, the emphasis is on guidelines for the conduct of pōwhiri (formal welcomes) on the University Marae.

text: Tikanga Tainui: Tikanga Whare Wananga This paper is a preliminary report on an ongoing research project begun in 1999. The project involves consultation with Waikato-Tainui, the tangata whenua of the Waikato region, about the construction of guidelines for University of Waikato staff (both Māori and non-Māori) who are involved in gatherings that call for adherence to Tainui protocols. Here, the emphasis is on guidelines for the conduct of pōwhiri (formal welcomes) on the University Marae.

year: 2005-09-01