V. Shared Experimental Facilities

Development of energy-efficient and environmentally friendly processes based on liquid

and supercritical CO₂ requires unique, innovative instrumentation and effective collaboration and communication between researchers at a distance and from varied backgrounds. These Shared Experimental Facilities (SEF) are being funded in order to facilitate collaboration and to provide:

* the desired collaborative working environment for STC and associated personnel

* state-of-the-art equipment/facilities needed by STC personnel to achieve their goals

* unique facilities to the scientific community at large primarily for collaborative research

In support of these goals, NSF STCERSP is establishing six new major Shared Experimental Facilities:

* NMR Laboratory for the Study of Compressible Media

* Interfacial Science Laboratory

* Rheology Laboratory

* Reaction Kinetics Laboratory

* Computational Facilities

* Distributed Collaboratories

In addition, commonly needed instruments and equipment as well as specialized equipment of somewhat lower cost are being distributed to the various sites supporting specific key programs.

Table V in Appendix G summarizes all capital equipment purchases.

The design of facilities and procurement of equipment are major undertakings. During the past nine months, approximately twenty PI’s have collaborated in designing instruments, writing up specifications, negotiating with vendors, requesting bids, etc. In the following, the PI’s summarize the status of this work and the plans for the next year. In spite of unavoidable delays in purchasing procedures, construction time, shipping, and installation, the facilities are taking shape. In particular the center piece research instrument, a 600 MHz NMR system has already been delivered to UNC-CH and is expected to be operational in August, 2000. The Beowulf Super-Computer Cluster is in operation at UNC, and numerous smaller instruments have been designed or have been purchased.

NMR Laboratory for the Study of Compressible Media NMR is the premier analytical tool for the study of supramolecular systems: for the identification of molecules, the determination of molecular structure and transport properties of selected species in mixtures, and the characterization of intermolecular interactions. We initially concluded that we needed (1) high field for sensitivity and dispersion and (2) a widebore magnet accommodating special purpose probes. Since the new NMR spectrometer will be integrated into the NMR Laboratory at UNC-Chapel Hill and managed by the NMR laboratory staff it is important to consider the total capabilities of the NMR laboratory. In 1999 the NMR Lab. placed an order for a 400 MHz widebore spectrometer, paid for by a gift from Glaxo-Welcome. Since this widebore machine will be available to the CERSP, it was concluded that the most effective use of Center funds was to acquire a higher field spectrometer (600 MHz - standard bore) with an array of special purpose probes. A committee consisting of C. Johnson, E. Samulski, and S. Wallen reviewed the offerings of vendors during and submitted a request for bids in February for a three channel spectrometer with various probes. After bids were received the following system was ordered on May 18:

* Varian 600 MHz 3-channel spectrometer with 1H-19F 5mm tunable PFG triple probe

* Nalorac 5mm 1H-19F diffusion probe providing 20 gauss/cm.ampere

* Nalorac 5mm 1H- 19F decouple, gradient broadband switchable probe

* Varian 5mm 1H{13C/15N} PFG triple resonance probe

The spectrometer will be installed in August, and the probes will be delivered by November.

The NMR laboratory will have two permanent staff members plus part time to insure that the nine spectrometers including the 600 MHz system are operational and are available. The laboratory manager, will arrange for the training of users on the 600 MHz spectrometer as well as on lower field spectrometers. The hourly use charges will be the same for all machines.

Interfacial Science Laboratory Three major pieces of equipment comprise this SEF: (1) the High-pressure Pendant Drop Interfacial Tensiometer, (2) the Fluorescence Spectrometer and (3) the Picosecond Laser System.

High-Pressure Pendant Drop Interfacial Tensiometer We have designed, constructed and tested a new user-friendly high-pressure pendant drop tensiometer, fully automated, capable of measuring static and dynamic surface (air/water) and interfacial (liquid/supercritical fluid) tension up to 400 bar. It consists of a variable volume view cell equipped with side sapphire windows (measurement cell), an HPLC pump, a syringe pump, an optical rail for proper alignment, a Sony CCD video camera, a fluorescent light source and a computer. Pendant drops are formed at the end of a stainless steel needle with blunt tip, with inside and outside diameters of 0.019” and 0.005”, respectively, or at the end of silica capillary. Once a suitable drop is formed, the six-port switching valve connecting the pump to the cell is closed and timing of the drop age starts. Images of the drop are acquired with a Matrox Meteor II frame grabber and are analyzed by a software package. Interfacial tension is obtained from the shape of the drop using the Laplace equation. Rapid data acquisition is available up to 40 ms/frame. The use of an HPLC-type pump allows the fast and accurate measurement of interfacial tension between CO₂ and different brine solutions or even mixture of surfactants (one primarily H₂O-philic and the other CO₂-philic.)

Fluorescence Spectrometer A novel, high-pressure, low-angle dynamic light scattering apparatus has been designed for the study of water-in-CO2 microemulsions and other colloids. It is capable of studying continuous angles from 10-30° by placing the sample in a high-pressure cell between two sapphire windows of 0001 orientation (lattice perpendicular to the sample so as not to disrupt light polarization). The high pressure cell has been constructed and tested. A second generation is being designed with fiber optic detection. It will complement the facility at UNC for larger angles starting at 45 degrees. Low angles are particularly useful for particle sizes in the range of 1 to 10 nm. The correlator has 522 channels with individual channel time selection available so that both small (micelles, microemulsions) and large (emulsion) droplets can be studied simultaneously.  The photo-detector can be directly connected to GRIN fiber-optic pickups to allow multiple angles to be studied.  The system will be operational in September.

The DLS apparatus will be available to researchers both inside and outside of the center. Within the center it will be useful for studies of microemulsions, emulsions, latexes and inorganic suspensions. It will be highly complementary to the interfacial tension laboratory.

Picosecond Laser System Final negotiations are underway for the purchase of the sum-frequency generation laser system. The details are confidential and are contained. P. Tundo

Rheology Laboratory Funds from the CERSP are being used to construct the high-pressure magnetically levitated sphere rheometer. This instrument will complement the high-pressure extrusion rheometer and enable measurements of viscosity of a wide range of materials, from high viscosity melts to polymer solutions. In addition, the equipment can be used to obtain other material properties besides viscosity. Information from these experiments will facilitate polymer processing as well as designing new materials including blends and foams. This equipment will enable us to achieve our overall objectives of elucidating relationships between rheology and polymer molecular architecture of various systems including polymer/surfactant systems.

The rheology laboratory will be invaluable in developing new materials and processes. The equipment is readily available to all PIs within the CERSP as well as to other members of the community. Anyone interested in using this equipment can do so by contacting the rheology laboratory and scheduling a time. In-house training will be provided to other members of the STC when they need to use the equipment.

Reaction Kinetics Laboratory DeSimone has received a ReactIR High Pressure ATR System from ASI.  The manufacturer was unable, initially, to meet the design specifications (5,000 psi pressure rating) on the ultra-high pressure probe.  A probe that supposedly works up to 3,000 psi was recently shipped to us to use in the interim until a probe that meets specifications is available (according to ASI, this is projected to be late 2000).

Kelly was allocated funds to purchase a GC as well as build a CO2 reactor for our lab (total cost < $50K). These have not yet been acquired because of changes in experimental plans that may alter our analytical requirements. We plan to discuss these with the CERSP Directors and to have the issue resolved by October 2000.

The initial phase of the joint Murray/DeSimone research project is to design, construct, and assemble an electrochemical instrument system. This system consists of CO₂ pumping and valving system, batch and flow-through CO₂ compatible electrochemical cells and electrodes, and electronics for electrochemical control, measurement, and data acquisition. A first-generation instrument has been assembled for the initial measurement targets of ionic conductivity. Underway is design and construction of a flow-injection cell that will allow facile exposure of a voltammetry cell insert to different CO₂ solutions or electrolyte, electrolyte plus redox probe, etc. An ac impedance instrument setup for high impedance measurements has been achieved, from existing equipment. The electrochemical instrument system, and its anticipated successors are central to this project. We do not anticipate use by other groups owing to its specialized nature. However, it will be available if there is interest. It is probable that, in due course and as we come to understand the scope of possible electrochemical measurements and their attributes, measurements will be conducted on CO₂ reaction systems of interest to others in the CERSP.

Adewuyi (NCA&T) has ordered a Finnigan GC/MS system with accessories including an
Xcalibur software and data system, and library. This equipment also consists of electron impact ion source, quadrupole analyzer, photomultiplier detector and an automatic dual differential vacuum system. It offers the high levels of sensitivity, flexibility and robustness needed to analyze

reaction products and elucidate kinetics and reaction mechanisms.

Computational Facilities The Beowulf Super-Computer Cluster provides a state-of-the-art computer platform capable of performing computer simulations of large systems over long length scales, both of which are necessary for the simulation of micellar systems. The choice of such a modular super-computer system is also advantageous, as expanding and upgrading the cluster is more cost effective than for other traditional types of super-computers. The Cluster at UNC-CH consists of 17 Compaq DS10 Alpha server workstations, each powered by the Alpha 21264 processor, connected into a local area network via a 100Mb/s ethernet switch. The computational efficiency of this cluster is comparable to that of super-computers (e.g., Cray T3E); however the inter-processor communication reduces our efficiency for parallel computations. That said, preliminary molecular dynamics simulations have shown that many serial simulations running in parallel is a more efficient use of computational power than using parallel methods.

At NCSU a 12-node Beowulf cluster was ordered. It consists of 6 separate machines, each supporting two 667 Mhz alpha processors with 4MB of cache on each processor. Each of these six machines will have 512MB of RAM, a 14.4GB hard disk drive, and 100MBit ethernet for data communication. A separate RAID array with a capacity of 108GB will be used for data storage, supplemented by a Sony DDS-4 DAT drive for data backup. The Beowulf system can be used for both parallel and serial calculations. The primary function of this facility will be to carry out large-scale molecular simulations of CO₂ solvent systems, including micellar solutions.

Collaboration Equipment Since we submitted our proposal, all four universities have created video conference (VC) centers easily accessible to CERSP personnel. Rather than create additional VC facilities, we are collaborating with the staff at each University both to support our weekly CERSP video meetings using existing facilities and to upgrade these facilities to better meet our needs and general educational needs. For example, both our meetings and the distance education classes at UNC-CH would benefit from larger video displays. By using CERSP capital to purchase multi-purpose equipment we help others achieve their education and research goals as well as our own. In return we receive technical support and consultation, improving the quality of our video conferences.