Copper mediated reversible deactivation radical polymerization in aqueous media

Key advances within the past 10 years have transformed copper mediated radical polymerization from a technique which was not very tolerant to protic media into a range of closely related processes capable of control over the polymerization of a wide range of monomers in pure water at ppm catalyst loadings; yielding water soluble macromolecules of desired molecular weight, architecture and chemical functionality, with applications ranging from drug delivery to oil field recovery. In this review we highlight and critically evaluate the synthetic methods that have been developed to control radical polymerization in water using copper complexes, identify future areas of interest and challenges still to be overcome

The GEM-T2 gravitational model

The GEM-T2 is the latest in a series of Goddard Earth Models of the terrestrial field. It was designed to bring modeling capabilities one step closer towards ultimately determining the TOPEX/Poseidon satellite's radial position to an accuracy of 10-cm RMS (root mean square). It also improves models of the long wavelength geoid to support many oceanographic and geophysical applications. The GEM-T2 extends the spherical harmonic field to include more than 600 coefficients above degree 36 (which was the limit for its predecessor, GEM-T1). Like GEM-T1, it was produced entirely from satellite tracking data, but it now uses nearly twice as many satellites (31 vs. 17), contains four times the number of observations (2.4 million), has twice the number of data arcs (1132), and utilizes precise laser tracking from 11 satellites. The estimation technique for the solution has been augmented to include an optimum data weighting procedure with automatic error calibration for the gravitational parameters. Results for the GEM-T2 error calibration indicate significant improvement over previous satellite-only models. The error of commission in determining the geoid has been reduced from 155 cm in GEM-T1 to 105 cm for GEM-T2 for the 36 x 36 portion of the field, and 141 cm for the entire model. The orbital accuracies achieved using GEM-T2 are likewise improved. Also, the projected radial error on the TOPEX satellite orbit indicates 9.4 cm RMS for GEM-T2, compared to 24.1 cm for GEM-T1

Copper mediated polymerization without external deoxygenation or oxygen scavengers

Overcoming the challenge of rigorous deoxygenation in copper mediated controlled radical polymerization processes (e.g. ATRP), we report a simple Cu(0)‐RDRP system in the absence of external additives (e.g. reducing agents, enzymes etc.). By simply adjusting the headspace of the reaction vessel, a wide range of monomers, namely acrylates, methacrylates, acrylamides and styrene, can be polymerized in a controlled manner yielding polymers with low dispersities, near‐quantitative conversions and high end group fidelity. Significantly, this approach is scalable (~ 125 g), tolerant to elevated temperatures, compatible with both organic and aqueous media and does not rely on external stimuli which may limit the monomer pool. The robustness and versatility of this methodology is further demonstrated by the applicability to a number of other copper mediated techniques including conventional ATRP and light‐mediated approaches

Ultra-low volume oxygen tolerant photoinduced Cu-RDRP

We introduce the first oxygen tolerant ultra-low volume (as low as 5 μL total reaction volume) photoinduced copper-RDRP of a wide range of hydrophobic, hydrophilic and semi-fluorinated monomers including lauryl and hexyl acrylate, poly(ethylene glycol methyl ether acrylate) and trifluoroethyl (meth)acrylate. In the absence of any external deoxygenation, well-defined homopolymers can be obtained with low dispersity values, high end-group fidelity and near-quantitative conversions. Block copolymers can be efficiently synthesized in a facile manner and the compatibility of the system to larger scale polymerizations (up to 0.5 L) is also demonstrated by judiciously optimizing the reaction conditions. Importantly, the online monitoring of oxygen consumption was also conducted through an oxygen probe and the role of each component is identified and discussed

Spherical harmonic expansion of the Levitus Sea surface topography

Prior information for the stationary sea surface topography (SST) may be needed in altimetric solutions that intend to simultaneously improve the gravity field and determine the SST. For this purpose the oceanographically derived SST estimates are represented by a spherical harmonic expansion. The spherical harmonic coefficients are computed from a least squares adjustment of the data covering the majority of the oceanic regions of the world. Several tests are made to determine the optimum maximum degree of solution and the best configuration of the geometry of the data in order to obtain a solution that fits the data and also provides a good spectral representation of the SST

Methacrylic block copolymers by sulfur free RAFT (SF RAFT) free radical emulsion polymerisation

We demonstrate the use of sulfur free reversible addition-fragmentation chain transfer polymerisation (RAFT as a versatile tool for the controlled synthesis of methacrylic block and comb-like copolymers. Sulfur free RAFT (SF-RAFT) utilises vinyl terminated macromonomers obtained via catalytic chain transfer polymerisation (CCTP) of methacrylates as a chain transfer agent (CTA), and thus precluding adverse aspects of the RAFT such as toxicity of dithioesters. We have synthesised a range of narrow dispersity block copolymers (Đ < 1.2) and comb-like macromolecules by employing emulsion polymerisation allowing for the preparation of relatively large quantities (~50 g) of the above mentioned copolymers promptly and straightforwardly. Copolymers were characterised using 1H NMR, size exclusion chromatography (SEC), thermogravimetric analysis (TGA) and matrix-assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF-MS) techniques

Block and multi block copolymers via SF-RAFT : utilising macromonomers as chain transfer agents

The objective of this work is to investigate and expand the use of methacrylic macromonomers as chain transfer agents. Although chain transfer activity had been demonstrated previously, the limits of the technique have not been fully explored. As such, a new approach for the efficient synthesis of methacrylic polymers in emulsion is presented, aiming at fully exploiting the vinyl end-group of the CCTP-derived macromonomers and consequently their chain transfer activity. Moreover, the preparation of higher MWt copolymers as well as more complex structures (e.g. triblocks etc) by this method will be investigated as research so far has only been focusing on certain degrees of polymerisation, mainly resulting in diblock copolymers of relatively low MWt. In addition, macromonomers based on diverse methacrylic monomers will be employed, as most studies to date have focused on a narrow monomer pool. In parallel, another aspect of radical polymerisation in the presence of macromonomers is the livingness of the system. Even though living-like characteristics have been observed, previous studies did not reach definitive conclusions, according to the generally set criteria of livingness. At the same time, the use of macromonomers as precursors for comb-like polymers will be described. Despite the technique being known and well-reported, the aim is to successfully employ solvents that satisfy the needs of automotive applications, such as mineral oil. In detail, both the macromonomer synthesis and the subsequent comb formation will be attempted in this solvent. A similar approach has not been reported so far. It needs to be noted, that this part is an ongoing work with the Lubrizol Corporation and as such it only demonstrates a few initial steps towards developing materials with interesting properties and applications

Moxifloxacin in Pediatric Patients With Complicated Intra-abdominal Infections: Results of the MOXIPEDIA Randomized Controlled Study

Background: This study was designed to evaluate primarily the safety and also the efficacy of moxifloxacin (MXF) in children with complicated intraabdominal infections (cIAIs). Methods: In this multicenter, randomized, double-blind, controlled study, 451 pediatric patients aged 3 months to 17 years with cIAIs were treated with intravenous/oral MXF (N = 301) or comparator (COMP, intravenous ertapenem followed by oral amoxicillin/clavulanate; N = 150) for 5 to 14 days. Doses of MXF were selected based on the results of a Phase 1 study in pediatric patients (NCT01049022). The primary endpoint was safety, with particular focus on cardiac and musculoskeletal safety; clinical and bacteriologic efficacy at test of cure was also investigated. Results: The proportion of patients with adverse events (AEs) was comparable between the 2 treatment arms (MXF: 58.1% and COMP: 54.7%). The incidence of drug-related AEs was higher in the MXF arm than in the COMP arm (14.3% and 6.7%, respectively). No cases of QTc interval prolongation-related morbidity or mortality were observed. The proportion of patients with musculoskeletal AEs was comparable between treatment arms; no drug-related events were reported. Clinical cure rates were 84.6% and 95.5% in the MXF and COMP arms, respectively, in patients with confirmed pathogen(s) at baseline. Conclusions: MXF treatment was well tolerated in children with cIAIs. However, a lower clinical cure rate was observed with MXF treatment compared with COMP. This study does not support a recommendation of MXF for children with cIAIs when alternative more efficacious antibiotics with better safety profile are available

Analysis of sea surface topography using SEASAT altimeter data

Prepared for National Oceanic and Atmospheric Administration, Rockville, Maryland: Contract No. 78-4326The sea surface topography (SST) is required for both oceanographic and geodetic purposes. Using geodetic techniques the SST can be determined from altimeter data and knowledge of the geoid. A set of time averaged sea surface heights at 1° intersections in the oceanic areas is used, derived from the adjusted SEASAT altimeter data. A geoid corresponding to these sea surface heights is computed up to minimum wavelengths of 2000 km, using the GEML1 gravity model. A best fit ellipsoid to the mean sea surface is determined. The differences between the sea surface heights and the geoid are computed to give raw estimates of SST. These estimates contain GEML1 errors and residual geoid information. These last quantities are filtered out by using a spherical harmonic analysis and retaining the spherical harmonics up to degree 6. The primary limitation in the determination of SST for higher harmonic degrees is due to the errors of the GEML1 gravity model. A two dimensional filter has also been implied as an alternative method. Using the spherical harmonic coefficients, estimates of SST are computed and global maps of SST and current directions are constructed. The solution is compared with oceanographic solutions as well as with other satellite derived solutions

Radial Orbit Error Reduction and Sea Surface Topography Determination Using Satellite Altimetry

A method is presented in satellite altimetry that attempts to simultaneously determine the geoid and sea surface topography with minimum wavelengths of about 500 km and to reduce the radial orbit errors caused by geopotential errors. The modeling of the radial orbit error is made using the linearized Lagrangian perturbation theory. Secular and second order effects are also included. After a rather extensive validation of the linearized equations, alternative expressions of the radial orbit error are derived. A Fourier series formulation allows for easier computations, examination of the frequency content of the error and computation of different statistics. A geographic representation with respect to geocentric latitude and longitude gives a significantly better insight on the spatial variations of the error. Similar expressions are derived for the geoid undulation error and sea surface topography. Numerical estimates for the radial orbit error and geoid undulation error are computed using the differences of two geopotential models as potential coefficient errors, for a Seasat orbit. To provide statistical estimates of the radial distances and the geoid, a covariance propagation is made based on the full geopotential covariance. Accuracy estimates for the Seasat orbits are given which agree quite well with already published results. Observation equations are developed using sea surface heights and crossover discrepancies as observables. A minimum variance solution with prior information provides estimates of parameters representing the sea surface topography and corrections to the gravity field that is used for the orbit generation. The potential of the method is demonstrated in a solution where simulated geopotential errors and the Levitus sea surface topography are used to generate the observables for a three day Seasat arc. The simulation results show that the method can be used to effectively reduce the radial orbit error and recover the sea surface topography