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The micellar properties of sodium glycodeoxycholate (NaGDC) and polyoxyethylene tert-octylphenyl ether (Triton X-100) and their binary combinations have been investigated using tensiometry and fluoresence techniques. The critical micelle concentrations of the micellar species were determined from surface tension and spectrofluorimetric methods. The CMC's of mixed micelles are found to be lower than the ideal values according to Clint's equation. The microenvironment of the micelles were explored from the viewpoint of aggregation characteristics and polarity index. The mean aggregation numbers were obtained from steady state quenching experiments. The values decreased with increasing mole-fraction of the bile salt in the co-micelle. The ratio of the first and third vibronic peaks (I1/I3) in a monomeric pyrene emission spectrum provided an estimate of the polarity index of the micelle interior. The results indicate that the pyrene solubilization site changes with the concentration of the micellar species and the hydrophobic character of the mixed agregates increases with the increase of NaGDC mole-fraction. The CMC's and composition of the mixed systems have been calculated following molecular thermodynamic approach. The calculated mole-fractions of NaGDC are lower than the analytical ones and the evaluated interaction parameter gives a measure of the synergism of the interacting amphiphiles.

Poly (lactic-co-glycolic acid) nanoparticles loaded with Aripiprazole has been developed as a new therapeutic strategy to achieve its controlled release profile suitable for parenteral administration. Nanospheres composed of different lactic/glycolic acid ratios and drug compositions were synthesized and loaded with Aripiprazole by emulsion/solvent evaporation method and subsequently characterized by particle-size distribution, scanning electron microscopy, encapsulation efficiency and in–vitro drug release studies. Specific drug-polymer interactions are engineered by optimizing the lactide to glycolide ratio (L:G ratio) and including specific polymer hydrophobicity.

Shilajit (asphaltum) is produced by the long term humification of dead plant material and organic vegetable matter by different micro-organisms and has great potential for the treatment of a variety of human conditions. This treatise reviews its origin, sources, chemical composition, biological and commercial importance. Phytochemical analysis was done by standard methods to evaluate different Shilajit (asphaltum) classes of compounds in different samples of shilajit which are responsible for their biological activity. Shilajit`s anti-microbial activity has been evaluated against four different bacterial strains viz., Escherichia coli, Psuedomonas aeuroginosa, Klebisella pneumonia and Staphylococcus aureus. Phytochemical analysis illustrated that shilajit contains terpenoids, cardiac glycosides, saponins and reducing sugars. Surprisingly, some classes of compounds are absent in shilajit viz., alkaloids, flavonoids, tannins and anthraquinones. . Shilajit showed no response towards halophytic bacteria and negligible activity was shown towards other strains of bacteria. Since anti-microbial activity is based on environmental factors its activity varied between locations.

The leaf extract of Berberis orthobotrys Bien. ex Aitch. (B.o.) afforded three compounds viz., β-sitosterol (1), sesamin (2) and 10-eicosanol (3) which were identified by spectroscopic methods including 1D and 2D NMR, GC-MS, IR and comparison of their spectral data with the published data. To the best of our knowledge these three compounds are reported here for the first time to be isolated from Berberis orthobotrys Bien. ex Aitch. (B.o.). Moreover the root extract exhibited good antilieshmanial activity and root and fruit extracts demonstrated minor antifungal activity against Fusarium solani.

Date (Phoenix dactylifera L.) seeds (pits) account for ca. 10% of the date fruit and it is the date pits that present a major problem to the date palm industry in the USA as a waste product. Currently date pits are employed as a food source for animals and poultry, as a soil fertilizer and also as a road base gravel In order to understand the varietal effects of Omani date seeds on the nutritional properties of dates and to explore the use of this waste product from the food industry, twenty two native date seeds (Phoenix dactylifera L.) including the varieties; Qushbu Narenjahn, Fardh, Naghal, Manhi, Qush Balquan, Helali Oman, Khasab, Seedi, Qush Jabrin, Khalas, Qush Basrah, Qushbu Maan, Handal, Khunaizi, Qush Mamoor, Barshi, Barni, Azad, Zabad, Qush Tabak, Qush LuLu, and Halali Alhasa were collected from six regions of the Sultanate of Oman and were examined for their nutritional value, antioxidant and urease properties. Energy values, dry matter, and carbohydrate level were the predominant components examined in the date seeds , followed by fiber, moisture, along with small amounts of ash, protein, and fat. The results of the 22 varieties of date seeds showed a significant energy value of between 283.0 to 407.9 kcal/100g, dry matter of between 93.3%-96.3%, carbohydrate content of between 43.8%-80.6%, moisture in the range of 4.3%-6.6%), fat in the range of 5.0%-10.9%, ash content of between 0.73%-1.08%, protein content of 0.2%-6.9% and fiber content of between 5.0%-32.5%. Furthermore the antioxidant potential ranged between 7.4 - 88.3% depending upon the type of date seeds and location of samples. In this regard the Handal date seeds collected from Al-Hamra showed the highest antioxidant potential with 88.3% inhibition. Similarly urease inhibition ranged from 0.94-70.3% and Qush Tabak date seeds collected from Al-Hamra demonstrated the highest urease potential with 70.3% inhibition. It is noteworthy that Qush Basrah, Seedi, Qush Balquan, and Handal date seeds h

Phytochemical and biological investigations were undertaken on ethanolic extracts of the leaves and root bark of Justica adhatoda L. Alkaloids, cardiac glycosides, tannins, steroids and saponins were detected in extracts from both parts of the title plant. Reducing sugars were not detected in either extract whereas flavonoids were detected in ethanolic extract of J. adhatota leaves only. Significant antibacterial and antifungal activities against Escherichia coli, Staphylococcus aureus and Aspergillus niger were demonstrated by both the leaf and root bark extracts. Additionally, both extracts displayed good antioxidant and heomolytic potential. Interestingly, eight metal ions were detected in both extracts in different concentrations.

Controlled release of Levofloxacin Hemihydrate drug through Methyl Methacrylate grafted Poly (vinyl alcohol) (PVA-g-MMA) hydrogel membranes have been investigated. These graft co-polymer hydrogel membranes of various formulations were prepared using conventional solution casting method by varying, monomer, cross-linker and drug content. An attempt has been made to characterize these hydrogel membranes by various instrumental techniques like, Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). The release patterns of the drug from the hydrogel membrane were carried out in pH 7.4 media and the samples were analysed spectrophotometrically at 294 nm wavelength on a UV Vis spectrophotometer. The mechanical properties of the hydrogel membranes were characterized by UTM. FTIR spectra of the membranes indicated complete esterification of the free carboxyl groups of Methyl Methacrylate. XRD studies indicated that the crystallinity of the membranes was mainly due to Methyl Methacrylate. The experimental results indicated that the hydrogel membrane could be tried for various biomedical applications

The development of injectable microspheres for controlled drug delivery to the desired site is a major challenge. We demonstrated the possibility of entrapping an anticancer drug, Imatinib mesylate, in collagen coated biodegradable poly (lactic acid) microspheres with a mean diameter of 10-20 µm. The collagen coating on polymeric matrix surfaces through various surface modification techniques was the current scenario to improve bio-integration of the polymers with the in-vivo system. Here protein adsorption principle is used and various characterization techniques like FTIR, DSC and SEM analysis are used to confirm collagen coating. The reduction in burst release of the Imatinib from the PLA microspheres further confirms its presence and role in controlled release. This collagen coated PLA microspheres may have potential for the targeted delivery of Imatinib mesylate to treat gastrointestinal stromal tumors, chronic myeloid leukemia cancer.

In this study, Lornoxicam (LX) loaded spermaceti (SC) microspheres were prepared using meltable emulsified dispersion cooling induced solidification technique and the bioavailability of the marketed product (Flexispaz® capsule-reference-product A) was compared with the optimized formulation (lornoxicam loaded spermaceti microspheres–test–product B). Morphological studies of wax microspheres were evaluated using scanning electron microscopy (SEM). The SEM images showed the spherical shape of wax microspheres and more than 97% of the isolated microspheres were in the size range 309-317 μm. Differential scanning calorimetry (DSC), Fourier transforms infrared (FTIR) spectroscopy and stability studies showed that the drug after encapsulation with SC microspheres was stable and compatible. A single dose, randomized, complete cross over study of LX (8mg) microspheres were carried out on 10 healthy male and female Albino sheep’s under fasting conditions. Plasma LX concentrations and other pharmacokinetic parameters obtained were statistically analyzed. Based on this study, it can be concluded that drug loaded LX microspheres and Flexispaz® capsule are bioequivalent in term of the rate and extent of absorption.Key words: Lornoxicam; Wax microspheres; Release kinetics; Bioavailability; Bioequivalence

This work analyses the high-strain extensional behavior of long-chain branched polyethylenes, employing two novel extensional rheometer devices, the filament stretching rheometer and the cross-slot extensional rheometer. The filament stretching rheometer uses an active feedback loop to control the imposed strain rate on a filament, allowing Hencky strains of around 7 to be reached. The cross-slot extensional rheometer uses optical birefringence patterns to determine the steady-state extensional viscosity from planar stagnation point flow. The two methods probe different strain-rate regimes and in this paper we demonstrate the agreement when the operating regimes overlap and explore the steady-state extensional viscosity in the full strain-rate regime that these two complimentary techniques offer. For long-chain branched materials, the cross-slot birefringence images show a double cusp pattern around the outflow centre line (named W-cusps). Using constitutive modeling of the observed transient overshoot in extension seen in the filament stretching rheometer and using finite element simulations we show that the overshoot explains the W-cusps seen in the cross-slot extensional rheometer, further confirming the agreement between the two experimental techniques. © 2013 The Society of Rheology.

Biodegradable polymers with high mechanical strength, flexibility and optical transparency, optimal degradation properties and biocompatibility are critical to the success of tissue engineered devices and drug delivery systems. Most biodegradable polymers suffer from a short half life due to rapid degradation upon implantation, exceedingly high stiffness, and limited ability to functionalize the surface with chemical moieties. This work describes the fabrication of microfluidic networks from poly(ester amide), poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS), a recently developed biodegradable elastomeric poly(ester amide). Microfluidic scaffolds constructed from APS exhibit a much lower Young’s Modulus and a significantly longer degradation half-life than those of previously reported systems. The device is fabricated using a modified replica-molding technique, which is rapid, inexpensive, reproducible, and scalable, making the approach ideal for both rapid prototyping and manufacturing of tissue engineering scaffolds., Charles Stark Draper Laboratory

Electrical conductivity of graphene/poly(benzimidazobenzophenanthroline) (BBL) composites was evaluated. Both graphene oxides (GOs) and reduced GOs (rGOs) were found to be well dispersed in BBL; in situ thermal reduction of GO was possible due to the high thermal degradation temperature of BBL (600 degrees C). Electrical conductivity of the GO/BBL composite increased by approximately 4 orders after annealing at 500 degrees C for 30 minutes. Chemically-reduced GOs were also applicable to the rGO/BBL nanocomposite system and the post-heat treatment of the GO/BBL composite was also effective to impart good electrical conductivity to BBL.

Torsional compliance of the torque transducer can be an important issue in linear viscoelastic (LVE) measurements when the sample stiffness is high relative to the instrument stiffness. We evaluated compliance effects of the ARES 2K-FRT on LVE measurements by systematically comparing the results of the frequency sweep mode obtained with 25 and 8 mm plates, respectively. In addition to the transducer, the test fixtures do contribute significantly to the system compliance. Without correction, the upper limit for the complex modulus ∣ G ∗ ∣ is approximately close to 4 × 105 Pa at 10% uncertainty, when using 25 mm plates. This limit is lower than the plateau modulus $\left( {G_N^0 } \right)$ of most polymers. Therefore, instrument compliance can lead to significant errors for $G_N^0 $ and wrong scaling for G ″ in the plateau and Rouse regions. The respective roles of transducer and tool compliances are discussed. The FRT transducer compliance is corrected in real time in the instrument firmware. Tool compliance is a common problem for all rheometers when measuring stiff samples.

We have developed a novel route for the synthesis of the thermoresponsive core-shell nanoparticles that consist of the magnetite core and the poly(N-isoproplyacrylamide) (poly(NIPAAm) shell in aqueous medium. Magnetic nanoparticles (MNPs) were coated with first oleic acid (OA) and then vinyl carboxylic acid-beta-cyclodextrin (MAH-beta-CD). The OA-MNPs and the MAH-beta-CD-MNPs showed mono-dispersion in a n-hexane and aqueous medium, respectively. NIPAAms were successfully polymerized from the vinyl double bonds of the MAH-beta-CD MNPs and cross-linked with N, N-methylenebisacrylamide (MBA) to make the stable thermo-responsive core-shell morphology with the MNP core and the poly(NIPAAm) shell (poly(NIPAAm)-MNP). The aqueous solutions dispersed with poly (NIPAAm)-MNPs showed magnetic heating due to a super paramagnetic property, and the poly (NIPAAm) shell shrank above its LCST temperature. Apart from aqueous dispersed solution PNIPAAm magnetite composite film can also be prepared via photopolymerization using APS as a photo initiator. The film synthesized is cross linked with MBA and thus insoluble in water. When AC magnetic field is applied on such a PNIPAAm nanocomposite film, MNPS oscillate and produce heat and as a result PNIPAAm shrinkage can be observed. The combination of these properties are potentially important in target delivery of therapeutic agent in vivo, hyperthermic treatment of tumors, magnetic resonance imaging (MRI) as contrasting agents, tissue repair, immunoassay, cell separation, biomagnetic separation of biomolecules, etc.

This research work focuses on the microscopic description of constraint release (CR) events in melts of branched polymers. In this respect, it models CR events by means of Rouse-like hops. Two cases are examined: (i) CR events mediated by the release of backbone-backbone entanglements, and (CR) events mediated by the rlease of backbone-arm entanglements. The derived model predicts strain hardening (thinning) at extension (shear) during start-up of the flow. The maximum stretch, however, becomes dependent on flow-rate.

Unique methods for the encapsulation of biologically-derived materials within ordered mesoporous silica films, the preparation of mesoporous silica films using a biodegradable template system, and the preparation of thermally stable, mesoporous silica spheres with tunable diameters ranging from 40 nm to 560 nm, narrow size distributions on the order of 10%, surface areas greater than 1000 m2/g, and pore volumes on the order of 1 cc/g were demonstrated. The stable spheres were synthesized using tetraethylorthosilicate at room temperature and near-neutral pH using cysteamine as the catalyst and cetyltrimethylammonium bromide (CTAB) as the structure directing agent in a mixed water and ethanol system. The pore walls were resistant to collapse at temperatures exceeding 750-deg C in air and upon hydrothermal treatment in boiling water for over 100 hours. Silica formed using bio-inspired small molecule catalysts including cysteamine, glutathione and methionine alone or in combination provided highly condensed silica networks at room temperature over a broad range of pH as evidenced by 29Si NMR., The original document contains color images.

Despite environmental hazards, cadmium (Cd) is still widely used in the plating industry (especially for fasteners) because of its unique combination of properties. There is no drop-in replacement for Cd-plated high-strength steels, but commercial zinc (Zn) and aluminum (Al)-filled polymers deposited by the dip-spin coating technique have shown initial promise. Although they are quite effective, the coating tends to clog fastener threads, and their torque characteristics tend to change over the course of multiple assemblies. This is a serious drawback for aerospace and other DoD applications where weapon systems require periodic strip-down and maintenance. In order to meet the environmental challenge of replacing Cd on high strength steel substrates without the loss of performance, a novel approach using electro-active polymers (EAP s) as the corrosion inhibition layer has been investigated. All of the objectives of this SERDP SEED have been accomplished successfully. The synthesis and characterization of new monomers and the synthesis, using electroless deposition techniques and electropolymerization of EAPs that adhere to steel substrates has been completed. Both electropolymerization and electroless deposition are non-lineof- sight (NLS) techniques for coating EAPs onto steel plates and other geometries. The characterization of critical coating properties, using a combination of standard methods for fastener performance such as galling testing and hydrogen embrittlement testing, along with an evaluation of corrosion performance using impedance spectroscopy and neutral salt fog testing, EDS/SEM, has also been completed.

Poly-p-phenelenebenzobisoxazole (PBO, commercial name ZylonTM, Toyobo Co.)is one of the rigid-rod polymers which produces fiber with excellent mechanical properties. This polymer, originally developed by the U.S. Air Force to replace metals in space and aviation applications, is currently one of the more promising materials for fibers used in personnel ballistic armors. In this study we evaluate the degradation mechanisms of PBO fibers and investigate strategies to stabilize them using supercritical CO2 as an extraction medium, a transport medium, and a polymerization medium. Various treatments and their effects are reported herein., Paper title: Stabilization of Poly-p-phenylenebenzobisoxazole Fibers. The original document contains color images.

By using Brillouin Light Scattering (BLS), we have investigated phononic properties of Wiseana iridovirus (WIV) assemblies and dispersed individual viruses at hypersonic frequency window. Propagating modes in virus assemblies and localized vibrational eigenmodes of individual virus have been identified. Based on phonon spectra, Young's modulus of the virus has been estimated to be ~7 GPa, suggesting that the WIV virions are mechanically more similar to their DNA cores than to their capsid (protein) shells. The results also indicate that viral colloids are mechanically coupled during assembly in contrast to a system of synthetic polymeric colloids., See also ADM002137. Presented at the IEEE International Conference on Nanotechnology (8th), held in Arlington, TX on August 18-21, 2008. Published in the proceedings of the conference, 2008. Sponsored in part by Air Force Research Laboratory (AFRL), Wright-Patterson AFB, OH; University of Dayton, OH; and University of Otago, Dunedin, New Zealand. U.S. Government or Federal Rights License. The original document contains color images.

Swelling, states of water, morphology, stability in the aqueous solution, and electro-mechano- chemical bending behaviors of the gelatin/chitosan blend system were studied in order to clarify the potential use of this blend system as an actuator. The gelatin/chitosan blend system was prepared in order to avoid dissolution of the pure chitosan film system in an aqueous medium and the rigidity and easy degradation of the pure gelatin system in the swollen state. The blend systems showed improved material properties: the vacuum-dried blend sample at the G75/C25 (w/w, gelatin/chitosan) ratio showed approx. 4 times swelling (in distilled water, at neutral pH and room temperature), approx. 5 times stability (in distillated water), and approx. 6 times bending (at 6V/53mm and in 0.02 M NaCl aqueous solution) as compared to pure gelatin. These enhanced properties could be explained by the introduction of free -OH, -NH2, and -NHOCOCH3 groups of the amorphous chitosan in the blend and the network structure through the electrostatic interactions between the ammonium (-NH3+) ions of the chitosan and the carboxylate (-COO-) ions of the gelatin. The scanning electron microscopy (SEM) micrographs of the surfaces of the blend films showed homogeneous and smooth surfaces due to the good miscibility between gelatin and chitosan. However, a different morphology from the fractured surface was found for the pure gelatin and blend systems which showed condensed and foliaceous morphologies, respectively. The leafy morphology indicates a large and homogenous pore structure, which would cause increased ion diffusion into the gel and might lead to increased bending.

No Abstract.

The work focused on (1) design, synthesis and characterization of nanoscale-ordered carbon nanotubes and C60 with high photoconductivity, and (2) study of potential implementation the resulting materials to photovoltaic applications.

This report describes 7 publications that led from this grant: Buried Interface Modification Using Supercritical Carbon Dioxide, Controlled Growth of Silicon Dioxide from "Nanoholes" in Silicon-Supported Tris(trimethylsiloxy)silyl Monolayers, Adsorption of Poly(vinyl alcohol) onto Hydrophobic Substrates (2 papers), A General Approach for Hydrophilizing and Chemically Activating Surfaces, Chemical Surface Modification of Poly(p-xylylene) Thin-Films, Nylon Surface Modification (2 papers).

The electroluminescence of a number of conjugated macromolecules has been studied with particular reference to finding systems with high quantum yields. Various strategies have been investigated to optimize the light output from devices incorporating these polymers. The program included complementary studies of relevant optical and other physical properties of these materials., The original document contains color images.

Structural types of dendrimer nanocomposites have been studied and the respective formation mechanisms have been described, with illustration of nanocomposites formed from poly(amidoamine) PAMAM dendrimers and zerovalent metals, such as gold and silver. Structure of {(Au(0)) n??? PAMAM} and {(Ag(0)) n??? PAMAM} gold and silver dendrimer nanocomposites was found to be the function of the dendrimer structure and surface groups as well as the formation mechanism and the chemistry involved. Three different types of single nanocomposite architectures have been identified, such as internal (???I???), external (???E???) and mixed (???M???) type nanocomposites. Both the organic and inorganic phase could form nanosized pseudo-continuous phases while the other components are dispersed at the molecular or atomic level either in the interior or on the surface of the template/container. Single units of these nanocomposites may be used as building blocks in the synthesis of nanostructured materials.

The mechanism of the spontaneous polymerization of 4-vinylpyiridine on quaternization or protonation has been investigated. Results indicate that initiation is caused by the nucleophilic attack of 4-vinylpyridine on the double bond of 4-vinylpyridinium ion. It was shown that halide ions do not contribute significantly to the initiation. In the case of acid salts of 4-vinylpyridine a hydrogen-transfer polymerization occurred to give an ionene polymer with pyridinium units in the main chain. The "matrix" polymerization of 4-vinylpyridine on poly(phosphoric acid) or poly(acrylic acid) also resulted in ionene formation. Conditions under which stable 4-vinylpyridinium salts can be obtained are discussed.

Despite environmental hazards, cadmium (Cd) is still widely used in the plating industry (especially for fasteners) because of its unique combination of properties. There is no drop-in replacement for Cd-plated high-strength steels, but commercial zinc (Zn) and aluminum (Al)- filled polymers deposited by the dip-spin coating technique have shown initial promise. Although they are quite effective, the coating tends to clog fastener threads, and their torque characteristics tend to change over the course of multiple assemblies. This is a serious drawback for aerospace and other DoD applications where weapon systems require periodic strip-down and maintenance. In order to meet the environmental challenge of replacing Cd on high strength steel substrates without the loss of performance, a novel approach using electro-active polymers (EAP s) as the corrosion inhibition layer has been investigated. Several of the objectives of this SERDP SEED have been accomplished successfully. The synthesis and characterization of new monomers and the synthesis, using electroless deposition techniques, of EAPs that adhere to steel substrates has been completed. Electroless deposition is a non-line-of-sight coating onto steel plates and other geometries. The characterization of critical coating properties, using a combination of standard methods for fastener performance such as galling testing and hydrogen embrittlement testing, along with an evaluation of corrosion performance using impedance spectroscopy and neutral salt fog testing, has also been completed.

A number of investigations concerning the synthesis, characterization and properties of electro-optical macromolecules has been completed. A wide range of structures mostly based on a conjugated main chain and focused on providing high photo-luminescent and electroluminescent quantum yields, were produced and fabricated into opto-electronic devices. Parallel investigations have continued the long established study of polymer blends by various physical means. Amongst others, a dielectric relaxation study has compared the properties of a prototypical blend with that of a statistical copolymer of equal overall composition to probe the dimensions of micro-heterogeneity in such systems. Further studies of the below-(-) temperature collapse (coil-globule) transition in solvated polymer chains has included polyelectrolyte systems. Some 46 papers were published or were in press during the grant period.

The overall objective is to connect the near surface behavior of a model pressure sensitive adhesive with its macroscopic adhesive performance. Work with a new tackifier suggested that for complex commercial tackifiers the mixture of species in the tackifier may benefit miscibility. When miscibility is impaired, aging phenomena become more prominent. Force-distance measurements made at different frequencies can reveal viscoelasticity effects in such adhesives, but the frequency range that can be studied is limited. X-modulation is an excellent technique for probing differences in mechanical properties of adhesive surfaces. For example, changes due to enrichment of the surface by a lower molecular weight species can be detected. However, a characterization protocol combining X-modulation with a force-distance measurement is superior, yielding better reproducibility, higher precision, and more information in one experiment. Using contact mechanics and simplifying assumptions, estimates of modulus at the surface have been made. The new protocol was also demonstrated by characterizing changes in surface behavior with humidity. Humidity effects were most pronounced with the aged model adhesive that we had already shown to have the most strongly adhesive surface of the blends of various tackifier composition. The observed changes with humidity are consistent with the contention that the surface is enriched in tackifier., The original document contains color images.

Current research will lead to rapid-prototyping of chemical sensors that utilize microfabricated molecularly imprinted (MI) materials. CFD/CAD software may be used to model flow and chemical binding properties of Ml materials in microfluidic channels. Use of this type of software expedites results when changes in properties are made. The surface concentration of bound analyze on a monolithic molecularly imprinted polymer (MIP) within microfluidic channels can be modeled using its experimental binding kinetics. The time necessary to reach a detection limit is calculated and optimized as a function of flow parameters. In this report, we discuss the unique issues associated with the modeling of chemical sensors that utilize MI materials., This article is from the Mat. Res. Soc. Symp. Proc. Vol. 723, (pages), 2002. Prepared in cooperation with the Univ. of California at Irvine; Portland State Univ., Oregon; Texas A and M Univ., College Station, Texas; Univ. of California at San Diego, La Jolla, California, p79-83. This article is from ADA412559 Materials Research Society Symposium Proceedings. Volume 723. Molecularly Imprinted Materials - Sensors and Other Devices. Symposia Held in San Francisco, California on April 2-5, 2002

The drawing behavior of Ultrahigh Molecular Weight Polyethylene (UHMWPE) fibers in supercritical CO2 (scCO2) is compared to that in air at different temperatures. Temperature substantially influences the drawing properties in air, while in scCO2 a constant draw stress and tensile strength are observed. Differential Scanning Calorimetry (DSC) shows an apparent development of a hexagonal phase along with significant improvements in crystallinity of air-drawn samples with increasing temperature. The existence of this phase is not confirmed by WIDE ANGLE X-RAY SCATTERING (WAXS) showing that air-drawn samples crystallize in an internally constrained manner. In contrast, scCO2 allows crystals to grow without constraints through a possible crystal-crystal transformation, increasing the processing temperature to 110 deg. C., Original contains color plates: All DTIC reproductions will be in black and white.

Absolute number-average molecular weights were carefully measured for very-low to low molecular-weight poly(diisopropyl trimethylene-1,1-dicarboxylate) polymers that had been obtained from diisopropyl cyclopropane-2,2-dicarboxylate using a living anionic ring-opening polymerization technique (degree of polymerization in the range of 11-45 and polydispersity indices <1.13). Results obtained from four different analytical techniques, including end-group analysis (H-1 NMR), vapor pressure osmometry (WO), size-exclusion chromatography coupled to a multi-angle laser light-scattering detector (SEC-MALLS), and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-ToF), were compared and discussed. Although only crude estimates could be obtained by end-group analysis using H-1 NMR (experimental errors of up to 20%), (M) over bar (n) values estimated by SEC-MALLS were in perfect agreement with results obtained by VPO and MALDI-ToF. As the overall experimental protocol had been designed to prevent bias arising from some initial knowledge upon the exact molecular weights by the operator during the SEC-MALLS experiments, these results confirm a previous claim that SEC-MALLS is effective in measuring molecular weights in the oligomeric range. (C) 2002 Elsevier Science Ltd. All rights reserved.

Polymers provide a useful tool for the controlled assembly of colloidal nanoparticles. We have developed a bricks and mortar" strategy in which colloidal gold particles functionalized with recognition elements serve as the bricks and polymers bearing complementary functionality serve as mortar to hold together the nanoparticles. In this methodology, the conformational flexibility of the polymer compensates for irregularities in the size and shape of the aggregate structure. We have used this method to create discrete micrometer-scale spherical assemblies based on 2 nm gold nanoparticles. Both the size and shape of these assemblies can be controlled, providing spherical assemblies ranging from 50 nm to 1500 nm, as well as network structures., Pres: Symposium, 27-29 Nov 2000, Boston, MA, pC1.3.1-C1.3.4.. This article is from ADA395000 Materials Research Society Symposium Proceedings Volume 635. Anisotropic Nanoparticles - Synthesis, Characterization and Applications

The goal of the proposed research is lightweight elastomers to be used in clothing that protects soldiers from chemical warfare agents (CWAs). Outward transport of water from perspiration is another important requirement. Our approach addresses the simultaneous fulfillment of these requirements through the manipulation of the heterogeneous architecture, followed by the inorganic modification of hard/soft block copolymer (BCP) elastomers. An inorganic component is inserted within the sulfonated hard block domains in block copolymer ionomers (BCPIs) via in situ sol-gel reactions for hydrolyzed silicon alkoxides.

The goal of this project is to understand how variations in the molecular architecture of block and graft copolymers can be manipulated in order to develop materials with exceptional mechanical, transport, and optical properties, tailored for Army applications. We systematically explored the effect of these different molecular architectures on the nanometer scale, morphological self assembly of the materials. Our research has demonstrated, that a large number of the possible molecular variations can be represented by a single molecular asymmetry parameter, which we have used to develop an understanding of morphology in these materials. We have demonstrated that long range order of microphase separated morphology is reduced as the number of branch points increases in graft copolymers. Additionally, excellent elastomeric mechanical properties are obtained in graft copolymers with tetrafunctional branch points and seven or more branch points per molecule.

Instrumentation was purchased as planned set up, and used to support the ongoing ARO grant "Elastomeric Nanocomposites Based On Sol-Gel Reactions of Silicon Alkoxides In lonomeric Derivatives Of Finely-Architectured Block Copolymers". Research results are presented in the attached document.

The aim is to precisely characterize the tackifier distribution in model pressure sensitive adhesives and correlate variations in this distribution with the adhesives properties. Work focused on investigating the mechanical properties of the model adhesives near the surface, following the aging of a phase separated model adhesive, and synthesizing and isolating a new model tackifier which is closer in structure to common commercial tackifiers derived from wood rosin. Probing of the surface mechanical properties was done on two scales. Force-distance measurements done with a spherical indenter probed the behavior averaged over lateral areas on the order of millimeters and to depths of order microns. Force-distance measurements done with an atomic force microscope were able to resolve differences in the behavior of various domains in a phase segregated model adhesive and to limit the depth with which the mechanical properties were probed to less than one aim. In the phase segregated model adhesive a viscoelastic behavior was seen in the tackifier enriched domains, an intermediate behavior in the domain interfaces, and a viscous response in the matrix. The tackifier enriched phase appears to contribute primarily to the surface adhesion. AFM images and force-distance curves were collected for model adhesives of various compositions and after aging for 3.5, 7, 10, and 12 months.

Two different types of polymers were synthesized and their degradation and combustion behavior were investigated. The first class, 1,1-dichloro-2,2-(4-hydroxyphenyl)ethylidene (bisphenol C) based polymers, were found to be among the most fire- resistant polymers with peak heat release capacities as low as 20 J/g-K. Polymers containing bisphenol C all exhibited exothermic decomposition behavior. When compared to corresponding bisphenol-A-based polymers, these bisphenol-C- containing polymers had higher char yields and lower decomposition temperatures. The presence of bisphenol C in materials, whether as a co-monomer or blends, showed a char enhancement effect; yielding higher char than what is expected by a purely additive effect. Bisphenol C polyarylates and polycarbonates yielded large amounts of HCl and carbon dioxide upon decomposition. Compared with other bisphenol-based polymers, polycarbonates and polyarylates containing bisphenol C yielded significantly less amounts of monomer. Decreasing the concentration of bisphenol C in the copolymers or blends yielded relatively more monomer in the degradation products.

The aim is to study the use of molecules of novel architecture for tailoring the surface properties of blends. Key to this work is understanding the bulk miscibility of blends of linear and branched molecules and characterizing the surface segregation that occurs in such blends. The thermodynamic interaction between two polymers due only to the effect of regular branching has been measured for polystyrene blends of linear and star polymers as well as for one blend of a comb polymer with linear chains. Blends of star and linear polybutadiene have been investigated as well. The bulk interaction grows in size with the number of arms in the star. The interaction for the comb/linear blend is a order of magnitude larger than for a star/linear blend in which the star has the same number of arms as the comb. Segregation of the star to both interfaces of a film is observed for the polystyrene blends. For polybutadiene blends the isotopic effect is so strong that for small numbers of arms the isotopic effect dominates. The collective dynamics of two star polybutadienes are seen to be identical to those of linear analogs when the arms have lengths many times the entanglement length.

Enhancements in ballistic protective wear for soldiers rely heavily on the development of lightweight materials with increased moduli and strength. It is well established that an armors ballistic limit can be increased significantly by using materials with increased moduli and strength. The development of high performance fibers from flexible chain polymers has been a subject of intense interest over the past 30 years. However, to date the mechanical properties of commercial fibers are far below their theoretical values. This is due in large part to our inability to process the materials to achieve highly crystalline structures from highly extended chain conformations. In this STIR research program the feasibility of using subcritical and supercritical 002 in the processing of fibers with superior mechanical properties was investigated. The synergistic effects of 002 as both a pressurizing medium as well as a reversible plasticizer was shown to dramatically improve the mechanical stiffness and strength of both nylon6,6 and ultrahigh molecular weight polyethylene. In the case of Nylon6,6 fibers a greater than 30% increase in stiffness along with a 20% increase in strength was realized. Similarly, post treatment on UHMWPE fibers (Dyneema) showed an increase in modulus of greater than 50% of the commercial fibers. In both cases, the 002 treatment primarily increased the overall degree of crystallinity compared to air drawn fibers. It should be noted that, although the research has strong fundamental interests, it provides an environmentally benign approach to process fibers with superior mechanical properties. Once additional studies are conducted to isolate optimum process ranges, scale-up should be relatively quick since the polymeric materials and process equipment are all commercially available.

Conjugated/non-conjugated alternating block copolymers containing cyano-modified distirylbenzene units as emitting chromophores were synthesized via Knoevenagel and Wittig reactions; the non-conjugated block was an alkylene spacer. The polymers were differentiated with respect to the location of the cyano groups in the chromophoric block (double bond or phenylene ring). When photoluminescence and electroluminescence spectra of these materials were compared with those of a similar structure without the cyano group, a strong bathochromic effect was observed. A more pronounced red shift and a higher electroluminescence efficiency was observed in the polymer with the cyano group attached to the aromatic ring. These materials show promise for device manufacture.

Several investigations concerning the synthesis, structure and properties of polyphenylene vinylene (PPV) and related macromolecules with novel electro-optical characteristics have been completed. Selected homopolymers and copolymers of systematic ally varying architecture have been designed and synthesized and shown to be highly efficient chromophores in electroluminescent devices. Several of these polymers have also been shown to be efficient lasing materials in optically-pumped configurations. The study of the phase behavior of polymer blends has continued with emphasis on sequence distribution effects in the respective copolymer constituent(s). Dynamic light scattering studies of solvated flexible polymer chains have probed the coil-globule transition below the 0-point and related this to current theory. Other studies have investigated the properties of polyvinyl butyral blends, the detailed structure of doped polyphenylene vinylene and other conducting polymers, and the photophysics of stilbene derivatives.

During the past year our group has demonstrated that polymer enhanced ultrafiltration may be utilized to effectively remove organic foulants from a wastewater stream. This technology is an advancement of micellar enhanced ultrafiltration that is commonly found in many remediation efforts. Micellar enhanced ultrafiltration is characterized by the addition of a small molecule surfactant to the aqueous stream containing an organic foulant. The foulant is solubilized within the micellar hydrophobic core and the stream is then passed through a microporous membrane, such that most of the organic solute and surfactant remain in the retentate. Although this method often achieves high efficiencies of removing a foulant, monomeric surfactant continuously crosses the membrane into the permeate. Therefore, added surfactant is required as time progresses to maintain a critical micelle concentration. In order to circumvent this problem, we have utilized a commercially available polymeric surfactant (Pluronic F127) as the solubilization agent. In this case, the size of the surfactant is sufficiently large to prevent passage through the membrane into the permeate and the addition of surfactant to the retentate is unnecessary. We have shown that the PEO-PPO-PEO triblock copolymer will associate with model water foulants in an ultrafiltration application such that this technology may be utilized in a closed system such as that would be required on a naval vessel.

In the last funding period, we continued to focus on the formation of polyurethanes by controlling the relative kinetics of crosslinking versus phase separation of hard segments. These materials exhibit interesting mechanical behavior and controllable barrier properties. A series of polyurea urethanes was isothermally synthesized from toluene diisocyanate (TDI), water, and trifunctional poly(propylene oxide) in the temperature range of 50 - 150 deg C. Morphologies of the samples vary significantly as a function of reaction temperature. in this system, phase separation competes with polymerization and crosslinking. Both transmission electron microscopy and atomic force microscopy have displayed a network type structure for the 50 deg C samples; the 150 deg C samples appear to be homogeneous. Infrared analysis reveals that samples prepared at 150 deg C possess a morphology that is less strongly hydrogen bonded and with a broader distribution of hydrogen bonded states in comparison to those prepared at lower temperatures. From this combination of techniques, it can be inferred that phase separation occurs more rapidly than crosslinking at low temperatures; consequently, a phase separated morphology results. In contrast, crosslinking occurs more rapidly than phase separation at higher reaction temperatures.