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Boltron H30 is a polyester polyol with a dendritic structure, developed by Perstop Corp. Complete methacrylated H30 oligomers were obtained by using three different reaction routes, i.e., treatment of H30 with methacrylic anhydride, methacryloyl chloride and 2-isocyanatoethyl methacrylate (IEM). The viscosities of the three H30 hyperbranched materials at 45°C were 22.4, 23.5, and 42.8 Poise, respectively, compared to commonly used BisGMA having a viscosity of 33.5 Poise at 45°C. All three completely methacrylated H30 materials were combined with TEGDMA (50/50, wt/wt) to formulate visible light-curable (VLC) neat resins. The experimental VLC resins exhibited significant reduction of polymerization shrinkage and higher C˭C double bond conversion, compared to the VLC BisGMA/TEGDMA (50/50, wt/wt) control. The three new resins, with the exception of the H30-IEM based formulation, have mechanical properties comparable to a BisGMA/TEGDMA control. But, the VLC H30-IEM based resin exhibited higher compres...

Two novel trimethacrylates, i.e., 1,1,1-tri-[4-(methacryloxyethoxy)-phenyl] ethane (TMPE) and 1,1,1-tri-[4-(2-methyl-2-methacryloxyethoxy)-phenyl]ethane (TMMPE), have been synthesized by reacting methacryloyl chloride with the corresponding hydroxyl intermediates. Both trimethacrylate monomers, having a low viscosity of 11.5 and 13.1 Pa.S, respectively, were blended with TEGDMA at three different weight ratios, i.e., 90/10, 70/30, and 50/50. The mixtures were made visible light-curable (VLC) by the addition of camphorquinone (0.5 wt%) and N,N-dimethyl-aminoethyl methacrylate (1.0 wt%). In addition to evaluation as cured neat resins, VLC formulations with 70% by wt. of silanated microfiller were also prepared and evaluated. The control in both cases was a VLC formulation of BisGMA/TEGDMA (70/30 and 50/50 wt/wt). These new, formulated resins have both improved physical properties and higher double bond conversion than the BisGMA control, as well as decreased linear polymerization shrinkage (LPS). T...

High fluidity solvents, such as supercritical fluids, have several advantages over traditional solvents as polymerization media, such as offering a more environmentally-friendly reaction media, providing increased reaction rates, and simplifying the separation and purification of polymers. In this study, a traditional glass-ionomer polymer, poly(acrylic acid-co-itaconic acid) (PAA/IA) was synthesized by using mixtures of CO2 and methanol as the reaction solvent and was characterized by 1H-NMR, FT-IR, GPC, and viscometry. The mechanical and working properties of the glass-ionomer cements, prepared by mixing aqueous solutions of the polymers with Fuji II glass powder, were evaluated for compressive strength (CS), diametral tensile strength (DTS) and flexural strength (FS), as well as setting time and working time. The results showed that the polymerization reaction in CO2/methanol mixtures was faster and had higher conversion than the polymerization reaction in water. The glass-ionomer formulations...

Six new ether-linked bisoxazolines have been synthesized via reaction of p-hydroxyphenyl-2-oxazoline with dihalides. These bisoxazolines may be used as chain extenders or crosslinkers for resins, monomers or polymers containing various acidic groups, including phenolics, via step-growth (1 : 1) reactions. As an illustration, a phenol-formaldehyde polycondensate (Alnovol) and an enzyme oligomerized bisphenol A resin, as well as poly (p-hydroxystyrene), was chain extended and crosslinked to produce thermosets with high glass transition temperatures. The new bisoxazolines were also polymerized with diphenol compounds, such as diphone D and bisphenol P to generate linear or branched oligomers and polymers. Differential scanning calorimetry was used to evaluate the potential for polymerization and crosslinking reactions. Preliminary results showed that the new, ether-linked bisoxazolines have potential for formulating high performance thermosets. Copyright © 2002 John Wiley & Sons, Ltd.

The history and chemistry of conventional (chemically cured) and visible light-cured (VLC) glass polyalkeonates (glass-ionomers) is reviewed. The synthesis of new acrylic acid copolymers, containing amino acid residues, derived from amino acid based acrylamides or methacrylmides, and N-vinylpyrrolidone, is described, along with the use of the new polymers to prepare improved restoratives. Supercritical polymerizations for preparing new polyelectrolytes for use in formulating improved glass-ionomers are also described. A completely new method to prepare VLC glass-ionomers, via the use of methacrylate monomers having a cyclic imino ether group, to modify acrylic acid copolymers in aqueous solution, is additionally described.

Three series of neat resins, based on methacrylates or dimethacrylates modified with 1-[3-(methacryl)propyl]-3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.113,­9.15,15.17,13]octasiloxane (Methacryl-POSS or POSS-MA), were evaluated. Incorporation of POSS-MA into the polymeric matrix was accomplished in three ways: (a) resins series I was formulated with one-pot copolymerization of a bis-GMA/diluent monomer with POSS-MA; (b) the copolymer of 2-hydroxylethyl methacrylate (HEMA) and POSS-MA, with a weight ratio of 1 : 1, was first made, then the copolymer hydroxyl groups were converted into methacrylate groups to get a macromer; finally the macromer was copolymerized with bis-GMA/diluents to formulate the second series of neat resins; (c) copolymer of POSS-MA and t-butyl methacrylate (t-BMA) or 2-ethylhexyl methacrylate (EHMA) were first made, then they were combined with a mixture of bis-GMA and the corresponding diluent to make the third kind of neat resins. The amount of POSS incorporated into the neat resin matrix was controlled at 5, 10 and 15 wt%. Incorporating only 5 wt% substantially reduced the shrinkage of the prepared neat resins. The percentage of methacrylate-functionalized POSS monomer in the bis-GMA/diluent base, was compared to neat resins prepared without the POSS. The mechanical properties of neat resin having POSS were improved for approaches (b) and (c), but remained at the same level as the neat resins without POSS for approach (a). The results show that miscibility between the POSS component and the matrix, especially the diluent, plays a very important role in the improvement of the properties of the formulated thermosets. Copyright © 2001 John Wiley & Sons, Ltd.

Methacrylate-functionalized aromatic oxazolines are evaluated for attaching pendant methacrylate groups to acid containing polymers. Typically, these reactions use the toxic liquid 2-isocyanatoethyl methacrylate (IEM) to functionalized the acid containing polymer. Methacrylate-functionalized oxazolines will add to acid containing polymer in aqueous solvent. Thus, in a one-pot, two-step reaction the acid containing polymer can be synthesized and then reacted with the methacrylate-functionalized oxazoline. The visible light-curable (VLC) polymer can then be formulated in resin modified glass-ionomers. The resulting glass-ionomers have properties that are comparable to commercial materials. Copyright © 2001 John Wiley & Sons, Ltd.

The purpose of this research is to demonstrate the usefulness of the synthesized hyperbranched multi-methacrylates (H-MMAs) in dental applications. We synthesized three hyperbranched multi-methacrylate oligomers and evaluated them as modifiers for use in the dental resin system: bisphenol A glycidyl dimethacrylate (BisGMA)/tri(ethylene glycol) dimethacrylate (TEGDMA). Their photo-polymerization activities, viscosity, mechanical properties, such as compression, diametral tensile, and flexural strength, were evaluated. H-MMAs (10%) modified dental resins have lower polymerization shrinkage and about 15% increase in mechanical strength compared to the Bis-BisGMA control. For example, H30-MMA has compressive, diametral tensile, and flexural strength of 576, 47, and 85 MPa, compared with the BisGMA control having 497, 43, and 77 MPa. In addition, hyperbranched polymer modified resins have higher glass transition temperature (Tg) and lower thermal expansion coefficient (α) than the control. This research is sig...

Three hyperbranched multi-methacrylates (H20-MMA, H30-MMA and H40-MMA) have been synthesized by reacting Boltorn dendritic polyols with methacrylic anhydride and methacryloyl chloride. Their struct...

The visible light-curable N-methacryloylglutamic acid (MGA) modified polymers (VLC MGA MPs), with the optimal molar ratio of 8:1:1 (acrylic acid: itaconic acid: MGA) in the copolymer backbone, were synthesized by a one pot reaction. The compressive strength (CS) was used as the initial basic screening property to determine the best graft ratio. A statistical design of experiment (DOE) technique was utilized to predict the optimal formulation for the VLC MGA MP with the best graft ratio based on the CS. The VLC MGA MPs were synthesized under the same reaction conditions, using a free-radical polymerization process to produce the copolymers, followed by grafting 2-isocyanatoethyl methacrylate (IEM) onto the copolymer backbone to form the VLC materials. Specimens were prepared by mixing the polymer solutions with the basic glass powders and their strength values were measured after the test specimens were conditioned in distilled water at 37°C for 7 days. In this study, polymer solutions containing VLC MGA M...

New cyclic imino ether monomers, functionalized with acetylacetoxy, acetylacetamide, or acetylacetanilide moieties are described for the first time. These monomers readily form metal complexes. Also, it is shown that these monomers may be cationically homo- or copolymerized with other cyclic imino ethers, to provide polymers having metal complexing ability. The monomers have potential applications in a wide variety of applications.

Conventional analysis of the cytotoxic T lymphocyte (CTL) response to HIV-1 may underestimate the true breadth of CTL epitopes recognized. This underestimation could be due to several reasons, including (1) the use of laboratory-adapted stains of HIV or consensus sequences, which would lead to the identification of only highly conserved epitopes, (2) the use of EBV-transformed B cells (B-LCLs) and vaccinia virus constructs in standard assays that may obscure low level CTL responses due to high EBV or vaccinia reactivity, and (3) relatively insensitive assays wherein PBMCs instead of professional APCs are used to stimulate CTL responses. To address these problems, we first identified an immunodominant HLA-B7-restricted CTL epitope, by standard cloning methods, in a long-term nonprogressor (LTNP). To determine whether the patient had CTLs specific for autologous viral sequences other than the dominant epitope, proviral DNA was cloned and sequenced. A matrix-based epitope algorithm (EpiMatrix) was used to identify the top 2% of peptides from the viral sequences with the highest likelihood of binding to HLA-B7. These 55 peptides were synthesized and tested for HLA-B7 binding in a T2/B7 cell line; 10 peptides were able to stabilize HLA-B7 on the cell surface. By using peptide-pulsed autologous dendritic cells as a more sensitive method of CTL stimulation, we found three additional subdominant CTL epitopes.

In a previous study, we showed that the methacrylate derivatives of propoxylated bisphenol-A oligomers (EPBPA) have potential application for formulating visible light-curable (VLC) composites for dental restoratives. The purpose of this study was to evaluate the thermal, mechanical and biocompatibility properties of the EPBPA oligomers. The EPBPA oligomer multi-methacrylate: triethylene glycol dimethacrylate (TEGDMA) (50:50/wt:wt) blends were combined with 0.5 wt% camphorquinone (CQ) and 1.0 wt% N,N-di-methyl-aminoethyl methacrylate (DMAEMA). The control was 2,2-bis[4-(2-hydroxy-3-methacryloyloxpoxy) phenyl] propane (BisGMA:TEGDMA) (50:50/wt:wt) blends having the same levels of CQ/DMAEMA. The glass transition temperature (Tg) and the thermal expansion coefficient (α) were obtained for all materials studies, using a thermomechanical analyzer (TMA, TA Instruments 2940 with an expansion probe (heating rate 10°C/min, N2). The compressive (CS) and diametral tensile strength (DTS) tests were carried out using ...

The purpose of this investigation was to compare the degree of photo- and thermal-polymerization obtained using various tertiary amine co-initiators of differing reactivities and molar concentrations, utilizing differential scanning photocalorimetry (DPC) and DSC. Amines tested were 2-(dimethylamino)ethyl methacrylate (A), triethanolamine (B), N,N,3,5-tetramethyl-aniline (C), ethyl 4-dimethylaminobenzoate (D), 0.95 (A) and 0.05 (D) in combined mixture (E), 4-N,N-(dimethylamino)phe-nylacetic acid (F) and a newly-synthesized tertiary aromatic amine methacryloxyethyl substituted 4-N,N-(dimethyla-mino)phenylacetamide (G). The monomer system consisted of Bis-GMA and triethylene glycol dimethacrylate neat resins, and 0.5% camphoroquinone for all groups tested. Samples of the blended monomers with 0.5–4.0 mol/eq (co-initiator to initiator) were irradiated with visible light under N2. The heat of reaction (ΔH) was calculated for each run in order to determine the degree of polymerization (DP). D resulted in a sig...

This study focused on new visible light-curing (VLC) oligomers exhibiting low shrinkage, low sorption of water, and improved mechanical properties. A family of multi-methacrylates, based on poly(isopropylidenediphenol) resin (BPA), was synthesized, characterized, and evaluated. The commercial BPA resin is prepared from enzymatic polymerization (oligomerization) of bisphenol A. The BPA resin, having an average of eight phenolic hydroxyl groups per molecule, was treated with propylene carbonate and the resultant product, i.e., propoxylated BPA (PBPA) oligomer, was confirmed by Fourier transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (NMR). The propaxylated BPA (PBPA) was subsequently treated with methacryloyl chloride to produce the multi-methacrylates (EPBPA), identified by FT-IR and NMR. The EPBPA oligomer multi-methacrylate: triethylene glycol dimethacrylate (TEGDMA) (50:50/wt:wt) blends were combined with 0.5 wt% camphorquinone (CQ) and 1.0 wt% N,N-dimethyl-aminoethyl methacryl...

The monomers N-acryloyl (AGA) and N-methacryloylglutamic acid (MGA) have been prepared and copolymerized with acrylic acid (AA) and itaconic acid (IA) to make polyelectrolytes for evaluation in glass polyalkenoates or glass-ionomers. It was shown that poly(AA-co-IA-co-AGA) and poly(AA-co-IA-co-MGA), having a monomers ratio, respectively, of 7:3:3 could be formulated with glass powders used in Fuji II (GC America), α-Silver (DMG-Hamburg), α-Fil (DMG-Hamburg) and Ketac-Molar (ESPE, Seefeld, Germany) to produce conventional glass-ionomers with improved compressive strength (CS), flexural strength (FS) and fracture toughness (FT), compared to Fuji II, α-Silver, α-Fil and Ketac-Molar controls. Since MGA is much easier to produce in high yields than AGA, it was important to show that MGA could be used as well as AGA to produce new matrix resins for glass-ionomers. Furthermore, we demonstrated that both the 7:3:3 AGA and MGA copolymers could be reacted with 2-isocyanatoethyl methacrylate (IEM) to produce interme...

This study focused on the preparation and evaluation of several new fluorene-based dimethacrylates, as possible intermediates to formulate improved dental composites. As the first step towards modification of the composite formulation, the new monomers and unfilled resin matrix were prepared. The formulated and visible light-cured materials were found to be more hydrophobic, along with having higher wet (water saturated) glass transition temperatures (Tg) than the commonly used matrix resins based on 2,2-bis(4(2-hydroxy-3-methacryloxy-propyloxy))-phenylpropane (Bis GMA). In addition, the new matrix resins exhibited greater compressive strength, along with greater resistant to creep and fracture. Finally, the results suggested a correlation may exist between creep and the homologous temperature (T/Tg) of the light-cured neat resins, where the T/Tg may be used to compare the mechanical properties of different materials at various temperature. Copyright © 1999 John Wiley & Sons, Ltd.

Perfluorotriethylene glycol dimethacrylate (FTEGDMA), a fluoro analog of triethylene glycol dimethacrylate (TEGDMA), was evaluated in dental composites. Curing, physical properties, and water sorption of FTEGDMA-ethoxylated bisphenol A dimethacrylate (BisEMA) and bisphenol A glycol dimethacrylate (BisGMA) – TEGDMA as well as TEGDMA - BisEMA blends were evaluated and compared. BisEMA and FTEGDMA viscosities were lower than BisGMA and TEGDMA. FTEGDMA has the lowest refractive index and contact angle on silanated or nonsilanated glass. Polymerization studies showed that FTEGDMA did not significantly alter the decrease of C˭C conversion of the various formulations. Further, the experimental FTEGDMA resins absorbed much less water than the control formulations.

The fluorinated triethylene glycol dimethacrylate (FTEGDMA) was used to improve the properties of Bisphenol A glycol dimethacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) based dental resin system. Physical properties such as contact angle, polymerization shrinkage and water sorption, thermal properties such as glass transition temperature, dynamic modulus and thermal expansion, and mechanical properties such as compressive and diametral tensile strengths of the experimental neat resins and conventional controls were investigated and compared, using methods described in the text. Results showed that the FTEGDMA modified neat resins exhibited significant less water sorption and lower polymerization shrinkage and the 2,2'-bis(4-methacryloxy ethoxy phenyl) propane (BisEMA) also contributed significantly towards reducing water sorption. The resin containing FTEGDMA and BisEMA(10:90 molar ratio) (or F1E9) showed the highest values in mechanical strengths, due to its higher glass transitio...

The best graft ratio of the light-curable N-vinylpyrrolidone (NVP) modified terpolymers (LC NVPM TPs) with the molar ratio of 8:2:1 (acrylic acid:itaconic acid:NVP) and the optimal formulation for this light-curable glass-ionomer cement, based on the best graft ratio, were determined. Statistical models were utilized to predict the optimal formulations. The terpolymer was prepared using a free-radical polymerization reaction. The LC NVPM TPs were produced by grafting 2-isocyanatoethyl methacrylate (IEM) onto the terpolymer. Cements were formed by both light-curing and the reaction with glass particles. Compressive strength was used as the basic screening property to find the optimal formulation. Diametral tensile and flexural strengths were also used to evaluate the mechanical properties. The strength values were recorded on the specimens conditioned in distilled water at 37&C for 24 hours or 7 days. The best graft ratio for IEM in this system was 15% of the terpolymer by a molar ratio. The optim...

The bifunctional monomer 2-[4-(2-oxazolinyl) phenoxy]ethyl meth-acrylate [OPEM] was prepared in good yield using the starting material 4-cyanophenol, via a multi-step synthesis method. Since OPEM is very similar to 2-hydroxyethyl methacrylate [HEMA], OPEM readily copolymerizes with HEMA, using typical free radical initiators. In the presence of proton sources, such as alcohols and acids and using cationic initiators, the oxazoline groups undergo ring-opening polymerization, resulting in crosslinking. The free radical copolymerization and cationic polymerization were investigated by differential scanning calorimetry [DSC]. † Currently at Rutgers University, New Brunswick, NJ 08903

Several N-acryloyl and N-methacryloyl substituted amino acids have been prepared and copolymerized with acrylic acid and itaconic acid to prepare new polyelectrolytes. Due to an acid-base reaction, mixing of the water soluble copolymers with glass powders, having leachable Ca 2+ , Al 3+ , etc., type cations, produces inorganic-organic composites hardened by salt -bridge formation. These heretofore unexplored polyelectrolytes are shown to be very useful for preparing improved dental biomaterials.

To explore new VLC oligomers exhibiting low shrinkage, low water sorption, and improved mechanical properties, a family of multi-methacrylates, based on poly(isopropylidenediphenol) resin (BPA), was synthesized, characterized, and evaluated. The BPA resin, having an average of eight phenolic hydroxyl groups per molecule, was treated with ethylene carbonate and the resultant product esterified at four different grafted levels, using methacryloyl chloride. Structures of these EEBPA oligomers, were confirmed by FT-IR and 13C NMR. The EEBPA oligomer/TEGDMA (50/50, w/w) blends were combined with 0.5 wt% camphoroquinone(CQ) and 1.0 wt% N,N-dimethylaminoethyl methacrylate (DMAEM). The control was BisGMA/TEGDMA (50/50, w/w) blends having the same levels of CQ/DMAEM. Differential photocalorimetry (DPC) and differential scanning calorimetry (DSC) showed the multi-methacrylate/TEGDMA (neat resin) blends have polymerization characteristics comparable to the BisGMA/TEGDMA control. These multi-functional oligo...

The monomer 2-(4-aminophenyl)oxazoline has been prepared in good yield and briefly investigated for cationic, homopolymerization and copolymerization characteristics, using 2-ethyloxazoline as a comonomer. Cationic polymerizations can be conducted to producesoluble poly[2-(4-aminophenyl)oxazoline] and poly[2-(4-aminophenyl)-oxazoline-co-2-ethyloxazoline].

Multi-methacrylate derivatives of styrene-allyl alcohol copolymer (SAA) were obtained by esterification reaction with methyl methacrylate (MSAA). Thermal polymerizations of MSAA with styrene and methyl methacrylate (MMA) were investigated by differential scanning calorimetry. The content of MSAA and the methacrylate groups pendant on SAA strongly affected the polymerization behavior. The results of thermal analysis and extraction studies suggested that the cured PS-MSAA mixtures were stable, crosslinked networks, and the polymerized MAA-MSAA formulations exhibited semi-IPNs structure. The PS-MSAA semi-IPNs showed potential for improving the toughness modification of polystyrene.

The simultaneous cationic, ring-opening polymerization of 2-benzyl-2-oxazoline (BOX) with methyl tosylate in the presence of freeradical (benzoyl peroxide) initiated polymerization of methyl methacrylate (MMA), using ethylene glycol dimethacrylate (EGDMA) crosslinker produced transparent semi-interpenetrating polymer networks (semIPNs) with one glass transition temperature (T g), as shown by differential scanning calorimetry (DSC). The MMA/BOX ratios evaluated in the study were 70/30, 50/50, and 30/70. The simultaneous, free-radical, and cationic polymerization of MMA and 2-benzyl-2-oxazoline mixtures, without EGDMA and over the same monomer mixture ratio range, produced opaque plastics with two T g values, with both the PMMA and PBOX homopolymers soluble. The T g values of the two separated linear polymers were close to those previously reported for the two polymers. Over the monomers mixture range examined, the results clearly show that the simple blend of the PBOX and PMMA polymers are immisci...

Objectives. The objectives of this study were (1) to develop polyacid formulations through the incorporation of amino acid-derived monomers with carboxylic acid groups at various distances away from the polymer backbone to allow for greater flexibility, less rigid ionic cluster formation and improved solubility, and (2) to test selected physical and handling properties of experimental ionomers with a conventional glass ionomer as a control. Methods. The polycarboxylic acids prepared and used in the glass ionomer formulation in this study included N-acryloylglutamic acid (AGA) and N-acryloyl-6-aminocaproic acid (AACA)-modified acrylic aciditaconic acid copolymers, where the acrylic acid: itaconic acid:amino acid monomers were combined in different proportions. The characterization and purity of the monomers were determined by FTIR and their melting points. The characterization of synthesized polymers included molecular weight and relative viscosity determinations. The compressive strengths, diametral tensile strengths, flexural strengths and fracture toughness of the experimental ionomers and a commercially available ionomer (control) were measured after storage in water, at 37°C for 1 h or 7 d. The working times and setting times of the experimental ionomers were compared to the control specimens. Separate analysis of variance and Tukey's tests were used to study the statistical significance of the physical strength parameters as a function of materials and storage times. Results. Significant increases (p

Studies are presented describing an application of the NaBH4 reduction of soluble arsenite to form arsine for ultra-trace level arsenic determination by capacitively coupled microwave plasma atomic emission spectrometry. The arsine was condensed in a liquid nitrogen cooled trap, and introduced into the plasma after the elimination of reaction by-products that would reduce the excitation efficiency of the plasma. Use of a photodiode array detector provided a means of background correction. The procedure resulted in a limit of detection of 110 pg and linear dynamic range of 104 for arsenic.

Encephalitis developing after prolonged antineoplastic therapy in two patients with Hodgkin's disease and in one with multiple myeloma was found at autopsy to be caused by toxoplasmosis. To better understand the pathogenesis of the brain lesions, ranging from microscopic foci to some having a diameter of 6 cm. and characterized by proliferation of the organisms at the margins of expanding necrosis, an animal model was studied. Similar lesions were produced in hamsters by inducing relapse of chronic latent toxoplasmosis through administration of cortisone, cyclophosphamide, or whole body irradiation, but toxic doses of nitrogen mustard and urethane did not precipitate relapse. Notably, relapsing toxoplasmosis generally involves the brain exclusively, suggesting a special susceptibility related to immune mechanisms. The roles of cells and of antibodies in immune surveillance against this chronic infection in otherwise normal hosts are considered. In man the suppression of cellular immunities by certain antineoplastic agents would seem to be decisive in causing relapse of toxoplasmosis, rather than the replacement of immunologically active cells by neoplasm. Because the infection can be controlled with sulfadiazine and pyrimethamine, a high index of suspicion is essential to detect incipient cerebral toxoplasmosis. serial serologic testing is helpful by demonstrating titer elevations; however, poor antibody production or transferred antibody may be misleading clinically when single tests are evaluated. Similarly, a poor inflammatory cell response can make it difficult for the histopathologist to detect small lesions in these patients.

Polyimidines - A New Class of Polymers.- Synthesis and Properties of Acetylene Terminated Aryl-Ether Oligomers.- Phenylated Aromatic Hetrocyclic Polyphenylenes Containing Pendant Diphenylether and Diphenylsulfide Groups.- Substituted Polyamides as Precursors for Alkyl and Alkenyl Polybenzoxazoles.- The Synthesis of Aromatic Polyformals.- New Polymers Prepared From N-Cyanaourea Compounds.- Poly(N-acyl ethyleneimines) With Polarizable Aromatic Side Chain Substituents and Their Complexes: Synthesis, Structure and Electronic Properties.- Aqueous Solution Synthesis of Platinum II Polyureas, Polythioureas and Polyamides.- Synthesis of Dichloropalladium II Polyamines.- Star and Comb Shape Poly (oxyethylene-g-ethyleneimines).- Poly (azoalkylene-N,N'-dioxides), 2. ?-4 Nitroisopropylidenebicyclohexyl -?-nitropoly (azo-1,4-cylohexylene-isopropyliden-1,4-cyclohexylene-N,N'-dioxide) and ?-4--nitrobicyclohexyl-?-nitropoly (azo-4-4'-bicyclohexylene-N,N'-dioxide).- Macromolecular Dyes - Synthetic Strategies.- Quaternization of Condensation Polymers.- Para-Methylstyrene: A New Commercial Monomer For The Styrenics Industry.- New Vinyl Organometallic Monomers: Synthesis and Polymerization Behavior.- Synthesis of Organometallic Polymers For Inertial Fusion Applications.- Synthesis and NMR Characterization of Copolymers of ?-Fluorostyrene with Methyl Acrylate.- Quinodimethane Polymers.- Alkyllithium-Initiated Polymerization of Myrcene. New Block Copolymers of Styrene and Myrcene.- New Functional Methacrylate Polymers by Anionic Polymerization.- Conductive Polymers: An Opportunity For New Monomers and Polymers.- Polymerization of Butadiyne: Polymer Characterization and Properties.- Synthesis of Copolymers of m-Diisopropenylbenzene and m-Dimethoxybenzene.- Progress in Ring-Opening Polymerization of Cyclic Ethers and Cyclic Sulfides.

The flexural strengths of N-vinylpyrrolidone modified glass-ionomer cements were investigated. The optimal molar ratio of the monomers in copolymers, composed of the three components acrylic acid, itaconic acid and N-vinylpyrrolidone, was determined using a SAS statistical program. The copolymers were prepared using a free-radical polymerization process. The viscosities of aqueous solutions of these polymers were determined. Cements were formed by the reaction of these solutions with glass particles. Flexural strength (FS) was used as the basic screening property to find the optimum molar ratio. Statistical models were applied to predict the optimum molar ratios. All strength values were recorded on the specimens conditioned in distilled water at 37°C for 7 days. The optimal molar ratio for these copolymers was 7:1:3 for poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone), based on flexural strength and viscosity. The effect of molecular weight (MW) on FS was also evaluated. Copolymer with ...