- Materials Science Find out what NIST is currently working on in Materials Science.
Jack Pevenstein
Technology Partnership Office
301-975-5519
nisttech@nist.gov
100 Bureau Drive, M/S 2200
Gaithersburg, MD, 20899
The present invention is directed to an etchant/primer composition, an etchant/primer/adhesive monomer composition, kits using the same and methods using the same for improved bonding to dental structures. The etchant/primer composition comprises a compound having the formula: RN(CH2 YCO2 M)2 wherein R=R1 or R2 ; R1 =an aromatic group; R2 =a conjugated unsaturated aliphatic group; Y=a single bond, CH2, CHCH3 or C.dbd.CH2 ; and each M is independently H, an alkali metal, an alkaline earth metal, aluminum, a transition or redox metal or an alkyl group having 1 to 18 carbon atoms, with the proviso that when both M groups are alkyl groups, said compound is capable of being easily hydrolyzed, displaced, or exchanged with other reagents present in the etchant/primer composition, a polar solvent system, and nitric acid. The etchant/primer/adhesive monomer composition comprises a compound having the formula (I) as noted above, a polar solvent system, an acid selected from the group consisting of nitric acid, hydrochloric acid, citric acid, lactic acid, glycolic acid, formic acid, pyruvic acid and combinations thereof, and adhesive monomer resin, and an initiator. The above-noted compositions are applied to dental structures requiring dental restoration for improved bonding of adhesive resins and polymers to dental structures.
Composites in the form of a three-dimensional framework or skeleton of ceic particles are formed by a low cost, low temperature sintering process which decomposes a pre-ceramic inorganic or organic precursor. Upon heating, preferably in air, the precursor decomposes to form a ceramic phase in the form of necks between the individual ceramic particles. The properties of the resulting porous ceramic bodies can be modified, such as toughened by impregnation with monomers, oligomers or polymers which are polymerized or cured in situ. Such composites find use as cosmetic products or protheses for humans and animals, such as dental restoratives and bone implants. Methods of fabrication are disclosed which include the use of a pre-ceramic polymer as a binder for the ceramic particles which forms the necks of material between the individual ceramic particles upon firing.
A differential scanning microcalorimeter produced on a silicon chip enables microscopic scanning calorimetry measurements of small samples and thin films. The chip may be fabricated using standard CMOS processes. The microcalorimeter includes a reference zone and a sample zone. The reference and sample zones may be at opposite ends of a suspended platform or may reside on separate platforms. An integrated polysilicon heater provides heat to each zone. A thermopile consisting of a succession of thermocouple junctions generates a voltage representing the temperature difference between the reference and sample zones. Temperature differences between the zones provide information about the chemical reactions and phase transitions that occur in a sample placed in the sample zone.
A method and apparatus for measurement of stress in a specimen utilizing a motorized electromagnetic acoustic transducer (EMAT). Stress causes a rotation of the pure-mode polarization directions of SH-waves and a change in the phase of waves polarized along these certain directions. The method utilizes a rotating small-aperture EMAT, connected to a processor, to measure phase and amplitude data as a function of angle. The EMAT is placed on a workpiece at the location where the stress is to be measured. The acoustic birefringence B is determined from the normalized difference of these phases. From these data, an algorithm calculates values of B and φ. The workpiece is then stressed or its stress state is changed. The values are measured again at the same location. Stress is determined from the change in B and φ.
An electromagnetic acoustic transducer for inducing and sensing vibrations in a cylindrical object and methods of using an electromagnetic acoustic transducer to determine resonant frequencies and physical properties of cylindrical objects. The electromagnetic acoustic transducers produce specific modes of vibration in cylindrical objects including axial shear vibrations, torsional vibrations, radial vibrations and plane strain vibrations. The methods of determining physical properties of a cylindrical objects include comparing sensed resonant frequencies of the cylindrical object to known relationships between resonant frequency and the physical properties of interest. The methods can be used to determine the temperature, dimensions, elastic constants, and damping coefficients of cylindrical objects, the magnitude of a load applied to a cylindrical object, or the texture or grain orientation of the material forming a cylindrical object.
A new low temperature method for nanostructured metal and ceramic thin film growth by chemical vapor deposition (CVD) involves the use of a low pressure co-flow diffusion flame reactor to react alkali metal vapor and metal halide vapor to deposit metal, alloy and ceramic films. The reaction chemistry is described by the following general equation: (mn)Na+nMXm .fwdarw.(M)n +(nm)NaX where Na is sodium, or another alkali metal (e.g., K, Rb, Cs), and MXm is a metal-halide (M is a metal or other element such as Si, B or C; X is a halogen atom, e.g., chlorine, fluorine or the like; and m and n are integers). This reaction chemistry is a viable technique for thin film growth. In one mode, using the precursors of sodium metal vapor, titanium tetrachloride (the limiting reagent), and either argon or nitrogen gases, titanium (Ti), titanium nitride (TiN), titanium dioxide (TiO2), and titanium silicide (TiSi, Ti5 Si3, TiSi2, Ti5 Si4) thin films have been successfully grown on copper and silicon substrates. Conditions can be adjusted to prevent or minimize gas-phase particle nucleation and growth. Substrate temperatures can also be varied to prevent excessive salt deposition.
A thin-film thermocouple is provided which can be used at temperature of up to 900° C. The thin-film thermocouple includes: a silicon substrate; an SiO2 diffusion barrier layer formed on the substrate; a titanium oxide adhesion layer formed on the diffusion barrier layer; a palladium thin film formed on the diffusion barrier layer; and a platinum thin film formed on the diffusion barrier layer and overlapping a portion of the palladium thin film to form a thermocouple junction.
A silylated resin suitable for use as an adhesive binder for composites and in sealant and adhesive dental applications is represented by the general formula (I): STR1 in which: R1 is an aliphatic, cycloaliphatic, aryl, hydrocarbon, or fluorocarbon group; R2 is the same as R1 or a different aliphatic, cycloaliphatic, aryl, hydrocarbon, or fluorocarbon group; STR2 M2 is the same as M1 or a different functional or nonfunctional group selected from the group consisting of: STR3 n is 1-3; x is 1-20; and y is 1-20; which comprises the reaction product of the exchange reaction of a hydroxylated, aminated, or carboxylated acrylic resin represented by the general formula (II): STR4 in which: R4 is an aliphatic, cycloaliphatic, aryl, hydrocarbon, or fluorocarbon group with one or more protic functional groups selected from the group consisting of: OH, N--H, and CO2 H R5 is H or CH3; and R6 is H or CH3; with a trialkoxyorganosilane or triacyloxyorganosilane represented by the general formula (III): STR5 in which: R7, R8, and R9 each is: STR6 R10 is an aliphatic, or aryl group which can optionally be substituted with a group from the group of an acrylic group, a methacrylic group, an epoxy group, and a substituted amino, hydroxyl, or carboxylic acid group such as an ester or an amide.
The present invention provides a method for machining hard materials using the machining fluids containing long chain alcohol in which the machining fluid is applied to a machining tool and then lubricates the machining of the workpiece by the machining tool and protects the machining tool during machining. The method is particularly useful when used with machining tools having a Mohs hardness of at least 9 and is most particularly useful when used with diamond machining tools.
A detector of X-ray and the like in which very good resolution of energy can be obtained. The device is based on two basic components. The first is the x-ray absorber in which an x-ray interacts with a film and converts its energy into heat. Because the absorber is operated at cryogenic temperatures, approximately the range of 0.01 Kelvin to 1 Kelvin, its heat capacity is small and causes a measurable temperature rise. The second component of the invention is a base layer of normal metal which absorbs the heat generated by the x-ray. The third component of the invention is the method to detect the temperature rise. This thermometer is based on a normal metal-insulator-superconductor tunnel junction, where part of the base layer is the normal metal. When the tunnel junction is electrically biased at a voltage slightly below the gap voltage of the superconductor, the electrical current that flows through the junction is sensitively dependent on the temperature of the normal metal.
This invention provides an inexpensive, noninvasive optical method of quantitatively determining the volume fraction of anisotropic material in a mixture of anisotropic and isotropic material, and more particularly for determining the volume fraction of noncubic crystalline material in a mixed-phase specimen having noncubic crystalline material intermixed with cubic crystalline material. Polarized light is impinged on the specimen and the reflectance or transmission difference between two orthogonal polarization directions is measured. In cubic regions the reflectance or transmission is the same along both polarization directions so the contributions to the difference cancel, leaving a signal only from the noncubic regions. The optical difference can be measured as a function of wavelength and critical points in the band structure, including the band gap, can be profiled. From the band structure the film composition can be determined. This measurement is particularly suited to measuring III-V nitride semiconductor specimens having regions with zincblende symmetry mixed with regions of wurtzite symmetry.
The present invention is directed to a metal hydrides lamp and a fill for such a lamp. The lamp chamber includes a fill of at least one metal, a buffer gas, and hydrogen and/or deuterium. When energy is provided to the fill, metal combines with the hydrogen and/or deuterium to form a molecule at an excited energy level which emits visible light when the molecule moves to a ground state energy level. The lamp may be an electrode lamp, an electrodeless lamp, a microwave lamp, or any other power source capable of imparting energy into a fill contained within a lamp chamber.
A method and apparatus for irradiating a specimen with a beam of radiation are provided. The method comprises the steps of providing an integrating sphere, a radiation source radiatively communicating with the sphere, and a specimen, the integrating sphere radiatively communicating with the specimen through an aperture in the sphere. The apparatus comprises a radiation source, an integrating sphere in radiative communication with the radiation source, and a specimen holder in radiative communication with the integrating sphere. The disclosed apparatus and method allow the irradiance of a beam of radiation impinging on the specimen to be maintained at a uniform level across the width of the beam to allow quantitative specimen evaluation.
Oxygen-containing compounds, particularly compounds wherein the oxygen is present in OH-groups, such as alcohols, sulfonic and carboxylic acids, or metal salts thereof, serve as lubricants for ceramic materials, particularly silicon nitride materials under high stress and high load conditions.
Methods for reducing wear on silicon carbide ceramic surfaces comprise contacting the surface with a lubricating oil composition including an organic sulfide. Preferred organic sulfides are of the formula R1 --S--(S)n --R2 wherein R1 and R2 are individually selected from the group consisting of alkyl, aryl, arylalkyl and alkaryl groups and hydrogen, but not both R1 and R2 are hydrogen, and n is 0, 1 or 2.
An antioxidant additive for an engine or propulsion system lubricant subjected to high temperatures which includes a high molecular weight substituted phenolic carboxylic acid tetraester of pentaerythritol. A lubricant blend which is capable of solubilizing the antioxidant additive and includes a polyolester, a phosphate ester and at least one of a polyalphaolefin and an alkylated naphthalene.
A chemical process for producing bulk quantities of an iron-silica gel composite in which particle size, form, and magnetic state of the iron can be selected. The process involves polymerizing an ethanolic solution of tetraethylorthosilicate, ferric nitrate and water at low temperature under the influence of an HF catalyst. The chemical and magnetic states of the iron in the resultant composite are modified in situ by exposure to suitable oxidizing or reducing agents at temperatures under 400° C. Iron-containing particles of less than 200 angstrom diameter, homogeneously dispersed in silica matrices may be prepared in paramagnetic, superparamagnetic, ferrimagnetic and ferromagnetic states.
Aluminum hydroxides are used as solid lubricants for aluminum oxides, ceramics and other materials having oxide surfaces. Aluminum oxide hydroxides and aluminum trihydroxides are preferred compositions for such lubricating purposes. In particular, the use of boehmite in an aqueous solution significantly reduces frictional coefficients between contacting surfaces.
The present invention uses a high energy x-ray, neutron, or gamma source for monitoring the interface between a molten and solidified crystalline phase while in a furnace in a casting process. The radiation can also be used to determine the quality and orientation of the crystals in the crystalline phase. The invention uses the distinctive diffraction patterns produced by crystalline and amorphous phases to locate the interface.
The change in the peak fluorescence wavelength of a small amount of a fluorescent compound, i.e., a fluorophore, which has been dissolved in a polymerizing material or a thermoplastic polymer is used to determine the extent of cure or solidification, respectively. The measured wavelength-shift can either be compared with a previously determined correlation to obtain an absolute value for the extent of cure, or can be utilized to compare or maintain an acceptable extent of cure throughout a manufacturing or a clinical process. Similarly, in the processing of a thermoplastic polymer by injection molding, the measured wavelength shift can either be compared with a previously determined correlation to obtain an absolute value for the temperature of the polymer, or can be utilized to adjust the injection molding cycle so that the mold is opened at the optimum times. The fluorophores used in the method are preferably selected from a class of fluorophores comprising alpha, omega substituted linear alkenes having an electron accepting group attached at the alpha position and an electron donating group attached at the omega position.
Disclosed is a high nitrogen stainless steel alloy and alloy powder comprising chromium (Cr), molybdenum (Mo), manganese (Mn), nickel (Ni), nitrogen (N) and iron (Fe). The composition of the stainless steel alloy and powder comprises between about 27 and about 30% by weight Cr, between about 1.5 and about 4.0% by weight Mo, Mn present and is present in an amount up to 15% by weight, at least about 8% by weight Ni, and about 0.8 to about 0.97% by weight N with the balance being iron. It has been discovered that forming an alloy of this chemistry using nitrogen gas atomization process, followed by a consolidation process, the alloy is less likely to form detrimental ferrite, stable nitride and sigma (.sigma.) phases, without the need for further processing, such as solution treating and quenching. This allows for the formation of stainless steel articles having a thicker cross-section with reduced processing cost.
A high lead solder exhibiting improved wettability to metal substrates, an advantageously controlled melting range, and excellent thermal fatigue properties. It comprises about 98-100% lead and a minor amount, typically about 0.0005-0.1 wt %, based on the total weight of the solder composition, of an alkali metal selected from the group consisting of Na, K, and Li. Additional embodiments additionally comprise an amount of a grain-size controlling additive, e.g., 0.001-0.5 wt % (based on the total weight of all the components in the solder composition) selected from the group consisting of Ce, Ba, La, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Y, Lu, Sc, Mg, Na, Se, Te, oxides thereof and mixtures thereof, in amount effective to control the Pb grain size; and 0-1 wt % of an element selected from the group consisting of Sn, In, Bi, Sb, Ag, Au, and Ga, and mixtures thereof.
A nanocomposite superparamagnetic material that includes nanosize particles of a magnetic component, preferably a rare earth and a transition element, dispersed finely within a bulk matrix component provides finely dispersed magnetic clusters, whereby a high magnetocaloric effect is obtained in using the nanocomposite material in a conventional magnetic refrigeration system. In one aspect of the present invention, an element formed of such a nanocomposite superparamagnetic material is reciprocated into and out of a heat exchanger within a controlled magnetic field and is in heat transfer communication with a second heat exchanger to facilitate the production of a refrigeration heat transfer effect thereby. In another aspect of the present invention, a generally disk-like element formed of the nanocomposite superparamagnetic material is rotated so that portions thereof move between a first heat exchanger and a second heat exchanger that is within a controlled magnetic field, to thereby perform refrigeration heat transfer between the two heat exchangers.
The dielectric slit die is an instrument that is designed to measure electrical, rheological, ultrasonics, optical and other properties of a flowing liquid. In one application, it is connected to the exit of an extruder, pump or mixing machine that passes liquefied material such as molten plastic, solvents, slurries, colloidal suspensions, and foodstuffs into the sensing region of the slit shaped die. Dielectric sensing is the primary element of the slit die, but in addition to the dielectric sensor, the die contains other sensing devices such as pressure, optical fiber, and ultrasonic sensors that simultaneously yield an array of materials property data. The slit die has a flexible design that permits interchangeability among sensors and sensor positions. The design also allows for the placement of additional sensors and instrumentation ports that expand the potential data package obtained.
The present invention relates to x-ray diffraction measurement by using moving x-ray source x-ray diffraction. The invention comprises a raster-scanned x-ray source, a specimen, a collimator, and a detector. The x-ray source is electronically scanned which allows a complete image of the x-ray diffraction characteristics of the specimen to be produced. The specimen is placed remote from the x-ray source and the detector. The collimator is located directly in front of the detector. The x-rays are diffracted by the specimen at certain angles, which cause them to travel through the collimator and to the detector. The detector may be placed in any radial location relative to the specimen in order to take the necessary measurements. The detector can detect the intensity and/or the wavelength of the diffracted x-rays. All information needed to solve the Bragg equation as well as the Laue equations is available. The x-ray source may be scanned electronically or mechanically. The present invention is used to perform texture analysis and phase identification.
Disclosed is a fluid mixer that mixes liquids while simultaneously promoting rapid mixing entrainment of vapor in the liquid. The device includes a vertical rotor mounted centrally on a base assembly. The rotor comprises a tube which is hollow from an open top end to a bottom closed end, having an external screw thread in a right-side configuration relative from top to bottom and one or more holes located in the sidewall of the tube at the bottom of the hollow portion of the tube, preferably located centrally between two flanking surfaces of the screw thread. The base assembly comprises a stirbar and a supporting disk which contains a ceramic magnet. The base rests on the floor of a containment vessel. A magnetic stirring motor is centrally located sufficiently close to and beneath the containment vessel as to achieve magnetic flux coupling with the base magnet. Operation of the mixer develops a liquid vortex in the liquid phase material. As the speed increases, the external screw threads generate turbulence and draw vapor into the liquid from above the tube and urge the vapor into intimate contact with the turbulent, droplet-forming liquid. A circulation develops causing a vortex to develop. As the speed of circulation increases, the surface of the liquid is lowered until it matches the hole in the sidewall of the tube. The liquid enters the holes in the sidewall of the tube along with entrained vapor, and rises through the liquid in the hollow tube, and exits the open top end.
A method for the removal of carbonyl sulfide from liquefied petroleum is disclosed. Removal of carbonyl sulfide is accomplished by contacting a liquid petroleum gas stream containing a carbonyl sulfide as an impurity with a calixarene complexing agent as the principal agent for the removal of the carbonyl sulfide.
A composition formed from Group II fluorides in which the composition has little or no intrinsic birefringence at a selected wavelength. The composition is a mixed solid solution of CaF.sub.2 with a second crystal of SrF.sub.2 or BaF.sub.2. The resulting composition is in the form of Ca.sub.1-xSr.sub.xF.sub.2 or Ca.sub.1-xBa.sub.xF.sub.2, or a combination of SrF.sub.2 and BaF.sub.2, in the form of Ca.sub.1-x-ySr.sub.xBa.sub.yF.sub.2. The specific form of the composition that effectively nulls out the intrinsic birefringence at a selected wavelength within the UV range is determined in one preferred method from the magnitudes of the intrinsic birefringences of the components, CaF.sub.2, SrF.sub.2, and BaF.sub.2.
A spray pyrolysis method for producing pure metal and/or metal oxide particles uses a mixture of a carrier gas and a solution of a metal salt precursor, water and a co-solvent reducing agent. The metal salt precursors preferably comprise metals from the group consisting of Fe, Co, Ni, Cu, Zn, Pd, Ag and Au, whereas the salt anions preferably comprise nitrates, acetates, oxalates and chlorides. The co-solvents are those that act as a reducing agent, are vaporizable, are inert with respect to the carrier gas, and are hydrophilic, such as alcohols, in particular, low-carbon numbered alcohols such as methanol or ethanol.
A method for the chemical precipitation of metallic silver powder employs a two solution technique in which a solution of a tin salt and a solution a silver salt are mixed in the presence of an inorganic or organic acid, alumina, an anionic surfactant, and a colloid to form a precipitation solution at a temperature and pH suitable to effect the chemical precipitation of silver. Almost 80% by weight of the precipitated powder agglomerate is less than 25 µm in diameter, and the individual powder particles which compose the agglomerate range in size from 0.2 to 2.0 µm. In addition to the favorable size distribution, silver particles precipitated in the presence of a gelatin colloid can be used with a minimal amount of sieving so that little work hardening is imparted to the particles. The powder can be annealed at a temperature of up to 750° C. for two hours in air with minimal sintering, and the acid-assisted hand consolidation of powder produced according to the present technique is capable of producing silver compacts which are nearly 80% dense. Advantageously, a hand consolidated silver compact which comprises the powder of the present invention equals or exceeds the transverse rupture strength, shear strength, creep, toughness, corrosion resistance, microleakage, and wear properties of conventional silver amalgam.
Method of Stabilization of Functional Nanoscale Pores for Device Applications: Application # 20050191616
A membrane is disclosed made from a compound having a hydrophilic head group, an aliphatic tail group, and a polymerizable functional group. The membrane spans an aperte and may be polymerized. The membrane may be useful for DNA sequencing when the membrane includes an ion channel.
Single Molecule Mass Spectrometry in Solution Using a Solitary Nanopore: Docket # 08-003
The invention consists of a means to measure an electrical current passing through a stable nanopore under an applied voltage while partial occlusion of the pore occurs by molecules that reduce the electrical current because the pore's size is commensurate with the molecules'. The pores may be modified to interact selectively with chosen targets. Specific averaging methods are used that, in effect, act as signal averaging of the individual currents and allows these current levels to be assigned to molecules of different sizes. In addition, the time courses of the chemical interactions of the analytes with the pore can be found once the current levels are assigned. The set of current levels together with the time courses provide a novel two-dimensional method of analysis for charged and uncharged molecules in solution.
A magnetoresistive sensing apparatus is disclosed, comprising a magnetic film having a zig-zag shaped structure, a central axis, and a magnetization associated with the magnetic film, wherein the zig-zag shaped structure biases the magnetization direction alternately at positive and negative angles thereof, thereby permitting the magnetoresistive sensing apparatus to be sensitive to a magnetic field parallel to the axis of the magnetoresistive sensing apparatus and insensitive to magnetic fields perpendicular to the axis.
A digester-evaporator interface for partially digesting a sample mixed in a solvent with an acid and for evaporating the solvent and the acid after partial digestion, said digester-evaporator including a digester portion and an evaporator portion. The digester includes at least one reaction coil having an input and an output, said at least one reaction coil adapted for receiving at its input a flow of a sample in a solvent and an acid suitable for partial digestion of the sample so as to partially mix and begin partial digestion in the reaction coil; a heating element arranged along a portion of the reaction coil; at least a portion of the reaction coil proximate to its output being preheated by the heating element to a degree sufficient to convert a partially digested sample into vapor; a collector spoon with carrier water for collecting sample vapor; and an evaporator portion including an evaporation chamber including a cover with a first opening having the substantially vertically-oriented tube extending from the cover, and the evaporation chamber includes an axial opening longitudinally arranged therein, and the evaporation chamber adapted to contain fluid at a bottom portion. The collector spoon is arranged in the top of the substantially vertically-oriented tube after a vapor sample has been collected from the digester portion, and a gas supply tube for supplying a preheated gas provided in a top of the substantially vertically-oriented tube and in the axial opening of the evaporation chamber so as to create a cyclonic gas flow into the chamber and carry the sample to a container area in a bottom portion of the chamber. The interface is especially useful in the separation and quantification of selenium containing proteins.
The invention is the exploitation of a difference in scaling with length of the hydrodynaiic drag on a nanotube, and the buoyancy force of the same nanotube to sort the nanotubes by their length. The buoyancy is generated by using a commercial density medium, a surfactant, such as sodium deoxycholate, that forms a miceller shell around the nanotube. The surfactat shell acts both to keep the nanotube individually dispersed, and as a buoyant volume with an effective density different from the surrounding medium.
The invention, a Particle Transfer Apparatus, facilitates the transfer of atmospheric particles for fibrous filter such as quartz fiber to a smooth substrate that is suitable for scanning electron micrscopy (SEM) and x-ray microanalyisis. The invention may also be suitable for transferring particles embedded in clothing textiles for this purpose.
A stationary phase for a liquid chromatography and process for making is provided. The stationary phase material may have a modified base substrate and a fluorinated carboxylic acid covalently bonded thereto through an amide or ester bond. The stationary phase may have a substantially consistent shape selectivity characteristic with an .alpha..sub.TBN/BaP of less than 1 within a temperature range of at least 10-70.degree. C. Advantageously, a fluorinated stationary phase has a shape selectivity characteristic exhibited with an .alpha..sub.TBN/BaP of less than 1 with a mobile phase having up to at least 30% water. A process for making the stationary involves mixing a substrate material or fluorinated carboxylic acid with a reactive alkylsilane linker and at least one organic solvent to form a first solution. The other of the substrate material or fluorinated carboxylic acid is then added to the first solution, or to a product separated from the first solution, to form a second solution. The second solution is reacted to form the stationary phase.
Polymers with quaternary ammonium functional groups in their molecular structures constitute an important class of biocidal materials. Because of the widespread incidence of dental caries there is a need for effective anti-bacterial polymeric dental and biomedical materials, e.g., restorations, adhesives, sealants, endodontic materials, denture and maxillofacial materials, and bone cements. For example, a major cause for the clinical failure of composite restorations is bacterial infiltration at the filling-tooth interface, which leads to secondary or recurrent caries and requires the replacement of the filling and removal of the carious tooth structure. One approach to prevent the occurrence of recurrent caries is to use polymeric materials with anti-microbial properties. In this research it is demonstrated that the classical, facile Menschutkin reaction can be adapted
to the synthesis of multi-functional, thermosetting monomers and resins that have one or more quaternary ammonium groups in their chemical structures.