Methods and materials for fabrication of alumoxane polymers

Details Methods and materials for fabrication of alumoxane polymers Methods and materials for fabrication of alumoxane polymers

1998-08-13

2002-04-09

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From silicon reactant having at least one...

C525S326100, C525S330600, C525S370000, C525S400000, C525S408000, C525S397000, C525S418000, C525S454000, C525S475000, C525S508000, C525S519000, C525S533000, C525S535000, C528S055000, C528S087000, C528S230000, C528S271000, C528S395000, C528S485000, C528S044000, C528S106000, C528S129000, C528S166000, C528S010000

Reexamination Certificate

active

06369183

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to compositions of matter and methods for the preparation of composite and hybrid polymers and resins in which at least one component is a chemically modified carboxylate-alumoxane. The carboxylate-alumoxanes are chemically bonded into the polymer backbone through reaction of the appropriate functional groups of a polymer precursor with the carboxylate-alumoxane. The method of the present invention can be used to produce polymers with organic and inorganic backbones. The polymers produced according to the invention can be either a thermoset or a thermoplastic and can be prepared by either a condensation polymerization reaction or an addition polymerization reaction. The invention provides for the formation of carboxylate-alumoxane materials prepared by the reaction of carboxylate-alumoxanes with polymer precursors including without limitation: epoxides, phenol-formaldehyde resins, polyamides, polyesters, polyimides, polycarbonates, polyurethanes, quinone-amine polymers, and acrylates.
BACKGROUND OF THE INVENTION
Condensation polymers are an important class of polymers that are prepared by the reaction of low molecular weight precursors that contain reactive functional groups such as amines, hydroxyls, acid chlorides, anhydrides and carboxylic acids. Polymeric materials prepared by condensation polymers include (but are not limited to) epoxies, phenol-formaldehyde resins, polyurethanes, polyamides, polyesters, polyimides, polycarbonates, quinone-amine polymers and polysulfones. These materials possess a range of properties and their applications are widespread.
Another name for the class of materials known as condensation polymers are thermoset polymers. Thermosettable polymers, in general, exist as liquids that, upon heating, undergo reactions to form solid, highly cross-linked polymer matrices. Once formed, thermoset polymers cannot be reformed into different shapes by heating.
In general, unfilled thermoset polymers tend to be harder, more brittle and not as tough as thermoplastic polymers. Thus, it is common practice to add a second phase (i.e., fillers) to thermosetting polymers to improve their properties. In addition, incorporation of fillers into the polymer matrices also strengthens and stiffens the polymer matrix allowing the polymers to be used in an expanded range of structural applications.
A common technique for improving the properties of thermoset resins is the use of inorganic fillers (
Handbook of Fillers and Reinforcements for Plastics
11-58; Katz, H. J. and Milewski, J. V., eds.; Van Nostrand Reinhold Co.; New York). Inorganic fillers impart a number of desirable mechanical and barrier properties to the polymer. These properties include improved tensile strength, stiffness, abrasion resistance, dimensional stability and barriers to gases, solvents and water-vapor. As a second phase, the inorganic fillers can also affect other polymer properties such as pot life, cure exotherms, shrinkage, thermal conductivity, thermal shock resistance, heat deflection temperature, machinability, hardness, compressive strength, flexural strength, impact strength and electrical conductivity. The properties of polymers can also be modified by incorporation of a second organic or polymer phase into the thermoset polymers. For example, epoxy resins are routinely toughened (strengthened) by the incorporation of an elastomeric polymer.
The extent to which the inorganic fillers affect polymer properties is closely associated with the volume fraction of filler incorporated into the polymer, the particle size of the filler and the degree to which the filler is bound to the polymer matrix. Thus, the properties of the filler-modified polymers depend on the size, shape and dispersion uniformity of the inorganic modifier, as well as the degree of interaction between the inorganic modifier and the organic matrix. Therefore, the best performance is achieved with inorganic fillers consisting of small particles that are uniformly dispersed throughout the polymer and interact strongly with the organic matrix.
Until recently, the particle sizes of fillers used to improve polymeric properties have been on the micron length scale or even larger. These dense fillers have relatively low surface areas. The surface area of a filler is one of its more important properties, as the surface area determines the amount of contact and bonding between the polymer and the filler (Katz and Milewski, 1978). The size of the particles also determines the volume fraction that can be obtained with a given filler at a given weight loading. Most of the properties (mechanical and barrier) of filled polymers are directly related to volume fraction (and correspondingly to the particle size) of the fillers.
The greatest effect of fillers on the properties of polymer-filler composites appears to occur for fillers possessing dimensions on the nanometer length scale. Nano-particles are ordinarily defined as materials with sizes ranging from 1 nm to 1 &mgr;m. Nano-particles have higher surface areas and at the same weight have higher volume loadings than do larger particles. The total sum of the interactions between filler particles and the polymer are larger for nanometer sized particles than for larger particles. In addition, smaller particles produce smaller stress concentrations in the composite material. Unfortunately, the handling and dispersing of nanometer sized particles can be difficult; for example, small particles rapidly build up large static charges that can lead to the formation of hazardous breathable dusts. Additionally, inorganic oxides are hydrophilic, while most polymers are hydrophobic. This leads to segregation of the two phases and agglomeration of the powders resulting in a decrease in the overall performance of the polymer composite. Hence, it is desired to provide a technique for incorporating advantageous nanoparticle fillers into condensation polymers.
Like condensation polymers, addition polymers are an increasingly important class of polymers and have widespread applications. Addition polymers are prepared by the reaction of a monomer with an unsaturated group. Industrially, addition polymerizations are typically carried out in one of four general ways: in bulk, in solutions, in suspensions, or in emulsions. For the bulk case, only a monomer and polymerization initiator are reacted exothermically to produce polymers such as polystyrene, or poly(vinyl chloride). While this process is usually difficult to control and generates a lower yield polymer, it does have the advantages of producing polymers with high optical clarity and low contamination.
Solution polymerization is similar to bulk polymerization with the simple addition of a solvent medium. The advantage of solution polymerization is that the solvent allows for heat transfer during the reaction, which results in a much higher yield of polymer. The disadvantage of solution polymerization is that solvents must be chosen carefully, as side chain reactions can occur. Solution polymerization, however, is used frequently to polymerize such monomers as vinyl acetate and ethylene. Suspension polymerization, while utilizing a solvent, is much more akin to the bulk polymerization method rather to the solution method, in that droplets of the monomer are suspended in a carrier in which the monomer is insoluble. The carrier allows the advantageous transfer of heat, and the occurrence of unwanted side reactions is drastically diminished. Finally, emulsion polymerization is similar to suspension polymerization with two important differences: (1) the monomer droplet size is smaller, and (2) the initiator is insoluble in the monomer, but soluble in the carrier. This method is chiefly used to polymerize acrylics, poly(vinyl acetate), and numerous other copolymers. The advantage to emulsion polymerization is that the chain length of the monomer can be controlled without regard to reaction rates.
These different polymerization methods are based on several features associated with addition reactions: (1

Affiliated with

Also associated with

Rating

Methods and materials for fabrication of alumoxane polymers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Methods and materials for fabrication of alumoxane polymers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and materials for fabrication of alumoxane polymers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2843168