Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...
Reexamination Certificate
2001-07-31
2003-02-25
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From heterocyclic reactant containing as ring atoms oxygen,...
C528S271000, C528S403000, C528S406000, C528S408000, C528S409000, C528S418000, C524S714000, C524S755000, C524S765000
Reexamination Certificate
active
06525170
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to processes for the preparation of highly branched functional and reactive polymers, and to novel highly branched functional and reactive polyesters prepared through a one-step process.
BACKGROUND OF THE INVENTION
Branched polymers and copolymers have attracted considerable attention over the past decades, since many advanced materials with new or improved properties can be obtained therefrom. The terms “hyperbranched” and “highly branched” used herein with respect to branched polymers are intended to designate polymers having a relatively high percentage of propagated branching sites per number of polymerized monomer units, e.g. at least one branching site per every ten monomer units, preferably at least one branching site per every five monomer units and more preferably at least one branching site per every two monomer units. Highly branched polymers can be made by multi-step or one step processes. Multi-step generation processes were exemplified by Frechet in U.S. Pat. No. 5,041,516 and by Hult in U.S. Pat. No. 5,418,301. Both patents described that the highly branched polymers known as dendrimer or “starburst polymer” were made through a series of growth steps consisting of repeatedly reacting, isolating, and purifying.
One-step process was first conceptualized by Flory (J. Am. Chem. Soc., 74, p2718 (1952)) who demonstrated by theoretical analysis that a highly branched and soluble polymers could be formed from monomers comprising the structure AB
2
, where A and B are reactive groups, by one-step condensation polymerization. In contrast to the dendrimers, the polymer formed by AB
2
polymerization is randomly branched. One-step process for formation of a highly branched polymer may also use an A
2
+B
3
approach. In A
2
+B
3
polymerization, di- and tri-functional monomers are reacted together. For ideal A
2
+B
3
polymerization, intramolecular cyclization must be minimized as a competing and chain terminating process during polymer propagation, all A groups and all B groups should have near equal reactivity in both the monomers as well as the growing polymers, and the A and B groups should have exclusive reactivity with each other. In view of such requirements, relatively few specific combinations of A
2
+B
3
polymerization schemes have been proposed.
With regard to AB
2
-type monomers, Baker in U.S. Pat. No. 3,669,939 described that highly branched aliphatic polyesters could be prepared by one-step melt condensation polymerization of monomers having a single carboxylic acid and multiple alcohols. Kim et al in U.S. Pat. No. 4,857,630 disclosed that hyperbranched polyphenylenes can be prepared by one-step polymerization of monomers such as (3,5-dibromophenyl)boronic acid and 3,5-dihalophenyl Grignard reagents. Hawker et al disclosed that all aromatic, highly branched polyesters can be made by melt polymerization of 3,5-bis(trimethylsiloxy)benzoyl chloride (J. Am. Chem. Soc., 113, p4583 (1991)). U.S. Pat. No. 5,196,502 disclosed the use of diacetoxybenzonic acids and monoacetoxydibenzonic acids to produce wholly aromatic polyesters. U.S. Pat. No. 5,225,522 and 5,227,462 disclose highly branched aliphatic-aromatic polyesters and processes for making the same. U.S. Pat. No. 5,418,301 disclosed a process for preparing dendritic macromolecules. U.S. Pat. No. 5,514,764 disclosed preparation of hyperbranched aromatic polyesters and polyamides by a one-step process of polymerizing a monomer of the formula A—R—B
2
where R represents an aromatic moiety. U.S. Pat. No. 5,567,795 disclosed synthesis of highly branched polymers in a single processing step by using branching aromatic monomers and an end-capping monomer. U.S. Pat. No. 5,663,247 disclosed a hyperbranched macromolecule of polyester type comprising a central monomeric or polymeric epoxide group containing nucleus and at least one generation of a branching chain extender having at least three reactive sites of which at least one is a hydroxyl or hydroxyalkyl substituted hrodroxyl group and at least one is a carboxyl or terminal epoxide group and the process for making the same.
With regard to A
2
+B
3
polymerization, Jikei et al (Macromolecules, 32, 2061 (1999)), e.g., has reported synthesis of hyperbranched aromatic polyamides from aromatic diamines and trimesic acid. Emrick et al (Macromolecules, 32, 6380 (1999)) has disclosed the synthesis of hyperbranched aliphatic polyethers by means of proton-transfer polymerization of 1,2,7,8-diepoxyoctane as A
2
monomer and 1,1,1-tris(hydroxymethyl)ethane as B
3
monomer.
It is known that ring open reaction between terminal epoxides with acid chlorides, in the presence of tetrabutylammonium bromide, can form an anti-Markinovkov ester product containing a primary chloride. This reaction was applied to diepoxides and diacid chlorides to form polyesters (Kameyama et al., Macromolecules 25, p.2307 (1992)). Copending, commonly assigned U.S. Ser. No. 09/697,205 of Wang describes the synthesis of highly branched functional and reactive polyesters using an A
2
+B
3
approach by reacting multi-functional acid chloride and multi-functional epoxide monomers, where at least one of such monomers is at least tri-functional. The use of such monomers advantageously results in highly branched polyesters having a multiplicity of very reactive epoxy or acid chloride groups or both on the outside surface which can be further converted to other functional groups. One-step processes for formation of a highly branched polymer which use an A
2
+B
3
approach, however, require care to prevent undesired competing reactions, such as crosslinking and chain terminating processes, during the desired polymer propagation. As a result, molecular weight may not be as high, and polydispersity may not be as low, as may be desired for the resulting polymer. No prior art teaches the use of AB
2
type monomers comprising epoxide and acid chloride reactive groups to prepare highly branched polymers.
It would be desirable to provide a process for producing highly branched polyesters of high molecular weight and low polydispersity without requiring the use of multi-step reactions and purification. It would be further desirable to provide such a process which results in highly branched polyesters having a multiplicity of very reactive epoxy or acid chloride groups or both on the outside surface which can be further converted to other functional groups.
SUMMARY OF THE INVENTION
In accordance with one embodiment of the invention, a polymerization process for producing highly branched polyesters is disclosed comprising reacting functional groups A and B of multi-functional branching monomer reactants of the formula A—L—B
n
, where one of A and B represents an epoxide group, the other of A and B represents an acid chloride group, L represents a linking group between A and B, and n is at least 2; wherein polymerization proceeds by reaction of an epoxide group of a first monomer with an acid chloride group of second monomer to open the epoxide group ring and form a reaction product having an ester linkage between the first and second monomers, and repeating such esterification reaction between additional epoxide groups and acid chloride groups of the multifunctional monomers and reaction products of the multifunctional monomers to form a highly branched polyester.
In accordance with a specific embodiment of the invention, branched polyesters are obtained in accordance with the above process which have a number average molecular weight of at least 1000 and a ratio of weight average molecular weight to number average molecular weight of less than 2.
The invention provides a process for producing highly branched polyesters in one reaction step. The invention has the capability of making highly branched structures of high molecular weight and low polydispersity and has the advantages of not requiring multi-step reactions and purification. The invention yields highly branched polyesters having a multiplicity of very reactive epoxy or acid chlor
Acquah Samuel A.
Anderson Andrew J.
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