Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-11-28
2003-10-28
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S145000, C526S146000, C526S147000, C526S185000, C526S217000, C526S237000, C526S238000, C528S085000, C528S271000
Reexamination Certificate
active
06639032
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the synthesis of commodity and specialty polymeric materials. Specifically, the present invention relates to manufacture of polymers with hyperbranched architecture from telomerization.
BACKGROUND OF INVENTION
Highly 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 three 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 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 dendrimers, the polymer formed by AB
2
polymerization is randomly branched.
Frechet et al disclosed that vinyl hyperbranched polymers could be obtained by means of living chain polymerization of AB monomers (Frechet et al. U.S. Pat. Nos. 5,587,441, 5,587,446), which was termed as self-condensation vinyl polymerization. AB monomer was defined as one that contains two reactive groups, A and B, in the same molecule, which react independently of each other within a molecule. The A group is typically a polymerizable vinyl group and the B group is a reactive group that can be activated by an activator and add to the A group to promote the polymerization. The general mechanism of formation of hyperbranched polymer can be described in accordance with Scheme 1 below, where the A group is a polymerizable vinyl group.
As indicated in Scheme 1 above, B with AB vinyl monomer, a B group may be activated to a B* moiety that itself is capable of initiating the polymerization of a vinyl monomer. The polymerization process is initiated by reaction of one initiating B* group with the double bond A of another AB* monomer unit to yield the dimer. The dimer now has one vinyl group and two reactive sites, and subsequently functions like an AB
2
-monomer. Additional condensation of dimer, trimer, and eventually larger oligomeric species produced by sequential condensations gives rise to a hyperbranched polymer. The polymerization of AB monomer described by Frechet displays a “living-like” character, as side reactions such as chain transfer and elimination are substantially eliminated. Based on the same mechanism as Frechet's, a number of vinyl hyperbranched polymers have been prepared by various living polymerization processes, such as atom transfer radical polymerization (Wang, et al. U.S. Pat. No. 5,807,937 (1998)), group transfer polymerization (Muller, et al. Polymer Preprint, 38(1), 498 (1997)), and stable radical polymerization (Hawker et al. J. Am. Chem. Soc. 113, 4583 (1991)).
There are, however, disadvantages associated with the polymerization processes described in the prior art for the manufacture of vinylic hyperbranched polymers by living polymerization processes. First, in the cases of living anionic, cationic, and group-transfer polymerization, the polymerizations systems need to be very pure. In the case of living cationic and group transfer polymerization, e.g., a trace of impurity such as water often prevents polymerization from proceeding, so often that there is even no polymer obtained. Thus, these living polymerization processes are not preferred in industrial productions. Second, the use of heavy metal containing inorganic salts in atom transfer radical polymerization is not environmentally friendly and practical.
In 1946, Handford first defined telomerization as the reaction between a compound XY called the telogen and one or several molecules of polymerizable species M called the taxogen, under polymerization conditions which lead to the formation of telomers X—(M)
n
—Y (U.S. Pat. No. 2,396,786). Telomerization is generally regarded as chain reaction that, in contrast to polymerization, leads to oligomers having very low molecular weight, and even monoaddition compounds, which are referred to as telomers. The general mechanism of formation of telomer can be described in accordance with Scheme 2 below.
In Scheme 2, Initiator I (e.g., a peroxide, a peracid, or a diazoic compound) generates activated species R* (e.g., free radical group). R* then reacts with telogen XY to form activated species X* and R—Y. X* can then react with taxogen M monomer to form species X—M*, which can react with further M monomers through propagation to form oligomeric species X—M(
n−1
)—M*. X—M(
n−1
)—M* species upon transfer reaction with telogen XY forms telomer X—M
n
—Y and activated species X*, which can then initiate further telomerization. The reaction can terminate by combination of two X—M(
n−1
)—M* and/or X—M* species to form non-activated species. The average degree of chain growth (n) in telomerization is generally from 2 to about 100, more typically 2 to 30, or even 2 to 10, dependent upon the relative reaction rates for the propagation and chain transfer steps. Telomerization generally requires that the chain growth (propagation) and chain transfer steps have reaction rates within two orders of magnitude of each other, as if the propagation reaction rate is too fast relative to the chain transfer reaction rate, regular polymerization will occur. If the chain transfer reaction rate is significantly faster than the propagation reaction rate, on the other hand, a 1:1 adduct (i.e., X—M—Y) will be obtained.
The telomerization products can thus be classified as intermediate between organic monomeric and macromolecular polymeric compounds and have been found in wide industrial applications (Stark, Free Radical Telomerization, Academic Press, Inc., New York, 1974; Boutevin et al, in Comprehensive Polymer Science, Pergamon: Oxford, 1991, vol. 3, p 185). However, no prior art discloses the synthesis of hyperbranched polymer by telomerization.
It would be desirable to provide a simple, practical, and environmentally friendly process for the manufacture of soluble hyperbranched polymers. Accordingly, one object of the present invention is to make hyperbranched polymers by telomerization.
SUMMARY OF THE INVENTION
The invention comprises a process for making hyperbranched polymers from A
n
—L
z
(XY)
m
type monomers wherein A is a polymerizable group moiety, XY is a telogen group moiety in which Y is a transferable atom or group which can participate in a transfer reaction with the formation of reactive X*, L is a linkage between A and XY, z is 0 or 1, and n and m are integers of at least 1, comprising
(a) initiating reaction by forming activated species from reaction between either an A or an XY group of the A
n
—L
z
(XY)
m
type monomer and an external stimulus to form activated monomer species with an activated polymerizable group moiety A* or an activated moiety X* derived from the telogen group moiety XY; and
(b) polymer segment chain growth by
(i) propagation reaction between the polymerizable group A moieties of the A
n
—L
z
(XY)
m
type monomers with the activated moieties A* and X* of activated species, and further reaction between the polymerizable group moieties with the activated moieties of the reaction products thereof, and
(ii) chain transfer reaction be
Anderson Andrew J.
Zalukaeva Tatyana
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