Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-03-22
2003-12-23
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S204000, C526S217000, C526S222000
Reexamination Certificate
active
06667376
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to new compounds useful in assisting in the polymerization of monomers in a free radical polymerization that has living-type kinetics. Polymers made with the control agents and processes for polymerization are also included.
BACKGROUND OF THE INVENTION
The use and mechanism of control agents for free radical polymerization is now generally known; see for example U.S. Pat. No. 6,153,705, WO 98/01478, WO 99/35177, WO 99/31144, and WO 98/58974, each of which is incorporated herein by reference. Despite this knowledge, there remains a need for new agents that may lead to a commercializable process. In particular, control agents that work to control the polymerization of vinyl monomers are of interest. In this context, vinyl monomers are typically monomers with a radically polymerizable double bond not conjugated to any other double bonds such as C═C, C═O or C≡N. Typical examples of vinyl monomers include vinyl acetate, vinylformamide, vinyl pyrrolidone and olefins (such as &agr;-olefins).
The control agents described in WO 98/01478, WO 99/35177, WO 99/31144, and WO 98/58974 generally operate according to a reversible addition-fragmentation transfer mechanism, which confers a “living” character to the free radical polymerization of ethylenic monomers. These control agents, however have not been known to show control of the polymerization of vinyl monomers, such as vinyl acetate. Typically, when using the known control agents with vinyl monomers, the polymerization reaction is either unacceptably slow (e.g., an inhibition effect is observed) or uncontrolled.
In U.S. Pat. No. 6,153,705, control agents of the xanthate type (for instance, CH(CH3)(CO
2
Et)S—C(═S)OEt) are disclosed that may at least partially control the polymerization of vinyl acetate. However, even partial loss of control is undesirable for certain applications.
This invention provides control agents that unexpectedly provide superior control in the polymerization of vinyl monomers in comparison to known control agents. In particular these new control agents give a narrower molecular weight distribution when compared with known control agents, and, as opposed to the latter, they show a continuous decrease in the polydispersity as the monomer conversion increases. These modified properties allow for improved conditions of the polymerization process and/or improved properties of the polymers obtained from the processes. These control agents showed unexpectedly good results in the control polymerization of vinyl type monomers, such as vinyl acetate, vinylformamide, vinyl pyrrolidone and ethylene.
SUMMARY OF THE INVENTION
This invention provides control agents that are have an O—N bond covalently bonded to a thiocarbonyl moiety. In some embodiments the control agents can be characterized by the general formula:
wherein R
1
is generally any group that is sufficiently labile to be expelled as its free radical form; R
2
and R
3
are each independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, and combinations thereof, and optionally, R
3
combines with R
2
to form a ring structure, with said ring having from 3 to 50 non-hydrogen atoms.
Another aspect of this invention is directed toward multi-functional control agents, so that the control agents may occupy either a central portion of a polymer chain and/or two or more ends of a polymer. In those embodiments where the control agent occupies a central portion of the polymer backbone, the oxygen-nitrogen bond provides the unique opportunity to degrade the polymer backbone into smaller pieces by external stimuli (e.g., heat, chemical reaction, irradiation, etc.). Such a process is unique as compared to known free radical polymerization and “living” free radical polymerization techniques. In addition, some of the multi-functional control agents are cyclic, which provide the unique opportunity to prepare block copolymers with reduced processes steps. Furthermore, some multi-functional control agents allow for ring opening polymerizations, which heretofore have not found commercial applications in free radical polymerization.
In another aspect, this invention provides control agents that are easy to prepare and economically useful on a commercial scale (e.g., batch, semi-batch or continuous).
Other aspects of this invention include certain of the control agents, which are novel compounds. Polymerization processes using all of the control agents of this invention and polymers that can be made with the control agents of this invention are additional aspects of this invention. In particular, the control agents of this invention provide living-type kinetics and as such allow for the preparation of desired products, including block polymers, star architectures, grafts and hyperbranched polymers.
Thus, it is an object of this invention to provide novel control agents for a living-type free radical polymerization process.
It is another object of this invention to provide novel compounds, which are useful as control agents in a free radical polymerization process.
It is a further object of this invention to provide a novel system for free radical polymerization of monomers that employs living-type kinetics, and in particular for vinyl monomers.
It is still a further object of this invention to polymerize a variety of monomers under commercially acceptable conditions with a family of control agents, and in particular for vinyl monomers.
It is yet a further object of this invention to make controlled architecture polymers with a polymerization process that employs a control agent.
It is further another object of this invention to provide multifunctional control agents that may occupy a central portion of a polymer chain allowing for the polymer chain to be degraded.
Further aspects and objects of this invention will be evident to those of skill in the art upon review of this specification.
DETAILED DESCRIPTION OF THE INVENTION
In the most general terms, the control agents of this invention contain at least one O—N bond covalently bonded to a thiocarbonyl group. In structural terms, the following moiety must be present in the control agents of this invention:
In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. A named R group will generally have the structure that is recognized in the art as corresponding to R groups having that name. For the purposes of illustration, representative R groups as enumerated above are defined herein. These definitions are intended to supplement and illustrate, not preclude, the definitions known to those of skill in the art.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.
The following definitions pertain to chemical structures, molecular segments and substituents:
As used herein, the phrase “having the structure” is not intended to be limiting and is used in the same way that the term “comprising” is commonly used. The term “independently selected from the group consisting of” is used herein to indicate that the recited elements, e.g., R groups or the like, can be identical or different (e.g., R
2
and R
3
in the structure of formula (1) may all be substituted alkyl groups, or R
2
may be hydrido and R
3
may be methyl, etc.).
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example,
Chang Han-Ting
Charmot Dominique
Jayaraman Manikandan
Nava-Salgado Victor
Pezzuto Helen L.
Symyx Technologies Inc.
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