Multi-functional initiators for atom transfer radical...

Details Multi-functional initiators for atom transfer radical... Multi-functional initiators for atom transfer radical...

2000-10-13

2003-07-08

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...

C526S222000, C526S234000, C526S307100, C526S319000, C526S329700, C526S209000

Reexamination Certificate

active

06590049

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a (co)polymer prepared with novel initiators in a controlled radical (co)polymerization process, as well as a novel controlled radical (co)polymerization process that utilizes the novel initiators.
BACKGROUND OF THE INVENTION
A wide variety of radically polymerizable monomers, such as methacrylate and acrylate monomers, are commercially available and can confer to a polymer or copolymer (hereinafter, collectively referred to as (co)polymer) produced therefrom a wide range of properties including, for example, hydrophilic and hydrophobic properties or the ability to interact with crosslinkers or to self crosslink. The use of conventional, i.e., non-living or free-radical (co)polymerization methods to synthesize (co)polymers provides little control over molecular weight, molecular weight distribution and, in particular, (co)polymer chain structure.
U.S. Pat. No. 5,807,937, 5,789,487, 5,763,548, and International Patent Publication Nos. WO 98/40415, WO 98/01480, WO 97/18247 and WO 96/30421 describe a radical polymerization process referred to as atom transfer radical polymerization (ATRP). The ATRP process is described as being a living radical polymerization that results in the formation of polymers having predictable molecular weight and molecular weight distribution. The ATRP process also is described as providing highly uniform products having controlled structure (i.e., controllable topology, composition, etc.). The 5,807,937 and 5,763,548 patents also describe (co)polymers prepared by ATRP, which are useful in a wide variety of applications including, for example, dispersants and surfactants.
A number of initiators and macroinitiator sytems are known to support ATRP polymerization. These initiators are described, for example, in U.S. Pat. Nos. 5,807,937 and 5,986,015. U.S. Pat. No. 5,807,937 discloses a number of initiators, including halide groups attached to a primary carbon. Halides attached to primary carbons are known as efficient initiators in ATRP processes. U.S. Pat. No. 5,986,015 discloses polymer macroinitiators prepared from vinyl chloride and another monomer, and their use in preparing graft (co)polymers with low polydispersity.
Described in Heise, Andreas, et al., (“Starlike polymeric Architectures by Atom Transfer Radical Polymerization: Templates for the Production of Low Dielectric Constant Thin Films,”
Macromolecules
, (2000) 33:2346-2354) are starlike dedrimeric polymers prepared by an ATRP process. The polymers are useful in the production of semiconductor devices. The polymers are initiated with a polyfunctional initiator prepared by reacting an aromatic group-containing alcohol, diol or polyol with an esterified trimer of 2-bromo-2-methylpropionyl bromide. The initiator contains aromatic moieties as well as a large number of ester linkages. The presence of aromatic moities renders the resultant polymer susceptible to UV degradation. The ester linkages are susceptible to hydrolysis under acidic conditions (i.e. acid rain). It is therefore an object of the present invention to provide a polyfunctional initiator for a controlled radical polymerization process that has minimal aromatic content and reduced number of ester content with reduced susceptibility to UV degradation and acid hydrolysis.
It also is desirable to have multiple initiation sites on an initiator in order to create unique branched (co)polymer structures, such as star (co)polymers. Such (co)polymers have a variety of practical applications, including as a resin component of a film-forming coating composition. These unique (co)polymers also will find use in the health care or cosmetics industries for instance, as materials for bioengineering. (Co)polymers of low polydispersity (Mn/Mw) are also desirable not only for their structural regularity and related usefulness in producing defined block and multiblock (co)polymer structures, but for their unique physical characteristics. For instance, a star (co)polymer having low polydispersity is a high molecular eight material having low viscosity in solution.
It is therefore desired to have a polyfunctional (two or more initiator sites) ATRP initiator where each initiator site has the same or very similar initiation efficiency (K
i
) as the other initiator sites. It is also desirable that the initiators can be easily prepared from inexpensive and readily available compounds.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a novel ether or sulfide group-containing polyfunctional initiator for controlled radical (co)polymerization that includes two or more initiation sites. The initiator includes two or more halide group-containing initiation sites that are connected by substantially aliphatic groups and having the structure R—[L—I]
n
: in which, a) n is an integer greater than 1; b) R is an organic n-valent linking group containing at least one ether or sulfide linkage; c) L is optionally present for each instance of I and is a divalent polyether or polysulfide segment; and d) I is a group having the formula:
in which X is a halide, which may be the same or different for each instance of I and Z is either oxygen or sulfer.
Preferably, I is a group having the formula:
in which R
1
and R
2
are independently the same or different hydrogen, C
1-20
alkyl, C
1-20
substituted alkyl, C
1-20
alkenyl, C
3-8
cycloalkyl, heterocyclyl or aryl groups. For each instance of 1, each instance of X, R
1
or R
2
may be the same or different. The initiator is most preferably di-(trimethylolpropane)-tetra-(2-haloisobutyrate).
The present invention also is directed to a controlled radical polymerization process that utilizes the above-described high efficiency initiators to produce novel linear or branched, including star-shaped (co)polymeric compositions having low polydispersity. Lastly, the present invention is directed to (co)polymeric compositions prepared according to this process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Other than in the operating examples, or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc, used in the specification and claims are to be understood as modified in all instances by the term “about”.
The (co)polymer of the present invention is prepared by controlled radical polymerization. As used herein and in the claims, the term “controlled radical polymerization,” and related terms, e.g., “living radical polymerization,” refer to those methods of radical (co)polymerization that provide control over the molecular weight, molecular weight distribution, polydispersity and (co)polymer chain architecture. A controlled or living radical (co)polymerization is also described as a chain-growth (co)polymerization that propagates with essentially no chain transfer and essentially no chain termination. The number of living (co)polymer chains formed during a controlled radical (co)polymerization is often nearly equal to the number of initiators present at the beginning of the reaction. Each living (co)polymer chain typically contains a residue of the initiator at what is commonly referred to as its tail, and a residue of the radically transferable group at what is commonly referred to as its head.
In an embodiment of the present invention, the (co)polymer is prepared by atom transfer radical polymerization (ATRP). The ATRP process comprises: (co)polymerizing one or more radically polymerizable monomers in the presence of a specific initiation system; forming a (co)polymer; and isolating the formed (co)polymer. In the present invention, the initiation system comprises: a monomeric initiator having multiple radically transferable atoms or groups; a transition metal compound, i.e., a catalyst, which participates in a reversible redox cycle with the initiator; and a ligand, which coordinates with the transition metal compound. The ATRP process is described in further detail in International Patent Publication WO 98/40415 and U.S. Pat. Nos. 5,807,937, 5,763,548 and 5,789,48

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