Azlactone chain transfer agents for radical polymerization

Details Azlactone chain transfer agents for radical polymerization Azlactone chain transfer agents for radical polymerization

2003-05-05

2004-07-13

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...

C526S135000, C526S147000, C526S204000, C526S220000, C525S308000, C525S314000

Reexamination Certificate

active

06762257

ABSTRACT:

FIELD OF THE INVENTION
The present invention provides initiators for reversible addition-fragmentation chain transfer (RAFT) polymerization processes and telechelic polymers made thereby.
BACKGROUND
In conventional radical polymerization processes, the polymerization terminates when reactive intermediates are destroyed or rendered inactive; radical generation is essentially irreversible. It is difficult to control the molecular weight and the polydispersity (molecular weight distribution) of polymers produced by conventional radical polymerization, and difficult to achieve a highly uniform and well-defined product. It is also often difficult to control radical polymerization processes with the degree of certainty necessary in specialized applications, such as in the preparation of end functional polymers, block copolymers, star (co)polymers, and other novel topologies.
In a controlled radical polymerization process radicals are generated reversibly, and irreversible chain transfer and chain termination are absent. There are four major controlled radical polymerization methodologies: atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), nitroxide-mediated polymerization (NMP) and iniferters, each method having advantages and disadvantages.
RAFT processes are among the most versatile controlled radical polymerization techniques, as reported by M. Freemantle, Chemical and Engineering News, Sep. 9, 2002, pp. 36-40. In a RAF process a propagating polymer radical (P
m
•) adds to a chain transfer agent (P
n
-X) to generate a new radical intermediate (P
m
-X•-P
n
). This intermediate radical fragments either to a new propagating radical (P
n
•) and a new dormant species (P
m
-X), or back to (P
m
•) and (P
n
-X). The RAFT chain transfer agent establishes a dynamic addition-fragmentation equilibrium by transferring activity between the propagating radicals and the dormant species. The polymerization may be reactivated by addition of more thermal- or photoinitiator and monomer.
There is a need for a radical polymerization process which provides (co)polymers having a predictable molecular weight and a narrow molecular weight distribution (low “polydispersity”). A further need is strongly felt for a radical polymerization process which is sufficiently flexible to provide a wide variety of products, but which can be controlled to the degree necessary to provide highly uniform products with a controlled structure (i.e., controllable topology, composition, etc.). There is further need for a controlled radical polymerization process which provides telechelic (co)polymers capable of entering into further polymerization or functionalization through reactive end-groups, particularly electrophilic end groups.
SUMMARY OF THE INVENTION
The present invention provides chain transfer agents (RAFT agents) for controlled radical polymerization processes that comprise compounds of the formula:
wherein
R
1
and R
2
are each independently selected from H, an alkyl group, a nitrile group, a cycloalkyl group, a hetcrocyclic group, an arenyl group and an aryl group, or R
1
and R
2
taken together with the carbon to which they are attached form a carbocyclic ring;
R
3
and R
4
are each independently selected from an alkyl group, a cycloalkyl group, an aryl group, an arenyl group, or R
3
and R
4
taken together with the carbon to which they are attached form a carbocyclic ring;
Y—S is a xanthate group of the formula R
5
—O—C(S)—S—, a thioxanthate group (trithiocarbonate) of the formula R
5
—S—C(S)S—, or a dithioester group of the formula R
5
—C(S)S—, wherein
R
5
is selected from an alkyl group, a cycloalkyl group, an aryl group, an arenyl group or a heterocyclic group, R
5
is optionally substituted with phosphate, phosphonate, sulfonate, ester, halogen, nitrile, amide, and hydroxy groups; and R
5
may optionally be substituted with one or more caternary heteroatoms, such as oxygen, nitrogen or sulfur; Q is a linking group selected from a covalent bond, an arenyl group, an aryl group, (—CH
2
—)
o
, —CO—O—(CH
2
)
o
—, —CO—O—(CH
2
CH
2
O)
o
—, —CO—NR
8
—(CH
2
)
o
—, —CO—S—(CH
2
)
o
—, where o is 1 to 12, and R
8
is H, an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group; and n is 0 or 1.
The present invention also provides chain transfer agents that comprise the ring-opened reaction product of the chain transfer agents of Formula I and a reactive compound, such as an aliphatic compound, having one or more nucleophilic groups. Such chain transfer agents have the general formula:
wherein
R
1
and R
2
are each independently selected from H, a nitrile group, an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group and an aryl group or R
1
and R
2
taken together with the carbon to which they are attached form a carbocyclic ring; R
3
and R
4
are each independently selected from an alkyl group, a cycloalkyl group, an aryl, an arenyl group, or R
3
and R
4
taken together with the carbon to which they are attached form a carbocyclic ring;
Y—S is a xanthate group of the formula R
5
—O—C(S)—S—, a thioxanthate group of the formula R
5
—S—C(S)S—, or a dithioester group of the formula R
5
—C(S)—S—, wherein R
5
is selected from an alkyl group, a cycloalkyl group, an aryl group, an arenyl group or a heterocyclic group, R
5
is optionally substituted with phosphate, phosphonate, sulfonate, ester, halogen, nitrile, amide, and hydroxy groups; and R
5
may optionally be substituted with one or more caternary heteroatoms, such as oxygen, nitrogen or sulfur;
n is 0 or 1;
Z is O, S or NR
8
, wherein R
8
is H, an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclic group, or an aryl group;
R
7
is an organic or inorganic moiety and has a valency of m, R
7
is the residue of a mono- or polyfunctional compound of the formula R
7
(ZH)
m
;
Q is a linking group selected from a covalent bond, an aryl group, an arenyl group, (—CH
2
—)
o
, —CO—O—(CH
2
)
o
—, —CO—O—(CH
2
CH
2
)
o
—, —CO—NR
8
—(CH
2
)
o
—, —CO—S—(CH
2
)
o
—, where o is 1 to 12, and R
8
is H, an alkyl group, a cycloalkyl group, an aryl group, an arenyl group, a heterocyclic group or an aryl group;
m is an integer of at least 1, preferably at least 2.
The present invention also provides initiator compositions for controlled radical polymerization comprising the chain transfer agents of Formulas I or II, and a thermal or photoinitiator.
The chain transfer agents of the present invention provide (co)polymers having a predictable molecular weight and a narrow molecular weight distribution. Advantageously, the chain transfer agents provide novel multireactive addition polymers having first and second terminal reactive groups that may be used for further functionalization. The present invention further provides a controlled radical polymerization process useful in the preparation of terminal-functionalized (telechelic) (co)polymers, block copolymers, star (co)polymers, graft copolymers, and comb copolymers. The process provides these (co)polymers with controlled topologies and compositions.
The control over molecular weight and functionality obtained in this invention allows one to synthesize numerous materials with many novel topologies for applications in coatings, surface modifications, elastomers, sealants, lubricants, pigments, personal care compositions, composites, inks, adhesives, dental resins, water treatment materials, hydrogels, imaging materials, telechelic materials and the like.
In another aspect, the invention provides a method for polymerization of one or more olefinically unsaturated monomers comprising addition polymerizing one or more olefinically unsaturated monomers using the initiator composition comprising the azlactone chain transfer agents, or the ring-opened azlactone chain transfer agent and a thermal or photoinitiator.
It is to be understood that the recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and

Affiliated with

Also associated with

Rating

Azlactone chain transfer agents for radical polymerization does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Azlactone chain transfer agents for radical polymerization, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Azlactone chain transfer agents for radical polymerization will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3247938