Synthesis of terminally unsaturated oligomers

This invention relates to a method for preparing compositions comprising terminally unsaturated polymers of low molecular weight, referred to as oligomers or macromonomers. In particular, a first oligomer composition is obtained by free radical polymerization of a reaction mixture comprising monomers. Terminally unsaturated oligomers in the first oligomer composition, or a selected portion of the composition, are reinitiated into free radicals in order to continue their oligomerization to a desired endpoint. The process is useful for preparing an oligomer composition having a controlled degree of polymerization. The process is also useful for preparing block copolymers. Such oligomer compositions or block polymers are useful for preparing engineered or structured polymers used in making various end products, including plastics, coatings, films, and dispersants.

FIELD OF THE INVENTION 
This invention relates to a method of preparing compositions of terminally 
unsaturated polymers of low molecular weight, referred to as oligomers or 
macromonomers. The process is useful for preparing a mixture of terminally 
unsaturated oligomers having a desired degree of polymerization and for 
preparing block copolymers. 
TECHNICAL BACKGROUND 
Oligomers containing an olefinic end group are known in the art. For 
example, U.S. Pat. No. 5,362,826 discloses a process of obtaining 
terminally unsaturated oligomers (.omega.-ethylenically unsaturated 
oligomers). Such oligomers are known to be useful as non-metallic chain 
transfer agents. 
Terminally unsaturated oligomers can be made by a number of conventional 
means. One way is to employ metal-containing chain transfer catalysts, for 
example, consisting of cobalt (II or III) chelates such as disclosed in 
U.S. Pat. No. 4,680,352, U.S. Pat. No. 4,694,054, U.S. Pat. No. 5,324,879, 
or WO 87/03605 published Jun. 18, 1987. 
Conventional wisdom had been that, once formed, terminally unsaturated 
oligomers, including dimers and higher molecular weight species, are 
essentially inert to the oligomerization process. This belief is based 
upon the observation that the oligomers cannot be homopolymerized or 
copolymerized with methacrylic monomers to a reasonable extent. For 
example, K. J. Abbey et al., in J. Polymer Science: Part A: Polymer 
Chemistry, 31, p. 3417-3424 (1993) believe this is due to the instability 
of intermediates formed after addition of propogating radicals to the 
oligomers. The radicals are so sterically hindered that they cannot react 
with another oligomer or monomer and decompose (in a so-called 
.beta.-scission reaction) to yield initial oligomer or the like. This has 
now been confirmed in blank experiments (see Comparative Examples 3 and 5 
below), which show that, without an effective amount of chain transfer 
catalyst, incorporation into polymer occurs to only a negligible extent. 
Surprisingly, it has now been found that a metal-containing chain transfer 
catalyst can be used to reinitiate the terminated chains of a terminally 
unsaturated oligomer for further oligomerization. This has led to an 
improved polymerization process for making terminally unsaturated 
oligomers having a controlled degree of polymerization (DP) in the 
polymerization process without a significant yield loss or disposal 
problem. 
SUMMARY OF THE INVENTION 
This invention provides a method for preparing an oligomer composition by 
free radical polymerization. In particular, the invention relates to the 
free radical polymerization of a reaction mixture comprising monomers to 
produce a first or primary oligomer composition, and subjecting oligomers 
in the primary oligomer composition, or a portion thereof, to reinitiation 
as free radicals in order to continue their polymerization 
(oligomerization) to a desired endpoint. In particular, the present 
process is useful for preparing a mixture of oligomers or macromonomers 
having a desired average DP (degree of polymerization) or for preparing an 
oligomer composition or mixture with reduced amounts of oligomer species 
having a DP or molecular weight below a certain number. 
When using the present invention to prepare an oligomer composition having 
a desired average molecular weight or degree of polymerization, a lower 
molecular weight fraction of a first oligomer composition is separated out 
and oligomers contained therein are reinitiated as free radicals for 
further oligomerization, in order to increase the average degree of 
polymerization (DP) of the lower molecular weight fraction. 
In one embodiment of the present process, a first oligomer mixture, having 
a preselected degree of polymerization (DP) equal to n, is produced in a 
reaction zone by oligomerization in the presence of a metallic chain 
transfer catalyst. A fraction of this first oligomer mixture, including 
any unreacted monomer, is separated out, wherein essentially all of the 
oligomers in said fraction have a DP less than or equal to m, which is 
less than n. (For example, n may be equal to 4 or more and m may be 2 or 
3.) The separated fraction is then be recycled back to the oligomerization 
step where oligomers contained in the separated fraction are reinitiated 
as free radicals for further oligomerization in the presence, once again, 
of a metallic chain transfer catalyst. A metallic chain transfer catalyst 
may be added continuously or discretely to the reaction zone. In a 
continuous process, a portion of the first oligomer composition is 
continuously fractionated, a relatively higher DP or molecular weight 
fraction may be continuously withdrawn as a product stream, while a 
relatively lower DP or molecular weight fraction is recycled to the 
oligomerization reactor. New monomer and cobalt could be continuously or 
semi-continuously introduced into the oligomerization reactor. 
Accordingly, a continuous process could achieve a steady state 
concentration of dimer in the oligomerization reactor. 
Alternatively, oligomers in the separated fraction can be separately 
reinitiated by further exposure to a metallic chain transfer catalyst and 
then separately used, combined with a second stream, or, after separate 
reinitiation, recycled to the first oligomer mixture in the 
oligomerization reactor. 
When the present invention is used for making a block copolymer, oligomers 
contained in a first oligomer mixture are reinitiated as free radicals in 
the presence of a second monomer. This reinitiation with different 
monomers may be reiterated r times to make r+1 sequential blocks in a 
copolymer. 
The afore-mentioned first oligomer mixture or composition preferably has a 
degree of polymerization (DP) ranging from about 2 to about 12. In the 
case of a batch process, the DP of the product may increase beyond the DP 
of the first oligomer composition. In the case of a continuous (CSTR) 
process in which a lower molecular weight fraction is continuously 
removed, with continuous recycle, the average DP of the oligomer mixture 
in the reaction zone may be at steady state with a preselected DP of 3 or 
more. Similarly, block copolymers made by the present process may have an 
average DP of 3 or more.

DETAILS OF THE INVENTION 
The present process involves the initiation and reinitiation of oligomeric 
free radicals to make methacrylate-containing terminally unsaturated 
oligomers, sometimes referred to as macromonomers. The term "macromonomer" 
is also sometimes used to describe polymers of limited chain length or 
molecular weight which have such terminal olefinic moieties. 
The term molecular weight (M.sub.w), unless indicated otherwise, is used 
herein to mean weight average molecular weight. The term "degree of 
polymerization" or DP is used herein to mean an average DP in the case of 
a mixture of oligomers having a plurality of DPs. 
Conventionally, when making terminally unsaturated oligomers by a free 
radical polymerization process under conventional processing conditions 
and in the presence of a metal chain transfer agent, a molecular weight 
distribution of terminally unsaturated oligomers are produced, which 
includes "low end" oligomers having DPs of 2 and 3 (i.e., dimers and 
trimers). For some uses, such "low end" oligomers are less desirable than 
higher DP oligomers (i.e., tetramer and above). Previously, such "low end" 
oligomers might have been separated out and disposed of in a waste stream. 
Terminally unsaturated oligomers made by the present invention may be 
useful for incorporation into larger polymers, including structured or 
engineered polymers. Such oligomers may also be useful as non-metallic 
chain transfer agents, to control the molecular weight of other 
polymerization processes for making methacrylate-containing polymers or 
copolymers. For this latter purpose, trimers or tetramers and higher DP 
oligomers are generally preferable to dimers, because dimers are less 
effective chain transfer agents. On the other hand, trimers or tetramers 
and higher DP oligomers below a certain DP may be preferable to oligomers 
above a certain DP, because oligomers having a relatively higher DP may be 
relatively more expensive. Although requiring greater amounts of starting 
monomer, oligomers having a relatively higher DP may not be any more 
effective per mole than oligomers with a relatively lower DP. 
The present process allows greater control over the distribution of DP of 
the oligomers in the product composition made by catalytic chain transfer. 
The most desirable DP, or distribution of DP, may vary from application to 
application. For use as a non-metallic chain transfer agent, however, the 
least valuable oligomers, for reasons of properties or effectiveness, are 
dimer and trimer. Dimers and trimers, as already mentioned, may be less 
active as chain transfer agents. They may also be undesirable for reasons 
of volatility and odor. 
The present process may be a batch or continuous process. In a continuous 
process, "low end" oligomers can be separated out from the reaction 
mixture in a polymerization reactor and recycled back to the reaction 
mixture, thereby subjecting said "low end" oligomers to a metallic chain 
transfer catalyst for a second time. 
Alternatively or additionally, chain transfer agent can be added to the 
separated "low end" oligomers to convert them to higher order oligomers. 
For use as a non-metallic chain transfer agent, the oligomers prepared 
according to the present invention suitably have a final (average) degree 
of polymerization of about 3 to 20, more preferably about 4 to 12, even 
more preferably about 4 to 8, and most preferably about 6. For other uses, 
however, the desired ranges can vary, as indicated above. 
A typical continuous method of operation, according to the present 
invention, would involve polymerizing, in a reaction zone, monomer in the 
presence of an effective amount of metallic chain transfer catalyst such 
as cobalt (II or III) chelates, thereby producing a primary oligomer 
composition comprising terminally unsaturated oligomers having an average 
degree of polymerization ranging from about 2 to about 12. At least a 
portion of the primary oligomer composition would be removed from the 
reaction zone and fractionated in a separation zone into a relatively 
lower DP oligomer fraction and a relatively higher DP fraction. At least 
dimer, typically with some unreacted monomer, would be fractionated into 
the relatively lower DP oligomer fraction. Depending on the desired 
product, a mixture of monomer, dimer, and trimer may be fractionated into 
the relatively lower DP oligomer fraction. This relatively lower DP 
fraction could be recycled back to said reaction zone, where the 
terminally unsaturated oligomers in said relatively lower DP fraction 
would again be subjected to an effective amount of said metallic chain 
transfer catalyst in order to reconvert said terminally unsaturated 
oligomers in said relatively lower DP fraction to free radicals for 
further polymerization. A small portion of the the recycled fraction may 
be removed as purge. The relatively higher DP fraction, from the 
separation zone, may be withdrawn as a product composition comprising 
terminally unsaturated oligomers having, for example, a degree of 
polymerizaton of 3 to 12. 
According to one embodiment of the present invention, oligomer recycle and 
reinitiation according to the present invention can be used to form a 
monomodal distribution of oligomer, for example, centered at "decamer," 
with little or no remaining monomer, dimer, or trimer left in the final 
product. A composition consisting of tetramer and above is preferred. As 
mentioned above, on a molar basis, the dimers and trimers are less 
efficient stoichiometric chain transfer agents in methacrylate 
polymerizations. 
Dimer or dimers and other "low end" oligomers can be separated from a 
mixture of oligomers by distillation or other separation techniques, such 
as liquid chromatography, selective extraction, or membrane separation. 
Monomer and dimer could be recycled to the oligomerization step or 
reactor, where they would again be subjected to a metallic chain transfer 
catalyst. The remainder of the mixture could be withdrawn as product. Such 
a process could result in dimers or dimers and other "low end" oligomers 
being used up in the synthesis rather than being sent to a waste stream. 
As indicated above, block copolymers can also be made according to the 
present invention. The purity of the block copolymers is determined by the 
competitive reaction of oligomer and monomer for the cobalt catalyst. For 
that reason, a process which is "starve-feed" with respect to monomer, and 
high concentration with respect to oligomer, will provide the highest 
proportion of block copolymers. For example, when methyl methacrylate 
(MMA) dimer is reacted with "n" moles of butyl methacrylate monomer (BMA), 
in the presence of a cobalt chain transfer agent, a block copolymer is 
predominantly formed (MMA-MMA-BMA.sub.n). Without the cobalt chain 
transfer agent, but with an initiator such as AIBN, the product was 
poly(BMA), with only negligible incorporation of MMA dimer. BMA may be 
chain terminated by the MMA, but the MMA dimer will never initiate a 
chain. 
As written herein, the formulas of unsaturated oligomers or macromonomers 
are meant to convey structural information. For example, the formula 
MMA.sub.2 BMA explicitly implies the structure: 
H--CH.sub.2 --CMe(CO.sub.2 Me)--CH.sub.2 --CMe(CO.sub.2 Me)--CH.sub.2 
--C(CO.sub.2 Bu).dbd.CH.sub.2. 
Regarding this structure, the propagation of the radical chain is from left 
to right structure. Thus, the oligomers are initiated with a hydrogen 
atom, giving a saturated end on the left of the structure. The oligomer is 
then terminated by hydrogen atom abstraction by the catalyst, giving an 
olefinic group at the right end of the oligomer. 
In the present invention, the oligomers mentioned herein, including those 
contained in the reaction mixture or the product composition, suitably 
comprise, by weight, 80 to 100% of methacrylates of the formula CH.sub.2 
.dbd.C(CH.sub.3)CO.sub.2 J wherein J is H, C.sub.1 -C.sub.12 alkyl, 
C.sub.2 -C.sub.12 alkenyl, glycidyl, C.sub.2 -C.sub.12 hydroxyalkyl, 
allyloxyethyl, 2,4-hexadienyl, C.sub.x H.sub.(2x+1-y) F.sub.y where x is 1 
to 16 and y is 0 to 2x+1, R.sub.6 R.sub.7 N(CH.sub.2).sub.z where R.sub.6 
and R.sub.7 are independently C.sub.1 to C.sub.12 alkyl and z is 1 to 10, 
or R.sub.8 R.sub.9 R.sub.10 Si(CH.sub.2).sub.z where R.sub.8, R.sub.9 and 
R.sub.10 are independently C.sub.1 to C.sub.12 alkyl or C.sub.1 to 
C.sub.12 alkoxy and z is 1 to 10. In addition the monomers may comprise 
methacrylonitrile, .alpha.-methyl styrene, methacrylamide derivatives of 
the formula CH.sub.2 .dbd.C(CH.sub.3)CON(R).sub.2 wherein each R is 
independently H, C.sub.1 to C.sub.10 alkyl or (CH.sub.2).sub.n Z, n is an 
integer from 1 to 10, Z is COOY, OH, N(R.sub.1).sub.2, SO.sub.3 Y and Y is 
H, Li, Na, K, or N(R).sub.4 ; vinyl esters and acetates of the formula 
CH.sub.2 .dbd.CHOOCR, wherein R is C.sub.1 to C.sub.12 alkyl; and any and 
all monomer mixtures thereof. 
The monomers forming the macromonomer may also comprise minor amounts (less 
than about 20% by weight) of styrene, maleic anhydride, fumarate 
derivatives such as fumaronitrile, dialkylfumarate and fumaric acid. 
In another embodiment, the monomers may further comprise minor amounts 
(less than about 20% by weight) of the following monomers: vinyl halides 
of the formula CH.sub.2 .dbd.CHX wherein X is Cl or F, vinylidene halides 
of the formula CH.sub.2 .dbd.C(X).sub.2 wherein each X is independently Cl 
or F, substituted butadienes of the formula CH.sub.2 
.dbd.C(R)C(R).dbd.CH.sub.2 wherein each R is independently H, C.sub.1 to 
C.sub.10 alkyl, Cl or F, ethylenesulfonic acid derivatives of the formula 
CH.sub.2 .dbd.CHSO.sub.3 X wherein X is Na, K, Li, N(R).sub.4, H, R or 
(CH.sub.2).sub.n Z where n is an integer from 1 to 10, Z is COOY, OH, 
N(R).sub.2, or SO.sub.3 Y, Y is H, Li, Na, K or N(R) and R is 
independently C.sub.1 to C.sub.10 alkyl, acrylamide derivatives of the 
formula CH.sub.2 .dbd.CHCON(R).sub.2 wherein each R is independently H, 
C.sub.1 to C.sub.10 alkyl, or (CH.sub.2).sub.n Z, n is an integer from 1 
to 10, Z is COOY, OH, N(R.sub.1).sub.2 or SO.sub.3 Y and Y is H, Li, Na, K 
or N(R.sub.1).sub.4 where R is Cl to C.sub.10 alkyl. 
The methacrylates described above would thus include branched alkyl or 
n-alkyl esters of C.sub.1 -C.sub.12, alcohols (for example, methyl and 
ethyl methacrylate), methacrylic acid, and allyl, glycidyl, hydroxyalkyl 
(for example, hydroxyethyl and hydroxypropyl), allyloxyethyl, 
2,4-hexadienyl (sorbyl), dialkylaminoalkyl, fluoroalkyl, and 
trialkylsilylalkylene methacrylates. 
Of the contemplated monomers or comonomers, methacrylates are preferred for 
reasons of commercial applicability, cost, and/or ease of synthesis. 
The oligomers produced according to the present process therefore include 
those oligomers having the following end group: 
##STR1## 
where X is --CONR.sub.2, --COOR, OR.sup.1, --OCOR, --OCOOR.sup.1, 
--NRCOOR.sup.1, halo, cyano, or a substituted or unsubstituted phenyl or 
aryl, wherein each R is independently selected from the group of hydrogen, 
silyl, or a substituted or unsubstituted alkyl, alkyl ether, phenyl, 
benzyl, or aryl, wherein said groups may be substituted with epoxy, 
hydroxy, isocyanato, cyano, amino, silyl, acid (--COOH), halo, or acyl; 
and wherein R.sup.1 is the same as R except not H; wherein each alkyl is 
independently selected from the group consisting of branched, unbranched, 
hydrocarbons having 1 to 12, preferably 1-6, and most preferably 1-4 
carbon atoms or cyclical hydrocarbons having 4-12, preferably 4-6 carbon 
atoms; halo or halogen refers to bromo, iodo, chloro and fluoro, 
preferably chloro and fluoro, and silyl includes --SiR.sup.2 
(R.sup.3)(R.sup.4) and the like, wherein R.sup.2, R.sup.3, and R.sup.4 are 
independently alkyl, phenyl, alkyl ether, or phenyl ether, preferably at 
least two of R.sup.2, R.sup.3, and R.sup.4 being a hydrolyzable group, 
more preferably two of which are alkyl ether, wherein alkyl is as defined 
above, preferably methyl or ethyl. A plurality of silyl groups may be 
condensed, for example, an organopolysiloxane such as --Si(R.sup.2).sub.2 
--O--Si(R.sup.3).sub.2 R.sup.4, wherein R.sup.2, R.sup.3, and R.sup.4 are 
independently alkyl. See U.S. Pat. No. 4,518,726, hereby incorporated by 
reference, for further exemplification of silyl groups in general. 
A preferred class of oligomers made according to the present process are 
those oligomers according to the above structure in which X is 
--CONR.sub.2, --COOR, unsubstituted or substituted phenyl, aryl, halo, or 
cyano, and R is as defined above. 
A more preferred class of oligomers made according to the present process 
are those oligomers according to above structure in which X is --COOR, 
cyano, or phenyl and R is hydrogen, alkyl or phenyl unsubstituted or 
substituted with epoxy, hydroxy, or alkoxysilyl. 
Preferably, the oligomers prepared according to the present process are 
characterized by the following end group: 
##STR2## 
wherein X.sup.1 and X.sup.2 are independently (the same or different) X as 
defined above. 
The general chemical structure of oligomers prepared in the present process 
have the following structure: 
##STR3## 
wherein X.sup.1 to X.sup.n is independently defined as above for X and n 
is on average 2 to 100, preferably 4 to 12. 
For example, a general formula for a methacrylate oligomeric chain transfer 
agent is as follows: 
##STR4## 
wherein R.sup.1 to R.sup.n are independently (the same or different) and 
defined as above for R and n is on average 2 to 20, preferably 4 to 8. 
As a further very specific example, a methyl methacrylate trimer, wherein n 
equals 3 and R equals --CH.sub.3, is as follows. 
##STR5## 
The concentration of terminally unsaturated oligomer in a composition 
prepared according to the present invention is at least about 80 mol %, 
preferably at least about 85 mol %, more preferably at least about 90 mol 
%, up to about mol %. 
The present invention for producing macromonomers involves free radical 
polymerization of unsaturated monomers, some of which may carry functional 
groups for later crosslinking. This polymerization may occur in 
suspension, emulsion or solution, in aqueous or organic media, as will be 
familiar to those skilled in the art. 
The oligomers are typically prepared in a polymerization reaction by 
standard solution polymerization techniques, but may also be prepared by 
emulsion, suspension or bulk polymerization processes. A metal-containing 
chelate chain transfer catalyst is employed in the method of preparation. 
Preferred metallic chain transfer catalysts for use in making the present 
oligomers are cobalt (II) and (HI) chelates. Examples of such cobalt 
compounds are disclosed in U.S. Pat. No. 4,680,352, U.S. Pat. No. 
4,694,054, U.S. Pat. No. 5,324,879 WO 87/03605 published Jun. 18, 1987, 
U.S. Pat. No. 5,362,826, and U.S. Pat. No. 5,264,530, all hereby 
incorporated by reference in their entirety. Other useful cobalt compounds 
(cobalt complexes of porphyrins, phthalocyanines, tetraazoporphyrins, and 
cobaloximes) are respectively disclosed in Enikolopov, N. S. et at., USSR 
Patent 664,434 (1978); Golikov, I. et at., USSR Patent 856,096 (1979), 
Belgovskii, I. M., USSR Patent 871,378 (1979), and Belgovskii, I. M. et 
al., USSR Patent 1,306,085 (1986), all hereby incorporated by reference in 
their entirety. 
These catalysts operate at close to diffusion-controlled rates and are 
effective at part-per-million concentrations. There is an inverse 
relationship between the level of cobalt catalyst and the molecular 
weights obtained, as described by Janowicz et al. in U.S. Pat. 4,680,352. 
The plot of 1/(M.sub.w) or 1/DP versus the concentration of the catalyst 
is linear, wherein M.sub.w is the molecular weight and DP is the degree of 
polymerization. With respect to the present invention, the concentrations 
of the cobalt (Co) catalyst are somewhat higher than those normally 
employed in catalytic chain transfer reactions, as exemplified in U.S. 
Pat. No. 4,680,352. The preferred concentration will range from 10.sup.-4 
to 10.sup.-2 molar cobalt. 
When employing a cobalt chelate in the preparation of the present 
oligomers, it may be feasible to remove cobalt as well as any color from 
the reaction product by precipitation with a solvent and the subsequent 
use of activated charcoal. For example, the addition of ethyl acetate 
(Rhone-Poulenc AR grade, 99.5%, 0.005% acetic acid) in various proportions 
has been found to cause substantial precipitation of cobalt as a dark 
brown solid and therefore decreased color in the final solution. Other 
precipitating solvents include a mixture of acetone and water and a 
mixture of acetonitrile and water. Color may be further removed by 
classical techniques, for example, simple treatment with activated 
charcoal for about 15 minutes followed by filtration though a short column 
packed with Celite.RTM. 545 filter aid. 
An initiator such as an azo compound, which produces carbon-centered 
radicals, sufficiently mild not to destroy the metal chelate chain 
transfer agent, is typically also employed in preparing the oligomers. 
Suitable initiators are azo compounds having the requisite solubility and 
appropriate half life, including azocumene; 
2,2'-azobis(2-methyl)butanenitrite; 4,4'-azobis(4-cyanovaleric acid); and 
2-(t-butylazo )-2-cyanopropane. 
The polymerization or oligomerization process, employing the above 
described metallic chain transfer catalysts, is suitably carried out at a 
temperature ranging from bout room temperature to about 200.degree. C. or 
higher, perferably about 40.degree. C. to 100.degree. C. The 
polymerization process can be carried out as either a batch, seimi-batch, 
continuous or feed process. When carried out in the batch mode, the 
reactor is typically charged with metal chain transfer catalyst and 
monomer, or monomer and medium (or solvent). To the mixture is then added 
the desired amount of initiator, typically such that the M/I (monomer to 
initiator) reaction is 5 to 1000. The mixture is then heated for the 
requisite time, usually about 30 minutes to about 12 hours. In a batch 
process, the reaction may be run under pressure to avoid monomer reflux. 
After the reaction is complete, a low DP fraction can be separated out and 
subjected to further metallic chain transfer catalyst in order to increase 
its DP. 
If the polymerization is to be carried out as a feed system, the reaction 
may typically be carried out by heating and stirring at least the medium, 
typically an organic solvent, in a reaction vessel, while any of the other 
components, or combination of components, such as monomer, chain transfer 
catalyst, and initiator are introduced, for example, by a syringe pump or 
other pumping device, until the reaction is completed and the first 
oligomer composition prepared. 
As indicated above, the polymerization can be carried out in the absence 
of, or in the presence of, any medium or solvent suitable for free-radical 
polymerization, including, but not limited to, ketones such as acetone, 
butanone, pentanone and hexanone, alcohols such as isopropanol, amides 
such as dimethyl formamide, aromatic hydrocarbons such as toluene and 
xylene, ethers such as tetrahydrofuran, diethyl ether and ethylene glycol, 
dialkyl ethers such as Cellosolves.RTM. solvent, alkyl esters or mixed 
ester ethers such as monoalkyl ethermonoalkanoates, and mixtures or two or 
more solvents. 
Terminally unsaturated oligomers or block copolymers prepared according to 
the present invention can be employed, not only as non-metallic chain 
transfer agents, but as useful components or intermediates in the 
production graft polymers, non-aqueous dispersed polymers, microgels, star 
polymers, branched polymers, and ladder polymers. For example, using 
standard polymerization techniques, graft polymers can be synthesized by 
reacting one or more oligomers made according to the present invention 
with one or more monomers having polymerizing compatibility with the 
oligomers and with each other. 
Oligomers made by the present process, sometimes referred to as 
macromonomers, are useful in a wide variety of coating and molding resins. 
Other potential uses can include cast, blown, spun or sprayed applications 
in fiber, film, sheet, composite materials, multilayer coatings, 
photopolymerizable materials, photoresists, surface active agents, 
dispersants, adhesives, adhesion promoters, and coupling agents, among 
others. End products taking advantage of available characteristics can 
include, for example, automotive and architectural coatings or finishes, 
including high solids, aqueous, or solvent based finishes. 
In the following examples, HPLC analysis was performed with a 
Hewlett-Packard.RTM. liquid chromatograph model 1090, microstyrogel 
columns, with THF used as solvent at 35.degree. C. at a flow rate of 1 
ml/min. 
K.sup.+ IDS mass spectroscopy is an ionization method that produces 
pseudomolecular ions in the form of [M]K.sup.+ with little or no 
fragmentation. Intact organic molecules are desorbed by rapid heating. In 
the gas phase the organic molecules are ionized by potassium attachment. 
Potassium ions are generated from an aluminosilicate matrix that contains 
K.sub.2 O. All of these experiments were performed on a Finnegan.RTM. 
model 4615B GC/MS quadrupole mass spectrometer. An electron impact source 
configuration operating at 200.degree. C. and a source pressure of 
&lt;1.times.10.sup.-6 torr was used. 
All molecular weights are by GPC (gel permeation chromatography) using 
styrene as an example. The following abbreviations are used in the 
examples below: 
TAPCo=meso-tetra(4-methoxyphenyl)porphyrin-Co 
PcCo=tetrakis(tert-butyl)phthalocyanine Co 
AIBN=2,2'-azobis(isobutyronitrile) 
MMA=methylmethacrylate 
BMA=butylmethacrylate 
GMA=glycidylmethacrylate 
HEMA=2-hydroxyethyl methacrylate 
PMMA=poly(methylmethacrylate) 
Py=pyridine 
dmg=dimethylglyoxime 
dpg=diphenylglyoxime 
M.sub.n =number average molecular weight 
M.sub.w =weight average molecular weight 
EXAMPLE 1 
This example illustrates the preparation of a block copolymer according to 
the present invention (predominantly MMA-MMA-BMA). A solution of 11.2 mg 
of TAPCo and 32.5 g of AIBN in 14 mL of CHCl.sub.3 was divided into two 
unequal parts. To a 10 mL portion, 2 mL of MMA-dimer and 2 mL of freshly 
vacuum-distilled BMA was added. A 0.35 mL amount of BMA was added to a 3 
mL portion of the solution as a reference experiment. The samples were 
degassed by three freeze-pump-thaw cycles, sealed and immersed into an 
isothermal bath at 70.degree. C. After 5 hours, the samples were taken out 
and chilled until they could be analyzed by K+IDS mass-spectroscopy. The 
analysis by mass-spectroscopy showed that approximately 80% of the product 
was MMA-MMA-BMA, with the remaining approximately 20% being starting 
MMA-dimer, MMA.sub.2 BMA.sub.2 and low oligomers of BMA. 
In another reference sample, made as described above with MMA-dimer and 
BMA, but without TAPCo, the major product was poly(BMA) with M.sub.n =7193 
and M.sub.w =12,400. Only negligible incorporation of MMA-dimer into BMA 
product was observed. 
EXAMPLE 2 
This Example illustrates the conversion of dimer to a higher DP oligomer 
according to the present invention. A mixture of 8 mg of TAPCo, 0.2 mL of 
MMA-dimer, 0.05 mL of fleshly-distilled MMA and 4 mg AIBN in 1.3 mL of 
CHCl.sub.3 was degassed and sealed as described in Example 1. The sample 
was kept 1 hour at 70.degree. C. Then it was chilled and another 0.05 mL 
of MMA was added followed again by degassing and sealing. The procedure 
was repeated after 2 and 3 hours. Thus, at the end of the experiment, 
equal portions of monomer and dimer had been added. Then the sample was 
kept an additional 2 hours. The content was investigated by HPLC. Most of 
the product was dimer through hexamer (M.sub.n =282, M.sub.w =319). Dimer 
content was well below half of the mass that would have been expected if 
it had not reacted with monomer. 
COMATIVE EXAMPLE 2 
As a control, a sample was prepared and treated as described in Example 2, 
except that no oligomer was added. The product was dimer through hexamer 
with essentially the same distribution of oligomers as in Example 2 
(M.sub.n =291, M.sub.w =336). 
COMATIVE EXAMPLE 3 
As an additional control experiment, the same experiment as described in 
Comparative Example 2 was carried out without TAPCo. The reaction product 
showed practically no MMA-dimer incorporation and the resulting Poly(MMA) 
had M.sub.n =5770 and M.sub.w =10600. 
EXAMPLE 4 
This Example illustrates the conversion of trimer to a higher DP oligomer 
according to the present invention. The sample was prepared and treated as 
in Example 2, except trimer was used instead of dimer. The product was 
again dimer through hexamer with a slightly higher number average 
molecular weight (M.sub.n =303, M.sub.w =346). Dimer content was well 
below half of the mass that would have been expected if it had not reacted 
with monomer. 
COMATIVE EXAMPLE 5 
As an additional control experiment, the same experiment as described in 
Example 4 was carried out without TAPCo. It showed practically no 
MMA-trimer incorporation and the resulting Poly(MMA) had an M.sub.n =1200 
and M.sub.w =2000. 
EXAMPLE 6 
This Example illustrates the preparation of a block copolymer according to 
the present process, employing another Co chain transfer catalyst. A 
mixture of 2 mg of PcCo, 0.15 mL of MMA-dimer, 0.05 mL of BMA, 0.35 mL of 
tetrachloroethane (TCE) and 3 mg of VAZO-88.RTM. was degassed and sealed 
as described in Example 1. The mixture were kept at 110.degree. C. for 30 
min. Another 0.05 mL of BMA was added followed by degassing and sealing. 
The ampoule was kept for additional hour at 110.degree. C. K.sup.+ IDS 
analysis showed that 70% of the reaction product consists of MMA.sub.2 
BMA.sub.n where 1.ltoreq.n.ltoreq.5. 
EXAMPLE 7 
This Example illustrates the preparation of a block copolymer according to 
the present process, employing yet another Co chain transfer catalyst. The 
experiment was carried as it is described in the Example 6 but with 2 mg 
of (BF.sub.2).sub.2 (dmg).sub.2 Co(2-propyl)H.sub.2 O instead of PcCo. 
Analysis showed MMA.sub.2 BMA was obtained with 50% yield. 
EXAMPLE 8 
This Example illustrates the preparation of a block copolymer according to 
the present process, employing yet another Co chain transfer catalyst. 
Degassed and sealed as described in the Experiment 1, a mixture of 15 mL 
of chloroform, 3 mL of MMA-dimer, 32 mg of AIBN, 3 mg of (dpg).sub.2 
Co(Cl)Py and 1.8 mL of BMA was kept at 70.degree. C. for two hours. 
According to KIDS data, MMA.sub.2 BMA was obtained with a 67% yield. 
EXAMPLE 9 
This Example illustrates the preparation of a block copolymer according to 
the present process, employing a hydroxy-functional monomer. Degassed and 
sealed as described in the Experiment 1, a mixture of 0.9 mL of 
chloroform, 0.21 mL of MMA-trimer, 3 mg of AIBN, 2.6 mg of TApCo and 0.03 
mL of 2-hydroxyethyl methacrylate (HEMA) was kept at 80.degree. C. for 45 
min. Then 0.03 mL of HEMA was added and the mixture was repeatedly 
degassed, sealed and kept at 80.degree. C. for another 45 min. Then 
another 0.03 mL portion of HEMA was added and the mixture was degassed and 
sealed followed by keeping 1.3 hours at 80.degree. C. According to KIDS 
data, a product, MMA.sub.n HEMA.sub.m, composition where n=3 and m=1 or 2 
was obtained. 
EXAMPLE 10 
This Example illustrates the preparation of a block copolymer according to 
the present process, employing another hydroxy-functional monomer. 
Degassed and sealed as described in the Experiment 1, a mixture of 0.9 mL 
of chloroform, 0.2 mL of MMA-dimer, 3 mg of AIBN, 2.6 mg of TAPCo and 
0.045 mL of glycidyl methacrylate (GMA) was kept at 80.degree. C. for 45 
min. Then 0.045 mL of GMA was added and the mixture was repeatedly 
degassed, sealed and kept at 80.degree. C. for another 45 min. Then 
another 0.045 mL portion of GMA was added and the mixture was degassed and 
sealed followed by keeping 1.3 hours at 80.degree. C. According to KIDS 
data, the product, MMA.sub.2 GMA, was obtained with 78% yield.