Branched polymer synthesis

Details Branched polymer synthesis Branched polymer synthesis

1998-08-19

2000-08-08

Wu, David W.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

5263031, 526316, 5263171, 526319, 526332, 526341, C08F 242

Patent

active

061003506

DESCRIPTION:

BRIEF SUMMARY
Precise macromolecular engineering using commodity monomers is becoming a major trend in polymer technology to satisfy the demand for new properties, improved cost effectiveness, ecology and quality. Functional polymers with low molecular weight, low polydispersity, compact, branched structures and terminally located reactive groups are expected to exhibit superior performance/cost characteristics, by virtue of lower inherent viscosity and higher reactivity vs. conventional linear statistical copolymers.
The terminally functional branched polymers appear to be ultimate reactive substrates for networks, because the branch points can substitute for a significant portion of expensive reactive groups and provide a better control of the reactive groups distribution. Particularly polymers having large numbers of short branches below critical molecular weight are unlikely to form any entanglements and should exhibit low inherent viscosity and good flow even in concentrated solutions.
Conventional techniques for sythesizing well defined branched polymers require expensive multistep processes involving isolation of reactive intermediate macromonomers. The macromonomers have polymerizable end groups, which are usually introduced using functional initiator, terminating or chain transfer agent. Well defined branched polymers are prepared by the macromonomer homopolymerization or copolymerization with suitable low molecular weight comonomer selected based on known reactivity ratios.
U.S. Pat. No. 4,680,352 describes molecular weight reduction and macromonomer (polymers or copolymers with unsaturated end-groups) synthesis in copolymerizations with acrylates and styrene with various Co(II) complexes.
J. Antonelli, et. al., U.S. Pat. No. 5,362,813 and C. Berge, et al., U.S. Pat. No. 5,362,826 disclose the preparation of macromonomers by radical addition-fragmentation processes and the copolymerization of macromonomers. Branched structures were not well characterized and the reincorporation of the branched macromonomers into more complex structures was not considered.
Dendrimers or hyperbranched polymers prepared using expensive, special multifunctional monomers or expensive multistep methods requiring repetitive isolation of the reactive intermediates have been reviewed by J. C. Salamone, ed., Polymeric Materials Encyclopedia, Vol.5 (1996).
The references cited above cover the copolymerization of vinyl monomers in the presence of chain transfer reagents, but do not disclose synthetic conditions for production of macromonomers or polymers containing branches upon branches.


SUMMARY OF THE INVENTION

This invention relates to a general process for the synthesis of addition polymers containing branches upon branches and having a polymerizable olefin end group by a convenient one-pot polymerization of selected vinyl monomers with chain polymerization initiators and a method to provide olefin end groups by chain transfer or termination agents. The polymerization is carried out in such a manner that chain transfer occurs frequently and each chain transfer event terminates that particular polymer chain with terminal polymerizable olefinic functionality. Subsequent reincorporation of the polymer chains produced early in the reaction leads to branching of subsequently-formed polymer chains which are terminated with polymerizable olefinic functionality. Subsequent reincorporation of the branched polymer chains leads to subsequently-formed polymer chains containing branches-upon-branches which are terminated with polymerizable olefinic functionality. Spontaneous repetition of the process leads to highly branched or hyperbranched products still retaining termini with polymerizable olefinic functionality.
This invention concerns an improved process for the free-radical polymerization of at least one unsaturated vinylic monomer to form a polymer whose molecular architecture includes branches upon branches and a polymerizable vinyl-terminated end group, comprising contacting, in the presence of a free-radical initiator: CO.sub.2 H, COR

REFERENCES:
patent: 4680352 (1987-07-01), Janowicz et al.
patent: 5362813 (1994-11-01), Antonelli et al.
patent: 5362826 (1994-11-01), Berge et al.
patent: 5773534 (1998-06-01), Antonelli et al.
Salamone, Polymeric Materials Encyclopedia, 3, 1799-1830, 1996.
Salamone, Polymeric Materials Encyclopedia, 5, 3049-3185, 1996.

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