Polyisobutylene-based thermoplastic elastomers
AssigneeThe University of Akron
InventorsJoseph P. Kennedy, Turgut Nugay, Nihan Nugay
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Abstract
The present invention is directed to a new class of thermoplastic elastomers (TPEs) and processes for making them. In some embodiments of the present invention, the end groups of the multi-arm PIB copolymer is a conjugated diene, whereas the other component is a multi-functional dienophile. The components of the TPE of the present invention are chemically connected via the well-known Diels-Alder reaction which is thermally reversible (by the retro-Diels-Alder reaction) at moderately elevated temperatures. The reversibility of the Diels-Alder retro-Diels-Alder reactions allows the recovery of the original components of the TPE and thus its recyclability and also gives the TPE the ability to be reshaped or reformed.
Claims14
A multi-arm polyisobutylene (PIB) polymer comprising:
- a) an oligomeric styrene pre-polymer having a sec-butyl head group, a poly(α-methylstyrene) segment from 3 to 5 units in length and a poly[3-(2-methoxyisopropyl)styrene] segment from 3 units to 50 units in length and having the structure of formula (v):
- wherein n is an integer from 3 to 5 and m is an integer from 3 to 50;
- and
- b) at least one PIB arm extending from each 3-(2-methoxyisopropyl)styrene wherein said PIB arms are terminated with end groups selected from the group consisting of allyls, dienes, and furans.
A method for synthesizing a multi-arm polyisobutylene having an oligomeric styrene, a sec-butyl head group, and allyl end groups comprising:
- a) reacting a sec-butyl lithium and an α-methylstyrene to form an α-methylstyrene oligomer of from 3 units to 5 units in length, said α-methylstyrene oligomer having a sec-butyl head group and a lithium ion;
- b) reacting the α-methylstyrene oligomer of step (a) with potassium tert-butoxide to replace the lithium ion on the α-methylstyrene oligomer with a potassium ion;
- c) reacting the methylstyrene oligomer of step (b) with a 3-(2-methoxyisopropyl)styrene to form an oligomeric styrene pre-polymer having a sec-butyl head group, a poly(α-methylstyrene) segment of from 3 to 5 units in length, and a poly[3-(2-methoxyisopropyl)styrene] segment of from 3 to 50 units in length;
- d) combining the oligomeric styrene pre-polymer of step (c), a stoichiometric excess of isobutylene, and a photoinitiator, wherein said isobutylene is added to at least one of the 3-(2-methoxyisopropyl)styrene units of said poly[3-(2-methoxyisopropyl)styrene] segment of said oligomeric styrene pre-polymer by cationic polymerization to create PIB arms of from 10 units to 10,000 units in length extending from each of said 3-(2-methoxyisopropyl)styrene units;
- and
- e) adding allyltrimethylsilane to terminate the isobutylene polymerization and place an allyl end group on the end of said PIB arms.
Dependencies are inferred from the claim text.