Novel Thermoplastic Elastomers: Star-Blocks Consisting of Eight Poly(Styrene-b-Isobutylene) Arms Radiating from a Calix[8]Arene Core

Abstract

The first synthesis by a core-first strategy of novel star-block copolymers consisting of eight poly(styrene-b-isobutylene) (PSt-b-PIB) arms radiating from a calix[8]arene core is described. An octafunctional methoxy calix[8]arene derivative was used to initiate the living polymerization of isobutylene (IB) to desirable molecular weights, then styrene (St) was added to obtain the sought star-blocks. Molecular weights and PSt contents were determined by triple-detector GPC and 1H NMR spectroscopy. Star-block thermoplastic elastomers containing 17–32% PSt showed high strength and elongation (up to ∼26 MPa and >500%) and relatively low melt viscosities. The mechanical and rheological properties of these star-blocks are superior to those of linear PSt-b-PIB-b-PSt triblocks. PIB-based thermoplastic elastomers may be of use as novel biomaterials.

Heat makes a difference in activity‐based anorexia: A translational approach to treatment development in anorexia nervosa

“…Generally, AB‐type diblock copolymers such as PIB‐ block ‐PS and PS‐ block ‐PIB (where PS is polystyrene and PIB is polyisobutylene) have been prepared by sequential cationic polymerization including three‐step1 or two‐step2–5 synthesis with end‐functionalized PS or PIB in conjunction with an alkylaluminum, such as diethylaluminum chloride (Et 2 AlCl);1–5 the final copolymers have been obtained by selective solvent extraction. Diblock copolymers and glassy–rubbery–glassy ABA‐type linear or three‐arm star triblock copolymers, where A is PS or poly(α‐methylstyrene) and B is PIB, have also been prepared by the one‐pot sequential monomer addition to living cationic polymer charges 6–16. These procedures use a monofunctional, difunctional, or trifunctional initiator in conjunction with TiCl 4 6–14.…”

“…These procedures use a monofunctional, difunctional, or trifunctional initiator in conjunction with TiCl 4 6–14. A mixture of BCl 3 –TiCl 4 coinitiators has been used for the one‐pot synthesis of block star copolymers consisting of PIB‐ b ‐PS arms 15, 16. PIB‐based block copolymers have also been prepared, with the site‐transformation techniques, by sequential synthesis combining cationic→anionic polymerization17–25 or cationic→ATRP26–28 with end‐functionalized PIBs used as macroinitiators.…”

Synthesis of methyl methacrylate, styrene, and isobutylene multiblock copolymers using atom transfer and cationic polymerization

“…Diblock copolymers and glassyrubbery-glassy ABA-type linear or three-arm star triblock copolymers, where A is PS or poly(-methylstyrene) and B is PIB, have also been prepared by the one-pot sequential monomer addition to living cationic polymer charges. [6][7][8][9][10][11][12][13][14][15][16] These procedures use a monofunctional, difunctional, or trifunctional initiator in conjunction with TiCl 4 . [6][7][8][9][10][11][12][13][14] A mixture of BCl 3 -TiCl 4 coinitiators has been used for the one-pot synthesis of block star copolymers consisting of PIB-b-PS arms.…”

“…[6][7][8][9][10][11][12][13][14] A mixture of BCl 3 -TiCl 4 coinitiators has been used for the one-pot synthesis of block star copolymers consisting of PIB-b-PS arms. 15,16 PIB-based block copolymers have also been prepared, with the site-transformation techniques, by sequential synthesis combining cationic?anionic polymerization [17][18][19][20][21][22][23][24][25] or cationic?ATRP [26][27][28] with end-functionalized PIBs used as macroinitiators.…”

Synthesis of Polyisobutylene-Based Block Copolymers with Precisely Controlled Architecture by Living Cationic Polymerization

“…Using trifunctional initiators many groups have prepared three arm star-block copolymers such as poly(IBVE-b-2-hydroxyethyl vinyl ether) 3 [73], poly(IB-b-St) 3 [74,75], and poly(IB-b-pMeSt) 3 [76] star-block copolymers. The synthesis of eight arm poly(IB-b-St) 8 starblock copolymers was reported recently [77]. An octafunctional calix [8]arene-based initiator was used to initiate the living cationic polymerization of IB to desirable molecular weight followed by sequential addition of St to obtain the star-block copolymer.…”