Tailored Nanostructuring of End‐Group‐Functionalized High‐Density Polyethylene Synthesized by an Efficient Catalytic Version of Ziegler’s “Aufbaureaktion”

Abstract

Monoguanidinato titanium complexes are efficient catalysts to make OH end-group-functionalized polyethylene (PE-OH) by a catalyzed version of Ziegler's "Aufbaureaktion". This PE-OH can be structured to mesoporous polyethylene or polyethylene nanofibers/ribbons through diblock copolymer synthesis, microphase separation, and etching of the sacrificial polylactide block.

Efficient Synthesis of Aluminium‐Terminated Polyethylene by Means of Irreversible Coordinative Chain‐Transfer Polymerisation Using a Guanidinatotitanium Catalyst

“…Guanidinato‐trichloridotitanium(IV) complexes are generally accessible through carbodiimide insertion into titanium–amide bonds (Scheme ) 37. The required carbodiimides are accessible by desulfurisation of N , N ′‐substituted thioureas with a three‐component system of PPh 3 , CCl 4 and triethylamine46 and subsequent fractional crystallisation from ethanol.…”

“…We recently developed a titanium‐based catalyst system stabilised by bulky guanidinato ligands, which is highly efficient in CCTP 37. We pointed out that the variation of the substituents at the non‐coordinating nitrogen atom has only a marginal influence on the catalytic performance.…”

“…Ethylene (AGA polymer grade) was passed over BASF R3‐11‐supported Cu oxygen scavenger and molecular sieves (Aldrich, 4 Å). N , N′ ‐Bis(2,6‐dimethylphenyl)thiourea ( 1b ),47 N ‐ tert ‐butyl‐ N′ ‐(2,6‐dimethylphenyl)thiourea ( 1c ),48 N , N′ ‐bis(2,6‐dimethylphenyl)carbodiimide ( 2b ), N ‐ tert ‐butyl‐ N′ ‐(2,6‐diisopropylphenyl)carbodiimide ( 2c ),46 N′ , N″ ‐bis(2,6‐diisopropylphenyl)‐ N , N ‐diethylguanidinatotrichloridotitanium(IV) ( 3a )37 and [(Et 2 N)TiCl 3 ]49 were prepared according to the published procedures. Commercial n ‐butyllithium (2.5 M in n ‐hexane), methylmagnesium chloride (3.0 M in thf) (Aldrich), N , N′ ‐bis(2,6‐diisopropylphenyl)carbodiimide ( 2a ), triethylaluminium (TEA, 25 wt.‐% in toluene, Aldrich), [R 2 N(CH 3 )H][B(C 6 F 5 ) 4 ] (R = C 16 H 33 –C 18 H 37 ), 6.2 wt.‐% B(C 6 F 5 ) 4 – in Isopar (Dow Chemicals) and all other chemicals were used as received without further purification.…”

“…Recently, we communicated a guanidinatotitanium catalyst ( 3a ) that showed very high activity in the presence of very high amounts of CTA (triethylaluminium) 37. The catalyst system seemed to be able to mediate chain growth and chain transfer in a parallel fashion.…”

A Highly Efficient Titanium Catalyst for the Synthesis of Ultrahigh‐Molecular‐Weight Polyethylene (UHMWPE)

“…We are investigating Group 4 metal based polymerization catalysts stabilized by very bulky monoanionic bidentate N ligands 4. Recently, our group discovered a guanidinato titanium catalyst system that is able to polymerize ethylene by coordinative chain‐transfer polymerization 5. It is highly active in the presence of very high chain‐transfer‐agent to catalyst ratios and undergoes polyethylene chain transfer to triethylaluminum.…”