Shigetaka Hayano

Living polymerization of substituted acetylenes by MoOCl4–n-Bu4Sn–EtOH in anisole which features high initiator efficiency

Abstract Various solvents and cocatalysts were examined for the purpose of achieving high initiator efficiency in the living polymerization of substituted acetylenes catalyzed by MoOCl 4 -based catalysts. Eventually, anisole and n -Bu 4 Sn were found to be very useful as solvent and cocatalyst, respectively. The initiator efficiency of the MoOCl 4 – n -Bu 4 Sn–EtOH (1:1:2)/anisole system was as high as 40% in the polymerization of o -CF 3 -phenylacetylene, whereas the value for the corresponding toluene system was no more than 10%. o -Me 3 Si-phenylacetylene, 1-chloro-1-octyne, 2-octyne, and 1-chloro-2-phenylacetylene and a few other monomers were also polymerized in a living manner by the present catalyst/solvent system, the initiator efficiencies being 20–40% and larger than those of the previous systems.

Living metathesis polymerization of substituted acetylenes by MoOCl4–Et2Zn–EtOH and MoOCl4–n-BuLi systems

Several organometallic compounds were examined as second catalyst components (cocatalysts) of the MoOCl 4 -cocatalyst(-EtOH) system with the motivation of development of novel catalysts for the living polymerization of substituted acetylenes. Catalyst systems such as MoOCl 4 -Et 2 Zn-EtOH and MoOCl 4 -n-BuLi have proven to be very effective for the living polymerization of substituted acetylenes. Suitable mole ratios of the catalyst components (MoOCl 4 :Et 2 Zn:EtOH = 1:1:3 and MoOCl 4 :n-BuLi = 1:1) made it possible to achieve living polymerization of substituted acetylenes including (o-trifluoromethyl)phenylacetylene, (o-trimethylsilyl)phenylacetylene, o-isopropylphenylacetylene, and 1-chloro-1-octyne. Use of anisole instead of toluene as solvent remarkably improved the living nature of polymerization to provide polymers with extremely narrow molecular weight distributions (1.03-1.14) in quantitative yields. Sequential living polymerization of two monomers by these catalyst systems produced block copolymers with low polydispersities without the formation of homopolymers.

Living polymerization of [o‐(trifluoromethyl)phenyl]acetylene by a new catalyst system, MoOCl4–Et3Al–EtOH (1 : 1 : 4)

A new MoOCl 4 -based living polymerization catalyst, MoOCl 4 -Et 3 Al-EtOH (mole ratio 1:1:4)/anisole, has been developed. Polymerization of [o-(trifluoromethyl)phenyl]acetylen by this catalyst in anisole at 30°C yielded a polymer having very narrow molecular weight distribution (M w /M n = 1,02), a four-fold excess of ethanol over MoOCl 4 was necessary to attain narrow molecular weight distributions. Multistage polymerization experiments clearly showed the living nature of the polymerization, which was maintained in the temperature range of 0 to 30°C. The absolute number-average molecular weight of the polymer measured by vapor pressure osmometry could be correlated with the number-average molecular weight measured by gel permeation chromatography as follows: M n (VPO)= 1,48 × M n (GPC). The propagation rate constant (k p ) at 30°C is 1,5 mol L -1 . S -1 .

Novel catalyst systems for the polymerization of substituted acetylenes

Abstract This article reviews two types of novel catalyst systems for the polymerization of substituted acetylenes; i.e., i) MoOl4-based catalysts and ii) metal carbonyl-based catalysts. The MoOCl4–n-Bu4Sn–EtOH(1:1:1) catalyst achieves living polymerization of 1 -chloro-1-octyne, tert-butylacetylene, and phenylacetylenes having bulky ortho substituents. The initiator efficiency for the polymerization of o-CF3-phenylacetylene reaches about 40% in anisole. Et3Al, Et2Zn, and n-BuLi also work as useful cocatalysts in the MoOCl4-based system; the polydispersity ratios of poly(o-CF3-phenylacetylene) are as small as 1.06 to 1.02. The binary MoOCl4–n-BuLi system serves without ethanol. Block copolymers of o-CF3- and o-Me3Si-phenylacetylenes can be obtained by using MoOCl4–Et3Al–EtOH(1:1:4). Whereas CCl4 is used as solvent in the polymerization of phenylacetylene by W(CO)6–CCl4–hn, only a few equivalents of Ph2CCl2 to tungsten is needed in the W(CO)6–Ph2CCl2–hn system. A tungsten complex, WCl2(CO)3-(AsPh3)2 by its...

Living polymerization of several substituted acetylenes with WOCl4–Bu4Sn–tert‐BuOH (1 : 1 : 1) as a catalyst

Living polymerization of several substituted acetylenes was studied with a W-based ternary catalyst, WoCl 4 -Bu 4 Sn-tert-BuOH (1:1:1), [o-(Trimethylsilyl)phenyl]acetylene forms a polymer with a narrow molecular weight distribution (MWD) (M w /M n 1.08). The living nature of this polylmerization system was proved by both multistage polymerization and the conversion dependence of the polymer molecular weight. Linear internal alkynes (e.g., 5-dodecyne) also yield polymers with a narrow MWD (M w /M n 1.10), which were proven to be obtained by living polymerization by examination of the conversion dependence of the polymer molecular weight. However, neither 1-chloro-1-alkynes nor tert-butylacetylene, polymerize in a living fashion with this catalyst. A block copolymer was selectively prepared by sequential polimerization of [o-trimethylsilyl)phenyl]acetylene and [o-(trifluoromethyl)phenyl]acetylene.

Living Metathesis Polymerization of Diethyl Di‐2‐butynyl Malonate by Molybdenum‐Based Ternary Catalysts

The living polymerization of diethyl di-2- butynyl malonate (DEDBM) was achieved with a MoOCl 4 -based ternary catalyst, MoOCl 4 -Bu 4 Sn-EtOH, to give a polymer with five- and six-membered rings in the main chain. In contrast, the polymerization of diethyl dipropargyl malonate (DEDPM) with the same catalyst led to gelation. Block copolymers were obtained from DEDBM and other substituted acetylenes such as 1-chloro-1-octyne. Poly(DEDBM) forms a condensed monomolecular membrane at the air-water interface.

Synthesis of block copolymers containing 1-chloro-2-phenylacetylene, 2-nonyne, and (p-n-butyl-o,o,m,m-tetrafluorophenyl)acetylene through sequential living polymerization by MoOCl4-based catalysts

Abstract Block copolymerization of 1-chloro-2-phenylacetylene (ClPA), 2-nonyne, and ( p - n -butyl- o , o , m , m -tetrafluorophenyl)acetylene ( p -BuF 4 PA) as novel comonomers through the sequential addition process was studied by use of MoOCl 4 -based living polymerization catalysts. The acetylenes that are known to undergo living polymerization and block copolymerization, i.e. 1-chloro-1-octyne (ClOc), [ o -(trimethylsilyl)phenyl]acetylene ( o -Me 3 SiPA), and [ o -(trifluoromethyl)phenyl]acetylene ( o -CF 3 PA) were employed as conventional comonomers. When ClPA was used in combinations with these conventional comonomers, diblock copolymers with narrow molecular weight distribution were selectively formed in the presence of MoOCl 4 - n -Bu 4 Sn-EtOH irrespective of the order of monomer addition. On the other hand, 2-nonyne and p -BuF 4 PA selectively produced block copolymers with the conventional comonomers only when the comonomers were supplied in suitable addition orders. Several diblock copolymers with higher molecular weight were obtained by using either MoOCl 4 -Et 3 Al-EtOH or MoOCl 4 - n -BuLi catalyst, which is due to their lower initiation efficiencies. Use of MoOCl 4 - n -Bu 4 Sn-EtOH enabled the preparation of ABA-type triblock copolymers composed of ClPA and ClOc. ABC-type triblock copolymers were produced using MoOCl 4 - n -Bu 4 Sn-EtOH from o -Me 3 SiPA, o -CF 3 PA, and p -BuF 4 PA.

Selective synthesis of various di- and triblock copolymers from substituted acetylenes through sequential living polymerization by MoOCl4-based catalysts in anisole

Abstract Block copolymerization of substituted acetylenes through the sequential addition process was studied by use of three MoOCl 4 -based living polymerization catalysts in anisole solvent. In the case of the MoOCl 4 – n -Bu 4 Sn–EtOH catalyst system, diblock copolymers with very narrow molecular weight distributions were selectively formed from any combinations of two monomers among 1-chloro-1-octyne (ClOc), [ o -(trimethylsilyl)phenyl]acetylene ( o -Me 3 SiPA), and [ o -(trifluoromethyl)phenyl]acetylene ( o -CF 3 PA) irrespective of the order of monomer addition. When the MoOCl 4 –Et 3 Al–EtOH and MoOCl 4 – n -BuLi catalysts were employed, several diblock copolymers with higher molecular weights were obtained owing to lower initiation efficiencies. With these catalysts, however, the order of monomer addition affected the block copolymerization, and reversing the orders that selectively gave block copolymers resulted in contamination by the homopolymers from the first monomers. The use of MoOCl 4 – n -Bu 4 Sn–EtOH enabled to produce ABC- and ABA-type triblock copolymers composed of ClOc, o -Me 3 SiPA, and o -CF 3 PA regardless of the order of monomer addition. ABC-type triblock copolymers with very high molecular weights could be synthesized using MoOCl 4 –Et 3 Al–EtOH and MoOCl 4 – n -BuLi, when the monomers were successively polymerized in the order of ClOc, o -Me 3 SiPA, and o -CF 3 PA.

Polymerization of aliphatic disubstituted acetylenes by MoOCl4-n-Bu4Sn-EtOH catalyst: Formation of polymers with narrow MWDs and confirmation of the living character

The polymerization of aliphatic disubstituted acetylenes was examined with MoOCl 4 -n-Bu 4 Sn-EtOH (1/1/2) ternary catalyst in anisole at 0 °C. Various linear aliphatic disubstituted acetylenes such as 2-nonyne provided polymers with narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.05-1.20). The living character of the polymerization was proven by both the time profile of the polymerization and the multistage polymerization of 2-nonyne. The initiation efficiency was about 3%, which is rather low. Although 5-dodecyne, which has a triple bond in a more inner part, polymerized more slowly than 2-nonyne, their living characters were hardly different. Diblock copolymers were synthesized by the sequential living polymerization of internal linear alkynes.

LIVING METATHESIS POLYMERIZATION OF 1-CHLORO-2-PHENYLACETYLENE BY MoOCI4-BASED CATALYSTS

The living polymerization of 1-chloro-2-phenylacetylene was accomplished by use of the MoOCl4–n–Bu4Sn-EtOH/anisole cata-lyst/solvent system. The polydispersity ratio of the produced poly(1-chloro-2-phenylacetylene) was as small as 1.1. Living polymerization was verified by the multi-stage polymerization and the monomer-conversion dependence of the molecular weight. Only n-Bu4Sn was effective as cocatalyst of the MoOCl4-based catalyst, and Et3Al, Et2Zn, and n-BuLi were not. Among 1-chloro-2-phenylacetylene analogues, only para substituted derivatives appeared to polymerize in a living fashion.