Alternating Intramolecular and Intermolecular Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization: Synthesis of Boronate‐Terminated π‐Conjugated Polymers Using Excess Dibromo Monomers

The Suzuki–Miyaura coupling polymerization of dibromoarene 1 and arylenediboronic acid (ester) 2 with a Pd catalyst having a high propensity for intramolecular catalyst transfer is reported. The polymerization of excess 1 with 2 affords high‐molecular‐weight π‐conjugated polymer having boronic acid (ester) moieties at both ends, contrary to Flory's principle. This unstoichiometric polycondensation behavior is accounted for by intramolecular transfer of the Pd catalyst on 1 . In the polymerization of 1 and 2 having different aryl residues, high‐molecular‐weight polymer is obtained when the stronger donor aromatic is used as the dibromo monomer and the weaker donor or acceptor aromatic is used as diboronic acid (ester) monomer. The pinacol boronate moieties at both ends of the obtained poly(p‐phenylene) (PPP) can be converted to benzoic acid ester, hydroxyl group, and bromine. Furthermore, the reaction of the pinacol boronate‐terminated PPP with poly(3‐hexylthiophene) (P3HT) having bromine at one end yields a triblock copolymer of P3HT‐b‐PPP‐b‐P3HT.

     

Investigation of Suzuki–Miyaura catalyst‐transfer polycondensation of AB‐type fluorene monomer using coordination‐saturated aryl Pd(II) halide complexes as initiators

Novel triarylamine‐based coordination‐saturated aryl Pd(II) halide complexes ligated by PEt₃, PCy₃, and P(o‐tol)₃ were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. Suzuki–Miyaura coupling polymerization of 2‐(7‐halide‐9,9‐dioctylfluoren‐2‐yl)?1,3,2‐dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy₃ or P(o‐tol)₃ exhibited catalytic activity and realized the catalyst‐transfer polycondensation at 75 °C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt₃ did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P(o‐tol)₃ can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst‐transfer polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1457–1463     

Tris[tri(2‐thienyl)phosphine]palladium as the catalyst precursor for thiophene‐based Suzuki‐Miyaura crosscoupling and polycondensation

Zero‐valent palladium complex, Pd(PTh₃)₃, with three tri(2‐thienyl)phosphine ligands was prepared and characterized. Pd(PTh₃)₃ is superior to Pd(PPh₃)₄ in catalyzing Suzuki‐Miyaura coupling and polymerization of thiophene‐based derivatives. The Suzuki polycondensation of 3‐hexyl‐5‐iodothiophene‐2‐boronic pinacol ester with Pd(PTh₃)₃ as the catalyst precursor afforded high‐molecular‐weight P3HT with high regularity and yield. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4556–4563, 2008     

Investigation of catalyst‐transfer condensation polymerization for the synthesis of n‐type π‐conjugated polymer,poly(2‐dioxaalkylpyridine‐3,6‐diyl)

Kumada‐Tamao coupling polymerization of 6‐bromo‐3‐chloromagnesio‐2‐(3‐(2‐methoxyethoxy)propyl)pyridine 1 with a Ni catalyst and Suzuki‐Miyaura coupling polymerization of boronic ester monomer 2 , which has the same substituted pyridine structure, with ^tBu₃PPd(o‐tolyl)Br were investigated for the synthesis of a well‐defined n‐type π‐conjugated polymer. We first carried out a model reaction of 2,5‐dibromopyridine with 0.5 equivalent of phenylmagnesium chloride in the presence of Ni(dppp)Cl₂ and then observed exclusive formation of 2,5‐diphenylpyridine, indicating that successive coupling reaction took place via intramolecular transfer of Ni(0) catalyst on the pyridine ring. Then, we examined the Kumada‐Tamao polymerization of 1 and found that it proceeded homogeneously to afford soluble, regioregular head‐to‐tail poly(pyridine‐2,5‐diyl), poly(3‐(2‐(2‐(methoxyethoxy)propyl)pyridine) (PMEPPy). However, the molecular weight distribution of the polymers obtained with several Ni and Pd catalysts was very broad, and the matrix‐assisted laser desorption ionization time‐of‐flight mass spectra showed that the polymer had Br/Br and Br/H end groups, implying that the catalyst‐transfer polymerization is accompanied with disproportionation. Suzuki‐Miyaura polymerization of 2 with ^tBu₃PPd(o‐tolyl)Br also afforded PMEPPy with a broad molecular weight distribution, and the tolyl/tolyl‐ended polymer was a major product, again indicating the occurrence of disproportionation. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Use of N‐methyliminodiacetic acid boronate esters in suzuki‐miyaura cross‐coupling polymerizations of triarylamine and fluorene monomers

Polytriarylamine copolymers can be prepared by Suzuki‐Miyaura cross‐coupling reactions of bis N‐methyliminodiacetic acid (MIDA) boronate ester substituted arylamines with dibromo arenes. The roles of solvent composition, temperature, reaction time, and co‐monomer structure were examined and (co)polymers prepared containing 9, 9‐dioctylfluorene (F8), 4‐sec‐butyl or 4‐octylphenyl diphenyl amine (TFB), and N, N′‐bis(4‐octylphenyl)‐N, N′‐diphenyl phenylenediamine (PTB) units, using a Pd(OAc)₂/2‐dicyclohexylphosphino‐2′,6′‐dimethoxybiphenyl (SPhos) catalyst system. The performance of a di‐functionalized MIDA boronate ester monomer was compared with that of an equivalent pinacol boronate ester. Higher molar mass polymers were produced from reactions starting with a difunctionalized pinacol boronate ester monomer than the equivalent difunctionalized MIDA boronate ester monomer in biphase solvent mixtures (toluene/dioxane/water). Matrix‐assisted laser desorption/ionization mass spectroscopic analysis revealed that polymeric structures rich in residues associated with the starting MIDA monomer were present, suggesting that homo‐coupling of the boronate ester must be occurring to the detriment of cross‐coupling in the step‐growth polymerization. However, when comparable reactions of the two boronate monomers with a dibromo fluorene monomer were completed in a single phase solvent mixture (dioxane + water), high molar mass polymers with relatively narrow distribution ranges were obtained after only 4 h of reaction. © 2017 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2798–2806     

Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Stilbene Monomer: Different Polymerization Behavior Depending on Halide and Aryl Group of ArPd(tBu3P)X Initiator

We report Suzuki–Miyaura coupling polymerization of tetraalkoxy‐substituted 4‐bromostilbene‐4′‐boronic acid 1 with several t‐Bu₃P‐ligated Pd initiators; this is the first example of catalyst‐transfer condensation polymerization (CTCP) of a monomer containing a carbon–carbon double bond. When o‐tolylPd(^tBu₃P)Br was used as the initiator, the o‐tolyl group was not introduced at the polymer end, but polymer with boronic acid at one end and bromine at the other was obtained. However, when we employed stilbenePd(^tBu₃P)I generated in situ from iodostilbene and Pd(^tBu₃P)G2 precatalyst, or isolated ArPd(^tBu₃P)X (Ar, X = Ph, I; o‐tolyl, I; and Ph, Br), the aryl group was introduced at the polymer end, indicating that CTCP of 1 proceeded. Therefore, the iodide and aryl group of the Pd initiator complex is crucial for CTCP of 1 . However, the molecular weight distribution of the obtained polymer was broad, possibly because coordination of the carbon–carbon double bond of 1 to ArPd(^tBu₃P)I resulted in slow initiation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 297–304     

Synthesis,characterization, and star polymer assembly of boronic acid end‐functionalized polycaprolactone

Boronic acid end‐functionalized polycaprolactone (PCL) polymers were synthesized by ring‐opening polymerization using a pinacol boronate ester‐containing (Bpin) initiator. The polymerization provides access to boron‐terminated polymers (i.e. Bpin‐PCL‐OH) with narrow molecular weight distributions (PDI = 1.09). Postsynthetic manipulation of the polymer's terminal hydroxyl group by copper‐catalyzed azide‐alkyne cycloaddition chemistry provides a series of bis end‐functionalized polymers with significant structural diversity at the termini. Deprotection of the boronate ester end group was accomplished with an acidic solid phase DOWEX resin. The boronate ester deprotection methodology does not result in hydrolysis of the polymeric backbone. The boronic acid‐tipped polymers were converted into star polymer assemblies using thermal dehydration and ligand‐facilitated trimerization. Thermal dehydration of (HO)₂B‐PCL‐OAc to the corresponding boroxine‐based star polymer assembly was inefficient and lead to degradation products. Ligand‐facilitated trimerization using either pyridine or 7‐azaindole as the Lewis base was efficient and mild. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Investigation of Mizoroki‐Heck coupling polymerization as a catalyst‐transfer condensation polymerization for synthesis of poly(p‐phenylenevinylene)

Mizoroki‐Heck coupling polymerization of 1,4‐bis[(2‐ethylhexyl)oxy]‐2‐iodo‐5‐vinylbenzene ( 1 ) and its bromo counterpart 2 with a Pd initiator for the synthesis of poly(phenylenevinylene) (PPV) was investigated to see whether the polymerization proceeds in a chain‐growth polymerization manner. The polymerization of 1 with ^tBu₃PPd(Tolyl)Br ( 10 ) proceeded even at room temperature when 5.5 equiv of Cy₂NMe (Cy = cyclohexyl) was used as a base, but the molecular weight distribution of PPV was broad. The polymerization of 2 hardly proceeded at room temperature under the same conditions. In the polymerization of 1 , PPV with H at one end and I at the other was formed until the middle stage, and the polymer end groups were converted into tolyl and H in the final stage. The number‐average molecular weight (M_n) did not increase until about 90% monomer conversion and then sharply increased after that, indicating conventional step‐growth polymerization. The occurrence of step‐growth polymerization, not catalyst‐transfer chain‐growth polymerization, may be interpreted in terms of low coordination ability of H‐Pd(II)‐X(^tBu₃P) (X = Br or I), formed in the catalytic cycle of the Mizoroki‐Heck coupling reaction, to π‐electrons of the PPV backbone; reductive elimination of H‐X from this Pd species with base would take place after diffusion into the reaction mixture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 543–551     

Investigation of catalyst‐transfer condensation polymerization for synthesis of poly(p‐phenylenevinylene)

Kumada‐Tamao coupling polymerization of 1,4‐dialkoxy‐2‐bromo‐5‐(2‐chloromagnesiovinyl)benzene ( 1 ) and 1,4‐dialkoxy‐2‐(2‐bromovinyl)‐5‐chloromagnesiobenzene ( 2 ) with a Ni catalyst and Suzuki‐Miyaura coupling polymerization of 2‐{2‐[(2,5‐dialkoxy‐4‐iodophenyl)]vinyl}‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane ( 3 ), its bromo counterpart 4 , and 2,5‐dialkoxy‐4‐(2‐bromovinyl)phenylboronic acid ( 5 ) with a Pd initiator were investigated under catalyst‐transfer condensation polymerization conditions for the synthesis of well‐defined poly(p‐phenylenevinylene) (PPV). The Kumada‐Tamao polymerization of vinyl Grignard‐type monomer 1 with Ni(dppp)Cl₂ at room temperature did not proceed, whereas aryl Grignard‐type monomer 2 afforded oligomers of low molecular weight. Matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectra of the polymer obtained from 2 implied that the Grignard end group reacted with tetrahydrofuran to terminate polymerization. On the other hand, Suzuki‐Miyaura polymerization of vinyl boronic acid ester type monomers 3 and 4 and phenylboronic acid type monomer 5 with a Pd initiator and aqueous KOH at ?20 °C to room temperature yielded the corresponding PPV with high molecular weight within a few minutes. However, the molecular weight distribution was broad, and MALDI‐TOF mass spectra showed the peaks of polymers bearing no initiator unit at the chain end, as well as those of polymers with the initiator unit. These results indicated that intermolecular chain transfer of the Pd catalyst occurred. Dehalogenation and disproportionation of the growing end also took place as side reactions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2643‐2653     

Mechanistic Investigation of Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Thiophene–Pyridine Biaryl Monomers with the Aid of Model Reactions

We have investigated the requirements for efficient Pd‐catalyzed Suzuki–Miyaura catalyst‐transfer condensation polymerization (Pd‐CTCP) reactions of 2‐alkoxypropyl‐6‐(5‐bromothiophen‐2‐yl)‐3‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)pyridine ( 12 ) as a donor–acceptor (D –A) biaryl monomer. As model reactions, we first carried out the Suzuki–Miyaura coupling reaction of X–Py–Th–X′ (Th=thiophene, Py=pyridine, X, X′=Br or I) 1 with phenylboronic acid ester 2 by using tBu₃PPd⁰ as the catalyst. Monosubstitution with a phenyl group at Th‐I mainly took place in the reaction of Br–Py–Th–I ( 1 b ) with 2 , whereas disubstitution selectively occurred in the reaction of I–Py–Th–Br ( 1 c ) with 2 , indicating that the Pd catalyst is intramolecularly transferred from acceptor Py to donor Th. Therefore, we synthesized monomer 12 by introduction of a boronate moiety and bromine into Py and Th, respectively. However, examination of the relationship between monomer conversion and the M_n of the obtained polymer, as well as the matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectra, indicated that Suzuki–Miyaura coupling polymerization of 12 with (o‐tolyl)tBu₃PPdBr initiator 13 proceeded in a step‐growth polymerization manner through intermolecular transfer of the Pd catalyst. To understand the discrepancy between the model reactions and polymerization reaction, Suzuki–Miyaura coupling reactions of 1 c with thiopheneboronic acid ester instead of 2 were carried out. This resulted in a decrease of the disubstitution product. Therefore, step‐growth polymerization appears to be due to intermolecular transfer of the Pd catalyst from Th after reductive elimination of the Th‐Pd‐Py complex formed by transmetalation of polymer Th–Br with (Pin)B–Py–Th–Br monomer 12 (Pin=pinacol). Catalysts with similar stabilization energies of metal–arene η²‐coordination for D and A monomers may be needed for CTCP reactions of biaryl D–A monomers.     

Controlled ring‐expansion polymerization of thiiranes based on cyclic aromatic thiourethane initiator

Ring‐expansion polymerization (REP) of thiiranes was investigated using 3H‐benzothiazol‐2‐one (BT) as the cyclic aromatic thiourethane initiator in the presence of tetrabutylammonium chloride (TBAC) catalyst. The polymerization proceeded in a well‐controlled manner to afford cyclic polysulfides with one BT moiety per macrocycle, as confirmed by MALDI‐TOF MS spectroscopy. Differential scanning calorimetry (DSC) measurement of the obtained cyclic polysulfides revealed slight decrease in the glass‐transition temperature as the increase in the molecular weight, supporting the cyclic topology of the products. Postpolymerization of thiiranes using the BT‐initiated cyclic polysulfide as the macroinitiator afforded the ring‐expanded product while maintaining the narrow polydispersity and well‐defined cyclic structure, which enabled precise synthesis of cyclic block copolymer with different thiirane combination. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2442–2449     

Iron‐mediated atom transfer radical polymerization of styrene with tris(3,6‐dioxaheptyl) amine as a ligand

The atom transfer radical bulk polymerization of styrene with FeX₂ (X = Br or Cl)/tris(3,6‐dioxaheptyl) amine as the catalyst system was successfully implemented at 110 °C. The number‐average molecular weight of the polymers with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight = 1.2–1.5) increased linearly with the monomer conversion and matched the predicted molecular weight. The polymerization rate, initiation efficiency, and molecular weight distribution were influenced by the selection of the initiator and iron halide. The high functionality of the halide end group in the obtained polymers was confirmed by both ¹H NMR and a chain‐extension reaction. Because of its water solubility, the iron complexes could be removed easily from the reaction mixture through the washing of the polymerization mixture with water. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 483–489, 2006     

Synthesis of Poly(Arylene Alkenylene)s by Pd‐Catalyzed Three‐Component Coupling Polycondensation of Diiodoarenes,Non‐Conjugated Dienes,and Nucleophiles that Involves Chain Walking Isomerization

The Pd‐catalyzed three‐component coupling polycondensation of diiodoarenes, nonconjugated dienes, and carbonucleophiles afforded poly(arylene alkenylene)s with moderate molecular weight in good yield. The reaction involves Mizoroki‐Heck coupling, olefin migration via chain walking, and addition of the carbonucleophile to the resulting π‐allylpalladium species. The polymerization with a slight excess of nucleophile with respect to diiodoarene also proceeded to give the polymer without significant decrease in molecular weight in spite of the nonstoichiometric mixture of the monomers. The Pd‐catalyzed three‐component coupling polycondensation of diiodoarenes, nonconjugated dienes, and diimide also proceeded. The base used in the reaction is critical for yield and molecular weight of the product. The reaction using NaHCO₃ afforded the product with low solubility, which can be explained by the high molecular weight of the polymer and/or the strong interaction of the electron donating dimethoxyphenylene groups and electron accepting diimide groups in the polymer. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2535–2542     

Influence of the catalyst and polymerization conditions on the long‐chain branching of metallocene‐catalyzed polyethenes

A study was made on the effects of polymerization conditions on the long‐chain branching, molecular weight, and end‐group types of polyethene produced with the metallocene‐catalyst systems Et[Ind]₂ZrCl₂/MAO, Et[IndH₄]₂ZrCl₂/MAO, and (n‐BuCp)₂ZrCl₂/MAO. Long‐chain branching in the polyethenes, as measured by dynamic rheometry, depended heavily on the catalyst and polymerization conditions. In a semibatch flow reactor, the level of branching in the polyethenes produced with Et[Ind]₂ZrCl₂/MAO increased as the ethene concentration decreased or the polymerization time increased. The introduction of hydrogen or comonomer suppressed branching. Under similar polymerization conditions, the two other catalyst systems, (n‐BuCp)₂ZrCl₂/MAO and Et[IndH₄]₂ZrCl₂/MAO, produced linear or only slightly branched polyethene. On the basis of an end‐group analysis by FTIR and molecular weight analysis by GPC, we concluded that a chain transfer to ethene was the prevailing termination mechanism with Et[Ind]₂ZrCl₂/MAO at 80 °C in toluene. For the other catalyst systems, β‐H elimination dominated at low ethene concentrations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 376–388, 2000     

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 MoOCl₄–n‐Bu₄Sn–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. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2697–2701, 2000     

Synthesis of poly(1‐chloro‐2‐arylacetylene)s with high cis‐content and examination of their absorption/emission properties

A series of 1‐chloro‐2‐arylacetylenes [Cl‐C?C‐Ar, Ar = C₆H₅ ( 1 ), C₆H₄‐p‐i Pr ( 2 ), C₆H₄‐p‐Oi Pr ( 3 ), C₆H₄‐p‐NHC(O)Ot Bu ( 4 ), and C₆H₄‐o‐i Pr ( 5 )] were polymerized using (tBu₃P)PdMeCl/silver trifluoromethanesulfonate (AgOTf) and MoCl₅/SnBu₄ catalysts. The corresponding polymers [poly( 1 )–poly( 5 )] with weight‐average molecular weights of 6,500–690,000 were obtained in 10–91% yields. THF‐insoluble parts, presumably high‐molecular weight polymers, were formed together with THF‐soluble polymers by the Pd‐catalyzed polymerization. The Pd catalyst polymerized nonpolar monomers 1 and 2 to give the polymers in yields lower than the Mo catalyst, while the Pd catalyst polymerized polar monomers 3 and 4 to give the corresponding polymers in higher yields. The ¹H NMR and UV–vis absorption spectra of the polymers indicated that the cis‐contents of the Pd‐based polymers were higher than those of the Mo‐based polymers, and the conjugation length of the Pd‐based polymers was shorter than that of the Mo‐based polymers. Pd‐based poly( 5 ) emitted fluorescence most strongly among poly( 1 )–poly( 5 ). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 382–388     

High molecular weight atactic polypropene synthesized with (η5‐pentamethylcyclopentadienyl)tribenzyl titanium activated with MAO

The half‐titanocene (η⁵‐pentamethylcyclopentadienyl)tribenzyl titanium (Cp*TiBz₃) with methylaluminoxane (MAO) as the cocatalyst was employed to catalyze propene polymerization at ambient pressure. A novel atactic polypropene elastomer with a high molecular weight (M̄_w = 2 − 8 × 10⁵) was produced. The effects of the polymerization conditions on the catalytic activity and polymer molecular weight are discussed. ¹³C NMR analysis confirmed that the catalyst system Cp*TiBz₃/MAO produced atactic polypropenes, and the polymerization mechanism was in agreement with the Bernoullian process. The triad sequence distribution of the polymer was measured and found to be as follows: mm = 6.15%, mr = 40.87%, and rr = 52.98% (Bernoullian factor B = 1.03); this indicated that the insertion of propene with the catalyst system followed a chain‐end control model. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 411–415, 2000     

Cationic polymerization of n‐hexyloxyallene by using halogen‐bonding organocatalysts

The cationic polymerization of n‐hexyloxyallene was investigated by using halogen‐bonding organocatalysts ( Cat A – Cat D ). Although the neutral catalyst Cat C showed a poor polymerization activity, iodine‐carrying bidentate cationic catalyst Cat A brought about the smooth polymerization giving rise to a polymer with M_n of 2710 under [ Cat A ]:[IBVE‐HCl]:[monomer] = 10:10:500 in mM concentrations. Judging from the color change of polymerization system and electrospray ionization mass spectra of recovered catalyst, the decomposition of organocatalyst was suggested. When α‐bromodiphenylmethane was used as an initiator, the relatively controlled polymerization proceeded at the low monomer conversion likely due to the weak halogen‐bonding interaction of Cat A with the bromide anion. On the other hand, bromine‐carrying bidentate catalyst Cat D gave low‐molecular‐weight polymers (M_n < 1550) to be less suitable for polymerization. From the ¹H‐NMR spectrum, it was found that the 1,2‐polymerization unit and 2,3‐polymerization unit are included in 75:25. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2436–2441     

Synthesis of high molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts

High molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) was prepared under reduced pressure in the presence of a well‐defined Schrock‐type catalyst, Mo(CHCMe₂Ph)(N‐2,6‐Me₂C₆H₃)[OCMe(CF₃)₂]₂, in toluene. The effect of initial monomer concentration was found to be an important factor for preparing high molecular weight polymers with unimodal molecular weight distributions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2463–2470, 2001     

Synthesis and palladium‐catalyzed addition polymerization of norbornene carrying epoxy moiety

A norbornene monomer carrying epoxy moiety 1 was successfully synthesized from 5‐norbornene‐2‐carbardehyde by treating it with thioylide. With using a catalytic system consisted of palladium (II) acetate/tricyclohexylphosphine/triphenylcarbenium tetrakis(pentafluorophenyl)borate, homopolymerizations and copolymerization of 1 and 5‐butyl‐2‐norbornene (BNB) were examined. The homopolymerization of 1 was slower than that of BNB presumably due to coordination of the epoxy moiety to the palladium‐center in competition with the C? C double bond of norbornene. This deceleration became less significant in the copolymerizations with low initial feed ratios [ 1 ]₀/[BNB]₀, leading to successful formation of the corresponding copolymers having a rigid poly(norbornene) main chain and epoxy moiety in the side chains, of which composition ratios agreed with the feed ratios. Influence of the epoxy moiety of 1 on its Pd‐catalyzed addition polymerization was elucidated by studying the homopolymerization of BNB in the presence of 1,2‐epoxyhexane. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3982–3989, 2009