Cationic Ring-Opening Polymerization of 1,3-Dehydroadamantanes

Ring-opening polymerizations of [3.3.1]propellane derivatives, 1,3-dehydroadamantane ( 1 ) and 5-butyl-1,3-dehydroadamantane ( 2 ), were carried out with CF₃SO₃H in CH₂Cl₂ at 0 °C for 6–42 h. The central σ-bonds in 1 and 2 were exclusively opened to afford novel poly([3.3.1]propellane)s, poly(1,3-adamantane)s, in 52–95% yields. The resulting poly( 2 ) possessing flexible butyl substituent was soluble in chloroform, THF, and 1,2-dichlorobenzene, and the degree of polymerization was estimated to be greater than 30, while the poly( 1 ) was hardly soluble in the common organic solvents. All aliphatic poly( 1 ) and poly( 2 ) showed high thermal stability, their 10% weight loss temperatures were 421 and 486 °C, respectively.     

Ring-opening polymerization of six- and seven-membered cyclic pseudoureas

The cationic ring-opening polymerization of six-membered cyclic pseudoureas, 2-(1-pyrrolidinyl)- ( 2a ) and 2-morpholino-5,6-dihydro-4H-1,3-oxazine ( 2b ), was examined, which proceeded in two different ways, depending on the nature of initiator. The polymerization of 2 with methyl p-toluenesulfonate or trifluoromethanesulfonate (MeOTf) produced poly[(N-carbamoylimino)trimethylene], while that with benzyl chloride or bromide or methyl iodide gave a polymer consisting of 1,3-diazin-2-one-1,3-diylalkylene unit (the main component) and (N-carbamoylimino)trimethylene unit. The cationic ring-opening polymerization of seven-membered cyclic pseudourea, 2-(1-pyrrolidinyl)-4,5,6,7-tetrahydro-4H-1,3-oxazepine ( 3 ) was also examined. The polymerization of 3 with MeOTf as initiator gave poly{[N-(1-pyrrolidinycarbonyl)imino]tetra-methylene}. With benzyl chloride, on the other hand, no polymerization of 3 proceeded but, instead, the quantitative isomerization of 3 to 1,1′-carbonyldipyrrolidine took place. The polymerization mechanism of 2 and 3 as well as the isomerization mechanism of 3 were discussed with comparing them to the polymerization mechanism of five-membered pseudoureas. © 1977 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 933–945, 1997     

Synthesis,characterization, and ring-opening polymerization of novel high Tg macrocyclic oligomers based on 1,2-dihydro-4-(4-hydroxyphenyl)(2H)- phthalazin-1-one

Preparation of novel high T_g (220–280°C) macrocyclic oligomers in high yield by the reaction of 1,2-dihydro-4-(4-hydroxyphenyl)(2H)phthalazin-1-one with activated difluoro-monomers is described. The reaction, conducted under pseudo-high dilution conditions, produces cyclic oligomers in 90–97% isolated yield. Detailed structural characterization of these novel oligomers by the combination of NMR, MALDI–TOF–MS, GPC, and reverse-phase HPLC confirm the cyclic nature and reveal the composition of these cyclic oligomers. MALDI–TOF–MS which enables the detection of oligomers with mass up to 6000 Da, is shown to be a very powerful tool for determination of and the proof of the cyclic nature of the cyclic oligomers. The MALDI results provide answers to the possible combinations of monomer units in the cyclic oligomeric components for random co-cyclic oligomers. Rheological measurement of cyclic oligomers 3c shows that the cyclic oligomers are thermally stable in the melt and the molten cyclic oligomers essentially behave like Newtonian fluids. At 340°C and 100 s⁻¹ the steady-state shear viscosity of the molten cyclic oligomers 3c is only about 14 poise. Ring-opening polymerization of the co-cyclic oligomers 4 to a high molecular weight polymer with M_w = 87,000 is achieved by heating at 340°C for 45 min in the presence of a nucleophilic initiator. © 1996 John Wiley & Sons, Inc.     

Determination of propagation rate coefficients for an α‐substituted acrylic ester: Pulsed laser polymerization of dimethyl itaconate

Pulsed laser polymerization experiments have been performed on the bulk polymerization of dimethyl itaconate over the temperature range 20–50 °C. The activation energy and frequency factor were calculated as 24.9 kJ/mol⁻¹ and 2.15 × 10⁵ L/mol⁻¹s⁻¹, respectively. The activation energy is comparable with the methacrylate series of monomers. The frequency factor is relatively small and reflects steric hindrance in the transition state caused by the bulky 1,1, disubstitution in the monomer (and consequently the radical). The Mark–Houwink–Kuhn–Sakurada constants were also determined for poly(dimethyl itaconate) in tetrahydrofuran, these are reported as 46 × 10⁻⁵ dL/g (K) and 0.51 (α). The influence of penultimate units (γ‐substituents) on homopropagation reactions is discussed particularly for polymerizations leading to significant 1,3 interactions in the resultant polymer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2192–2200, 2000     

Synthesis of a novel [60]fullerene pearl-necklace polymer,poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide)

A novel [60]fullerene pearl-necklace polymer, poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide), was synthesized by a direct polycondensation of trans-2-[60]fullerenobisacetic acid with 4,4′-diaminobenzophenone in the presence of large excesses of triphenyl phosphite and pyridine. In the present polymer, [60]fullerene pearls and diamine linkers were attached to each other by methano-carbonyl connectors. The molecular weight M_w of the polymer was determined to be 4.5 × 10⁴ on the basis of the TOF-MS, and a GPC analysis of the polymer using polystyrene standards showed a weight-average molecular weight of 5.3 × 10⁴. The UV-vis spectrum of the resultant polymer in N,N-dimethylacetamide (DMAc) exhibited a broad absorption (λ_max 310 nm, ε 2.1 × 10⁴ L · mol⁻¹ · cm⁻¹), tailing to longer wavelengths, and a fluorenscence peak centered at 550 nm was observed in DMAc. There was observed a large downfield-shift of the cyclopropane methyne proton in the ¹H-NMR spectra from 4.57 ppm of the ethyl ester to 5.78 ppm of the polyamide. These observations indicate that the present polyamide is a high-molecular-weight [60]fullerene pearl-necklace polymer and that the cyclopropane rings are efficient to make the [60]fullerene cages and the diamine components conjugatable. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3632–3637, 1999     

Cationic ring‐opening polymerization of novel 1,3‐dehydroadamantanes with various alkyl substituents: Synthesis of thermally stable poly(1,3‐adamantane)s

Cationic ring‐opening polymerizations of 5‐alkyl‐ or 5,7‐dialkyl‐1,3‐dehydroadamantanes, such as 5‐hexyl‐ ( 4 ), 5‐octyl‐ ( 5 ), 5‐butyl‐7‐isobutyl‐ ( 6 ), 5‐ethyl‐7‐hexyl‐ ( 7 ), and 5‐butyl‐7‐hexyl‐1,3‐dehydroadamantane ( 8 ), were carried out with super Brønsted acids, such as trifluoromethanesulfonic acid or trifluoromethanesulfonimide in CH₂Cl₂ or n‐heptane. The ring‐opening polymerizations of inverted carbon–carbon bonds in 4–8 proceeded to afford corresponding poly(1,3‐adamantane)s in good to quantitative yields. Poly( 4–8 )s possessing alkyl substituents were soluble in 1,2‐dichlorobenzene, although a nonsubstituted poly(1,3‐adamantane) was not soluble in any organic solvent. In particular, poly( 8 ) exhibited the highest molecular weight at around 7500 g mol^?1 and showed excellent solubility in common organic solvents, such as THF, CHCl₃, benzene, and hexane. The resulting poly( 4–8 )s containing adamantane‐1,3‐diyl linkages showed good thermal stability, and 10% weight loss temperatures (T₁₀) were observed over 400 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4111–4124     

Polymerization of meta-naphthoquinone methide: 3,4-benzo-6-methylenebicyclo [3.1.0] hex-3-ene-2-one

Polymerization behavior of meta-naphthoquinone methide, 3,4-benzo-6-methylenebicyclo[3.1.0]hex-3-ene-2-one ( 1 ), was studied. Radical initiator 2,2′-azobis(isobutyronitrile) (AIBN) induced polymerization of 1 , but ionic initiators potassium tert-butoxide, butyllithium, and boron trifluoride etherate did not. Polymerization of 1 proceeded via ring-opening and aromatization to give a polymer with head-to-tail monomer unit placement. Compound 1 copolymerized with methyl methacrylate (MMA) in the presence of AIBN to obtain the monomer reactivity ratios r₁ ( 1 ) = 0.28 ± 0.07 and r₂(MMA) = 0.39 ± 0.02 at 60°C and Q and e values of Q = 1.04 and e = −1.03, indicating that 1 is a conjugative and electron-donating monomer. Ring-opening and aromatization of 1 also took place in the copolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 741–746, 1997     

Synthesis and characterization of ABA-type block copolymer of poly(trimethylene carbonate) with poly(ethylene glycol): Bioerodible copolymer

ABA-type block copolymers of poly(trimethylene carbonate) with poly(ethylene glycol) (M_n 6820), PTMC-b-PEG-b-PTMC, were synthesized by the ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) in the presence of poly-(ethylene glycol) with stannous octoate catalyst, and the copolymers with various compositions were obtained. The PTMC-b-PEG-b-PTMC copolymers were characterized with Fourier transform infrared and nuclear magnetic resonance spectroscopies. The intrinsic viscosities of resulting copolymers increased with the increase of 1,3-dioxan-2-one content in feed while the molar ratio of monomer over catalyst kept constant. It has been observed that the glass transition temperature (T_g) of the PTMC segments in copolymers, recorded from differential scanning calorimetry, was dependent on the composition of copolymers. The melting temperature (T_m) of PEG blocks in copolymer was lower than that of PEG polymer, and then disappeared as the length of PTMC blocks increased. The results of dynamic contact angle measurement clearly revealed that the hydrophilicity of resulting copolymers increased greatly with the increase of PEG content in copolymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 695–702, 1998     

Synthesis and properties of the polythiourethanes obtained by the cationic ring‐opening polymerization of cyclic thiourethanes

The cationic ring‐opening polymerization of a five‐membered thiourethane [3‐benzyl‐1,3‐oxazolidine‐2‐thione (BOT)] with boron trifluoride etherate afforded the corresponding polythiourethane with a narrow molecular weight distribution in an excellent yield. The molecular weight of the polymers could be controlled by the feed ratio of the monomer to the initiator. A kinetic study of the polymerization revealed that the polymerization rate of BOT (1.3 × 10^?2 L mol^?1 min^?1) was two times larger than that of the six‐membered thiourethane [3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione (BTOT); 6.8 × 10^?3 L mol^?1 min^?1], and the monomer conversion obeyed the first‐order kinetic equation. These observations, along with the successful results in the two‐stage polymerization, supported the idea that this polymerization proceeded in a controlled manner. Block copolymerizations of BOT with BTOT were also carried out to afford the corresponding di‐ and triblock copolymers with narrow molecular weight distributions. The order of the 5% weight loss temperatures was as follows: poly(3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione) [poly(BTOT)] > poly(BTOT₅₄‐b‐BOT₄₆) > poly(3‐benzyl‐1,3‐oxazolidine‐2‐thione) [poly(BOT)]. This indicated that an increase in the BTOT unit content raised the decomposition temperature. The order of the refractive indices was poly(BOT) > poly(BTOT₅₄‐b‐BOT₄₆) > poly(BTOT₅₄‐b‐BOT₄₆‐b‐BTOT₅₀) > poly(BTOT); this was in accord with the order of the sulfur content in the polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4795–4803, 2006     

Influence of tertiary diamines on the synthesis of high‐molecular‐weight poly(1,3‐cyclohexadiene)

The living synthesis of poly(1,3‐cyclohexadiene) was performed with an initiator adduct that was synthesized from a 1:2 (mol/mol) mixture of N,N,N′,N′‐tetramethylethylenediamine (TMEDA) and n‐butyllithium. This initiator, which was preformed at 65 °C, facilitated the synthesis of high‐molecular‐weight poly(1,3‐cyclohexadiene) (number‐average molecular weight = 50,000 g/mol) with a narrow molecular weight distribution (weight‐average molecular weight/number‐average molecular weight = 1.12). A plot of the kinetic chain length versus the time indicated that termination was minimized and chain transfer to the monomer was eliminated when a preformed initiator adduct was used. Chain transfer was determined to occur when the initiator was generated in situ. The polymerization was highly sensitive to both the temperature and the choice of tertiary diamine. The use of the bulky tertiary diamines sparteine and dipiperidinoethane resulted in poor polymerization control and reduced polymerization rates (7.0 × 10⁻⁵ s⁻¹) in comparison with TMEDA‐mediated polymerizations (1.5 × 10⁻⁴ s⁻¹). A series of poly(1,3‐cyclohexadiene‐block‐isoprene) diblock copolymers were synthesized to determine the molar crossover efficiency of the polymerization. Polymerizations performed at 25 °C exhibited improved molar crossover efficiencies (93%) versus polymerizations performed at 40 °C (80%). The improved crossover efficiency was attributed to the reduction of termination events at reduced polymerization temperatures. The microstructure of these polymers was determined with ¹H NMR spectroscopy, and the relationship between the molecular weight and glass‐transition temperature at an infinite molecular weight was determined for polymers containing 70% 1,2‐addition (150 °C) and 80% 1,4‐addition (138 °C). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1216–1227, 2005     

Lateral thermal expansion of chitin crystals

Measurements of the thermal expansion coefficients (TECs) of chitin crystals in the lateral direction are reported. We investigated highly crystalline α chitin from the Paralithodes tendon and an anhydrous form of β chitin from a Lamellibrachia tube from room temperature to 250 °C, using X‐ray diffraction at selected temperatures in the heating process. For α chitin, the TECs of the a and b axes were α_a = 6.0 × 10⁻⁵ °C⁻¹ and α_b = 5.7 × 10⁻⁵ °C⁻¹, indicating an isotropic thermal expansion in the lateral direction. However, the anhydrous β chitin exhibited an anisotropic thermal expansion in the lateral direction. The TEC of the a axis was constant at α_a = 4.0 × 10⁻⁵ °C⁻¹, but the TEC of the b axis increased linearly from room temperature to 250 °C, with α_b = 3.0–14.6 × 10⁻⁵ °C⁻¹. These differences in the lateral thermal expansion behaviors of the α chitin and the anhydrous β chitin are due to their different intermolecular hydrogen bonding systems. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 168–174, 2001     

New chemosensory materials based on disubstituted polyacetylene with strong green fluorescence

A new imidazole‐containing disubstituted polyacetylene ( P1 ) with strong green fluorescence was successfully prepared through polymer reaction, which was nearly impossible to be obtained from the direct polymerization of its corresponding monomer. The polymer was soluble in common organic solvents, and its strong green fluorescence could be quenched completely by the Cu²⁺ and Co²⁺ ions, at the concentrations as low as 1.33 and 1.67 × 10⁻⁵ mol/L (0.85 and 0.92 ppm), respectively. Because of the high stability of the complex formed by cyanide and copper ions, the quenched green fluorescence of P1 by copper ions could be turned on upon the addition of trace cyanide (as low as 2.70 × 10⁻⁵ mol/L, 0.70 ppm), making P1 a new sensitive cyanide chemosensor. The results thus provided a new opportunity to develop anion chemosensors based on good cation chemosensors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8070–8080, 2008     

Organocopper‐catalyzed living radical polymerization initiated with aromatic sulfonyl chlorides

The living radical polymerization of methyl methacrylate initiated from aromatic sulfonyl chlorides and catalyzed by the new catalytic systems CuSBu/bpy CuSPh/bpy and CuCCPh/bpy (bpy = 2,2′‐bipyridine) is described. For a target degree of polymerization of 200, lowering the ratio of catalyst to sulfonyl chloride group from 1/1 to 0.25/1 mol/mol decreases the values of the experimental rate constant of polymerization from 5.12 × 10⁻², 2.4 × 10⁻², and 1.87 × 10⁻² min⁻¹ to 1.8 × 10⁻³, 4.9 × 10⁻³, and 4.2 × 10⁻³ min⁻¹ for CuSBu, CuSPh, and CuCCPh, respectively, whereas the corresponding initiator efficiency increases from 62 to 99%. The external orders of reaction in the catalyst are 0.79 for CuSPh, 0.88 for CuCCPh, and 1.64 for CuSBu. A mechanistic interpretation that involves the in situ generation of, most likely, the real catalyst CuCl, starting from combinations of CuSBu, CuSPh, and CuCCPh and sulfonyl chloride or alkyl halide growing species, is suggested. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4353–4361, 2000     

Kinetic study of gas-phase reactions of pinonaldehyde and structurally related compounds

Rate constants for the reactions of OH, NO₃, and O₃ with pinonaldehyde and the structurally related compounds 3-methylbutanal, 3-methylbutan-2-one, cyclobutyl-methylketone, and 2,2,3-trimethyl-cyclobutyl-1-ethanone have been measured at 300±5 K using on-line Fourier transform infrared spectroscopy. The rate constants obtained for the reactions with pinonaldehyde were: k_OH=(9.1±1.8)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_NO3=(5.4±1.8)×10⁻¹⁴ cm³ molecule⁻¹ s⁻¹, and k_O3=(8.9±1.4)×10⁻²⁰ cm³ molecule⁻¹ s⁻¹. The results obtained indicate a chemical lifetime of pinonaldehyde in the troposphere of about two hours under typical daytime conditions, [OH]=1.6×10⁶ molecule cm⁻³. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 527–533, 1997.     

Reaction of benzoxazine-based phenolic resins with strong and weak carboxylic acids and phenols as catalysts

The reaction of 3,4-dihydro-3,6-dimethyl-2H-1,3-benzoxazine using strong and weak carboxylic acids and phenols as catalysts has been studied using Fourier transform infrared (FTIR) spectroscopy. The auto-accelerated curing using sebacic acid as catalyst is further documented using ¹H-nuclear magnetic resonance (NMR) and dielectric analysis. Termination of curing, using strong acids or no catalyst, are discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1913–1921, 1999     

Water sorption by poly(tetrahydrofurfuryl methacrylate‐co‐2‐hydroxyethyl methacrylate). I. A mass‐uptake study

Cylindrical samples (≈5 mm × 20 mm) of poly(2‐hydroxyethyl methacrylate) and copolymers of 2‐hydroxyethyl methacrylate and furfuryl methacrylate were prepared, and the sorption of water into these cylinders was studied by the mass‐uptake method and by the measurement of the volume change at equilibrium. The equilibrium water content and volume change for the cylinders both varied systematically with the copolymer composition. The diffusion of water into the cylinders followed Fickian behavior, with the diffusion coefficients, dependent on the copolymer composition, varying from 2.00 × 10⁻¹¹ m²s⁻¹ for poly(2‐hydroxyethyl methacrylate) to 5.00 × 10⁻¹² m²s⁻¹ for poly(2‐hydroxyethyl methacrylate‐co‐tetrahydrofurfuryl methacrylate) with a 1 : 4 composition. The polymers that were rich in 2‐hydroxyethyl methacrylate were characterized by a water‐sorption overshoot, which was attributed to a slow reorientation of the polymer chains in the swollen rubbery regions formed after water sorption. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1939–1946, 2000     

The synthesis of poly(phenylacetylene)s with bulky chiral silyl groups and the thermal stability of their helical conformation

The polymerization of (−)‐p‐[(tert‐butylmethylphenyl)silyl]phenylacetylene (t‐BuMePhSi*PA) and (+)‐p‐[{methyl(α‐naphthyl)phenyl}silyl]phenylacetylene (MeNpPhSi*PA) with the [(nbd)RhCl]₂ Et₃N catalyst yielded polymers with very high molecular weights over 2 × 10⁶ in high yields. The optical rotations of the formed poly(t‐BuMePhSi*PA) and poly(MeNpPhSi*PA) were as high as −356 and −150° (c = 0.11 g/dL in CHCl₃), respectively. The circular dichroism (CD) spectrum of poly(t‐BuMePhSi*PA) in CHCl₃ exhibited very large molar ellipticities ([θ]) in the UV region: [θ]_max = 9.2 × 10⁴ ° · cm² · dmol⁻¹ at 330 nm and −8.0 × 10⁴ ° · cm² · dmol⁻¹ at 370 nm. The [θ]_max values of poly(MeNpPhSi*PA) were also fairly large: [θ]_max = 7.1 × 10⁴ ° · cm² · dmol⁻¹ at 330 nm and −5.3 × 10⁴ ° · cm² · dmol⁻¹ at 370 nm. The optical rotations of poly(t‐BuMePhSi*PA) and poly(MeNpPhSi*PA), measured in tetrahydrofuran, chloroform, and toluene solutions, were hardly dependent on temperature in the range 22–65 °C. The CD effects of these polymers hardly changed in the temperature range 28–80 °C, either. These results indicate that the helical structures of these polymers are thermally appreciably stable. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 71–77, 2001     

Polymerized ionic liquids: Effects of counter‐anions on ion conduction and polymerization kinetics

A novel imidazolium‐containing monomer, 1‐[ω‐methacryloyloxydecyl]‐3‐(n‐butyl)‐imidazolium (1BDIMA), was synthesized and polymerized using free radical and controlled free radical polymerization followed by post‐polymerization ion exchange with bromide (Br), tetrafluoroborate (BF₄), hexafluorophosphate (PF₆), or bis(trifluoromethylsulfonyl)imide (Tf₂N). The thermal properties and ionic conductivity of the polymers showed a strong dependence on the counter‐ions and had glass transition temperatures (T_g) and ion conductivities at room temperature ranging from 10 °C to −42 °C and 2.09 × 10⁻⁷ S cm⁻¹ to 2.45 × 10⁻⁵ S cm⁻¹. In particular, PILs with Tf₂N counter‐ions showed excellent ion conductivity of 2.45 × 10⁻⁵ S cm⁻¹ at room temperature without additional ionic liquids (ILs) being added to the system, making them suitable for further study as electro‐responsive materials. In addition to the counter‐ions, solvent was found to have a significant effect on the reversible addition‐fragmentation chain‐transfer polymerization (RAFT) for 1BDIMA with different counter‐ions. For example, 1BDIMATf₂N would not polymerize in acetonitrile (MeCN) at 65 °C and only achieved low monomer conversion (< 5%) at 75 °C. However, 1BDIMA‐Tf₂N proceeded to high conversion in dimethylformamide (DMF) at 65 °C and 1BDIMABr polymerized significantly faster in DMF compared to MeCN. NMR diffusometry was used to investigate the kinetic differences by probing the diffusion coefficients for each monomer and counter‐ion in MeCN and DMF. These results indicate that the reaction rates are not diffusion limited, and point to a need for deeper understanding of the role electrostatics plays in the kinetics of free radical polymerizations. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1346–1357     

Ring-opening polymerization of 1,5-dioxepan-2-one initiated by a cyclic tin–alkoxide initiator in different solvents

Ring-opening polymerization of 1,5-dioxepan-2-one initiated by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane was carried out in chloroform, dichloromethane, or 1,2-dichloroethane. Effects of reaction temperature, solvent, and monomer-to-initiator ratio were investigated. Polymerization kinetics showed a first-order dependence on the monomer for polymerization in chloroform and dichloromethane at 40°C. The kinetic order with respect to the initiator were a first order when dichloromethane was used as the solvent, the order in initiator changed, depending on the initiator concentration when chloroform was used. A maximum in molecular weight was observed at 40°C when chloroform was used as the solvent. The change of solvent did not markedly alter the polymerization rate or the molecular weight of the polymers prepared, as expected from the coordination insertion mechanism. Depolymerization of the polymers formed was observed when the reaction was allowed to continue after complete monomer conversion in chloroform as reaction medium at 40°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3407–3417, 1999     

Conjugated polymers based on 1,8‐naphthalene monoimide with high electron mobility

1,4,8,9‐Naphthalene diimides (NDIs) with strong electron accepting ability and high stability are excellent building blocks for semiconductor polymers. However, 1,8‐naphthalene monoimide (NMI) with similar structure and energy levels as that of NDI has never been used to construct conjugated polymers because of synthetic difficulty. Herein, 3,6‐dibromo‐NMI (DBNMI) with bulky alkyl groups was obtained effectively in a four‐step synthesis, and three donor‐acceptor (D‐A) type conjugated polymers based on NMI were firstly prepared. These polymers have strong absorption in the range of 300–600 nm, low LUMO level of 3.68 eV, and moderate bandgaps of 2.18 eV. Space charge limiting current measurements indicate these polymers are typical electron transporting materials, and the highest electron mobility is up to 5.8 × 10⁻³ cm² V⁻¹ s⁻¹, which is close to the star acceptor based on NDI (N2200, 5.0 × 10⁻³ cm² V⁻¹ s⁻¹). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 276–281