A Stimuli‐Responsive Nanogel‐Based Sensitive and Selective Fluorescent Sensor for Cr3+ with Thermo‐Induced Tunable Detection Sensitivity

Stimuli‐responsive poly(N‐isopropylacrylamide) nanogel with covalently labeled rhodamine B urea derivatives (P(NIPAM‐co‐RhBUA)) is utilized as a sensitive fluorescent probe for Cr³⁺ in aqueous solution, and its thermo‐induced tunable detection capacity is investigated. At 20 °C, non‐fluorescent nanogel can selectively bind with Cr³⁺ over some other metal ions, leading to prominent fluorescence OFF–ON switching due to the recognition of RhBUA with Cr³⁺. Upon heating above the phase transition temperature, enhanced fluorescence intensity is observed (≈61‐fold increase at 45 °C) for the nanogel in the presence of Cr³⁺, accompanied with an improved detection sensitivity, which suggest that hydrophobic microenvironment generated in the collapsed nanogel plays an active role for their detection performance.

     

New Transformation of 1,3‐Oxathiolane‐2‐thione into 1,3‐Dithiolan‐2‐one via Polymerization and Depolymerization

This article deals with the cationic and anionic depolymerization of polydithiocarbonate, which was synthesized by cationic polymerization of 5‐phenoxymethyl‐1,3‐oxathiolane‐2‐thione ( 1 ) using methyl triflate as the initiator. The cationic depolymerization of the obtained polymer was carried out in the presence of 5–20 mol‐% of methyl triflate or triflic acid catalyst in chlorobenzene at 60 °C for 96 h to afford 4‐phenoxymethyl‐1,3‐dithiolan‐2‐one ( 2 ) in 35–83% yield. The anionic depolymerization of the polymer was carried out in the presence of 5 mol‐% of triethylamine or potassium tert‐butoxide at 20 °C for 24 h to afford 2 in 85–100% yield.     

Cationic polymerization behavior of isobutyl vinyl ether with arenesulfonates as non‐salt‐type latent thermal initiators

Substituted and unsubstituted benzenesulfonic acid cyclohexyl esters (1–7) were synthesized, and their possibility as latent thermal initiators in the cationic polymerization of isobutyl vinyl ether (IBVE) was examined to develop novel non‐salt type latent cationic initiators. Thermal decomposition of cyclohexyl p‐nitrobenzenesulfonate (2) in C₆D₆ at 80°C proceeded to exclusively afford cyclohexene as well as p‐nitrobenzenesulfonic acid. Cationic polymerization of IBVE with 1 mol % of an arenesulfonate (1–6) in bulk was carried out at 40–100°C for 12 h. No polymerization took place below 50°C, while the consumption of IBVE depending on both the polymerization temperature and the structure of the arenesulfonates was observed above 60°C. The obtained polyIBVEs showed bimodal GPC curves in several cases, revealing the intervention of two independent propagation species in the polymerization. The cationic polymerization of IBVE with cyclohexyl 2,4,6‐triisopropylbenzenesulfonate (7) at 80°C confirmed the acceleration effect of bulkiness on the polymerization rate. It was concluded that the polymerization was largely dependent on both electronic and steric factors of the aryl groups of the initiators which were directly related to the stability of the sulfonate anions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 293–301, 1999     

Cationic addition polymerization of 1,4‐dioxene using gacl3 as lewis acid catalyst: Long‐lived species‐mediated polymerization

Effective cationic addition polymerization of 1,4‐dioxene, a six‐membered cyclic olefin with two oxygen atoms adjacent to the double bond, was performed using a simple metal halide catalyst system in dichloromethane. The polymerization was controlled when the reaction was conducted using GaCl₃ in conjunction with an isobutyl vinyl ether–HCl adduct as a cationogen at –78°C to give polymers with predetermined molecular weights and relatively narrow molecular weight distributions. The long‐lived properties of the propagating species were further confirmed by a monomer addition experiment and the analyses of the product polymers by ¹H NMR and MALDI–TOF–MS. Although highly clean propagation proceeded, the apparent rate constant changed during the controlled cationic polymerization of 1,4‐dioxene. The reason for the change was discussed based on polymerization results under various conditions. The obtained poly(1,4‐dioxene) exhibited a very high glass transition temperature (T_g) of 217°C and unique solubility. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Application of S‐alkylsulfonium salts of aromatic sulfides as new thermal latent cationic initiators

The cationic initiation activity of derivatives of S‐methylsulfonium salts of dibenzothiophene ( 3a ), diphenyl sulfide ( 4a ), thioanisole ( 4d ), and tetrahydrothiophene ( 5 ) was evaluated in the polymerization of glycidyl phenyl ether ( 1 ). These initiators were soluble in 1 and capable of initiating the cationic polymerization of 1 on heating, with the exception of methyltetrahydrothiophenium tetrafluoroborate ( 5 ; in the range of room temperature to 160 °C). Among them, methyldiphenylsulfonium tetrafluoroborate ( 4a ) showed a moderate thermal latency that brought about the polymerization of 1 efficiently at 160 °C but not below 80 °C. S‐Alkylsulfonium salts of aromatic sulfides such as phenoxathiin ( 6a ) and thianthrene ( 6b ) also were evaluated for their activity in the cationic polymerization of 1 , from which the thermal latent behavior of these salts also was confirmed (i.e., there was no reaction at 60 °C for 3 h, but there was a high enough conversion at 140 °C). Furthermore, the catalytic activity of S‐alkylsulfonium derivatives was controllable by both the property of the substituents on the aromatic rings and the character of the alkyl groups on the sulfur atom. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 18–27, 2000     

Cationic organoiron polyelectrolyte three‐arm stars

With nucleophilic aromatic substitution and ester condensation reactions, several new first‐generation dendrimers and star‐shaped molecules containing cationic cyclopentadienyl iron moieties were prepared. Although the solubility of the organoiron star‐shaped molecules with ether bridges in polar solvents was found to decrease with an increase in the size of the molecule, the addition of ester linkages resulted in a sharp decrease in the solubility, regardless of the size. The thermal behavior of these molecules was examined with differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperatures (T_g's) of these star‐shaped molecules ranged from 123 to 170 °C. However, the addition of the ester functionality allowed for an increase in the T_g's to 151–194 °C. The star‐shaped molecules were thermally stable up to 200 °C, above which a loss of the cationic cyclopentadienyl iron moieties occurred. Degradation of the ester chains started at 321 °C, and degradation of the ether chains started at 408 °C. Electrochemical studies of the ether star‐shaped molecules showed a reduction of the 18‐electron iron centers to 19‐electron centers. This redox system was reversible at low temperatures, whereas it was irreversible at room temperature. Moreover, an increase in the number of metal moieties caused an overlap and broadening of the redox wave. Viscosity studies showed a polyelectrolyte effect for the organoiron star‐shaped molecules. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1382–1396, 2005     

Bio‐based nanocomposites composed of photo‐cured epoxidized soybean oil and supramolecular hydroxystearic acid nanofibers

A mixture of epoxidized soybean oil (ESO), (R)‐12‐hydroxystrearic acid (HSA) and a photoinitiator for cationic polymerization in the ESO/HSA weight ratio 10/1 was heated to 100 °C and gradually cooled to room temperature to give bio‐based gelatinous material. The photo‐curing of the gel afforded a nanocomposite composed of crosslinked ESO and supramolecular HSA nanofibers. The transmission electron microscopy observation of the photo‐cured ESO/HSA revealed that dendritic clusters of HSA nanofibers are formed in the crosslinked ESO matrix. In the differential scanning calorimetry chart of the ESO/HSA, a thermal transition from the mesophase composed of supramolecular nanofibers to isotropic state was observed at 67 °C (ΔH = 22.6 J/g‐HSA), while the T_m of crystalline HSA is 77.7 °C (ΔH_m = 159 J/g‐HSA). Tensile strength at 20 °C of the ESO‐HSA was ～80% higher than that of photo‐cured ESO without HSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 669–673, 2009     

Synthesis of novel tri‐benzoxazine and effect of phenolic nucleophiles on its ring‐opening polymerization

A trifunctional benzoxazine, 1,3,5‐tris(3‐phenyl‐3,4‐dihydro‐2H‐benzo[1,3]oxazin‐6‐yl)benzene (T‐Bz) was synthesized and in an effort to reduce its curing temperature (curing maxima at 238 °C), it was mixed with various phenolic nucleophiles such as phenol (PH), p‐methoxy phenol (MPH), 2‐methyl resorcinol (MR), hydroquinone (HQ), pyrogallol (PG), 2‐naphthol (NPH), 2,7‐dihydroxy naphthalene (DHN), and 1,1'‐bi‐2‐naphthol (BINOL). The influence of these phenolic nucleophiles on ring‐opening polymerization temperature of T‐Bz was examined by DSC and FTIR analysis. T‐Bz undergoes a complete ring‐opening addition reaction in the presence of bi‐ and trifunctional phenolic nucleophiles (MR/HQ/PG/DHN) at 140 °C (heated for 3 h) and forms a networked polybenzoxazine (NPBz). The NPBzs showed a high thermal stability with T_d20 of 350–465 °C and char yield of 67–78% at 500 °C; however, a diminutive weight loss (6.9–9.8%) was observed at 150–250 °C (T_d5: 215–235 °C) due to degradation of phenolic end groups. This article also gives an insight on how the traces of phenolic impurities can alter the thermal properties of pure benzoxazine monomer as well as its corresponding polymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2811–2819     

Synthesis of cationic diacetylene‐co‐carbazole‐co‐fluorene polymers and their sensitive fluorescent quenching properties with DNA

Two neutral precursor conjugated copolymers based 2,7‐diethynylfluorene and 3,6‐diethynylcarbazole units in the main chain ( PFC and PF2C ) were prepared by Hay coupling polymerization. Their cationic copolymers ( CPFC and CPF2C ) were prepared by the methylation of their diethylpropylamino groups with CH₃I. For comparison, neutral conjugated homopolymers of 2,7‐diethynylfluorene ( PF ), 3,6‐diethynylcarbazole units ( PC ) and their cationic polymers ( CPF and CPC ) were also prepared with the same method. A comparative study on the optical properties of cationic polymers CPFC and CPF2C in DMF and DMF/H₂O showed that they underwent water‐induced aggregation. The spectral behaviors of CPFC and CPF2C with calf thymus DNA showed that a distinct fluorescent quenching took place with minute addition of CT DNA (3.3 × 10^?13 M). The results showed that the polymers would be promising biosensor materials for sensitive detection of DNA. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4168–4177, 2010     

Efficient Synthesis of 3‐Phenylnaphtho[2,3‐b]furan‐4,9‐diones in Water and Their Fluorimetric Study in Solutions

A simple and efficient protocol has been developed for the synthesis of 3‐phenylnaphtho[2,3‐b]furan‐4,9‐diones by domino reaction of α‐bromonitroalkenes to 2‐hydroxynaphthalene‐1,4‐dione. With the optimal reaction conditions [NaOAc (120 mol%), water, 70°C, 7 h], the scope of the domino reaction was explored and the green approach provided the desired products in moderate to good yields at elevated temperature under aqueous‐mediated conditions. A mechanistic rationalization for this reaction is also provided. The absorption characteristics of the compounds were examined by UV‐Vis spectra and fluorescence spectroscopy. All compounds were fluorescent in solution emitting at blue light (432–433 nm), green light (512–536 nm), or yellow light (591 nm).     

Preparation and phase behavior of poly(4‐trimethylsilylstyrene)‐block‐polyisoprene

Three poly(4‐trimethylsilylstyrene)‐block‐polyisoprenes (TIs), the molecular weights of which were 82,000, 152,000 and 291,000 (TI‐82K, TI‐152K, and TI‐291K), were synthesized by sequential anionic polymerizations. The component polymers were a miscible pair that presented a lower critical solution temperature phase diagram if blended. The TI phase behavior was investigated with transmission electron microscopy. The order–disorder transition could be observed at a temperature between 200 °C (the ordered state) and 150 °C (the disordered state) for the block copolymer TI‐152K. The block copolymer TI‐82K presented the disordered state at 200 °C, whereas TI‐291K was in the ordered state at 150 °C. With the Flory–Huggins interaction parameter between poly(4‐trimethylsilylstyrene) and polyisoprene, which was evaluated by small‐angle neutron scattering for the block copolymers, the TI phase behavior could be reasonably explained by mean‐field theory. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1214–1219, 2005     

Effect of Temperature on Self‐Interaction of Human‐Like Collagen

Effects of temperature on self‐interaction of human‐like collagen (HLC) were investigated by hydrophobic interaction chromatography, calorimetric measurement, and sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis. Results show that three types of interaction roles may exist between HLC molecules at 3–50°C, which were divided into three narrower temperature ranges. In temperature range from 3–22°C, hydrogen bonding plays a key role in the formation of a gelatinous aggregate. In the range of 22–38°C, hydrophobic bonds accompanied by hydrogen bonds are involved in the formation compact aggregates. When temperature is above 38°C the hydrophobic effect formed in the HLC monomer results in the loss of its ability to self‐interact.     

Block copolymer composition drives function of self‐assembled nanoparticles for delivery of small‐molecule cargo

Nanoparticles are useful for the delivery of small molecule therapeutics, increasing their solubility, in vivo residence time, and stability. Here, we used organocatalytic ring opening polymerization to produce amphiphilic block copolymers for the formation of nanoparticle drug carriers with enhanced stability, cargo encapsulation, and sustained delivery. These polymers comprised blocks of poly(ethylene glycol) (PEG), poly(valerolactone) (PVL), and poly(lactide) (PLA). Four particle chemistries were examined: (a) PEG‐PLA, (b) PEG‐PVL, (c) a physical mixture of PEG–PLA and PEG–PVL, and (d) PEG–PVL–PLA tri‐block copolymers. Nanoparticle stability was assessed at room temperature (20 °C; pH = 7), physiological temperature (37 °C; pH = 7), in acidic media (37 °C; pH = 2), and with a digestive enzyme (lipase; 37 °C; pH = 7.4). PVL‐based nanoparticles demonstrated the highest level of stability at room temperature, 37 °C and acidic conditions, but were rapidly degraded by lipase. Moreover, PVL‐based nanoparticles demonstrated good cargo encapsulation, but rapid release. In contrast, PLA‐based nanoparticles demonstrated poor stability and encapsulation, but sustained release. The PEG–PVL–PLA nanoparticles exhibited the best combination of stability, encapsulation, and release properties. Our results demonstrate the ability to tune nanoparticle properties by modifying the polymeric architecture and composition. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1322–1332     

Variable‐Temperature Powder X‐ray Diffraction of Aromatic Carboxylic Acid and Carboxamide Cocrystals

The effect of temperature on the cocrystallization of benzoic acid (BA), pentafluorobenzoic acid (FBA), benzamide (BAm), and pentafluorobenzamide (FBAm) is examined in the solid state. BA and FBA formed a 1:1 complex 1 at ambient temperature by grinding with a mortar and pestle. Grinding FBA and BAm together resulted in partial conversion into the 1:1 adduct 2 at 28 °C and complete transformation into the product cocrystal at 78 °C. Further heating (80–100 °C) and then cooling to room temperature gave a different powder pattern from that of 2 . BAm and FBAm hardly reacted at ambient temperature, but they afforded the 1:1 cocrystal 3 by melt cocrystallization at 110–115 °C. Both BA+FBAm ( 4 ) and BA+BAm ( 5 ) reacted to give new crystalline phases upon heating, but the structures of these products could not be determined owing to a lack of diffraction‐quality single crystals. The stronger COOH and CONH₂ hydrogen‐bonding groups of FBA and FBAm yielded the equimolar cocrystal 6 at room temperature, and heating of these solids to 90–100 °C gave a new crystalline phase. The X‐ray crystal structures of 1 , 2 , 3 , and 6 are sustained by the acid–acid/amide–amide homosynthons or acid–amide heterosynthon, with additional stabilization from phenyl–perfluorophenyl stacking in 1 and 3 . The temperature required for complete transformation into the cocrystal was monitored by in situ variable‐temperature powder X‐ray diffraction (VT‐PXRD), and formation of the cocrystal was confirmed by matching the experimental peak profile with the simulated diffraction pattern. The reactivity of H‐bonding groups and the temperature for cocrystallization are in good agreement with the donor and acceptor strengths of the COOH and CONH₂ groups. It was necessary to determine the exact temperature range for quantitative cocrystallization in each case because excessive heating caused undesirable phase transitions.     

Substituent effect on the cationic ring‐opening polymerization of acyloxymethyl five‐member cyclic dithiocarbonates

Five‐member cyclic dithiocarbonates were synthesized by the reactions of carbon disulfide with benzoic, p‐anisic, p‐chlorobenzoic, 1‐naphthalenecarboxylic, p‐nitrobenzoic, and p‐(tert‐butyl)benzoic glycidyl esters, and their cationic ring‐opening polymerizations were carried out with methyl trifluoromethane sulfonate and trifluoromethane sulfonic acid as initiators at room temperature to 80 °C. Polymers with number‐average molecular weights of 3400–24,900 were obtained in high yields, and their structures were estimated by NMR and IR spectroscopy. The monomers showed a clear difference in the polymerization rate according to the substituents. The rate of polymerization decreased in the order of p‐chlorobenzoic ≥ benzoic > 1‐naphthalenecarboxylic > p‐nitro‐benzoic > p‐tert‐butylbenzoic > p‐anisic. The data of the reaction kinetics, NMR studies, and molecular orbital calculations proved a plausible mechanism involving the participation of p‐substituted benzoyloxymethyl groups to stabilize the cationic propagating end. The polymers showed decomposition temperatures with 5% weight loss ranging from 200 to 260 °C. No glass‐transition temperatures for the polymers were observed below 200 °C by differential scanning calorimetry. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3967–3980, 2001     

Hyaluronic Acid/Poly(β‐Amino Ester) Polymer Nanogels for Cancer‐Cell‐Specific NIR Fluorescence Switch

Cancer‐cell‐specific pH‐activatable polymer nanogels consisting of CD44‐receptor‐targeting hyaluronic acid (HA), pH‐sensitive poly(β‐amino ester) (PBAE), and near‐infrared (NIR) fluorescent indocyanine green (ICG) were synthesized and used to detect cancer cells. The HA/PBAE/ICG‐polymer‐nanogel‐based NIR probe was nonfluorescent outside of tumor cells. After internalization by CD44‐receptor‐mediated endocytosis, the probe accumulated in the late endosomes or lysosomes where the acidic pH solubilized the PBAE and caused instant disassembly of the polymer nanogel. During endosomal maturation, the encapsulated ICG was released from its quenched state, inducing strong NIR fluorescence recovery. The nanogels generate a highly tumor‐specific NIR signal with a reduced background signal.     

Atom transfer radical polymerization of 6‐O‐methacryloyl‐1,2;3,4‐di‐O‐isopropylidene‐D‐galactopyranose in solution

A detailed exploration of the atom transfer radical polymerization (ATRP) of a sugar‐carrying monomer, 6‐O‐methacryloyl‐1,2;3,4‐di‐O‐isopropylidene‐D‐galactopyranose (MAIPGal) was performed. The factors pertinent to ATRP, such as initiators, ligands, catalysts, and temperature were optimized to obtain good control over the polymerization. The kinetics were examined in detail when the polymerization was initiated by methyl 2‐bromoisopropionate (2‐MBP), ethyl 2‐bromoisobutyrate (2‐EBiB), or a macroinitiator, [α‐(2‐bromoisobutyrylate)‐ω‐methyl PEO] (PEO–Br), with bipyridine (bipy) as the ligand at 60 °C or by 2‐EiBB with N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as the ligand at room temperature (23 °C). The effects of the catalysts (CuBr and CuCl) were also investigated. We demonstrate that the successful ATRP of MAIPGal can be achieved for 2‐EBiB/CuBr/bipy and 2‐MBP/CuCl/bipy at 60 °C and for 2‐EBiB/CuBr/PMDETA at room temperature. The initiation by 2‐EBiB at room temperature with PMDETA as the ligand should be the most optimum operation for its moderate condition and suppression of many side reactions. Chain extension of P(MAIPGal) prepared by ATRP with methyl methacrylate (MMA) as the second monomer was carried out and a diblock copolymer, P(MAIPGal)‐b‐PMMA, was obtained. Functional polymers, poly(D‐galactose 6‐methacrylate) (PGMA), PEO‐b‐PGMA, and PGMA‐b‐PMMA were obtained after removal of the protecting groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 752–762, 2005     

Tuning the LCST of poly(2‐cyclopropyl‐2‐oxazoline) via gradient copolymerization with 2‐ethyl‐2‐oxazoline

Poly(2‐propyl‐oxazoline)s can be prepared by living cationic ring‐opening polymerization of 2‐oxazolines and represent an emerging class of biocompatible polymers exhibiting a lower critical solution temperature in aqueous solution close to body temperature. However, their usability is limited by the irreversibility of the transition due to isothermal crystallization in case of poly(2‐isopropyl‐2‐oxazoline) and the rather low glass transition temperatures (T_g < 45 °C) of poly(2‐n‐propyl‐2‐oxazoline)‐based polymers. The copolymerization of 2‐cyclopropyl‐2‐oxazoline and 2‐ethyl‐2‐oxazoline presented herein yields gradient copolymers whose cloud point temperatures can be accurately tuned over a broad temperature range by simple variation of the composition. Surprisingly, all copolymers reveal lower T_gs than the corresponding homopolymers ascribed to suppression of interchain interactions. However, it is noteworthy that the copolymers still have T_gs > 45 °C, enabling convenient storage in the fridge for future biomedical formulations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3118–3122     

Tuning of the Temperature Window for Unit‐Cell and Pore‐Size Enlargement in Face‐Centered‐Cubic Large‐Mesopore Silicas Templated by Swollen Block Copolymer Micelles

The unit‐cell size and pore diameter as functions of temperature are investigated in the syntheses of FDU‐12 silicas with face‐centered cubic structure templated by Pluronic (PEO‐PPO‐PEO) block copolymer micelles swollen by toluene. The temperature range in which the unit‐cell size and pore size strongly increase as temperature decreases is correlated with the critical micelle temperature (CMT) of the surfactant. While Pluronic F127 affords a wide range of unit‐cell parameters (28–51 nm) and pore diameters (16–32 nm), it renders moderately enlarged pore sizes at 25 °C. The use of Pluronic F108 with higher CMT affords FDU‐12 with very large unit‐cell size (～49 nm) and large pore diameter (27 nm) at 23 °C. Large unit‐cell size (40–41 nm) and pore size (22 nm) were obtained even at 25 °C. The application of Pluronics F87 and F88 with much smaller molecular weights and higher CMTs also allows one to synthesize FDU‐12 with quite large unit‐cell parameters and pore sizes at room temperature. The present work demonstrates that one can judiciously select Pluronic surfactants with appropriate CMT to shift the temperature range in which the pore diameter is readily tunable.     

Anionic polymerization of N,N‐dialkyl‐2‐methylenebut‐3‐enamide: Effect of alkyl substituents on polymerization behavior

Anionic polymerizations of three 1,3‐butadiene derivatives containing different N,N‐dialkyl amide functions, N,N‐diisopropylamide (DiPA), piperidineamide (PiA), and cis‐2,6‐dimethylpiperidineamide (DMPA) were performed under various conditions, and their polymerization behavior was compared with that of N,N‐diethylamide analogue (DEA), which was previously reported. When polymerization of DiPA was performed at ?78 °C with potassium counter ion, only trace amounts of oligomers were formed, whereas polymers with a narrow molecular weight distribution were obtained in moderate yield when DiPA was polymerized at 0 °C in the presence of LiCl. Decrease in molecular weight and broadening of molecular weight distribution were observed when polymerization was performed at a higher temperature of 20 °C, presumably because of the effect of ceiling temperature. In the case of DMPA, no polymer was formed at 0 °C and polymers with relatively broad molecular weight distributions (M_w/M_n = 1.2) were obtained at 20 °C. The polymerization rate of PiA was much faster than that of the other monomers, and poly(PiA) was obtained in high yield even at ?78 °C in 24 h. The microstructure of the resulting polymers were exclusively 1,4‐ for poly(DMPA), whereas 20–30% of the 1,2‐structure was contained in poly(DiPA) and poly(PiA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3714–3721, 2010