1,3-二(炔丙基氧)苯与4,4'-二叠氮甲基联苯的聚合反应及聚合物性能的研究

研究了1,3-二(炔丙基氧)苯(BPOB)与4,4'-二叠氮甲基联苯(DAMBP)的本体聚合行为. 核磁共振氢谱(¹H NMR)表征了聚合物的结构, 通过傅立叶红外技术(FT-IR)观察了反应过程中的基团变化情况, 采用差示扫描量热技术(DSC)研究了聚合反应动力学, 在较低温度(80 ℃)下二元叠氮与二元炔发生了1,3-偶极环加成聚合反应, 生成了主链含三唑环的聚合物; 利用Kissinger法和Crane法处理得到了反应的动力学参数: 反应级数为0.92, 反应活化能E_a为79.8 kJ• mol^－1, 频率因子A为1.26×10¹⁰ min^－1. 利用凝胶渗透色谱(GPC)、动态热机械分析(DMA)和热重分析方法(TGA)研究了聚合产物的性能. 结果表明, 聚合物的数均分子量达4.22×10⁴, 聚合物有较高的玻璃化转变温度和良好的热稳定性, 玻璃化转变温度达到131 ℃, 热分解温度(T_d5)达355 ℃     

Synthesis of thermally-induced phase separating polymer with well-defined polymer structure by living cationic polymerization. I. Synthesis of poly(vinyl ether)s with oxyethylene units in the pendant and its phase separation behavior in aqueous solution

Living cationic polymerization of alkoxyethyl vinyl ether [CH₂?CHOCH₂CH₂OR; R: CH₃ (MOVE), C₂H₅ (EOVE)] and related vinyl ethers with oxyethylene units in the pendant was achieved by 1-(isobutoxy)ethyl acetate ( 1 )/Et_1.5AlCl_1.5 initiating system in the presence of an added base (ethyl acetate or THF) in toluene at 0°C. The polymers had a very narrow molecular weight distribution (M?_w/M?_n = 1.1–1.2) and the M?_n proportionally increased with the progress of the polymerization reaction. On the other hand, the polymerization by 1 /EtAlCl₂ initiating system in the presence of ethyl acetate, which produces living polymer of isobutyl vinyl ether, yielded the nonliving polymer. When an aqueous solution of the polymers thus obtained was heated, the phase separation phenomenon was clearly observed in each polymer at a definite critical temperature (T_ps). For example, T_ps was 70°C for poly(MOVE), and 20°C for poly(EOVE) (1 wt % aqueous solution, M?_n ～ 2 × 10⁴). The phase separation for each case was quite sensitive (ΔT_ps = 0.3–0.5°C) and reversible on heating and cooling. The T_ps or ΔT_ps was clearly dependent not only on the structure of polymer side chains (oxyethylene chain length and ω-alkyl group), but also on the molecular weight (M?_n = 5 × 10³-7 × 10⁴) and its distribution. © 1992 John Wiley & Sons, Inc.     

Radiation-induced polymerization of glass-forming systems. II. Effect of temperature on the polymerization rate at higher conversion

The effect of temperature and conversion on the polymerization rate at higher conversion was investigated with regard to the γ-ray-induced polymerization of hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the supercooled phase. The polymerization rate changed from acceleration to depression at various conversions, depending on the polymerization temperature. It was found that T_v at which the viscosity of the system became ca. 10³ cpoise influenced the shape of the polymerization time–conversion curve. The experimentally obtained conversion reflection point in the polymerization time–conversion curve agreed with the conversion where the polymerization temperature is the same as the calculated T_v of the system. When the polymerization temperature was lower than T_v of the monomer, no acceleration of the polymerization occurred. When the polymerization temperature was higher than T_v of the polymer, no depression of the polymerization rate was observed. The effect of temperature on the saturated conversion (final conversion) was also examined in terms of T_g of the polymerization system. The experimentally obtained saturated conversion agreed with the conversion where the polymerization temperature is the same as the calculated T_g of the system.     

Synthesis of isotactic,syndiotactic, and heterotactic poly(tributyltin methacrylate) and poly(tributyltin methacrylate-co-styrene)

Pure isotactic and enriched syndiotactic poly(tributyltin methacrylate) were synthesized by the reaction of the respective poly(methacrylic acid) with tributyltin oxide. The heterotactic polymer was prepared in a similar manner and from free radical initiated (AIBN or BPO) polymerization of tributyltin methacrylate. In each case, polymer configuration was confirmed by ¹H-NMR of the hydrolyzed/esterfied product. The relatively large ¹¹⁹Sn-NMR linewidth of the isotactic tributyltin containing polymer suggests an intra-molecular exchange of the pendant tin groups. T_g, T_d, and M _v data are also reported. Poly(tributyltinmethacrylate-co-styrene) was prepared by free radical polymerization and reactivity ratios [r(styrene) = 0.51, r(TBTM) = 0.49] and Q-e values for TBTM (0.78, 0.38) were determined.     

Branched polymer via free radical polymerization of chain transfer monomer: A theoretical and experimental investigation

A simple mathematic model for the free radical polymerization of chain transfer monomers containing both polymerizable vinyl groups and telogen groups was proposed. The molecular architecture of the obtained polymer can be prognosticated according to the developed model, which was validated experimentally by homopolymerization of 4‐vinyl benzyl thiol (VBT) and its copolymerization with styrene. The chain transfer constant (C_T) of telogen group in a chain transfer monomer is considered to play an important role to determine the architecture of obtained polymer according to the proposed model, either in homopolymerization or copolymerization. A highly branched polymer will be formed when the C_T value is around unity, while a linear polymer with a certain extent of side chains will be obtained when the C_T value is much bigger or smaller than unity. The C_T of VBT was determined to be around 15 by using the developed model and ¹H NMR monitored experiments. The obtained poly(VBT) and its copolymers were substantiated to be mainly consisted of linear main chain with side branching chains, which is in agreement with the anticipation from the developed model. The glass transition temperature, number average molecular weight, and its distribution of those obtained polymer were primarily investigated. This model is hopefully to be used as a strategy to select appropriate chain transfer monomers for preparing hyperbranched polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1449–1459, 2008     

Impact of degree of phosphorylation on intrinsic and thermal properties of poly(styrenephosphonate diethyl ester)s

The intrinsic and thermal characteristics of poly(styrenephosphonate diethyl ester)s (PSP) are described. The properties of the polymer prepared by two synthetic procedures, phosphorylation of monodispersed polystyrene and polymerization of vinylbenzenephosphonate ester, are compared with chloromethylated polystyrene and with each other. Empirical formulas are presented for the relationships between the degree of polymerization, degree of phosphorylation, molecular weight, and intrinsic viscosity (in methanol and toluene). Thermal analysis reveals a sharp drop in T_g with an increase in degree of phosphorylation; T_g of the fully phosphorylated polystyrene is in the range of 9–30°C. The T_g ΔC_p values show significant decrease with augmentation in the degree of phosphorylation, yielding a value of 14 cal g^?1 for the fully phosphorylated polymer, compared with ～ 29 cal g^?1 for the parent polymer. The PSP is shown to have substantial capacity for dissolving heavy metal salts, such as UO₂(NO₃)₂, causing significant elevation in the T_g.     

Synthesis of transition‐metal‐ion‐selective poly(N‐isopropylacrylamide) hydrogels by the incorporation of an Aza crown ether

A functionalized cyclam was synthesized by the attachment of a polymerizable acryloyl group to one of the four nitrogens on the cyclam molecule. The polymerization of the functionalized cyclam was performed with N‐isopropylacrylamide and N,N′‐methylene bisacrylamide, and the gels obtained were studied in the presence of different transition‐metal‐ion solutions. There was a drastic difference in the phase‐transition temperature (T_c) of the poly(N‐isopropylacrylamide) (PNIPAAm)/cyclam gel in comparison with the pure PNIPAAm gel. For the described system, a T_c shift of 15 °C was obtained. The presence of functionalized cyclam increased the hydrophilicity and T_c of the aforementioned polymer gels in deionized water (at pH 6) because of the presence of protonated amino moieties. The PNIPAAm/cyclam gels showed a dependence of the swelling behavior on pH. T_c of the pure PNIPAAm gel was weakly influenced by the presence of any transition‐metal ions, such as Cu²⁺, Ni²⁺, Zn²⁺, and Mn²⁺. The addition of Cu²⁺ or Ni²⁺ to the PNIPAAm/cyclam gel reduced T_c of the polymer gel, and a shift of approximately 12 °C was observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1594–1602, 2003     

NOTE: Synthesis and Characterization of a Poly(acrylamide) with Pendant 1,4-piperazine-2,5-dione Moieties via Post-polymerization Cyclization

A poly(acrylamide) was synthesized from N ^α -Boc-N ^? -acrolyl-l-lysylglycine methyl ester via radical polymerization. This polymer typically had Mn ～ 100,000 g/mol, Mw ～ 300,000 g/mol, and a T_g of 93°C. Removal of Boc with TFA and cyclization with DABCO? in DMSO at 65°C afforded a soluble piperazinedione-containing polymer that had a T_g of 157°C and thermal stability up to 300°C. These results demonstrate a viable and efficient synthetic route to piperazinedione-containing polyacrylamides of high molecular weight. Related polymers that incorporate substituted indane moieties could be useful high T_g materials for fabrication of LC and NLO devices.     

Selective synthesis of structurally isomeric poly-β-ester and poly-δ-ester from β-(2-acetoxy-ethyl)-β-propiolactone with Al and Zn catalysts

It was found that structurally isomeric polymers were formed by the ring-opening polymerization of β-(2-acetoxy ethyl)-β-propiolactone with (EtAlO)_n and Et(ZnO)₂ZnEt catalysts; that is, the Al catalyst catalyzed normal polymerization which led to poly-β-ester and the Zn catalyst formed isomerized poly-β-ester as the main product. The polymer structure was determined by nuclear magnetic resonance (NMR), T₁-value, thermal decomposition product, and (T_g). The NMR studies for the monomer–catalyst systems indicated that the Al catalyst interacted predominately with the lactone group, whereas the Zn catalyst interacted with the side-chain ester group. These site-selective interactions could be related to the difference in the stereoregulation by the two catalysts during the poly(β-ester)-forming polymerization process.     

VINYL RADICAL POLYMERIZATION INITIATED WITH CERIC ION AND N-(SUBSTITUTED PHENYL) ACETAMIDE SYSTEMS

The polymerization of acrylamide (AAM)in H_2O/DMF or in H_2O/CH_3CN mixed solvent initiated with ceric ion (Ce~(4+) )/N-(substituted phenyl)-acetamide systems have been studied. The redox polymerization was revealed by the low value of overall activation energy (E_α) of AAM polymerization using ceric ion/N-(substituted phenyl) acetamide system as an initiator. The end group of polymer formed was detected by IR spectrum analysis method, it revealed the presence of N-(m-acetoxy-methylphenyl) acetamide (m-AAe) moiety end group in the polymer obtained with ceric ion/m-AAe initiation system.     

The Relationship of Reaction Temperature,Tg and Rich‐Syndiotacticity of Poly(alkyl methacrylate)s in Modified Microemulsion Polymerization

Nanoscale poly(alkyl methacrylate)s including poly(methyl methacrylate), poly(ethyl methacrylate), poly(cyclohexyl methacrylate), poly(iso‐butyl methacrylate) and poly(benzyl methacrylate) were prepared by a modified microemulsion polymerization procedure. NMR analysis suggested that these poly(methacrylate)s samples were higher in syndiotactic content, lower in isotactic content and the glass transition temperatures (T_gs) of them were also higher than those reported in the literature. The tacticities of the poly(methacrylate)s, beside the restricted volume effect of nanoparticles during the modified microemulsion polymerization, were mainly influenced by the reaction temperature, the lower the reaction temperature, the higher the syndiotacticity of the products. The syndiotacticity of the product decreased obviously when the polymerization was carried out at a temperature far above the T_g of the resulting polymer. It was also shown that the tacticity of the polymer was affected by the monomer structure, a monomer with the bulkier alkyl side group would liable to result in a polymer with richer syndiotacticity. Possible mechanism of rich‐syndiotacticity was also discussed.     

Preparation of poly(methyl acrylate)/phosphate/composites and its possible use as storage medium for radioactive isotopes

The distribution of ¹³⁷Cs, ¹⁵²Eu, ²³⁸U, and ⁸⁵Sr in a solid/aqueous system (poly(methyl acrylate)/phosphate/composite in contact with groundwater, was investigated using γ-Spectrometry and flourometry. The results were compared with earlier results with mineral phosphate in the solid phase. The effect of contact time, pH and the concentration of concurrent element were studied. The ability of the prepared polymer composites to keep the studied radioisotopes in the solid phase is much higher than mineral phosphate. The used polymer composites have been prepared consisting of natural phosphate powder and the monomer methyl acrylate using gamma irradiation. The yield of polymerization was followed up with respect to the irradiation dose using thermogravimetric analyzer (TGA). A thermomechanical analyzer (TMA) was used to locate the area of the glass transition temperatures (T _g ) using the mode with alternative variable force; the mode with constant force was used to determine the T _g of the pure polymer and the polymer composite prepared at the same irradiation dose. The T _g of the pure poly(methyl acrylate) is 13 ± 3 °C, and the T _g of poly(methyl acrylate)/phosphate/composites is 8 ± 3 °C. The T _g were also determined using the DSC technique, and similar values were found.     

Studies in ring-opening polymerization. I. 5,5-diethyl-1,3,2-dioxathiolan-4-one-2-oxide

The polymerization of 5,5-diethyl-1,3,2-dioxathiolan-4-one-2-oxide has been examined in various solvents at 60–100°C. Kinetic studies have shown that steric hindrance by the C₅ ethyl substituents prevents the occurrence of a bimolecular propagation reaction involving direct attack by a terminal hydroxyl group on the ring. In dry, nonhydroxylic solvents, the first-order rate-determining step in the sequence of reactions leading to polymer formation is a primary ring scission reaction in which a reactive intermediate is formed and sulfur dioxide eliminated. This intermediate, which is formally depicted as an α-lactone, then takes part in a very rapid chain-propagation process, the individual steps of which govern the molecular weight distribution of the polymer. The values of the activation energy (25–30 kcal/mole) and frequency factor (10¹¹?10¹³ sec^?1) for this polymerization reaction are, therefore, those associated with monomer decomposition and not the chain growth process. The molecular weight of the resultant polymer, poly-(3-pentylidene carboxylate) is controlled by adventitious traces of water which produce one carboxyl and one hydroxyl group per chain. Polymers having M?_n ～ 20,000 are readily obtained; these are materials of moderately high melting point (T_m ? 200°C) which crystallize from the melt into a banded spherulitic structure.     

Determination of concentration of propagating species in cationic polymerization of tetrahydrofuran

A spectroscopic method is described for the determination of the concentration of propagating species, [P^*], in the polymerization of tetrahydrofuran catalyzed by a mixture of AlEt₃?H₂O (1:0.5) and epichlorohydrin. A phenyl ether group was introduced at the polymer chain end by the quantitative reaction of the propagating species with excess sodium phenoxide. From the amount of phenyl ether groups in the polymer and of the remaining sodium phenoxide, [P^*] was determined by means of ultraviolet spectroscopy. The [P^*] value so determined was found to be in good agreement with that calculated from the amount and molecular weight of polymer based on a stepwise addition mechanism without chain transfer or termination. The present method of [P^*] determination was employed to examine the course of polymerization. It has now been found that [P^*] increases progressively during an induction period and remains unchanged in the subsequent period of polymerization.     

“LIVING”/CONTROLLED RADICAL POLYMERIZATION OF ETHYL METHYLACRYLATE WITH 2,2’-AZOBISISOBUTYRONITRILE/FERRIC CHLORIDE/TRIPHENYLPHOSPHINE INITIATION SYSTEM

"Living"/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl_3)/triphenylphosphine (PPh_3) initiation system at 85℃. Thc numberaverage molecular weight (M_n) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The M_w of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.22). The conversion can reach up to～100% and M_w of the polymers obtained is close to that designed. Thepolymerization mechanism belongs to the reverse atom transfer radical polymerization (ATRP). The polymer was end-functionalized by chlorine atom, which acts as a macroinitiator to proceed extension polymerization in the presence ofCuBr/bipy catalyst system via an ATRP process. The presence of ω-chlorine in the PEMA obtained was identified by ~1H-NMR spectrum.     

Cyclopolymerization. VI. Polymerization mechanism of N-methyl-N-allylmethacrylamide at lower temperature

Mechanistic investigations on the polymerization of N-methyl-N-allylmethacrylamide (MAMA) at lower temperature were carried out based upon the ESR studies of MAMA and its monofunctional counterparts irradiated with ⁶⁰Co γ rays. Cyclopolymerizability of MAMA was also studied in connection with the hindered rotation about its amide C? N bond. The propagating radical observed is only related to the methacryl group but not to the allyl group both in MAMA and its monofunctional counterparts. Polymerization at ?78°C yielded a polymer with a lower degree of cyclization(88.8%) as compared with that of polymers formed at higher temperatures (93.5% above 0°C). A structural study revealed that the increment of the unsaturation in the poly-MAMA obtained at ?78°C is due to the allyl group and the content of pendant methacryl group is almost unchanged over the temperature range from ?78 to 120°C. These results led to the conclusion that the polymerization of MAMA at ?78°C proceeds mainly through the methacryl group, the rate-determining step is the cyclization reaction, and, in addition, cyclization reaction scarcely occurs when it polymerizes through the allyl group. Since MAMA is frozen into a glassy state, the effect of glass transition temperature (T_g) has been studied and it was suggested that the polymerization of MAMA proceeds only above T_g.     

Retardation of radical polymerization rate by phenoxy radical produced from T-butylperoxy phenylcarbonate

T-butylperoxy phenylcarbonate (BPPC) was prepared. Its decomposition rate constant in cumene is given by k_d = 2.39 × 10¹⁵ exp(?17,300/T), where T is the absolute temperature. When BPPC decomposes to polymerize styrene at 100°C, it produces 12% phenoxy radical to total primary radicals. The phenoxy radical hardly adds to styrene and reacts the other primary radicals and polymer radical. Thus it retards the rate of polymerization.     

Preparation of ureido group bearing polymers and their upper critical solution temperature in water

Poly(2‐ureidoethylmethacrylate) (PUEM_n) was synthesized via reversible addition‐fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEM_n samples with different degrees of polymerization (n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate‐buffered saline (PBS) solution. The phase separation temperature (T_p) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below T_p. Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above T_p. Based on a fluorescence study, the polymer formed slightly hydrophobic environments below T_p. The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2845–2854     

Silolene-Bridged zirconocenium polymerization catalysts

A new silolene-bridged compound, racemic (1,4-butanediyl) silylene-bis (1-η⁵-in-denyl) dichlorozirconium ( 1 ) was synthesized by reacting ZrCl₄ with C₄H₈Si (IndLi)₂ in THF. 1 was reacted with trialkylaluminum and then with triphenylcarbenium tetrakis (penta-fluorophenyl) borate ( 2 ) to produce in situ the zirconocenium ion ( 1 ⁺). This “constraint geometry” catalyst is exceedingly stereoselective for propylene polymerization at low temperature (T_p = ?55°C), producing refluxing n-heptane insoluble isotactic poly(propylene) (i-PP) with a yield of 99.4%, T_m = 164.3°C, δH_f = 20.22 cal/g and M?_w = 350 000. It has catalytic activities of 10⁷?10⁸ g PP/(mol Zr · [C₃H₆] · h) in propylene polymerization at the T_p ranging from ?55°C to 70°C, and 10⁸ polymer/(mol Zr · [monomer] · h) in ethylene polymerization. The stereospecificity of 1 ⁺ decreases gradually as T_p approaches 20°C. At higher temperatures the catalytic species rapidly loses stereochemical control. Under all experimental conditions 1 ⁺ is more stereospecific than the analogous cation derived from rac-dimethylsilylenebis (1-η⁵-indenyl)dichlorozirconium ( 4 ). The variations of polymerization activities in ethylene and in propylene for T_p from ?55°C to +70°C indicates a Michaelis Mention kinetics. The zirconocenium-propylene π-complex has a larger insertion rate constant but lower thermal stability than the corresponding ethylene π-complex. This catalyst copolymerizes ethylene and propylene with reactivity ratios of comparable magnitude r_E ? 4r_p. Furthermore, r_E.r_p ? 0.5 indicating random copolymer formation. Both 1 and 4 activated with methylaluminoxane (MAO) exhibit much slower polymerization rates, and, under certain conditions, a lower stereo-selectivity than the corresponding 1 ⁺ or 4 ⁺ system. © 1994 John Wiley & Sons, Inc.     

Living cationic polymerization of vinylnaphthalene derivatives

The living cationic polymerization of 6‐tert‐butoxy‐2‐vinylnaphthalene (tBOVN), a vinylnaphthalene derivative with an electron‐donating group, was achieved with a TiCl₄/SnCl₄ combined initiating system in the presence of ethyl acetate as an added base at –30 °C. The absence of side reactions at low temperature was confirmed by ¹H NMR analysis of the resulting polymer. In contrast to this controlled reaction at –30 °C, reactions performed at higher temperature, such as 0 °C, frequently involved unwanted intramolecular or intermolecular Friedel–Crafts reactions of naphthalene rings due to the high electron density of these rings. The cationic polymerization of 6‐acetoxy‐2‐vinylnaphthalene, a derivative with an acetoxy group, was also controlled under similar conditions, but chain transfer reactions were not completely suppressed during the polymerization of 2‐vinylnaphthalene. The glass transition temperature (T_g) of the obtained poly(tBOVN) was 157 °C, a value higher by 94 °C than that of the corresponding styrene derivative. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4828–4834