Hyperbranched Poly([1,2,3]-triazole-[1,3,5]-triazine)s: An Unusual High Degree of Branching as an Effect of a Polyaddition Kinetics

The results of the kinetic study of melt and solution polymerization at the 1,3-dipolar cycloaddition reaction of the AB₂ monomer – 2-azido-4,6-bis(prop-2-yn-1-yloxy)-[1,3,5]-triazine (ABPOT) are presented in this work as well as the results of the ¹³C-NMR characterization of the obtained hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazine)s. It is established, that the first-shell substitution effect during polyaddition process and unusual high degree of branching (up to 0.9) of polymers synthesized in melt are held.     

New hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazines)

New hyperbranched polymers have been synthesized through the 1,3-dipolar polycycloaddition of the AB₂ monomer—2-azido-4,6-bis(propynyloxy)-[1,3,5]-triazine. The polymers contain conjugated heteroaromatic triazine and triazole cycles and terminal acetylene groups. The products have been characterized by exclusion liquid chromatography and IR and ¹H NMR studies.     

2,4-双(三氯甲基)-6-(4-甲氧基-1-苯乙烯基)-s-三嗪光引发剂的合成与聚合动力学研究

本研究以4-甲氧基苯甲醛和2,4-双(三氯甲基)-6-甲-基1,3,5-三嗪为原料合成了一种引发剂2,4-双(三氯甲基)-6-(4-甲氧基-1-苯乙烯基)-s-三嗪(BMT),并利用红外光谱、紫外光谱、核磁共振等手段对其结构进行表征.利用实时红外光谱研究其光聚合动力学性能,结果表明,不同引发剂浓度,不同单体和不同光强对单体双键转化率都有一定的影响.     

A facile synthesis of hyperbranched polyimides from 2,6,12-triaminotriptycene

<正>Based on monomer 2,6,12-triaminotriptycene,hyperbranched polyimides with high molecular weight modified with different terminal functional groups were obtained by polymerization of A_2+B_3 system.The prepared hyperbranched polyimides had good solubility in CHCl_3,DMF and THF,and performed no detective T_gs in the range of 50-330℃and high T_ds(5%) above 455℃.     

Synthesis and photophysical properties of hyperbranched polyfluorenes containing 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine as the core

A series of new hyperbranched polymers containing a 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine core unit and polyfluorene chain arms have been synthesized via Suzuki coupling, and characterized by NMR, IR and GPC. All the polymers exhibit good thermal stability with a high decomposition temperature. By changing the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine/fluorene ratio the UV-vis absorption and emission spectra can be partially tuned. It has been found that the polymers containing a low ratio of 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine units (P1-P3) have an absorption maximum around 385 nm, localized in the polyfluorene chain, and a shoulder around 425 nm ascribable to a charge transfer state involving the fluorene and the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine core. Increasing the molar ratio of the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine unit enhances the charge transfer band which becomes dominant for P4. The LUMO level of these polymers is relatively low due to the electron affinity of the triazine group. The polymers show dual emission, with a structured band in the blue (410-440 nm), attributed to the polyfluorene, and a broad band in the red (470-500 nm) associated with the charge transfer state. All the polymers exhibit two-photon absorption activity in the range of 660 to 900 nm with the maximum two-photon absorption (TPA) cross-section red-shifted from the corresponding linear absorption. The values of the TPA cross-sections vary from 1000 to 5000 GM, following the 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine/fluorene ratio.     

Hyperbranched aromatic poly(ether imide)s: Synthesis,characterization, and modification

The synthesis and characterization of hyperbranched aromatic poly(ether imide)s are described. An AB₂ monomer, which contained a pair of phenolic groups and an aryl fluoro moiety activated toward displacement by the attached imide heterocyclic ring, was prepared. The nucleophilic substitution of the fluoride with the phenolate groups led to the formation of an ether linkage and, subsequently, to the hyperbranched poly(ether imide), which contained terminal phenolic groups. A similar one‐step polymerization involving a monomer that contained silyl‐protected phenols yielded a hyperbranched poly(ether imide) with terminal silylated phenols. The degree of branching of these hyperbranched polymers was approximately 55%, as determined by a combination of model compound studies and ¹H NMR integration experiments. End‐capping reactions of the terminal phenolic groups were readily accomplished with a variety of acid chlorides and acid anhydrides. The nature of the chain‐end groups significantly influenced physical properties, such as the glass‐transition temperature and the solubility of the hyperbranched poly(ether imide)s. As the length of the acyl chain of the terminal ester groups increased, the glass‐transition temperature value for the polymer decreased, and the solubility of the polymer in polar solvents was reduced, becoming more soluble in nonpolar solvents. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2536–2546, 2001     

NOVEL HYPERBRANCHED POLY（PHENYLENE OXIDE）S WITH PHENOLIC TERMINAL GROUPS： EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.     

Architecture of polysaccharides with specific structures: synthesis of hyperbranched polysaccharides

An oxazoline sugar monomer 1 having two hydroxy groups was employed as an AB₂ type monomer for the synthesis of a hyperbranched aminopolysaccharide 2. The polymerization of 1 was carried out in the presence of an acid catalyst. The unit structure of product polysaccharide was determined to be β‐glucopyranan. The degree of branching was estimated by calculation of the content of the terminal units in the total units after the reaction of the polymerization product with 1,3‐dichloro‐1,1,3,3‐tetraisopropyldisiloxane. The molecular weight determined by the light‐scattering method was higher than that estimated by gel permeation chromatography. The detosylation of 2 took place under the alkaline conditions, giving rise to a free hyperbranched aminopolysaccharide. Copyright © 2000 John Wiley & Sons, Ltd.     

Michael addition polymerizations of difunctional amines (AA′) and triacrylamides (B3)

Novel hyperbranched poly(amido amine)s containing tertiary amines on the backbones and acryl or secondary amines as the surface groups were successfully synthesized via the Michael addition polymerizations of a triacrylamide [1,3,5‐triacryloylhexahydro‐1,3,5‐triazine (TT)] and a difunctional amine [n‐butylamine (BA)] NMR techniques were used to clarify the structures of hyperbranched polymers and polymerization mechanism. The reactivity of the secondary amine formed in situ was much lower than that of the primary amines in BA. When the feed molar ratio was 1:1 TT/BA, the secondary amine formed in situ was almost kept out of the reaction before the BA (AA′) and TT (B₃) monomers were consumed, and this led to the formation of A′B₂ intermediates containing one secondary amine group and two acryl groups. The self‐polymerization of the A′B₂ intermediates produced hyperbranched polymers bearing acryl as surface groups. For the polymerization with the feed molar ratio of 1:2 TT/BA, A′₂B intermediates containing one acryl group and two secondary amine groups were accumulated until self‐polymerization started; the self‐polymerization of the intermediates formed hyperbranched polymers with secondary amines as their surface groups. Modifications of surface functional groups were studied to form new hyperbranched polymers. The hyperbranched poly(amido amine)s were amorphous. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6226–6242, 2006     

重氮偶合反应合成超支化偶氮聚合物的光响应性能研究

利用重氮偶合反应和后重氮偶合反应制备了主链和端基含有不同假芪型偶氮苯生色团的超支化偶氮聚合物.利用氢核磁共振、紫外光谱、红外光谱等分析手段确定了合成聚合物的结构、玻璃化转变温度和光谱特性等.研究了聚合物光致二向色性的性能,此聚合物的取向有序度为0.063.用两束相干的P偏振Ar+激光对聚合物膜进行光加工,得到形状规则的正弦波形表面起伏光栅,末端偶氮苯基团的引入极大地增加了超支化偶氮聚合物的光响应速度.     

Hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s: Synthesis,characterization, end‐group modification,and optical properties

Novel AB₂‐type monomers such as 3,5‐bis(4‐methylolphenoxy)benzoic acid ( monomer 1 ), methyl 3,5‐bis(4‐methylolphenoxy) benzoate ( monomer 2 ), and 3,5‐bis(4‐methylolphenoxy)benzoyl chloride ( monomer 3 ) were synthesized. Solution polymerization and melt self‐polycondensation of these monomers yielded hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s. The structure of these polymers was established using FTIR and ¹H NMR spectroscopy. The molecular weights (M_w) of the polymers were found to vary from 2.0 × 10³ to 1.49 × 10⁴ depending on the polymerization techniques and the experimental conditions used. Suitable model compounds that mimic exactly the dendritic, linear, and terminal units present in the hyperbranched polymer were synthesized for the calculation of degree of branching (DB) and the values ranged from 52 to 93%. The thermal stability of the polymers was evaluated by thermogravimetric analysis, which showed no virtual weight loss up to 200 °C. The inherent viscosities of the polymers in DMF ranged from 0.010 to 0.120 dL/g. End‐group modification of the hyperbranched polymer was carried out with phenyl isocyanate, 4‐(decyloxy)benzoic acid and methyl red dye. The end‐capping groups were found to change the thermal properties of the polymers such as T_g. The optical properties of hyperbranched polymer and the dye‐capped hyperbranched polymer were investigated using ultraviolet‐absorption and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5414–5430, 2008     

Self‐controlled synthesis of hyperbranched poly(ether‐ketone)s from A2 + B3 approach in poly(phosphoric acid)

Self‐controlled synthesis of hyperbranched poly(ether‐ketone)s (HPEKs) were prepared from “A₂ + B₃” approach by using different monomer solubility in reaction medium. 1,3,5‐Triphenoxybenzene as a hydrophobic B₃ monomer was reacted with commercially available terephthalic acid or 4,4′‐oxybis(benzoic acid) as a hydrophilic A₂ monomer in a hydrophilic reaction medium, polyphosphoric acid (PPA)/phosphorous pentoxide (P₂O₅). The resultant HPEKs were soluble in various common organic solvents and had the weight‐average molecular weight in the range of 3900–13,400 g/mol. The results implied that HPEKs were branched structures instead of crosslinked polymers. The molecular sizes and shapes of HPEKs were further assured by morphological investigation with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Hence, the applied polymerization condition was indeed strong enough to efficiently facilitate polycondensation via “direct” Friedel‐Crafts reaction without gelation. It could be concluded that the polymer forming reaction was kinetically controlled by automatic and slow feeding of the hydrophobic B₃ monomer into the hydrophilic reaction mixture containing hydrophilic comonomer. As a result, hyperbranched structures were formed instead of crosslinked polymers even at full conversion (equifunctional monomer feed ratio). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3326–3336, 2009     

Using hyperbranched macromers as crosslinkers of methacrylic networks prepared by photopolymerization

Hyperbranched polymers were modified with terminal methacryloyl groups to be used as crosslinkers. The photoinitiated polymerization of several methacrylic monomers was examined in the presence of the hyperbranched macromers and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819^®) as a photoinitiator, upon UV irradiation. The photopolymerization kinetics was systematically studied by fluorescence and photoDSC in real time and in situ. Six types of monofunctional methacrylic monomers, two types of difunctional methacrylic monomers and four types of (meth)acrylate-modified hyperbranched macromers with different structures were employed for series of photopolymerization reactions. The incorporation of the hyperbranched macromers allows to increase the conversion at gelation and thus, final conversion. This behaviour is dependent on monomer and macromer nature and has been explained as due to an increase of the free volume fraction and confirmed by fluorescence. The results indicate that H-bonding and π-stacking induce self-assembly of hyperbranched macromers leading to reaction induced phase separation at the highest concentration of hyperbranched macromer used.     

单体慢加入技术对超支化聚合物分子参数的影响

详细分析了单体慢加入到多官能度核分子中制备超支化聚合物的动力学过程,以单体转化率为参数导出了产物的聚合度分布函数、平均聚合度、多分散性指标和支化度等分子参数的解析式,计算结果与文献报道的实验数据十分一致.分子参数依赖于核的官能度(f)、核分数(α)和单体转化率(x),这为通过聚合反应条件来进行分子结构的设计提供了理论依据.与一步聚合方法的产物相比,单体慢加入技术能够改进产物的分子量分布,提高其支化度.     

Synthesis and characterization of the B3-monomer and hyperbranched poly(aryl ether ketone)s

Hyperbranched poly(aryl ether ketone)s were prepared by polymerization of hydroquinone (A₂) and 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy]benzene (B₃). The gelation of hyperbranched poly(aryl ether ketone)s was effectively avoided. Hydroxyl-term inated (HPAEK-OH) and fluoro-terminated (HPAEK-F) hyperbranched poly(aryl ether ketone)s were prepared by using different A₂/B₃ mass ratio. The structure of the B₃ monomer was confirmed by MS, ¹H NMR/IR. The glass transition temperatures of the HPAEK-F and HPAEK-OH are 114°C and 162°C respectively. Thermal stability of HPAEK-F is higher than HPAEK-OH. __________ Translated from Acta Scientianum Naturalium Universitatis Jilinensis, 2005, 5 (in Chinese)     

Novel hyperbranched polyimides from 2,6,12-triaminotriptycene

The monomer 2,6,12-triaminotriptycene was synthesized and the structure was confirmed by IR and 1H NMR spectra. Hyperbranched polyimides modified with different terminal groups were obtained from precursors, anhydride- and aminoterminated hyperbranched poly（amic acid）s from polymerization of A2 ＋ B3 system. From gel permeation chromatograrn （GPC） characterization, representative products had high molecular weight. All polymers had good solubility in CHCl3, DMF and tetrahydrofuran （THF）, and performed no detective Tgs in the range of 50-300 ℃ and high Tds above 455 ℃ when 5% weight loss.     

Kinetics of self‐condensing vinyl hyperbranched polymerization in three‐dimensional space

Self‐condensing vinyl hyperbranched polymerization (SCVP) with A‐B* type monomer is simulated applying Monte Carlo method using 3d bond fluctuation lattice model in three‐dimensional space. The kinetics of SCVP with zero active energy of reaction is studied in detail. It is found that the maximal number–average and weight–average polymerization degrees and the maximal molecular weight distribution, at varying the initial monomer concentration and double bond conversion, are about 52, 190, and 3.93, respectively, which are much lower than theoretical values. The maximal average fraction of branching points is about 0.27, obtained at full conversion at the initial monomer concentration of 0.75. The simulation demonstrated the importance of steric effects and intramolecular cyclization in self‐condensing vinyl hyperbranched polymerization. The results are also compared with experiments qualitatively and a good agreement is achieved. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4486–4494, 2008     

SYNTHESIS AND CHARACTERIZATION OF HYPERBRANCHED VINYL POLYMERS FROM RAFT POLYMERIZATION OF AN ASYMMETRIC DIVINYL MONOMER

Hyperbranched vinyl polymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization of a styrenic asymmetric divinyl monomer.This was achieved by using cumyl dithiobenzoate or S-dodecyl-S′- (α,α′-dimethyl-α″-acetic acid)trithiocarbonate as the chain transfer agent,1,1′-azobis(cyclohexanecarbonitrile) or thermal initiation as a source of radicals.Cross-linking was inhibited by a rapid RAFT-based equilibrium between active propagation chains and dormant species,and thus a h...     

A2和B3单体重氮偶合反应制备超支化偶氮聚合物

利用A2/B3单体通过重氮偶合反应制备了超支化偶氮聚合物.利用核磁共振、红外光谱、紫外光谱和DSC热分析手段表征了聚合物的结构、光谱性能和玻璃化转变温度.合成的超支化偶氮聚合物具有很好的光响应性能,用488nm Ar+激光对超支化偶氮聚合物薄膜进行光加工,得到了规则的表面起伏光栅.     

Effect of slow monomer addition on molecular parameters of hyperbranched polymers synthesized in the presence of multifunctional core molecules

This study develops the kinetics for the slow monomer addition technique in the synthesis of hyperbranched polymers. Taking the conversion of monomer (x) as a variable, we derived the analytic expressions of molecular size distribution function, average degree of polymerization, polydispersity index and degree of branching. These expressions are not only amenable to the polymerization with high monomer conversion, but also appropriate to describe the whole polymerization process. Comparison with the one-pot...