Preparation and characterization of brominated polyethersulfones

A novel derivative of aromatic polyethersulfone (PES) was obtained by bromination. Victrex PES was reacted with bromine under various conditions: in solution, in suspension, and without solvent; with or without catalyst; and at low and elevated temperatures. Practically no bromination occurred in solution; in the other cases, brominated PESs to various extents were obtained. The degree of substitution (DS) varied between 0.3 and 2.3. It was found that no catalyst is required for this reaction; the temperature, the concentrations of bromine and of polymer in the reaction mixture, and the duration of the reaction are the determinant factors of the DS. The modified polymers were characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, and PGC‐MS, and their thermal properties were investigated by TGA and DSC methods. Further transformations of brominated PES as well as other new chemical reactions of PES will be the subject of later publications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1–13, 1999     

Surface modification of polymer structures by an imido-alkylene substitution reaction. I. Polycarbonate

The surface characteristics of molded polycarbonate sheet was altered via an imidoalkylene substitution reaction. The reaction was effected by contacting the surface with N-hydroxymethylmaleimide and a Friedel-Crafts alkylation catalyst in the presence of a mixture of solvents having limited solubility for polycarbonate. The substitution reaction suggested an aromatic electrophilic substitution mechanism. When N-hydroxymethylmaleimide was used in the surface treatment of polycarbonate sheet, imido-alkylene substitution not only took place but pendent C?C bonds were also incorporated along the polymer chain. When these C?C bonds were photochemically reacted with each other, the surface of the polycarbonate sheet became crosslinked and solvent resistant.     

聚合松香的溴化及其生成物阻燃性的研究

研究了聚合松香与液溴反应生成溴化聚合松香的方法 ,测定了溴化聚合松香的红外光谱和差热分析曲线。溴化聚合松香本身不燃烧 ,由溴化聚合松香配成的涂料具有一定的阻燃性     

纤维素-甲基丙烯酸丁酯的原子转移自由基聚合

以2-溴异丁酰溴为溴化剂,在离子液体([Amim]Cl)中与纤维素反应制备溴化纤维素大分子引发剂,以溴化纤维素/CuBr/N,N',N',N″,N″-五甲基二乙烯基三胺(PMDETA)为引发体系,N,N-二甲基甲酰胺(DMF)为溶剂,研究了甲基丙烯酸丁酯(BMA)的原子转移自由基聚合反应(ATRP)。合成了结构明晰的以纤维素为主链,聚甲基丙烯酸丁酯为支链的接枝共聚物Cellulose-g-PBMA。通过FTIR、1HNMR和GPC分别对大分子引发剂和接枝聚合物进行了分析。考察了聚合反应的活性特征,反应时间、催化体系、溶剂对聚合物相对分子质量(简称分子量,下同)及分子量分布的影响。结果表明,聚合反应转换率随时间呈线性增加,反应过程是活性可控聚合,催化剂和溶剂分别选用PMDETA/CuBr和DMF使反应更高效。     

The relative physical and thermal properties of polyurethane elastomers: Effect of chain extenders of bisphenols,diisocyanate, and polyol structures

Polyurethane elastomers based on polyols such as polycaprolactone diol of molar mass 2000 and polytetramethylene glycol of molar mass 2000; diisocyanantes such as diphenyl methane 4,4′ diisocyanate and dicyclohexyl methane 4,4′ diisocyanate; and chain extenders such as bisphenol-A, bisphenol-S,bisphenol-AF, and their brominated derivatives were synthesized. The effects of polyol, diisocyanate, and chain extender on the physical and thermal properties were also studied. The polyurethane elastomers were investigated by X-ray diffraction (XRD), differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Their limiting oxygen indexes (LOIs), solubilities, tensile strengths, hardnesses, and elongations were also determined. XRD analyses revealed that all of the polyurethanes were semicrystalline. However, the addition of bromine atoms in the polyurethanes markedly decreased their degrees of crystallinity. The brominated polyurethane elastomers have good flame retardancy, as indicated by large LOIs. All of the unbrominated polyurethanes showed good mechanical properties and high thermal stabilities. Polyurethanes based on bisphenol-S had lower solvent resistance caused by the dipolar nature of sulfonyl groups in the polymer chains. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1251–1265, 1997     

Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

The polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1a ) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1b ) were carried out with TaCl₅‐n‐Bu₄Sn to give relatively high‐molecular‐weight polymers ( 2a and 2b ) (M_n > 5 × 10⁵). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [ 4a(2) ] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO₂/N₂ separation factor of PEG‐functionalized polymer [ 4a(2) ] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO₂ permselectivity, and their CO₂/N₂ separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

端羟基遥爪聚异丁烯的制备与表征

使用5-叔丁基-1,3-二（2-氯代异丙基）苯/四氯化钛引发体系,通过可控活性正离子聚合反应制备了含双活性链末端的聚异丁烯,再使用1,3-丁二烯封端制备具有烯丙基氯末端结构的聚异丁烯,并结合四丁基氢氧化铵存在条件下水解的方法制备了双端羟基遥爪聚异丁烯,研究了封端时间对封端反应的影响,探讨了所得聚合物的热稳定性和低温性能。结果表明,在四丁基氢氧化铵存在条件下,由含氯链末端亲核取代方式制备所得聚合物的端羟基转化率高,反应时间短,原料便宜易得且制备工艺简便,所得产物的热稳定性及低温性能优良。     

Modified polysulfones 5: synthesis and characterization of tetramethyl polysulfones containing trimethylsilyl groups and their gas transport properties

Polysulfones with rigid backbone structures and silyl-containing substituents were prepared as membrane materials with potentially enhanced gas transport properties. Tetramethylbisphenol-A polysulfone (TMPSf) and tetramethylbiphenol polysulfone (TMPPSf) were made by polycondensation then post-modified to introduce trimethylsilyl (TMS) groups by bromination and lithiation methodology. Substitution of high levels of TMS groups at the ortho-sulfone sites was achieved using direct lithiation followed by addition of a trimethylsilane electrophile. In an approach to increase the overall TMS substitution level as well as introduce these groups on the bisphenol segment, both TMPSf and TMPPSf were cleanly brominated to a degree of substitution (DS) of 2.0 for bromine. While the subsequent lithium-halogen exchange and reaction with TMS electrophile did not give high regioselectivity because of steric hindrance, the overall DS of TMS in the polymers was increased when excess n-butyllithium was used to activate both brominated and ortho-sulfone sites. The polymer structures were characterized by NMR spectroscopy. Their thermal properties as well as O₂, N₂, CO₂ and CH₄ gas transport properties were measured. Polymers with a high DS of TMS had very high CO₂ and O₂ permeabilities and good permselectivities from N₂. The permselectivities of CO₂/N₂ were at or close to the Robeson upper-bound performance line [J. Membr. Sci. 62 (1991) 165].     

Etude PAR spectroscopie de la deshydratation de dérivés de l'alcool polyvinylique: Mise en evidence d'une répartition séquentielle des substituants

The dehydration of sulfopropylic and alkyl derivatives of poly(vinyl alcohol), with varying degrees of substitution, was observed using ultraviolet and visible spectroscopy. The dehydration reactions were carried out in a KHSO₄/heptane system kept under nitrogen at 100°C. Spectroscopic results show that definite sequences of conjugated double bonds are formed. The distribution of the number and length of these conjugated sequences was determined and compared with the theoretical values obtained assuming statistical distribution of the substituents. From this work it is concluded that: (1) the grafting of propane-sultone onto poly(vinylalcohol) molecules does not follow a random, statistical pattern, rather the reaction is sequential, i.e., of a “zip” type. The product molecules contain blocks of sulfopropylic-substituted vinyl alcohol groups. (2) The grafting of alkyl groups onto the poly(vinyl alcohol) molecules also occurs in a sequential manner. Results obtained show that the polymer chains contain at least two unreacted hydroxyl functions between each substituent alkyl group; this is in agreement with x-ray studies of these derivates. Further evidence of an ordered distribution of the substituents along the polymer chain is given by the heterogeneity in the compositions of the substituted polymers. The difference in the observed structures of the two substituted polymers demonstrates the importance of the nature of the substituents in determining the reaction mechanism. It is concluded that the structural differences observed are due to differences in the solubility of the sulfopropylic and alkyl reactants in the original reaction medium, and the hydrophilic and hydrophobic character of the sulfopropylic and alkyl substituents in the polymer.     

天然胶乳小分子模型物的溴化反应历程研究

选择与天然橡胶（ NR）分子链节具有相似结构的小分子2－甲基－2－丁烯作为天然橡胶溴化反应的参照模型,通过乳液法使小分子发生溴化反应,应用傅立叶红外光谱和气相色谱－质谱联用等测试手段对小分子溴化反应产物结构进行表征,并探讨小分子溴化反应历程。结果表明,小分子2－甲基－2－丁烯的C＝C双键在溴化过程中被还原为C－C单键,同时发生甲基氢原子的溴化取代,但溴化产物中并没有醛类物质生成。乳液法小分子溴化反应可能是自由基反应历程,且没有出现次溴酸参与反应历程的现象。     

Sulfonated poly(aryl ether ketone)s

Several kinds of commercially available polymers of the type poly(oxy-1,4-phenylenecarbonyl-1,4-phenylene) were sulfonated by reaction with mixtures of sulfuric acid and oleum. The ether/carbonyl group ratio of the polymer chain varied from 0.67 to 2.0. With decreasing amounts of ether links in the polymer backbone the sulfonation is hindered and the reaction conditions have to be stronger. To yield the same degree of sulfonation, the sulfuric trioxide concentration of the reaction mixture has to be increased. The achievable degree of substitution is limited, in general, to one sulfonate group per substitutable unit (oxy-phenylene-oxy- or oxy-phenylene-carbonyl unit). In dependence on the polymer structure, polymers with contents of sulfonate groups between 1.2 and 2.0 meq·g^–1 polymer are well soluble in dimethylformamide or N-methylpyrrolidone and it is possible to produce membranes with permselectivities >96% and electrical resistances < 2 Ω cm^–2. The sulfonated polymers were characterized by viscosimetry, sedimentation analysis and ¹³C NMR spectroscopy.     

交联型特辛基酚醛树脂酚羟基间位的溴化改性

以交联型特辛基酚醛树脂为原料进行改性,得到了一种交联型酚羟基间位溴化特辛基酚醛树脂,采用红外光谱（FTIR）、核磁碳谱（NMR）对树脂的结构进行了表征,结果表明成功地在酚羟基的间位上取代上了溴。采用莫尔法滴定反应测定剩余溴含量,计算得到苯环上的溴化率为84.7%。采用凝胶渗透色谱（GPC）对改性前后的酚醛树脂进行表征,结果表明经过溴化改性的酚醛树脂的数均分子量、重均分子量有所降低,分子量分布变窄。根据交联型特辛基酚醛树脂的交联机理,分别对交联型特辛基酚醛树脂、交联型链端溴化特辛基酚醛树脂树脂和交联型酚羟基间位溴化特辛基酚醛树脂交联橡胶的硫化历程和物理力学性能进行测试,结果表明改性后的酚羟基间位溴化特辛基酚醛树脂交联橡胶的硫化程度、硫化速度、力学性能都有明显提升。     

Phase-transfer catalytic activity of polymer-supported macrocyclic polyethers

Polymer-supported crown-ethers 9 and 11 (4.5-62% ring substitution) have been obtained by the reaction of 1% crosslinked chloromethylated polystyrenes with (hydroxymethyl) and (ω-hydroxynonyl)-18-crown-6, respectively. (Hydroxymethyl) and (ω-hydroxynonyl) [2.2.2] cryptands have also been prepared and linked in a similar way to afford catalysts 10 and 12 (3-6% ring substitution). Condensation of (aminomethyl) and (ω-aminodecyl [2.2.2] crypands with carboxylated 1% crosslinked polystyrene gave catalysts 13 and 14 (5-20% ring substitution). Phase-transfer catalytic activity of polymer-supported crown-ethers and cryptands has been tested in anion promoted nucleophilic aliphatic substitutions, and compared with that of polymer-supported phosphonium salts. The results indicate that catalytic activity of crown-ethers strongly depends on the combination of three parameters: the nature of the nucleophile, the percent ring substitution, and the presence of a spacer chain. Catalytic activity of cryptands is higher than that of crown-ethers and quaternary salts with similar percent ring substitution. It is much less dependent on the nature of the anions and on the presence of a spacer chain. As for the related quaternary salts, phase-transfer reactions promoted by polymer-supported crown-ethers and cryptands follow a mechanism identical with that observed for soluble catalysts: the reactions occur in the organic shell surrounding a complexed ligand; anions are exchanged at the water-organic solvent interface, the exchange not requiring the concomitant transfer of cationic counterparts.     

Bromine — containing polyurethane ionomers

Summary Polyurethane ionomers with reduced flammability were obtained by incorporating a brominated chain extender (dibromoneophentyl glycol-DBNPG) into the ionomers based on isophoronediisocyanate, polyoxytetramethylene glycol and 2,2-bis(hydroxymethyl)propionic acid. To examine the influence of brominated diol on the characteristics of the synthesized polymers, model polyurethane compounds containing various amounts of brominated and nonbrominated chain extenders (1,4-butanediol and neopenthyl glycol) were prepared, as well. The products were studied by FTIR, DSC and TGA methods. Hydrolytic stability of the ionomers in water was controlled by FTIR; their flammability was examined by oxygen index measurements.     

Alkylation of mixed micro‐ and nanocellulose to improve dispersion in polylactide

Nanocellulose tends to be aggregated due to the hydrogen bonding between three of the hydroxyl groups in each repeat unit, resulting in poor dispersion in non‐polar polymer matrices. In this research, to improve the dispersion of cellulose particles in a polymer matrix, a long hydrophobic alkyl chain was substituted for hydrogen in the hydroxyl group of cellulose via a bimolecular nucleophilic substitution (S_N2) reaction with alkyl bromide. Octyl (? C₈H₁₇) and dodecyl (? C₁₂H₂₅) groups were applied in this reaction, which is faster and simpler than other substitution reactions. The chemical structures of octyl and dodecyl ether cellulose were identified using Fourier transform infrared and NMR analyses. The contact angle with water and methylene iodide was measured to calculate the surface energy of alkyl nanocellulose. The surface energy was decreased by the substituted alkyl chain. The thermal properties, morphology and crystal structure of octyl and dodecyl ether cellulose were also investigated to determine the possibility of use as a reinforcement. Furthermore, polylactide/alkyl ether cellulose composites were prepared to make certain of sufficient dispersion of the alkyl ether cellulose in the polylactide matrix. The thermal and mechanical properties of the polylactide composite films were investigated. The optical transmittance of the polylactide composites was measured to confirm the relative dispersity. © 2014 Society of Chemical Industry     

Polymerization of melamine and formaldehyde in homogeneous continuous-flow stirred-tank reactors using functional group approach: Part B: Molecular weight distribution

Polymerization of melamine and formaldehyde in homogeneous continuous-flow stirred-tank reactors (HCSTRs) is reversible and leads to formation of branched polymer due to the hexafunctional nature of melamine. The reversed reaction of branched molecules depends upon the chain structure, and herein a simple model is presented to account for this. The functional group analysis of part A of this series has been extended and the molecular weight distribution (MWD) relations for HCSTRs have been solved. The MWD of the polymer is extremely sharp and the molecules are more branched compared to those for batch reactors and can be explained as follows. A given reacted bond can react with water as well as free formaldehyde through the reversed reaction, and the rate constant for the latter step is much larger. Consequently, the chain growth is limited as long as there is free formaldehyde in the reaction mass. Lower conversion of melamine and formaldehyde in HCSTRs is used to explain the behavior observed.     

The effect of bromination and inherent vinyl unsaturation on the drawing behavior of high-density polyethylene

Various high-density polyethylenes were brominated in order to eliminate the inherent vinyl Unsaturation in the polymer. They were then drawn uniaxially at three different temperatures, and the resulting fibrous materials were studied under a scanning electron microscope. It was found that the brominated samples yielded transparent fibrous materials that had more regular fibrillar structure and fewer surface overgrowths, cracks, and voids compared with the unbrominated polymers drawn under identical conditions. Bromination also appeared to improve the mechanical properties of the drawn and the undrawn polymer. High-density polyethylene that had no inherent vinyl Unsaturation also yielded transparent fibrous material with fibrillar structure similar to that of brominated polymers.     

Oxygen transmission through highly crosslinked polymers

Highly crosslinked polymers of varying structure were produced by the reaction of poly(glycidyl acrylate) (PGA) and methacrylate (PGM) with a variety of anhydride crosslinking agents: chlorendic (CA), glutaric (GA), maleic (MeA), succinic (SA), and polyrnalonic (pMnA) anhydrides. Topology was also varied by the use of a diluent and a comonomer in the backbone chain. Oxygen permeation measurements were made on these polymers coated onto a polypropylene film substrate before crosslinking. The crosslinking process greatly reduced the O₂ permeability which, however, was dependent not only on the degree of crosslinking (yield of the crosslinking reaction), but also on the crosslink density, the chemical nature of the structural elements, and the topology of the polymer network. Thus the most impermeable coating (XPGA/CA) was made not from the stiffest and bulkiest components (PGM and CA), but by the reaction of the bulkiest anhydride (CA) with the more flexible polymer backbone chain (PGA). This is explained in terms of the need for chain flexibility to produce a crosslinked structure of optimum space filling character and network tightness.     

溴化环氧树脂合成新工艺

以四溴双酚A(TBBPA)与环氧氯丙烷为原料,通过对溴化环氧树脂(EP)合成工艺的改进,并配合使用自制的催化剂,成功合成了高相对分子质量(Mw)的溴化EP。研究了催化剂的种类及用量、反应溶剂、反应体系浓度、反应温度和反应时间等对溴化EP合成反应的影响规律。试验结果表明:当w(自制催化剂)=0.2%(相对于物料而言)、以环己酮为溶剂、反应体系初始浓度为75%(反应一段时间后稀释至60%)、180～190℃反应8.5h时,所得溴化EP产品的Mw为6.02×104、Mw分布窄、其热稳定性良好且产品质量与国外同类产品相当。     

Synthesis and Properties of Thermosetting Modified Polyphenylene Ether

Summary A novel method for preparing thermosetting modified Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was developed by introducing allyl groups into PPE. It was successfully prepared from the reaction between brominated PPE and a Grignand reagent. The effects of substitution of bromine on methyl group and dosage of allylated Grignard reagent on the substitution value of allyl group were studied. The structure of the resulting allylated PPE (A-PPE) was characterized by ¹H-NMR and FT-IR spectroscopy. The curing reaction process was researched by differential scanning calorimetry (DSC), and the properties of the cured A-PPE were also investigated. The curing reaction of the A-PPE was first order reaction. The curing reaction activation energy obtained by Kissinger equation was 121.7 kJ/mol. The cured A-PPE resin is excellent not only in solvent resistance and dielectric properties, but also in thermal properties, moisture absorption and adhesion with glass fiber. The dielectric constant (ε) and dissipation factor (tan δ) of A-PPE composites reinforced with E-glass cloth at 1 MHz were measured as 2.84 and 2.65×10^-3, respectively. In addition, A-PPE was very easy to form into films.