Polyamide‐6‐b‐polybutadiene block copolymers: Synthesis and properties

Polyamide‐6 (PA6)/polybutadiene (PB) block copolymers were synthesized with macroactivators (MAs) based on hydroxyl‐terminated polybutadiene functionalized with diisocyanates and having three N‐acyllactam chain‐growing centers per molecule. Two different diisocyanates, hexamethylene diisocyanate and isophorone diisocyanate, were applied as precursors for the MAs. The sodium salt of ε‐caprolactam was chosen as an initiator. The influence of the MA type and concentration on the anionic ring‐opening polymerization of ε‐caprolactam at 180°C was studied. A large percentage of the gel fraction in the copolymers was estimated, indicating crosslinked macromolecules. The structure and phase behavior of the copolymers were investigated with differential scanning calorimetry, wide‐angle X‐ray scattering, thermogravimetric analysis, and dynamic mechanical thermal analysis. In the copolymers, only the PA6 chains crystallized, and the crystallinity depended on the PB content. Different glass‐transition temperatures for the PB blocks and PA6 blocks were observed, indicating microphase separation in the copolymers. The mechanical properties of the copolymers were studied by notched impact testing and hardness measurements. The impact strength increased linearly with the soft component concentration up to 10 wt % and reached values six times higher than those of the PA6 homopolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 711–717, 2003     

Synthesis,and NMR and thermogravimetric characterisation of block polymers of methyl methacrylate and methacrylic acid

Block polymers of methyl methacrylate and methacrylic acid have been prepared using the technique of enolate-initiated anionic polymerisation, employing trimethylsilyl methacrylate as a precursor for the methacrylic acid component. The structure of the product has been characterised by infra-red and NMR spectroscopy, and by thermogravimetric analysis.     

Synthesis and characterization of poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate) triblock copolymers

Novel, monodispersed, and well‐defined ABA triblock copolymers [poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate)] were synthesized by oxyanionic polymerization with potassium tert‐butanoxide as the initiator. Gel permeation chromatography and ¹H‐NMR analysis showed that the obtained products were the desired copolymers with molecular weights close to calculated values. Because the poly(dimethylamino ethyl methacrylate) block was pH‐ and temperature‐sensitive, the aqueous solution behavior of the polymers was investigated with ¹H‐NMR and dynamic light scattering techniques at different pH values and at different temperatures. The micelle morphology was determined with transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

顺酐化苯乙烯-丁二烯-苯乙烯嵌段共聚物离聚体的制备及其结构和性能

在甲苯/环己烷混合溶剂体系中考察了顺酐化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)的制备条件,得到马来酸酐/SBS/过氧化苯甲酰质量比为30/100/1、SBS质量浓度为0.10 g/mL、过氧化苯甲酰/甲苯引发液的滴加时间为10 min及75 ℃下反应4 h的较为理想的反应条件.在此条件下既可以避免凝胶的生成,又可获得较高的接枝率(6.87%).所得顺酐化SBS经氢氧化钠溶液中和后生成钠离聚体,傅里叶变换红外光谱分析证实接枝反应和离聚体的合成均得到预期的产物.差示扫描量热分析结果表明离子化微区的存在使得离聚体在高温段有1个玻璃化转变温度.离聚体的拉伸强度、搭接剪切强度和乳化性能均随顺酐化程度的提高而改善.     

Synthesis of asymmetric H-shaped block copolymer by the combination of atom transfer radical polymerization and living anionic polymerization

A new asymmetric H-shaped block copolymer (PS)₂-PEO-(PMMA)₂ has been designed and successfully synthesized by the combination of atom transfer radical polymerization and living anionic polymerization. The synthesized 2,2-dichloro acetate-ethylene glycol (DCAG) was used to initiate the polymerization of styrene by ATRP to yield a symmetric homopolymer (Cl-PS)₂-CHCOOCH₂CH₂OH with an active hydroxyl group. The chlorine was removed to yield the (PS)₂-CHCOOCH₂CH₂OH ((PS)₂-OH). The hydroxyl group of the (PS)₂-OH, which is an active species of the living anionic polymerization, was used to initiate ethylene oxide by living anionic polymerization via DPMK to yield (PS)₂-PEO-OH. The (PS)₂-PEO-OH was reacted with the 2,2-dichloro acetyl chloride to yield (PS)₂-PEO-OCCHCl₂ ((PS)₂-PEO-DCA). The asymmetric H-shaped block polymer (PS)₂-PEO-(PMMA)₂ was prepared via ATRP of MMA at 130 °C using (PS)₂-PEO-DCA as initiator and CuCl/bPy as the catalyst system. The architectures of the asymmetric H-shaped block copolymers, (PS)₂-PEO-(PMMA)₂, were confirmed by ¹H NMR, GPC and FT-IR.     

Synthesis and photopolymerization of multifunctional methacrylates derived from Bis‐GMA for dental applications

Two multimethacrylates having three methacrylate groups (BPA‐3M) and four methacrylate groups (BPA‐4M) have been prepared by reacting hydroxyl groups of 2,2‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)phenyl]propane (Bis‐GMA) with methacryloyl chloride. BPA‐3M and BPA‐4M have much lower viscosities than the starting Bis‐GMA, because they have only one or no hydroxyl group. Photopolymerizations of the multifunctional methacrylates were conducted by exposure to visible light using camphorquinone and 2‐(N,N‐dimethylamino)ethyl methacrylate as a photoinitiating system. High conversions >50% resulted from photopolymerization of BPA‐3M, whereas Bis‐GMA showed lower conversions under the same condition, implying better mechanical properties for the composite resins made from BPA‐3M. BPA‐4M showed much lower conversions in the photopolymerization condition. Water sorption of the photocured composite of BPA‐3M containing 50 wt % of inorganic fillers was found to be 0.15%, which is only one‐tenth of the commercial Bis‐GMA composite. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2033–2037, 1999     

Miniemulsion copolymerizations of styrene and reactive alkyl methacrylate costabilizers

Miniemulsion copolymerizations of styrene (ST) and stearyl methacrylate (SMA) or lauryl methacrylate (LMA) were investigated. Miniemulsions comprising ST and various levels of SMA showed very good storage stability against the diffusional degradation of monomer droplets (Ostwald ripening), whereas miniemulsions comprising ST and various levels of LMA exhibited significant Ostwald ripening. In subsequent miniemulsion copolymerizations of ST and SMA, particle nucleation occurring in the continuous aqueous phase (homogeneous nucleation) plays an important role in the particle formation process in addition to monomer droplet nucleation. The final overall conversion and the individual conversions of ST and SMA all decrease with increasing SMA concentration. Furthermore, at a particular reaction time, the individual conversion of SMA is always greater than that of ST. Monomer droplet nucleation was retarded severely for the monomer pair ST/LMA, presumably due to the very strong Ostwald ripening effect. As a result, relatively slow rates of copolymerization of ST and LMA were attained compared with the ST/SMA counterpart. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The amphiphilic block copolymers of 2-(dimethylamino)ethyl methacrylate and methyl methacrylate: Synthesis by atom transfer radical polymerization and solution properties

Amphiphilic di- and tri-block copolymers of poly(methyl methacrylate) (PMMA) and poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) have been synthesized by atom transfer radical polymerization (ATRP) at ambient temperature (35 °C) in the environment-friendly solvent, aqueous ethanol (water 16 vol%) using CuCl/o-phenanthroline as the catalyst. The PDMAEMA blocks are contaminated with ethyl methacrylate (EMA) residues to the extent of 1-2 mol% of DMAEMA depending on the length of the PDMAEMA block. The EMA forms through the autocatalyzed ethanolysis of the DMAEMA monomer and undergoes random copolymerization with the latter. The rate of ethanolysis is unexpectedly greater in the aqueous ethanol than in neat ethanol, which has been attributed to the higher polarity of the former than of the latter. In contrast to the ethanolysis no hydrolysis of DMAEMA in the aqueous ethanol medium could be detected for 133 h. The block copolymers form micelles in water. Their solubility and CMC in neutral water have been studied. Dynamic light scattering (DLS) studies reveal that for a fixed degree of polymerization (DP) of the PMMA block the hydrodynamic diameter of the micelles in methanolic water (water 95 vol%) increases at a faster rate with the DP of the PDMAEMA block when it is much greater than that of the PMMA block compared to when it is less than or close to that of the latter.     

Block copolymers derived from 2,2′-azobis(2-cyanopropanol). I. Synthesis of poly(urethane-block-methyl methacrylate) and poly(urethane-block-styrene)

Block copolymers with polyester-urethane and polymethyl methacrylate (PMMA) or polystyrene (PS) sequences were obtained by the use of polyester- or polyether-urethane macroazo initiators (PUMAI). PUMAI with a well-defined number of azo groups per chain were prepared via a two-stage reaction procedure using 2,2′-azobis(2-cyanopropanol) (ACP), 4,4′-methylene diphenyl diisocyanate (MDI) and α, ω-hydroxy polycaprolactone (PCL). The characteristics of the obtained block copolymers depend on the reaction conditions, and a yield of 98% was obtained for a P(U-b-MMA) synthesized with a ratio of macroazo initiator to monomer equal to 1/400. In similar conditions, copolymerization of styrene was more difficult, and the maximum block copolymer yield obtained in this work was only of 37% for a ratio of macroazo initiator to monomer equal to 1/150. Combination of different analyses Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H-NMR), and size exclusion chromatography (SEC) carried out on both crude and fractionated copolymers showed this kind of synthesis yielding di- and triblock copolymers and only a little amount of PU homopolymer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 613–627, 1998     

Synthesis and application of novel UV-curable hyperbranched methacrylates from renewable natural tannic acid

With a view to developing high performance UV curable coatings with high renewable contents, acrylated epoxidized soybean oil (AESO) was combined with a novel kind of biorenewable tannic acid-based hyperbranched methacrylates (TAHAs). The TAHAs were synthesized by ring-opening reaction of glycidyl methacrylate (GMA), glycidyl ester of Versatic acid (CE10) and natural tannic acid (TA). The epoxy groups of GMA and CE10 were involved in the ring-opening reaction with the hydroxyl groups of TA while residual methacrylate groups can carry out photopolymerization. By controlling the ratio of GMA and CE10, TAHAs with varying degree of methacrylate groups have been prepared. The synthesized TAHAs were formulated into acrylated epoxidized soybean oil (AESO) based UV curable coatings to produce the biorenewable materials based UV curable coatings. The effects of TAHAs on AESO coated film properties of pendulum hardness, flexibility and adhesion were investigated. Mechanical properties, thermal properties and biodegradability of the cured films were also evaluated. With the incorporation of TAHAs, the hardness, adhesion, tensile strength of the cured coating films were remarkably improved, which were attributed to the unique structure of hyperbranched methacrylates. Meanwhile, the biorenewable content was not greatly decreased due to the biorenewable character of tannic acid in TAHAs. These results showed that TAHAs as efficient toughening agents could produce UV-curable coatings of balanced coating performance with reasonably high biorenewable content. Moreover, the environment degradability of AESO-based cured films was also enhanced after the addition of TAHAs.     

Synthesis of well-defined block copolymers of n-hexyl isocyanate with isoprene by living anionic polymerization

n-Hexyl isocyanate (HIC) was polymerized at different reaction temperatures and times, using alkali metal naphthalenide, via anionic polymerization in THF. To prevent the formation of trimers, the polymerization of HIC was also performed utilizing sodium tetraphenylborate (NaBPh₄) as a common ion salt. As the reaction temperature decreases, yield of the polymer increases due to stabilization of the active amidate anion at low temperature. In the absence of the additive, a quantitative yield was obtained at −98 °C. However, after most of the monomer was polymerized, further reaction led to trimerization. This was prevented in the presence of NaBPh₄ effectively and the living polymerization was performed successfully at −98 °C. The reaction rate retarded with increasing concentration of NaBPh₄, the optimum concentration of NaBPh₄ was 10 times the concentration of the initiator for the living polymerization of HIC. The living system led to the polymers of molecular weight (MW) as high as 50,000 g/mol. The observed MW was well in agreement with the calculated one. At the higher reaction temperature, −78 °C, the quantitative yield was obtained at 2 min of the reaction time, however the living character was not observed at longer reaction time. The study indicated that the amidate anion was stabilized using NaBPh₄ having bulky contact ion pair. The block copolymer of HIC with isoprene, poly(HIC-b-isoprene-b-HIC), was synthesized with help of the living character of polyisoprene and NaBPh₄. The morphology and composition of the block copolymers were investigated using TEM and ¹H NMR, respectively.     

Synthesis and characterization of poly(4‐diphenylaminostyrene)‐Poly(9‐vinylanthracene) binary block copolymer

Block copolymerization of plural types of monomers offers a new opportunity for the preparation of a variety of multifunctional polymers. Poly(4‐diphenylaminostyrene) (PDAS)‐poly(9‐vinylanthracene) (PVAN) binary block copolymer (PDAS‐PVAN) was synthesized by (living) anionic polymerization using the benzyllithium/N,N,N′,N′‐tetramethylethylenediamine system. The photoluminescence emission of PDAS‐PVAN was enhanced by the fluorescence resonance energy transfer from PDAS block to PVAN block in PDAS‐PVAN. The hole drift mobility of the copolymer was controllable by the amount of triphenylamino groups in the polymer chain. The optical and electrical properties of PDAS‐PVAN were adjustable through the polymer chain structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Accelerant‐promoted free radical polymerization of methacrylates by stabilized nitroxide unimolecular initiators: synthesis and characterization

BACKGROUND: This investigation evaluates the effectiveness of initiator adducts for living and controlled polymerization of methacrylates, crosslinking of dimethacrylates and thermal stabilities of the resulting polymers. Adducts of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy with benzoyl peroxide and with azobisisobutyronitrile were prepared and evaluated as stabilized unimolecular initiators for the free radical polymerization of methacrylate monomers using sulfuric acid as catalyst. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Successful polymerization was achieved at 70 and 130 °C with reaction times ranging from 45 min to 120 h. The dispersity (D) of poly(methyl methacrylate) (PMMA) was 1.09–1.28. The livingness and extent of control over polymerization were confirmed with plots of M_n evolution as a function of monomer conversion and of the first‐order kinetics. The glass transition temperature (T_g) for PMMA was 123–128 °C. The degradation temperature (T_d) for PMMA was 350–410 °C. T_d for poly(TEGMA) was 250–310 °C and for poly(EBPADMA) was 320–390 °C. CONCLUSION: The initiators are suitable for free radical living and controlled polymerization of methacrylates and dimethacrylates under mild thermal and acid‐catalyzed conditions, yielding medium to high molecular weight polymers with low dispersity, high crosslinking and good thermal stability. Copyright © 2008 Society of Chemical Industry     

Synthesis and physical properties of sulfonated syndiotactic polystyrene ionomers

Sulfonation of highly stereoregular syndiotactic polystyrene has been accomplished in 1,1,2‐trichloroethane and chloroform (60/40 v/v) mixed solvent. FTIR spectroscopy was used to confirm that the sulfonated syndiotactic polystyrene was the product of the sulfonation reactions. Sodium, potassium, zinc (II), manganese (II) and cobalt (II) salts of the sulfonated polymers exhibited behaviour indicative of strong interactions. FTIR spectroscopy and DSC data showed that the roles of the cation–anionic site interactions in alkali form and transition metal form ionomers are somewhat different. The DSC data also showed that the alkali metal cations had more pronounced effect on T_g than did the transition metal cations. In addition, the crystallization behaviour of the ionomers with a low degree of sulfonation also exhibited considerable differences in comparison with the neat syndiotactic polystyrene. The melting points (T_m) and the degree of crystallization (X_c) were significantly lowered by the presence of the sulfonic acid groups or the sulfonate metal groups. Moreover, the ionomers were more thermally stable and more hygroscopic than the unmodified polymer. © 2001 Society of Chemical Industry     

Thermal decomposition of copolymers of methyl methacrylate and alkyl methacrylates obtained from a CSTR

Thermal decomposition of the copolymers of methyl methacrylate (MMA) with ethyl methacrylate (EMA) or n-butyl methacrylate (BMA) were investigated. The copolymers were obtained in a continuous stirred tank reactor (CSTR) using toluene and benzoyl peroxide, as solvent and initiator, respectively, at 80C. The volume was 1.2 litters and residence time was 3 hours. The thermal decomposition followed the second order kinetics for both MMA/EMA and MMA/BMA copolymers, which were almost in accordance with the order of copolymerization in a CSTR. The activation energies of thermal decomposition were in the ranges of 32-37 kcal/mol and 27-37 kcal/mole for MMA/EMA and MMA/BMA copolymers, respectively and a good additivity rule was observed against each composition for both copolymers. The thermogravimetric trace curve agreed well with the theoretical calculation.     

苯乙烯-丁二烯-苯乙烯-甲基丙烯酸酯嵌段共聚物的合成与表征

用正丁基锂为引发剂,环已烷和四氢呋喃为混合溶剂,以苯乙烯、丁二烯、甲基丙烯酸酯为单体,按阴离子顺序加料方法合成了聚苯乙烯-丁二烯-苯乙烯-甲基丙烯酸酯嵌段共聚物,共聚物经GPC、IR、DSC、TEM等测试方法表征。结果表明,在30 ℃左右、1,1-二苯基乙烯(DPE)戴帽和LiCl配合的条件下,合成了窄分布(MWD<1.3)聚苯乙烯-丁二烯-苯乙烯-甲基丙烯酸酯嵌段共聚物,成功地在SBS中引入了一小段极性链段。     

Synthesis and photopolymerizations of new phosphonated methacrylates from alkyl α‐hydroxymethacrylates and glycidyl methacrylate

Novel aromatic mono‐ and di(phosphonate) or phosphonic acid monomers for use in dental composites were synthesized. Synthesis of monomer 1a involved three steps: (i) reaction of t‐butyl α‐bromomethacrylate (t‐BuBMA) and Bisphenol A, (ii) conversion to diacid chloride derivative using thionyl chloride, (iii) reaction of diacid chloride with diethyl (2‐hydroxyphenyl) phosphonate. Monomer 2a was synthesized from the reaction of 2‐chloromethacryloyl chloride and diethyl (2‐hydroxyphenyl) phosphonate. Synthesis of monomer 3a involved reaction of glycidyl methacrylate (GMA) with diethyl (2‐hydroxyphenyl) phosphonate. Hydrolysis of the phosphonate groups of monomers 1a and 2a with trimethylsilyl bromide (TMSBr) gave monomers 1b and 2b with phosphonic acid functionality, which is intended to improve binding ability of dental composites. The homopolymerization and copolymerization behaviors of the synthesized monomers with (Bis‐GMA) were investigated using photodifferential scanning calorimetry at 40°C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as photoinitiator. The interaction of the monomer 1b with hydroxyapatite (HAP) was investigated using Fourier transform infrared technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

全丙烯酸酯嵌段共聚物热塑性弹性体合成研究进展

作为一类新型的热塑性弹性体,全丙烯酸酯嵌段共聚物越来越引起人们的注意。主要介绍全丙烯酸酯嵌段共聚物的合成进展,分别介绍了阴离子聚合、基团转移聚合、稳定氮氧自由基聚合和原子转移自由基聚合在合成全丙烯酸酯嵌段共聚物热塑性弹性体中的应用,并对其前景进行了展望。     

Facile atom transfer radical homo and block copolymerization of higher alkyl methacrylates at ambient temperature using CuCl/PMDETA/quaternaryammonium halide catalyst system

Controlled polymerization of higher alkyl methacrylates, e.g. lauryl methacrylate (LMA) and stearyl methacrylate (SMA) has been successfully achieved by atom transfer radical polymerization (ATRP) at ambient temperature using CuCl/N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA)/tricaprylylmethylammonium chloride (Aliquat^®336) as the catalyst system and ethyl 2-bromoisobutyrate or 2,2,2-trichloroethanol as the initiator. Although the bulk polymerization gives satisfactory control, the latter becomes better when anisole or THF is added into the system. Without AQCl the control was lost. A large deviation of molecular weight from theory has been observed which has been attributed to the very high-molecular weight of the dead polymers formed during the building-up of the persistent radical. The controlled polymers have been used as macroinitiators for block (di, tri and penta) ATR copolymerization with several methacrylates.