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A series of miniemulsion systems based on styrene/azobisisobutyronitrile in the presence of poly(methyl methacrylate‐b‐2‐(dimethylamino)ethyl methacrylate) as a surfactant and hexadecane (HD) as a cosurfactant were developed. For comparison, a series of pseudoconventional emulsions also were carried out with the same procedure used for the aforementioned series but without the cosurfactant (HD). Both the droplet size and shelf life were also measured. Experimental results indicate that it is possible to slow the effect of Ostwald ripening and thereby produce a stable miniemulsion with the block copolymer as the surfactant and HD as the cosurfactant. In addition, the extent to which varying the surfactant concentration and copolymer composition could affect both the polymer particle size during the polymerization and the polymerization rate was examined. Variation in the polymer particle sizes during polymerization indicates that droplet and aqueous (micellar or both homogeneous) nucleation occurs in the miniemulsion polymerization. With the same concentration of the surfactant used in the miniemulsion polymerization, the polymerization rates of systems with M12B36 are faster than those of systems with M12B12. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1818–1827, 2000 相似文献
3.
Balazs Keszler Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》1994,32(16):3153-3160
A series of environmentally sensitive amphiphilic networks consisting of 2-sulfoethyl methacrylate (SEMA) chains linked by methacrylate-ditelechelic polyisobutylene (MA–PIB–MA) chains have been prepared and characterized. Network composition was determined after sequential solvent extraction by elemental analysis. These networks are two-phase microheterogeneous systems containing hydrophobic rubbery PIB domains (Tg ~ ?60°C) and hydrophilic poly(2-sulfoethyl methacrylate) domains (Tg ~ ?15°C). They exhibit large contact-angle hysteresis in water which is due to surface segmental mobility and microheterogeneity. By increasing the SEMA content of the networks the contact-angle hysteresis increases. This phenomenon is due to an increase in the advancing contact angle most likely caused by the migration of the nonpolar PIB domains toward the surface and concomitant decrease of the receding contact angle. These amphiphilic networks exhibit non-Fickian swelling in n-heptane, as well as in water, and show pH-sensitive swelling in aqueous media. They rapidly and reversibly swell and deswell in response to increasing or decreasing the pH of the media (cycling between pH = 2 and 12). © 1994 John Wiley & Sons, Inc. 相似文献
4.
ludk Toman Miroslav Janata Jií Spv
ek Barbora Dvonkov Petra Ltalov Petr Vl
ek Antonín Sikora Jií Michlek Michal Pekrek 《Journal of polymer science. Part A, Polymer chemistry》2006,44(9):2891-2900
Amphiphilic polymer networks consisting of hydrophilic poly(2‐hydroxyethyl methacrylate) (PHEMA) and hydrophobic polyisobutylene (PIB) chains were synthesized from a cationic copolymer of isobutylene (IB) and 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (IDI) prepared at ?50 °C in dichloromethane in conjunction with SnCl4. The isocyanate groups of this random copolymer, PIB(NCO)n, were subsequently transformed in situ to methacrylate (MA) groups in the dibutyltin dilaurate‐catalyzed reaction with 2‐hydroxyethyl methacrylate (HEMA) at 30 °C. The resulting PIB(MA)n with number–average molecular weight 8200 and average functionality Fn ~ 4 per chain was in situ copolymerized radically with HEMA at 70 °C, giving rise to the amphiphilic networks containing 41 and 67 mol % HEMA. PHEMA–PIB network containing 43 mol % HEMA was also prepared by radical copolymerization of PIB(MA)n precursor with HEMA using sequential synthesis. An amphiphilic nature of the resulting networks was proved by swelling in both water and n‐heptane. PIB(NCO)n and PIB(MA)n were characterized by FTIR spectroscopy, SEC and the latter also by 1H NMR spectroscopy. Solid state 13C NMR spectroscopy was used for characterization of the resulting PHEMA–PIB networks. Whereas single glass‐transition temperature, Tg = ?67.4 °C, was observed for the rubbery crosslinked PIB prepared by reaction of PIB(NCO)n with water, the PHEMA–PIB networks containing 67 and 41 mol % HEMA showed two Tg's: ?70.4 and 102.7 °C, and ?63 and 107.2 °C, respectively. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2891–2900, 2006 相似文献
5.
Shuxiang Zhang Junqiang Zhao Guohong Chu Luqing Zhang Anhou Xu Hui Li Bing Geng 《Journal of fluorine chemistry》2011,132(11):915-919
A fluorinated monomer of 2-(2,2,2-trifluoroethoxy)ethyl methacrylate (FEMA) was prepared by a “one pot” process and then a novel fluorinated methacrylate polymer, poly[2-(2,2,2-trifluoroethoxy)ethyl methacrylate] (PFEMA), was successfully synthesized via miniemulsion polymerization using cetyltrimethyl ammonium bromide (CTAB) as emulsifier, hexadecane (HD) as co-stabilizer and 2,2′-azobisisobutyronitrile (AIBN) as initiator. The chemical structure of PFEMA was characterized by FT-IR, 1H NMR and 19F NMR. GPC results show that the number average molecular weight (Mn) of PFEMA was as high as 8.5 × 105 g/mol and the polydispersity index (PDI) was only 1.3. SEM and DLS characterizations showed that the morphology of PFEMA latex was uniform spheres with the diameter of about 110–125 nm. It was also found that PFEMA has high thermo-stability (Td > 200 °C), low glass transition temperature (Tg = 13.0 °C), and nice hydrophobicity (θwater = 99.9°). Comparison studies on PFEMA and poly(2,2,2-trifluoroethyl methacrylate) show that an introduced functional group (–CH2CH2O–) has a significant effect on lowering Tg and improving hydrolysis resistance without impairing surface properties. 相似文献
6.
Wan Jiang Wuli Yang Xianbiao Zeng Shoukuan Fu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(3):733-741
Nanoscale poly(methyl methacrylate) (PMMA) particles were prepared by modified microemulsion polymerization. Different from particles made by traditional microemulsion polymerization, the particles prepared by modified microemulsion polymerization were multichain systems. PMMA samples, whether prepared by the traditional procedure or the modified procedure, had glass-transition temperatures (Tg's) greater than 120 °C and were rich in syndiotactic content (55–61% rr). After the samples were dissolved in CHCl3, there were decreases in the Tg values for the polymers prepared by the traditional procedure and those prepared by the modified process. However, a more evident Tg decrease was observed in the former than in the latter; still, for both, Tg was greater than 120 °C. Polarizing optical microscopy and wide-angle X-ray diffraction indicated that some ordered regions formed in the particles prepared by modified microemulsion polymerization. The addition of a chain-transfer agent resulted in a decrease in both the syndiotacticity and Tg through decreasing polymer molecular weight. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 733–741, 2004 相似文献
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Ludk Toman Miroslav Janata Jií Spv
ek Petr Vl
ek Petra Ltalov Antonín Sikora Bohumil Masa 《Journal of polymer science. Part A, Polymer chemistry》2005,43(17):3823-3830
ABCBA‐type pentablock copolymers of methyl methacrylate, styrene, and isobutylene (IB) were prepared by the cationic polymerization of IB in the presence of the α,ω‐dichloro‐PS‐b‐PMMA‐b‐PS triblock copolymer [where PS is polystyrene and PMMA is poly(methyl methacrylate)] as a macroinitiator in conjunction with diethylaluminum chloride (Et2AlCl) as a coinitiator. The macroinitiator was prepared by a two‐step copper‐based atom transfer radical polymerization (ATRP). The reaction temperature, ?78 or ?25 °C, significantly affected the IB content in the resulting copolymers; a higher content was obtained at ?78 °C. The formation of the PIB‐b‐PS‐b‐PMMA‐b‐PS‐b‐PIB copolymers (where PIB is polyisobutylene), prepared at ?25 (20.3 mol % IB) or ?78 °C (61.3 mol % IB; rubbery material), with relatively narrow molecular weight distributions provided direct evidence of the presence of labile chlorine atoms at both ends of the macroinitiator capable of initiation of cationic polymerization of IB. One glass‐transition temperature (Tg), 104.5 °C, was observed for the aforementioned triblock copolymer, and the pentablock copolymer containing 61.3 mol % IB showed two well‐defined Tg's: ?73.0 °C for PIB and 95.6 °C for the PS–PMMA blocks. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3823–3830, 2005 相似文献
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Bin Luan Bao‐Qing Zhang Cai‐Yuan Pan 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):549-560
A well‐defined branched copolymer with PLLA‐b‐PS2 branches was prepared by combination of reversible addition‐fragmentation transfer (RAFT) polymerization, ring‐opening polymerization (ROP), and atom transfer radical polymerization (ATRP). The RAFT copolymerization of methyl acrylate (MA) and hydroxyethyl acrylate (HEA) yielded poly(MA‐co‐HEA), which was used as macro initiator in the successive ROP polymerization of LLA. After divergent reaction of poly(MA‐co‐HEA)‐g‐PLLAOH with divergent agent, the macro initiator, poly(MA‐co‐HEA)‐g‐PLLABr2 was formed in high conversion. The following ATRP of styrene (St) produced the target polymer, poly(MA‐co‐HEA)‐g‐(PLLA‐b‐PS2). The structures, molecular weight, and molecular weight distribution of the intermediates and the target polymers obtained from every step were confirmed by their 1H NMR and GPC measurements. DSC results show one T = 3 °C for the poly(MA‐co‐HEA), T = ?5 °C, T= 122 °C, and T = 157 °C for the branched copolymers (poly(MA‐co‐HEA)‐g‐PLLA), and T = 51 °C, T = 116 °C, and T = 162 °C for poly(MA‐co‐HEA)‐g‐(PLLA‐b‐PS2). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 549–560, 2006 相似文献
9.
Maria Demetriou Theodora Krasia‐Christoforou 《Journal of polymer science. Part A, Polymer chemistry》2008,46(16):5442-5451
Four well‐defined diblock copolymers and one statistical copolymer based on lauryl methacrylate (LauMA) and 2‐(acetoacetoxy)ethyl methacrylate (AEMA) were prepared using reversible addition‐fragmentation chain transfer (RAFT) polymerization. The polymers were characterized in terms of molecular weights, polydispersity indices (ranging between 1.12 and 1.23) and compositions by size exclusion chromatography and 1H NMR spectroscopy, respectively. The preparation of the block copolymers was accomplished following a two‐step methodology: First, well‐defined LauMA homopolymers were prepared by RAFT using cumyl dithiobenzoate as the chain transfer agent (CTA). Kinetic studies revealed that the polymerization of LauMA followed first‐order kinetics demonstrating the “livingness” of the RAFT process. The pLauMAs were subsequently used as macro‐CTA for the polymerization of AEMA. The glass transition (Tg) and decomposition temperatures (ranging between 200 and 300 °C) of the copolymers were determined using differential scanning calorimetry and thermal gravimetric analysis, respectively. The Tgs of the LauMA homopolymers were found to be around ?53 °C. Block copolymers exhibited two Tgs suggesting microphase separation in the bulk whereas the statistical copolymer presented a single Tg as expected. Furthermore, the micellization behavior of pLauMA‐b‐pAEMA block copolymers was investigated in n‐hexane, a selective solvent for the LauMA block, using dynamic light scattering. pLauMA‐b‐pAEMA block copolymers formed spherical micelles in dilute hexane solutions with hydrodynamic diameters ranging between 30 and 50 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5442–5451, 2008 相似文献
10.
Khalid Ferji Cécile Nouvel Jérôme Babin Pierre‐Antoine Albouy Min‐Hui Li Jean‐Luc Six 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3829-3839
A cholesterol‐based liquid crystal monomer, diethylene glycol cholesteryl ether acrylate (DEGCholA), has been successfully polymerized by atom transfer radical polymerization (ATRP) for the first time. Appropriate experimental conditions to control the polymerization of DEGCholA have been investigated using a model initiator (ethyl 2‐bromoisobutyrate) in tetrahydrofuran (THF) or toluene at 60 °C. Well‐controlled ATRP of DEGCholA was obtained using N,N,N′,N′,N″‐pentamethyldiethylenetriamine as ligand in THF at 60 °C. These conditions were then applied to initiate the ATRP of DEGCholA from multifunctional macroinitiators based on dextran. Using a protection/deprotection synthetic scheme, novel graft glycopolymers (Dex‐g‐PDEGCholA) have been synthesized. The mesomorphic properties of DEGCholA, PDEGCholA, and Dex‐g‐PDEGCholA have been studied by thermal polarizing optical microscopy, differential scanning calorimetry, and X‐ray scattering. PDEGCholA and Dex‐g‐PDEGCholA show an interdigitated smectic A phase (SmAd) between Tg (~30 °C) and around 170 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3829–3839 相似文献
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Faezeh Hajiali Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2020,58(11):1503-1520
Nitroxide-mediated polymerization (NMP) was used to polymerize methacrylate-functionalized polyhedral oligomeric silsesquioxane, POSSMA, in a controlled manner with bio-based C13 methacrylate (C13MA) to improve the thermal stability of the latter by copolymerization (using 10 mol% acrylonitrile controlling comonomer). Kinetic experiments (80–110 °C) revealed the relatively low ceiling temperature of POSSMA (135 °C). Synthesis of poly(POSSMA-co-AN) with f AN,0 = 0.10 at 90 °C resulted in low dispersity (1.16) and relatively high conversion (~50%) after 3 hr in 50 wt% toluene. Assuming binary statistical copolymerizations, POSSMA was slightly less reactive than C13MA toward the propagating species (r POSSMA = 0.91 ± 0.07 and r C13MA = 1.94 ± 0.13). Incorporating POSSMA up to 68 mol% improved decomposition temperature of C13MA-based copolymers from 190 to 262 °C. Chain end fidelity of POSSMA-rich compositions was confirmed by subsequent chain extensions to make block and gradient copolymers. Differential scanning calorimetry revealed multiple transition temperatures in block copolymers, suggesting microphase separation. Powder X-ray diffraction confirmed crystalline domains ~30 nm in POSSMA-rich statistical copolymers while transmission electron microscopy revealed weakly ordered lamellar morphology for poly(C13MA-co-AN)-b-(POSSMA-co-AN) block copolymer at a smaller length scale. Oscillatory shear measurements of block copolymers indicated primarily viscous character below 200 s−1 but crossover above this frequency, indicating POSS–POSS interactions were increasing the elasticity of the block copolymers. 相似文献
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Faezeh Hajiali Adrien Métafiot Laura Benitez-Ek Lea Alloune Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2018,56(21):2422-2436
Nitroxide-mediated polymerization (NMP) of isobornyl methacrylate (IBOMA) and tridecyl methacrylate (TDMA), derived from sustainable feedstocks, with a low fraction of acrylonitrile (AN) co-monomer were conducted with unimolecular initiator BlocBuilder-MA™ (BB) and the succinimidyl ester-functionalized form, NHS-BB. IBOMA and TDMA-rich compositions were both polymerized at 100 °C in a controlled manner (i.e., linear increase in number average molecular weight [Mn] with conversion up to ∼40% and low dispersity, Đ < 1.5). SG1-terminated poly(IBOMA-stat-AN) macroinitiator was then cleanly chain-extended with poly(TDMA-stat-AN) and the diblock copolymers exhibited two distinct glass transition temperatures (Tgs), indicative of microphase separation. IBOMA/TDMA/AN terpolymers with different IBOMA/TDMA molar ratios were also synthesized where terpolymers with higher IBOMA content had higher apparent rate constants and higher Tgs. Moreover, chain growth was linear up to conversions of ∼60% and all Đs were 1.51 to 1.64. Finally, 2-hydroxyethyl methacrylate (HEMA) was incorporated into the IBOMA/TDMA/AN system, resulting in statistical quadripolymers. The quadripolymer Tg decreased with increasing TDMA content and Mn ranged from 12 to 15.4 kg mol−1 and the Đ were 1.39 to 1.54, suggesting the successful incorporation of sustainably sourced monomers into quadripolymers with a broad range of tunable Tgs via NMP with additional functionalities from HEMA. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2422–2436 相似文献
13.
Thermoresponsive star triblock copolymers by combination of ROP and ATRP: From micelles to hydrogels
Weipu Zhu Alper Nese Krzysztof Matyjaszewski 《Journal of polymer science. Part A, Polymer chemistry》2011,49(9):1942-1952
Novel biocompatible, biodegradable, four‐arm star, triblock copolymers containing a hydrophobic poly(ε‐caprolactone) (PCL) segment, a hydrophilic poly(oligo(ethylene oxide)475 methacrylate) (POEOMA475) segment and a thermoresponsive poly(di(ethylene oxide) methyl ether methacrylate) (PMEO2MA) segment were synthesized by a combination of controlled ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). First, a four‐arm PCL macroinitiator [(PCL‐Br)4] for ATRP was synthesized by the ROP of ε‐caprolactone (CL) catalyzed by stannous octoate in the presence of pentaerythritol as the tetrafunctional initiator followed by esterification with 2‐bromoisobutyryl bromide. Then, sequential ATRP of oligo(ethylene oxide) methacrylate (OEOMA475, Mn = 475) and di(ethylene oxide) methyl ether methacrylate) (MEO2MA) were carried out using the (PCL‐Br)4 tetrafunctional macroinitiator, in different sequence, resulting in preparation of (PCL‐b‐POEOMA475‐b‐PMEO2MA)4 and (PCL‐b‐PMEO2MA‐b‐POEOMA475)4 star triblock copolymers. These amphiphilic copolymers can self‐assemble into spherical micelles in aqueous solution at room temperature. The thermal responses of the polymeric micelles were investigated by dynamic light scattering and ultraviolet spectrometer. The properties of the two series of copolymers are quite different and depend on the sequence distribution of each block along the arms of the star. The (PCL‐b‐POEOMA475‐b‐PMEO2MA)4 star copolymer, with the thermoresponsive PMEO2MA segment on the periphery, can undergo reversible sol‐gel transitions between room temperature (22 °C) and human body temperature (37 °C). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
14.
Morphology of micron-sized monodispersed poly(butyl methacrylate)/polystyrene composite particles produced by seeded dispersion polymerization 总被引:1,自引:0,他引:1
In order to develop the seeded dispersion polymerization technique for the production of micron-sized monodispersed core/shell
composite polymer particles the effect of polymerization temperature on the core/shell morphology was examined. Micron-sized
monodispersed composite particles were produced by seeded dispersion polymerizations of styrene with about 1.4-μm-sized monodispersed
poly(n-butyl methacrylate) (Pn-BMA) and poly(i-butyl methacrylate) (Pi-BMA) particles in a methanol/water (4/1, w/w) medium in the temperature range from 20 to 90 °C. The composite particles,
PBMA/polystyrene (PS) (2/1, w/w), consisting of a PBMA core and a PS shell were produced with 2,2′-azobis(4-methoxy-2,4-dimethyl
valeronitrile) initiator at 30 °C for Pn-BMA seed and with 2,2′-azobis(isobutyronitrile) initiator at 60 °C for Pi-BMA seed. The polymerization temperatures were a little above the glass-transition temperatures (T
g) of both Pn-BMA (20 °C) and Pi-BMA (40 °C). On the other hand, when the seeded dispersion polymerizations were carried out at much higher temperatures than
the T
g of the seed polymers, composite particles having a polymeric oil-in-oil structure were produced.
Received: 14 October 1998 Accepted in revised form: 2 June 1999 相似文献
15.
Maria Rikkou‐Kalourkoti Eleni Kassi Costas S. Patrickios 《Journal of polymer science. Part A, Polymer chemistry》2012,50(4):665-674
Seven cyclolinear polymers bearing the tertiary‐butyl α‐(hydroxymethyl)acrylate (TBHMA) ether dimer were prepared using reversible addition–fragmentation chain transfer (RAFT) polymerization. Of the seven polymers, five were cyclolinear homopolymers of the TBHMA ether dimer with different degrees of polymerization, one was an “arm‐first” star homopolymer, and the other was an amphiphilic linear copolymer based on the positively ionizable hydrophilic 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and the TBHMA ether dimer. For comparison, two more polymers were prepared using RAFT polymerization where the TBHMA ether dimer was replaced by tertiary‐butyl methacrylate (tBuMA). In particular, an amphiphilic linear DMAEMA–tBuMA diblock copolymer and a tBuMA arm‐first star homopolymer were also synthesized. All polymers were characterized in terms of their molecular weights and composition using gel permeation chromatography and 1H NMR spectroscopy, respectively. Subsequently, the tertiary‐butyl groups of the TBHMA ether dimer units and those of the tBuMA units were cleaved by hydrolysis to yield carboxylic acid groups. The successful removal of the tertiary‐butyl groups was confirmed using 1H and 13C NMR and attenuated total reflectance‐Fourier transform infrared spectroscopies. The hydrolyzed (co)polymers exhibited pK values of the carboxylic acid groups of around 4.5, and glass transition temperatures, Tg, of around 200 °C, which were 50 °C higher than those of their nonhydrolyzed precursors. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
16.
Erika I. López‐Martínez Alfredo Márquez‐Lucero Claudia A. Hernández‐Escobar Sergio G. Flores‐Gallardo Rigoberto Ibarra‐Gómez Miguel J. Yacamán E. Armando Zaragoza‐Contreras 《Journal of Polymer Science.Polymer Physics》2007,45(5):511-518
Silver/carbon nanoparticles (9 nm) were incorporated, as reinforcements, into a matrix of poly(methyl methacrylate) via in situ miniemulsion polymerization. It was found by differential scanning calorimetry that the glass‐transition temperature of the poly(methyl methacrylate) showed an improvement of 14 °C with only 0.5 wt % nanoparticles in comparison with a pure poly(methyl methacrylate) control, which was also obtained by miniemulsion polymerization under the same conditions. This increase was related to a polymer chain mobility restriction due to a combination of bound plastic and joint plastic shell effects at the interphase and the surrounding regions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 511–518, 2007. 相似文献
17.
Petr Vlček Vladimír Raus Miroslav Janata Jaroslav Kříž Antonín Sikora 《Journal of polymer science. Part A, Polymer chemistry》2011,49(1):164-173
Here, we present the first example of application of single‐electron transfer living radical polymerization (SET‐LRP) process to a controlled grafting of cellulose esters, cellulose diacetate (CDA), and cellulose acetate butyrate (CAB). The cellulose ester macroinitiators with various functionality densities have been prepared by acylation of the backbones with 2‐bromoisobutyryl (BrIB) and dichloroacetyl (DCA) groups, respectively. Methacrylate monomers were polymerized using DCA‐functionalized macroinitiators in the presence of pentamethyldiethylene triamine as a ligand. At 30 °C, the reaction is rather slow, reaching about 10% conversion after 3 to 6 h of polymerization, whereas the higher temperature (60 °C) perceptibly speeds up the polymerization so that methyl methacrylate (MMA) conversion is ~30% after 5 h. Graft copolymers with random‐type and diblock‐type grafts having amphiphilic character were also synthesized. For acrylate grafting (BuA and t‐BuA), BrIB‐functionalized macroinitiators are more convenient in a combination with a low concentration of Cu(0) and Me6TREN as a ligand and polymerization is detectably faster even at the lower temperature than that of MMA. Kinetic studies show “living” character of both the graftings. Important advantages of SET‐LRP, compared with classic ATRP, are (i) higher polymerization rate, (ii) lower extent of recombination of the growing grafts and (iii) negligible coloration of the products with catalytic residua, so that the prepared polymers do not require additional careful purification. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
18.
以含氟接枝共聚物(PSG)单独作为助稳定剂,十二烷基硫酸钠(SDS)为乳化剂,过硫酸钾(KPS)为引发剂引发苯乙烯(St)的细乳液聚合。考察了聚合温度、乳化剂用量、引发剂用量和PSG用量对细乳液聚合转化率的影响。结果表明,以PSG单独作为助稳定剂,细乳液聚合过程较稳定,起始单体液滴数目与成核粒子数目几乎相等。最终转化率随着乳化剂用量和反应温度的提高而增加,引发剂用量影响不明显。在相同的反应条件下,分别以相同用量(w.t.%=0.091%时,占单体和水的总质量)的PSG和十六醇为助稳定剂用于苯乙烯细乳液聚合,反应290min后,PSG体系的聚合转化率达到87.2%,而十六醇体系的聚合转化率只有78.2%。 相似文献
19.
H. Matahwa J. B. McLeary R. D. Sanderson 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):427-442
Cationic and anionic amphiphilic monomers (surfmers) were synthesized and used to stabilize particles in miniemulsion polymerization. A comparative study of classical cationic and anionic surfactants and the two surfmers was conducted with respect to the reaction rates and molecular weight distributions of the formed polymers. The reversible addition–fragmentation chain transfer process was used in the miniemulsion polymerization reactions to control the molecular weight distribution. The reaction rates of the surfmer‐stabilized miniemulsion polymerization of styrene and methyl methacrylate were similar (in most cases) to those of the classical‐surfactant‐stabilized miniemulsion polymerizations. The final particle sizes were also similar for polystyrene latexes stabilized by the surfmers and classical surfactants. However, poly(methyl methacrylate) latexes stabilized by the surfmers had larger particle sizes than latexes stabilized by classical surfactants. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 427–442, 2006 相似文献
20.
Homogeneous polymerization of butyl methacrylate (BMA) using Pd(II)‐ and Ni(II)‐based acetylide complexes as single‐component initiators has been investigated in CHCl3 at 60°C. M(PPh3)2(C = CR)2 (M = Pd, Ni; R = Ph, CH2OH, CH2OOCCH3) were found to be a novel type of effective initiators for the polymerization of butyl methacrylate. Among them, Pd(PPh3)2(C‐CPh)2 (PPP) shows the highest activity. Besides, PPP alone can also initiate the homogeneous polymerizations of acrylates, e. g., methyl acrylate (MA), and n‐butyl acrylate (BA). The present type of polymerization is not hindered by the incorporation of hydroquinone. 相似文献