Supramolecular Self‐Assembly of Polymer‐Functionalized Carbon Nanotubes on Surfaces

Summary: Supramolecular self‐assembly of poly(methyl methacrylate)‐grafted multiwalled carbon nanotubes (MWNT‐g‐PMMA) was reported herein. The MWNT‐g‐PMMA (85 wt.‐% PMMA) dispersed in tetrahydrofuran could self‐assemble into suprastructures on surfaces such as gold, mica, silicon, quartz, or carbon films. With decreasing concentration of the MWNT‐g‐PMMA from 3 to 0.1 mg · mL⁻¹, the assembled structures changed from cellular and basketwork‐like forms to multilayer cellular networks and individual needles. SEM, AFM, and TEM measurements confirmed the morphology of the assembled suprastructures, and revealed the assembly mechanism. Phase separation during evaporation of the solvent drives the MWNT‐g‐PMMA nanohybrids to assemble and form the suprastructures, and the rigid MWNTs stabilize the structures.

SEM images of self‐assembled suprastructures of basketwork (a), cellular network (b), and needles (c) from the THF solution of the PMMA‐grafted MWNTs on gold surface.     

Synthesis and self‐assembly of polystyrene‐grafted multiwalled carbon nanotubes with a hairy‐rod nanostructure

Polystyrene‐grafted multiwalled carbon nanotubes (PS‐g‐MWNTs) with a hairy‐rod nanostructure were synthesized by the in situ free‐radical polymerization of styrene in the presence of multiwalled carbon nanotubes (MWNTs) terminated with vinyl groups. To quantitatively study the molecular weight and composition of polystyrene (PS) chains in PS‐g‐MWNTs, PS‐g‐MWNTs were fully defunctionalized by hydrolysis. The results showed that 1 of every 100 carbon atoms in MWNTs was functionalized at the tips and outer walls of the carbon nanotubes and grafted by PS with a weight‐average molecular weight of 9800 g/mol; therefore, a uniform thin layer (ca. 8–10 nm) of a PS shell was formed on the outer wall of MWNTs. PS‐g‐MWNTs were soluble in dimethylformamide and tetrahydrofuran. The thermal stability and glass‐transition temperature of PS in PS‐g‐MWNTs were obviously increased. Nanopins were formed on the glass substrates by the self‐assembly of PS‐g‐MWNTs, and the dewetting effect between the glass substrate and PS chains covered MWNTs during the evaporation of the solution. Both the length and diameter of the nanopins increased with the solution concentration. When PS‐g‐MWNTs were compression‐molded, MWNTs were dispersed uniformly in the PS matrix and formed good networks, such as circlelike and starlike structures, because of the entanglements of hairy PS chains on MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3869–3881, 2006     

Surface covalent encapsulation of multiwalled carbon nanotubes with poly(acryloyl chloride) grafted poly(ethylene glycol)

Multiwall carbon nanotube (MWNT) was grafted with polyacrylate‐g‐poly (ethylene glycol) via the following two steps. First, hydroxyl groups on the surface of acid‐treated MWNT reacted with linear poly(acryloyl chloride) to generate graft on MWNT; secondly, the remaining acryloyl chloride groups were subjected to esterification with poly(ethylene glycol) leading the grafted chains on the surface of MWNTs. Thus obtained grafted MWNT was characterized using Fourier transform infrared spectrometer, transmission electron microscopy, and X‐ray photoelectron spectroscopy. Thermogravimetric analysis showed that the weight fraction of grafted polymers amounted to 80% of the modified MWNT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6880–6887, 2006     

Functionalized multi‐walled carbon nanotubes with poly(N‐(2‐hydroxypropyl)methacrylamide) by RAFT polymerization

In this study, we grafted water‐soluble biocompatible polymer, poly(N‐(2‐hydroxypropyl)methacrylamide) (PHPMA), onto the surface of multi‐walled carbon nanotubes (MWNTs). The reversible addition‐fragmentation chain transfer (RAFT) agents, dithioesters, were successfully immobilized onto the surface of MWNTs first, PHPMA chains were then subsequently grafted onto MWNTs via RAFT polymerization by using dithioesters immobilized on MWNTs as RAFT agent. FTIR, XPS, ¹H NMR, Raman and TGA were used to characterize the resulting products and to determine the content of water‐soluble PHPMA chains in the product. The MWNTs grafted with PHPMA chains have good solubility in distilled water, PBS buffer, and methanol. TEM images of the samples provide direct evidence for the formation of a nanostructure that MWNTs coated with polymer layer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2419–2427, 2006     

Synthesis of polar block grafted syndiotactic polystyrenes via a combination of iridium‐catalyzed activation of aromatic C?H bonds and atom transfer radical polymerization

A combination of iridium‐catalyzed C H activation/borylation and atom transfer radical polymerization (ATRP) was used to generate polar graft copolymers of syndiotactic polystyrene (sPS). The borylation at aromatic C H bonds of sPS and subsequent oxidation of boronate ester proceeded without negatively affecting the molecular weight properties and the tacticity of sPS. A macroinitiator suitable for ATRP could be synthesized by the esterification of 2‐bromo‐2‐methylpropionyl bromide and hydroxy‐functionalized sPS. The graft polymerizations of methyl methacrylate and tert‐butyl acrylate from the macroinitiator using ATRP afforded polar block grafted sPS materials, syndiotactic polystyrene‐graft‐poly(methyl methacrylate) (sPS‐g‐PMMA) and syndiotactic polystyrene‐graft‐poly(tert‐butyl acrylate) (sPS‐g‐PtBA). The latter was hydrolyzed to yield an amphiphilic graft copolymer, syndiotactic polystyrene‐graft‐poly(acrylic acid) (sPS‐g‐PAA). The structures of the copolymers were characterized by NMR and FTIR spectroscopies. Size exclusion chromatography and ¹H NMR spectroscopy were used to study any changes in the molecular weight properties from the parent polymer. A decrease in the hydrophobicity of the graft copolymers was confirmed by water contact angle measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6655–6667, 2009     

Synthesis of highly dispersed,block copolymer‐grafted TiO2 nanoparticles within neat block copolymer films

The objective of the study is to formulate exclusive block copolymer (BCP) nanocomposites by dispersing bcp end‐grafted nanoparticles (bcp‐g‐nps) of PMMA‐b‐PS‐g‐TiO₂ within PS‐b‐PMMA matrix. PMMA‐b‐PS‐g‐TiO₂ is synthesized using a “grafting‐to” approach and characterized by XPS and TGA to establish that the copolymer chains were bonded to NPs. Good dispersion of bcp‐g‐nps in PMMA and PS‐PMMA bcp films is observed, in contrast to poor dispersion in PS films. In PS‐PMMA films, the compatible and identical bcp nature of the end‐grafted polymer, and large NP size caused it to span across entire PS‐PMMA domains. Poor and good dispersion in PS and PMMA matrices, respectively, can be rationalized by the fact that NPs interactions are driven by the PMMA at the outer corona of the bcp‐g‐nps. Developing bcp‐g‐nps as a strategic route to preparation of highly dispersed high permittivity NPs like titanium dioxide (TiO₂) in bcp matrix can have important ramifications for energy storage devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 468–478     

Preparation,structure, and property of polyoxymethylene/carbon nanotubes thermal conducive composites

Polyoxymethylene (POM)/multiwalled carbon nanotubes (MWNTs) nanocomposites were prepared through a simple solution‐evaporation method assisted by ultrasonic irradiation. To enhance the dispersion of MWNTs in POM, MWNTs were chemically functionalized with PEG‐substituted amine (MWNT‐g‐PEG), which exhibited strong affinity with POM due to their similar molecular structure. The thermal conductivity and the mechanical properties of the composites were investigated, which showed that the thermal conductive properties of POM were improved remarkably in the presence of MWNTs, whereas reduced by using MWNT‐g‐PEG due to the heat transport barrier of the grafted‐PEG‐substituted amine chain. A nonlinear increase of the thermal conductivity was observed with increasing MWNTs content, and the Maxwell‐Eucken model and the Agari model were used for theoretical evaluation. The relatively high effective length factor of the composite predicted with mixture equation indicated that there were few entangles of MWNTs for the samples of MWNT‐g‐PEG in the composites. The mechanical strength of the composites can be improved remarkably by using suitable content of such functionalized MWNTs, and with the increase of the aliphatic chain length of PEG‐substituted amine, the toughness of the composites can be enhanced. Transmission electron microscope result indicated that MWNT‐g‐PEG exhibited strong affinity with POM and a good dispersion of MWNTs was achieved in POM matrix. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 905–912, 2010     

Functionalization of Graphene Sheets via Chemically Grafting of PMMA Chains Through in-situ Polymerization

In this work, we report the preparation of graphene nanoplatelet which covalently functionalized with PMMA chains by introduction of vinyl groups onto graphene surface through simple esterification reaction between hydroxyl groups of graphite oxide and methacrylic anhydride. The synthesis is followed by in-situ polymerization with MMA monomers. The structural properties were characterized with X-ray diffraction spectroscopy (XRD) and scanning electronic microscopy (SEM) that showed the crystalline graphite is converted to individual layers during the synthesis steps. The grafting of PMMA chains was monitored with IR spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The TGA results revealed 40% wt of PMMA chains chemically grafted onto graphene surface. Significant increase in glass transition temperature (T_g) and existence of polymer chains in two positions (physically absorbed and chemically grafting onto graphite surface) are indicated by differential scanning calorimetric (DSC) analysis.     

Nanocomposites derived from in situ grafting of linear and hyperbranched poly(ether‐ketone)s containing flexible oxyethylene spacers onto the surface of multiwalled carbon nanotubes

Linear and hyperbranched poly(ether‐ketone)s (PEKs) containing flexible oxyethylene spacers grafted multiwalled carbon nanotube (PEK‐g‐MWNT) nanocomposites were prepared by direct Friedel‐Crafts acylation as the polymer forming and grafting reaction. To achieve the composites, in situ polycondensations of AB monomers 3‐(2‐phenoxyethoxy)benzoic acid (3‐PEBA) and 4‐(2‐phenoxyethoxy)benzoic acid (4‐PEBA), and AB₂ monomer 3,5‐bis(2‐phenoxyethoxy)benzoic acid (3,5‐BPEBA) were carried out in the presence of multiwalled carbon nanotubes (MWNTs). The reaction conditions, polyphosphoric acid (PPA) with additional phosphorous phentoxide (P₂O₅) in the temperature range of 110–120 °C, were previously optimized. The conditions were used as the polymerization and grafting medium that were indeed benign not to damage MWNTs but strong enough to promote the covalent attachment of PEKs onto the surface of the electron‐deficient MWNTs. From scanning electron microscopy (SEM) and transmission electron microscopy studies, the polymers were uniformly grafted onto the MWNTs. The resultant nanocomposites are soluble in most strong acids such as trifluoroacetic acid, methanesulfonic acid, and sulfuric acid. Both isothermal and dynamic TGA studies in air showed that nanocomposites displayed improved thermo‐oxidative stability when compared with those of corresponding PEK homopolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3471–3481, 2008     

聚合物对多壁碳纳米管的包覆改性研究

探讨了聚合物对碳纳米管的包覆改性.将多壁碳纳米管(MWNTs)通过浓硫酸和浓硝酸的混酸(体积比=3∶1)处理,使其带上羧基.将羧化MWNTs与甲基丙烯酸缩水甘油酯(GMA),苯乙烯双组分接枝聚苯乙烯(PS-g-(GMA-co-St))通过溶液共混方法,使其接在MWNTs上的羧基和GMA所带的环氧基团之间发生酯化反应,实现MWNTs表面接枝上PS-g-(GMA-co-St).扫描电镜观察表明,羧化MWNTs平均管径约为40nm,而接枝上PS-g-(GMA-co-St)的改性MWNTs管径可达约100nm.用四氢呋喃(THF)对表层包覆的PS-g-(GMA-co-St)刻蚀后,其直径降回到约40nm,这和先前观察到的羧化MWNTs的直径基本一致.对刻蚀后的MWNTs样品的FT-IR分析也表明MWNTs表面上存在接枝PS.表面经过PS-g-(GMA-co-St)修饰后,可以形成包覆层,为MWNTs在聚合物基体中分散、制备纳米功能材料提供了途径.     

Compatibilizing effect of a graft copolymer on bacterial poly(3‐hydroxybutyrate)/poly(methyl methacrylate) blends

Blends of isotactic (natural) poly(3‐hydroxybutyrate) (PHB) and poly(methyl methacrylate) (PMMA) are partially miscible, and PHB in excess of 20 wt % segregates as a partially crystalline pure phase. Copolymers containing atactic PHB chains grafted onto a PMMA backbone are used to compatibilize phase‐separated PHB/PMMA blends. Two poly(methyl methacrylate‐g‐hydroxybutyrate) [P(MMA‐g‐HB)] copolymers with different grafting densities and the same length of the grafted chain have been investigated. The copolymer with higher grafting density, containing 67 mol % hydroxybutyrate units, has a beneficial effect on the mechanical properties of PHB/PMMA blends with 30–50% PHB content, which show a remarkable increase in ductility. The main effect of copolymer addition is the inhibition of PHB crystallization. No compatibilizing effect on PHB/PMMA blends with PHB contents higher than 50% is observed with various amounts of P(MMA‐g‐HB) copolymer. In these blends, the graft copolymer is not able to prevent PHB crystallization, and the ternary PHB/PMMA/P(MMA‐g‐HB) blends remain crystalline and brittle. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1390–1399, 2002     

Synthesis of coil‐comb block copolymers containing polystyrene coil and poly(methyl methacrylate) side chains via atom transfer radical polymerization

A series of polystyrene‐b‐(poly(2‐(2‐bromopropionyloxy) styrene)‐g‐poly(methyl methacrylate)) (PS‐b‐(PBPS‐g‐PMMA)) and polystyrene‐b‐(poly(2‐(2‐bromopropionyloxy)ethyl acrylate)‐g‐poly(methyl methacrylate)) (PS‐b‐(PBPEA‐g‐PMMA)) as new coil‐comb block copolymers (CCBCPs) were synthesized by atom transfer radical polymerization (ATRP). The linear diblock copolymer polystyrene‐b‐poly(4‐acetoxystyrene) and polystyrene‐b‐poly(2‐(trimethylsilyloxy)ethyl acrylate) PS‐b‐P(HEA‐TMS) were obtained by combining ATRP and activators regenerated by electron transfer (ARGET) ATRP. Secondary bromide‐initiating sites for ATRP were introduced by liberation of hydroxyl groups via deprotection and subsequent esterification reaction with 2‐bromopropionyl bromide. Grafting of PMMA onto either the PBPS block or the PBPEA block via ATRP yielded the desired PS‐b‐(PBPS‐g‐PMMA) or PS‐b‐(PBPEA‐g‐PMMA). ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography data indicated the target CCBCPs were successfully synthesized. Preliminary investigation on selected CCBCPs suggests that they can form ordered nanostructures via microphase separation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2971–2983     

“Click” coupling between alkyne‐decorated multiwalled carbon nanotubes and reactive PDMA‐PNIPAM micelles

Covalent functionalization of alkyne‐decorated multiwalled carbon nanotubes (MWNTs) with a well‐defined, azide‐derivatized, thermoresponsive diblock copolymer, poly(N,N‐dimethylacrylamide)‐poly(N‐isopropylacrylamide) (PDMA‐PNIPAM) was accomplished by the Cu(I)‐catalyzed [3 + 2] Huisgen cycloaddition. It was found that this reaction could simultaneously increase the molecular size and bonding density of grafted polymers when PDMA‐PNIPAM micelles were employed in the coupling system. On the other hand, attachment of molecularly dissolved unimers of high‐molecular weight onto the nanotube resulted in low‐graft density. The block copolymer bearing azide groups at the PDMA end was prepared by reversible addition–fragmentation transfer polymerization, which formed micelles with a diameter of ～40 nm at temperatures above its critical micelle temperature. Scanning electron microscopy was utilized to demonstrate that the coupling reaction was successfully carried out between copolymer micelles and alkyne‐bearing MWNTs. FTIR spectroscopy was utilized to follow the introduction and consumption of alkyne groups on the MWNTs. Thermogravimetric analysis indicated that the functionalized MWNTs consisted of about 45% polymer. Transmission electron microscopy was utilized to image polymer‐functionalized MWNTs, showing relatively uniform polymer coatings present on the surface of nanotubes. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7187–7199, 2008     

Synthesis and characterization of grafted/crosslinked proton conducting membranes based on amphiphilic PVDF copolymer

A novel graft copolymer consisting of a poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) backbone and poly(glycidyl methacrylate) side chains, that is, P(VDF‐co‐CTFE)‐g‐PGMA, was synthesized through atom transfer radical polymerization (ATRP) using CTFE units as a macroinitiator. Successful synthesis and microphase‐separated structure of the polymer were confirmed by ¹H NMR, FTIR spectroscopy, and TEM. As‐synthesized P(VDF‐co‐CTFE)‐g‐PGMA copolymer was sulfonated by sodium bisulfite, followed by thermal crosslinking with sulfosuccinic acid (SA) via the esterification to produce grafted/crosslinked polymer electrolyte membranes. The IEC values continuously increased with increasing SA content but water uptake increased with SA content up to 10 wt %, above which it decreased again as a result of competitive effect between crosslinking and hydrophilicity of membranes. At 20 wt % of SA content, the proton conductivity reached 0.057 and 0.11 S/cm at 20 and 80 °C, respectively. The grafted/crosslinked P(VDF‐co‐CTFE)‐g‐PGMA/SA membranes exhibited good mechanical properties (>400 MPa of Young's modulus) and high thermal stability (up to 300 °C), as determined by a universal testing machine (UTM) and TGA, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1110–1117, 2010     

Functionalization of multiwalled carbon nanotubes with polyesters via bergman cyclization and “grafting from” strategy

In this work, pristine multiwalled carbon nanotubes (MWNTs) were functionalized by utilizing the free radicals generated through Bergman cyclization of enediyne containing compounds 3 . Polyesters were subsequently grafted from the surface of MWNTs through ring‐opening polymerization of ε‐caprolactone or lactide initiated by free hydroxy groups generated after hydrolysis of ester groups. Functionalized MWNTs were characterized with a variety of techniques, including TGA, NMR, IR, UV–vis, TEM, and Raman spectroscopy. After surface modification, MWNTs showed good solubility in common organic solvents and polymer solutions. Fabrication of MWNTs polymer nanocomposites was revealed through electrospinning with polycaprolactone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Effects of carbon nanotubes on crystallization and melting behavior of poly(L‐lactide) via DSC and TMDSC studies

In this work, multiwalled carbon nanotubes (MWNTs) were surface‐modified and grafted with poly(L ‐lactide) to obtain poly(L ‐lactide)‐grafted MWNTs (i.e. MWNTs‐g‐PLLA). Films of the PLLA/MWNTs‐g‐PLLA nanocomposites were then prepared by a solution casting method to investigate the effects of the MWNTs‐g‐PLLA on nonisothermal and isothermal melt‐crystallizations of the PLLA matrix using DSC and TMDSC. DSC data found that MWNTs significantly enhanced the nonisothermal melt‐crystallization from the melt and the cold‐crystallization rates of PLLA on the subsequent heating. Temperature‐modulated differential scanning calorimetry (TMDSC) analysis on the quenched PLLA nanocomposites found that, in addition to an exothermic cold‐crystallization peak in the range of 80–120 °C, an exothermic peak in the range of 150–165 °C, attributed to recrystallization, appeared before the main melting peak in the total and nonreversing heat flow curves. The presence of the recrystallization peak signified the ongoing process of crystal perfection and, if any, the formation of secondary crystals during the heating scan. Double melting endotherms appeared for the isothermally melt‐crystallized PLLA samples at 110 °C. TMDSC analysis found that the double lamellar thickness model, other than the melting‐recrystallization model, was responsible for the double melting peaks in PLLA nanocomposites. Polarized optical microscopy images found that the nucleation rate of PLLA was enhanced by MWNTs. TMDSC analysis found that the incorporation of MWNTs caused PLLA to decrease the heat‐capacity increase (namely, ΔC_p) and the C_p at glass transition temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1870–1881, 2007     

Structure–property relationships in modified natural rubber latexes grafted with methyl methacrylate and vinyl neo‐decanoate

A series of modified natural rubber latexes (NRLs) grafted with poly(methyl methacrylate) (PMMA) were prepared by seeded emulsion polymerization with NRL as the seed polymer. Two different redox systems, cumene hydroperoxide (CHP)/tetraethylene pentamine (TEPA) and tert‐butyl hydroperoxide (t‐BHP)/TEPA, were used to initiate polymerization, and phase mixing was promoted by the addition of vinyl neo‐decanoate (VneoD). The CHP/TEPA system was more efficient than t‐BHP/TEPA for the grafting of secondary polymers in modified natural rubber (NR). The enhanced phase mixing in the presence of VneoD was attributed to the solubility parameter of the VneoD‐rich methyl methacrylate–VneoD copolymer formed late in the reaction, lying between that of PMMA and NR, and the extent to which this polymer was grafted to the NR backbone. The viscoelastic properties of the polymers were investigated as a function of composition, temperature, and frequency; changes in viscoelastic behavior consistent with the presence of a high‐T_g PMMA phase (where T_g is the glass‐transition temperature) were observed. This suggested a degree of phase mixing that increased with increasing VneoD content and increasing flux of oxygen‐centered radicals within the NR particles. More phase mixing resulted in poorer film formation, which was consistent with the localization of a high‐T_g secondary polymer phase near the particle surface. The apparent concentration of PMMA near the surface of the particles was also observed with transmission electron microscopy. The localization of PMMA near the particle surfaces was consistent with the presumed locus of radical generation in these systems: the redox couple used to initiate the polymerization consisted of an oil‐soluble hydroperoxide and a water‐soluble amine that reacted predominantly at the water/particle interface. The viscoelastic properties of the modified NRLs that were prepared suggest that these synthetic procedures provide a means of controlling phase mixing and branching, such as for improving the suitability of these modified rubbers in pressure‐sensitive‐adhesive formulations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 809–822, 2002; DOI 10.1002/pola.10165     

Particle monolayer formation at the air–water interface by silica particle with well‐defined grafted polymer

Particle monolayer formation at the air–water interface by polymer‐grafted colloidal silica was investigated. Methyl methacrylate (MMA) was polymerized from initiative bromide groups at colloidal silica surface by atom transfer radical polymerization. We obtained polymer‐grafted silica particle (SiO₂‐PMMA) with relative narrow polydispersity of PMMA. For the polymer‐grafted particle with high graft density, particle monolayer formation was confirmed by π‐A isotherm measurement and SEM observation. Interparticle distance was controllable by surface pressure. Furthermore, grafted polymer chains were suggested to be fairly extended at the air–water interface. However, for the polymer‐grafted particle with low graft density, monolayer structure on substrate showed aggregation and voids. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2789–2797, 2006     

Synthesis of graft copolymers onto styrenic polymer backbone via “grafting from” raft process

A new synthetic methodology is developed for preparing graft copolymers via RAFT polymerization method by the “R group approach” onto styrenic polymers. In this approach, latent sites of the styrenic polymer was brominated first and then converted into macro‐RAFT agents with pyrazole and thio dodecyl as the Z groups. This was used to synthesize graft copolymer such as polystyrene‐graft‐polymethyl methacrylate (PS‐g‐PMMA), polystyrene‐graft‐poly(isobornyl acrylate), polystyrene‐graft‐poly[2‐(acetoacetoxy)ethyl methacrylate] (PS‐g‐PAEMA), and poly(para‐methoxystyrene)‐graft‐polystyrene (P(p‐MS)‐g‐PS). The polymers are characterized by gel permeation chromatography, ¹H NMR, IR, and atomic force microscopy (AFM). The morphology of PS‐g‐PMMA in THF was investigated using AFM and island‐like features were noticed. The AFM studies of the PS‐g‐PAEMA graft copolymers revealed the formation of globules and ribbon‐like morphological features. The PS‐g‐PAEMA graft copolymers form complex with Fe(III) in dimethylformamide and the AFM studies suggest the formation of globular superstructures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

聚氨酯接枝多壁碳纳米管的制备及表征

采用两步法成功地将聚氨酯分子链以共价键连接到碳纳米管表面. 首先将聚丙烯酰氯通过与强酸氧化后多壁碳纳米管表面产生的羟基及少量羧基之间的化学反应共价接枝到碳纳米管表面; 然后将接枝到碳纳米管表面的聚丙烯酰氯与端羟基聚氨酯发生酯化反应, 实现了聚氨酯对碳纳米管的表面共价接枝. 采用傅里叶变换红外光谱(FTIR)、透射电镜(TEM)、扫描电镜(SEM) 和热重分析(TGA)等对接枝后的产物进行了表征, 结果表明, 聚氨酯已共价接枝到碳纳米管表面, 被接枝的聚合物的含量接近90%.