Preparation and mechanical properties of clay/polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer (SBS) intercalated nanocomposites using organoclay containing stearic acid

Organoclays containing various amounts of stearic acid (SA) were synthesized, and clay/polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer (SBS) intercalated nanocomposites were prepared using organoclays containing SA by melt‐blending. Montmorillonite was the clay used, and both stearylamine and SA were used as surface modifiers. The amount of SA added was 0, 20, 50 and 100% of the cation‐exchange capacity (CEC). In this study, the effects of SA on the microstructure and mechanical properties of the clay/SBS nanocomposites were investigated. In clay/SBS with 100% CEC of SA, although no exfoliation of the clay occurred, the stacked clay layers were uniformly dispersed at the nanometer level (100–800 nm) without agglomeration. Clay/SBSs containing SA exhibited superior mechanical properties compared to clay/SBS without SA. It was found that SA effectively improved the clay dispersion in the SBS matrix and the mechanical properties of the clay/SBSs. Copyright © 2006 Society of Chemical Industry     

Toughening of epoxy thermosets with polystyrene‐block‐polybutadiene‐block‐ polystyrene triblock copolymer via formation of nanostructures

In this contribution, we reported to utilize polystyrene‐block‐polybutadiene‐block‐polystyrene (PS‐b‐PB‐b‐PS), a commercial triblock copolymer to toughen epoxy thermosets. First, a PS‐b‐PB‐b‐PS triblock copolymer was chemically modified with hydroboration‐oxidation reaction, with which the midblock was hydroxylated whereas the endblocks remained unaffected. It was found that the degree of hydroxylation was well controlled. One of the hydroxylated PS‐b‐PB‐b‐PS samples was then used as the macromolecular initiator to synthesize a poly(ε‐caprolactone)‐grafted PS‐b‐PB‐b‐PS via the ring‐opening polymerization. It was found that the PS‐b‐PB‐b‐PS with poly(ε‐caprolactone) grafts can be successfully employed to nanostructure epoxy thermosets; the “core‐shell” microdomains composed of PB and PS were generated in the nanostructured thermosets. The nanostructured thermosets displayed improved fracture toughness. POLYM. ENG. SCI., 59:2387–2396, 2019. © 2019 Society of Plastics Engineers     

Influence of the extrusion process on the morphology and micromechanical behavior of polystyrene‐block‐(polystyrene‐co‐butadiene)‐block‐polystyrene star block copolymer/homopolystyrene blends

The influence of the extrusion process on the morphology and micromechanical behavior of an asymmetric polystyrene‐block‐(polystyrene‐co‐butadiene)‐block‐polystyrene (SBS) star block copolymer and its blends with general‐purpose homopolystyrene (hPS) was studied with films prepared with a single‐screw extruder. The techniques used were transmission electron microscopy and uniaxial tensile testing. Unlike the pure SBS block copolymer possessing a gyroid‐like morphology, whose deformation was found to be insensitive to the processing conditions, the mechanical properties of the blends strongly depended on the extrusion temperature as well as the apparent shear rate. The deformation micromechanism was primarily dictated by the blend morphology. The yielding and cavitation of the nanostructures were the principal deformation mechanism for the blends having a droplet‐like microphase‐separated morphology, whereas cavitation dominated for the blends containing macrophase‐separated layers of polystyrene. The mechanical properties of the blends were further examined with respect to the influence of the temperature and shear rate on the phase behavior of the blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Correlation between artificial and natural weathering tests on polystyrene‐block‐polybutadiene‐block‐polystyrene block copolymer

The effects of artificial and natural weathering tests on the structure and mechanical properties of polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) block copolymer were studied by spectrophotometry, Fourier Transform Infrared (FTIR) Spectroscopy, hardness measurements, and tensile testing. The correlation between artificial and natural weathering tests was also investigated. The results showed that the surface of SBS became yellow with increasing aging time. FTIR spectra confirmed the formation of carbonyl group in the aging process. The elongation at break, the tensile strength, and the tear strength decreased rapidly in the initial stage of the aging process and then leveled off, while the hardness increased with aging time. The correlation between artificial and natural weathering tests in Wanning and Hailaer, in China, could be expressed in terms of t₁ = 2.50t₀^1.99 and t₂ = 1.92t₀^2.56, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Dynamic mechanical properties of polystyrene‐block‐poly[ethylene‐co‐(ethylene‐propylene)]‐block‐polystyrene triblock copolymer/hydrocarbon oil blends

Blend systems of polystyrene‐block‐poly(ethylene‐co‐(ethylene‐propylene))‐block‐polystyrene (SEEPS) triblock copolymer with three types of hydrocarbon oil of different molecular weight were prepared. The E″ curves as a function of temperature exhibited two peaks; one peak at low temperature (? ?50°C), arising from the glass transition of the poly[ethylene‐co‐(ethylene‐propylene)] (PEEP) phase and a high temperature peak (? 100°C), arising from the glass transition of the polystyrene (PS) phase. The glass transition temperature (T_g) of the PEEP phase shifted to lower temperature with increasing oil content. The shifted T_g depended on the types of oil and was lower for the low molecular weight oil. The T_g of PS phase of the present blend system, were found to be constant and independent of the oil content, when molecular weight of the oil is high. However, for the lower molecular weight oil, the T_g of the PS phase also shifted to lower temperatures. This fact indicates that the oil of high molecular weight is merely dissolved in the PS phase. The E′ at (75°C, at which temperature both of PEEP and PS phases are in glassy state, was found to be independent of oil content. In contrast, at 25°C, at which temperature the PEEP phase is in rubbery state, the E′ decreased sharply with increasing oil content. This result indicates that the hydrocarbon oil was a selective solvent in the PEEP phase. It mainly dissolved in the PEEP phase, although slightly dissolved into the PS phase as well, when molecular weight of oil is low. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Clay‐containing block copolymer nanocomposites with aligned morphology prepared by extrusion

Clay‐containing nanocomposites of polystyrene‐b‐poly(ethylene‐co‐butylene)‐b‐polystyrene (SEBS) copolymers having cylindrical domains were obtained by melt extrusion using a tape die. One type of sample (SEBS‐MA) had maleic anhydride attached to the middle block. Two types of organoclays were added, namely Cloisite 20A and Cloisite 30B. Small angle X‐ray scattering and transmission electron microscopy (TEM) analyses showed that the addition of 20A clay to SEBS and SEBS‐MA resulted in nanocomposites with intercalated and partially exfoliated structures, respectively. The addition of 30B clay to SEBS and SEBS‐MA promoted the formation of composites containing relatively large micron‐sized and partially exfoliated clay particles, respectively. Our TEM analysis revealed that clay particles embedded in SEBS are preferably in contact with the polystyrene cylindrical domains, while in SEBS‐MA they are in contact with the maleated matrix. The extrusion processing promoted alignment of the axes of the polystyrene cylinders along the extrusion direction in all samples, and the basal planes of the clay particles were mostly parallel to the main external surfaces of the extruded tapes. © 2013 Society of Chemical Industry     

Synthesis and characterization of novel polystyrene‐block‐polyurethane‐block‐polystyrene tri‐block copolymers through atom transfer radical polymerization

Background: Radical polymerization is used widely to polymerize more than 70% of vinyl monomers in industry, but the control over molecular weight and end group of the resulting polymers is always a challenging task with this method. To prepare polymers with desired molecular weight and end groups, many controlled radical polymerization (CRP) ideas have been proposed over the last decade. Atom transfer radical polymerization (ATRP) is one of the successful CRP techniques. Using ATRP, there is no report on the synthesis of polystyrene‐block‐polyurethane‐block‐polystyrene (PSt‐b‐PU‐b‐PSt) tri‐block copolymers. Hence this paper describes the method of synthesizing these tri‐block copolymers. To accomplish this, first telechelic bromo‐terminated polyurethane was synthesized and used further to synthesize PSt‐b‐PU‐b‐PSt tri‐block copolymers using CuBr as a catalyst and N,N,N,N″,N″‐pentamethyldiethylenetriamine as a complexing agent. Results: The ‘living’ nature of the initiating system was confirmed by linear increase of number‐average molecular weight and conversion with time. A semi‐logarithmic kinetics plot shows that the concentration of propagating radical is steady. The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and differential scanning calorimetry show that the novel PSt‐b‐PU‐b‐PSt tri‐block copolymers were formed through the ATRP mechanism. Conclusion: For the first time, PSt‐b‐PU‐b‐PSt tri‐block copolymers were synthesized through ATRP. The advantage of this method is that the controlled incorporation of polystyrene block in polyurethane can be achieved by simply changing the polymerization time. Copyright © 2007 Society of Chemical Industry     

Singlet oxygen generation and adhesive loss in stimuli‐responsive,fullerene‐polymer blends,containing polystyrene‐block‐polybutadiene‐block‐polystyrene and polystyrene‐block‐polyisoprene‐block‐polystyrene rubber‐based adhesives

The adhesive properties, as measured by bulk tack and peel strength analysis, were found to decrease in polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) and polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS) PSA films containing common singlet oxygen generators, acridine, rose bengal, and C₆₀ fullerene, when irradiated with a tungsten halogen light in air. The addition of the singlet oxygen quencher, β‐carotene, to the C₆₀ fullerene samples was found to significantly deter the rate of adhesive loss in the fullerene‐SBS and ‐SIS PSA nanocomposites. The presence of oxygen was essential to the mechanism of adhesive loss and, in combination with the effects of singlet oxygen generators and a singlet oxygen scavenger, strongly supports a singlet‐oxygen mediated process. FTIR investigations of fullerene‐SBS and ‐SIS systems suggest the initial formation of peroxides which, upon further irradiation, lead to the generation of carbonyl‐containing compounds of a ketonic type after crosslinking. Rates of SBS and SIS C‐H abstraction were comparable and found to decrease when the high‐pressure, mercury xenon irradiation source was filtered to allow only light of λ > 390 nm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Wetting behaviour and direct observation of thermally responsive polystyrene‐block‐poly(N‐isopropylacrylamide)‐block‐polystyrene electrospun fibres in aqueous environment

Electrospun fibres of thermally responsive triblock copolymer polystyrene‐block‐poly(N‐isopropylacrylamide)‐block‐polystyrene were prepared. Fibre morphology and swelling were studied below and above the lower critical solution temperature of poly(N‐isopropylacrylamide) (PNIPAM) using cryo‐electron microscopy. Cryo‐transmission electron microscopy showed that the fibre diameter increased up to 150% after immersion in water at 20 °C. In contrast, at 45 °C the fibre diameter increased considerably less. The sessile drop technique was used to characterize temperature‐dependent wetting of fibre mats. Contact angle (θ_CA) measurements revealed that a block copolymer fibre mat changed from hydrophobic (θ_CA > 90°) to hydrophilic (θ_CA < 90°) state within seconds after applying a water droplet on it at 20 °C. At 40 °C the initial contact angle was measured to be higher (135°) and it decreased much less than at 20 °C during the first minute of measurement. We observed using scanning electron microscopy that the electrospun fibres of the block copolymer having 77 wt% of PNIPAM lost their cylindrical shape and changed from fibres to thin sheets at both 20 and 40 °C within seconds after applying water on the fibres. Fibres having 55 wt% of PNIPAM were observed to be stable in water at both 20 and 40 °C, which resulted, surprisingly, in fibre mats with the strongest effects on thermally sensitive wetting. We discuss the surprising results and the implications that the evolution of fibre surface roughness has on the long‐term wetting behaviour, demonstrating a self‐adaptable hydrophilicity/hydrophobicity nature of the fibre mats. © 2013 Society of Chemical Industry     

Dewetting and microphase separation in symmetric polystyrene‐block‐polyisoprene diblock copolymer ultrathin films

The kinetics of surface structure evolution in ultrathin films of low‐molecular‐weight polystyrene‐block‐polyisoprene (M_w: 7300 g mol^?1–7300 g mol^?1) diblock copolymer at temperatures below the bulk order‐to‐disorder transition temperature are presented. Films with two different thicknesses were studied as a function of annealing temperature using atomic force microscopy. These film thicknesses enabled the investigation of the competition between microphase separation and dewetting that resulted in two different morphologies: long‐range bicontinuous structures and random holes. Three distinctive stages of structure evolution were observed in bicontinuous structure, with the underlying mechanism compared with spinodal dewetting. Thicker films presented holes on their surfaces upon annealing at elevated temperatures, and kinetics of formation of the holes were discussed. We found that the molecular mobility determined the rates of dewetting, while the microphase separation hardly affected the dewetting process. © 2015 Society of Chemical Industry     

Conductivity and mechanical properties of composites based on MWCNTs and styrene‐butadiene‐styrene block™ copolymers

Composites based on multiwall carbon nanotubes (MWCNTs) and the block copolymer styrene‐butadiene‐styrene with two different contents of styrene have been investigated and their electrical conductivity and mechanical properties have been evaluated. The composites were prepared by a solution casting procedure, using a dispersant agent for the MWCNTs. Conductivity values of 10^?4 and 1.6 S cm^?1 have been obtained for samples containing 1 and 12 wt % of MWCNTs, respectively. The percolation threshold achieved for these systems was ～0.25 wt %. According to dynamic mechanical analysis, the MWCNTs interact with both phases of the copolymers, acting as a reinforcement filler, whereas the dispersant agent acts as a plasticizer. However, it was shown that the reinforcing effect of the MWCNTs overcomes the latter, resulting in an overall improvement of mechanical properties of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Interfacial Modification of Polystyrene‐block‐polybutadiene‐block‐polystyrene/Magnesium Hydroxide Composites, 1

Composites based on polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS triblock thermoplastic elastomer) and magnesium hydroxide (Mg(OH)₂) (5–60 wt.‐%) have been prepared by twin screw extrusion. Interfacial modifiers included dispersants, i.e., isostearic acid, oleic acid, stearic acid; and coupling agents, i.e., maleanised polybutadiene and vinyltriethoxysilane. In each case, approximately one monolayer of treatment was used. A dual bore motor driven extrusion rheometer was used for assessment shear and elongation flow behavior (Cogswell's method) over a shear rate range of 100 s^?1 to 5 000 s^?1. Untreated filler and filler treated with coupling agents gave composites that become increasingly pseudoplastic as filler level increased. Fatty acid structure was shown to have some influence over the level of melt viscosity reduction normally associated with such treatments; stearic acid gave the most pronounced reduction in melt viscosity possibly due to the tightly packed monolayer. Elongational flow properties, determined using Cogswell's method, indicated significant chain extension/branching of the bulk matrix when high levels of untreated filler were present and long range filler‐matrix interaction in composites modified with maleanised polybutadiene.

Elongational viscosity versus extensional stress (obtained by Cogswell's method) for SBS blended with filler surface treatments (□) unfilled matrix, and unfilled matrix plus (?) Hⁱst and (?) MPBD.     

Synthesis of polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane via polysiloxane‐based macroinitiator in supercritical CO2

Polydimethylsiloxane‐block‐polystyrene‐block‐polydimethylsiloxane (PDMS‐b‐PS‐b‐PDMS) was synthesized by the radical polymerization of styrene using a polydimethylsiloxane‐based macroazoinitiator (PDMS MAI) in supercritical CO₂. PDMS MAI was synthesized by reacting hydroxy‐terminated PDMS and 4,4′‐azobis(4‐cyanopentanoyl chloride) (ACPC) having a thermodegradable azo‐linkage at room temperature. The polymerization of styrene initiated by PDMS MAI was investigated in a batch system using supercritical CO₂ as the reaction medium. PDMS MAI was found to behave as a polyazoinitiator for radical block copolymerization of styrene, but not as a surfactant. The response surface methodology was used to design the experiments. The parameters used were pressure, temperature, PDMS MAI concentration and reaction time. These parameters were investigated at three levels (?1, 0 and 1). The dependent variable was taken as the polymerization yield of styrene. PDMS MAI and PDMS‐b‐PS‐b‐PDMS copolymers obtained were characterized by proton nuclear magnetic resonance and infrared spectroscopy. The number‐ and weight‐average molecular weights of block copolymers were determined by gel permeation chromatography. Copyright © 2004 Society of Chemical Industry     

Self‐assembled structures in polystyrene‐block‐polyisoprene‐blend‐polystyrene and polystyrene‐block‐poly(methyl methacrylate)‐blend‐polystyrene or ‐blend‐poly(methyl methacrylate) in the strong segregation regime

This study deals with the investigation of microphase‐separated morphology and phase behaviour in blends of polystyrene‐block‐polyisoprene with homopolystyrene and blends of polystyrene‐block‐poly(methyl methacrylate) with homopoly(methyl methacrylate) or homopolystyrene in the strong segregation regime using small‐angle X‐ray scattering and transmission electron microscopy as a function of composition, molecular weight of homopolymers, r_M and temperature. Parameter r_M = M_H/M_C (where M_H is the molecular weight of homopolymer and M_C that of the corresponding block copolymer) was selected to encompass behaviour of the chains denoted as a ‘wet brush’ (i.e. r_M < 1). The relative domain spacing D/D_o increases in the regime 0 < r_M?1 with increasing concentration of homopolymer w_P and increasing r_M but depends on the specific implemented morphology. We tested a new approximate D/D_o versus w_P relation in the strong segregation regime using block copolymers of high molecular weights. It is shown that the parameters r_M and χ^3/2N determine the slope of the D/D_o versus w_P relation in the strong segregation regime and the new approximation generally matches the experimental data better than the approximations used so far. Copyright © 2010 Society of Chemical Industry     

Atomic force microscopy study of self‐assembly behaviors of hydrophobic poly(n‐butyl methacrylate)‐block‐polydimethylsiloxane‐block‐poly(n‐butyl methacrylate) ABA triblock copolymers

Poly(n‐butyl methacrylate)‐block‐polydimethylsiloxane‐block‐poly(n‐butyl methacrylate) (PBMA‐block‐PDMS‐block‐PBMA) ABA triblock copolymers were synthesized successfully via atom‐transfer radical polymerization using PDMS as macroinitiator. The effects of PDMS content and substrate nature on self‐assembly behaviors of PBMA‐block‐PDMS‐block‐PBMAs were systematically studied using atomic force microscopy. Two series of triblock copolymers with different molecular weights and compositions, i.e. PBMA‐block‐PDMSA12‐block‐PBMAs and PBMA‐block‐PDMSA21‐block‐PBMAs, were used, where the latter were of a higher PDMS content than the former. On silicon wafer, it was found that only spherical structures formed after annealing films spin‐coated from chloroform solutions of PBMA‐block‐PDMSA12‐block‐PBMAs. In contrast, films of PBMA‐block‐PDMSA21‐block‐PBMAs formed semi‐continuous structures. On mica wafer, it was found that ordered cylindrical pores formed after annealing films spin‐coated from chloroform solutions of PBMA‐block‐PDMSA12‐block‐PBMAs. In contrast, films of PBMA‐block‐PDMSA21‐block‐PBMAs formed isolated cylinders or worm‐like morphologies. Copyright © 2011 Society of Chemical Industry     

Syntheses of triblock polybutadiene–polydimethylsiloxane copolymers by coupling reactions

The reaction of epoxy‐telechelic polydimethylsiloxanes with polybutadienyllithium was used to prepare a series of low‐molecular‐weight polybutadiene‐block‐polydimethylsiloxane‐block‐polybutadiene copolymers. The copolymers were purified by repeated fractional precipitation/centrifugation and characterized with NMR, vapor pressure osmometry, size exclusion chromatography, and elemental analysis. The applicability of this method is discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3233–3240, 2006     

Effects of compatibility between tackifier and polymer on adhesion property and phase structure: Tackifier‐added polystyrene‐based triblock/diblock copolymer blend system

The effects of compatibility of tackifier with polymer matrix and mixing weight ratio of triblock/diblock copolymers as the matrix on the adhesion property and phase structure of tackifier‐added polystryrene triblock/diblock copolymer blends were investigated. For this purpose, polystyrene‐block‐polyisoprene‐block‐polystyrene triblock and polystyrene‐block‐polyisoprene diblock copolymers were used and the diblock weight ratio in the blend was varied from 0 to 1. Spherical polystyrene domains with a mean size of about 20 nm were dispersed in the polyisoprene (PI) continuous phase. In the case of the hydrogenated cycloaliphatic resin as tackifier having a good compatibility with PI and a poor compatibility with polystyrene, the peel strength increased with an increase of the tackifier content, and the degree of increase became significant above 40 wt % of tackifier. It was found that the nanometer‐sized agglomerates of tackifier in the PI matrix were formed and the distance between the nearest neighbors of agglomerates was about 15 nm from SAXS measurement. The peel strength increased with an increase of the nanometer‐sized agglomerates of tackifier from TEM observation. On the other hand, in the case of the rosin phenolic resin as tackifier having a good compatibility with both polystyrene and PI, the peel strength increased effectively at the lower tackifier content, while no significant increase at higher tackifier content was observed. The agglomerates of tackifier were never confirmed in this system. The higher peel strength was obtained at the diblock weight ratio in the blend of 0.5–0.7 for both tackifier‐added systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

AB‐ and ABC‐type di‐ and triblock copolymers of poly[styrene‐block‐(ε‐caprolactone)] and poly[styrene‐block‐(ε‐caprolactone)‐block‐lactide]: synthesis,characterization and thermal studies

Polystyrene terminated with benzyl alcohol units was employed as a macroinitiator for ring‐opening polymerization of ε‐caprolactone and L ‐lactide to yield AB‐ and ABC‐type block copolymers. Even though there are many reports on the diblock copolymers of poly(styrene‐block‐lactide) and poly(styrene‐block‐lactone), this is the first report on the poly(styrene‐block‐lactone‐block‐lactide) triblock copolymer consisting of two semicrystalline and degradable segments. The triblock copolymers exhibited twin melting behavior in differential scanning calorimetry (DSC) analysis with thermal transitions corresponding to each of the lactone and lactide blocks. The block derived from ε‐caprolactone also showed crystallization transitions upon cooling from the melt. In the DSC analysis, one of the triblock copolymers showed an exothermic transition well above the melting temperature upon cooling. Thermogravimetric analysis of these block copolymers showed a two‐step degradation curve for the diblock copolymer and a three‐step degradation for the triblock copolymer with each of the degradation steps associated with each segment of the block copolymers. The present study shows that it is possible to make pure triblock copolymers with two semicrystalline segments which also consist of degradable blocks. Copyright © 2009 Society of Chemical Industry     

Application of the biodegradable diblock copolymer poly(L‐lactide)‐block‐poly(L‐cysteine): Drug delivery and protein conjugation

A novel approach to self‐assembled and shell‐crosslinked (SCL) micelles from the diblock copolymer poly(L ‐lactide)‐block‐poly(L ‐cysteine) to be used as drug and protein delivery carriers is described. Rifampicin was used as a model drug. The drug‐loaded SCL micelles were obtained by self‐assembly of the copolymer in the presence of the drug in aqueous media. Their morphology and size were studied with dynamic light scattering and field emission scanning electron microscopy. The rifampicin loading capacity and encapsulation efficiency were studied with ultraviolet–visible spectrophotometry. The drug‐release rate in vitro depended on the oxidizing and reducing environment. Moreover, a straightforward approach to the conjugation of the copolymer with bovine serum albumin (BSA) was developed, and a gel electrophoresis test demonstrated that this conjugated BSA could be reversibly released from the copolymer substrate under reducing conditions. In conclusion, this L ‐cysteine copolymer can be used in drug delivery and in protein fixation and recovery. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crystal behavior of semicrystalline polystyrene‐block‐poly(l‐lactide) diblock copolymer in thin films with various structures

The crystal behavior of a semicrystalline polystyrene‐block‐poly(l ‐lactide) diblock copolymer in phase‐separated thin films with various thicknesses at different crystal temperatures has been investigated using atomic force microscopy and transmission electronic microscopy. Parallel and perpendicular lamellae could be obtained by annealing the thin films for different periods of time as reported previously (Chen et al., Macromolecules 40:6631 (2007)). At different temperatures, crystallization in thin films with parallel lamellar structure in the melt state gives dendrite crystals with orthorhombic structure, and the ordered structure in the melt is destroyed after crystallization. When crystallization occurs in thin films with perpendicular lamellar structure, crystal morphology and structure are greatly affected by the crystallization temperature (T_c). When T_c < T_g,ps, where T_g,ps is the glass transition temperature of a polystyrene block, crystallization is hardly confined within the lamellae. The morphology is preserved but the long period of the perpendicular lamellae is increased after crystallization. When T_c > T_g,ps, rod‐like crystals dominate the final morphology, and crystallinity destroys completely the structure in the melt.© 2012 Society of Chemical Industry