Surface morphology of adsorbed sulfur‐functionalized polystyrene thin film on gold on the basis of atomic force microscopic observation

Polystyrene thin film containing one‐terminal thiol (PS–SH) was spin‐coated and adsorbed from 0.1 to 0.001 wt % of polymer solution in toluene onto evaporated gold (Au) film supported on Si‐wafer substrate. The effect of polymer solution concentration on the aggregation structure of PS–SH thin films was determined on the basis of atomic force microscopic (AFM) observation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1248–1252, 2002     

Viscoelastic properties and film morphology of heterogeneous styrene–butadiene latexes

Heterogeneous carboxylated styrene–butadiene (S/Bu) latexes were prepared by a twostage emulsion polymerization process, using three PS seeds with different molecular weights. The second-stage polymer was a copolymer with a fixed S/Bu ratio of 1 : 1 and a methacrylic acid (MAA) content of either 1 or 10 wt %. Morphological studies by transmission electron microscopy (TEM) as well as studies of the viscoelastic properties by mechanical spectroscopy have been performed on films prepared from the latexes. The studies showed that the glass transition temperature, T_g, of the second-stage polymer was considerably affected by copolymerization with MAA. An increase in the MAA content in the second-stage polymer increased the T_g of this phase significantly. Addition of DVB as a crosslinking agent in the preparation of the PS seed phase substantially increased the rubbery moduli of the films, whereas the glass transition temperature of the second-stage polymer was unaffected. On the other hand, the presence of a chain transfer agent reduced the glass transition of the second-stage copolymer containing 1 wt % MAA dramatically, whereas the rubbery modulus was unaffected. When the MAA content was increased to 10 wt % the influence of the MAA monomer had a dominating effect on T_g. Latexes containing 10 wt % MAA had T_g values close to each other, regardless of chain transfer agent present in the second-stage polymerization. It was found that the morphology of the latex particles influenced the rubbery modulus of the films. The presence of irregularly shaped seed particles in samples prepared from a crosslinked PS seed had a considerable reinforcing effect on the films, whereas spherical seed particles originating from core–shell particles had a less reinforcing effect. © 1996 John Wiley & Sons, Inc.     

Increase of photoluminescence from fullerene‐doped polymers under laser irradiation

Photoluminescence (PL) from fullerene (C₆₀ and C₇₀)‐doped polymers such as poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(methyl phenyl silane) (PMPS) and poly(phenyl silsesquioxane) (PPSQ) increases gradually under laser irradiation in air (but not in vacuum and in nitrogen) and eventually becomes visible to the naked eye. Concomitantly, the PL peak is broadened and, in most cases, blue‐shifted. No such PL increases are observed for pure C₆₀ films made by vacuum vapor deposition and pure polymer films. Among the polymers used, fullerene‐doped PMMA has the greatest PL increase after several hours of laser irradiation and fullerene‐doped PMPS has the highest rate of PL increase at the initial stage of the laser irradiation. To gain an insight into the mechanism of the PL increase, laser‐irradiated fullerene‐doped PMMA samples were analyzed by UV‐Vis spectrophotometer, FT‐IR, mass spectrometry, GPC and NMR. The results show that the PL increase can be attributed to CH₆₀O_n‐polymer (or C₇₀O_n‐polymer) and oxidized fullerene‐polymer adducts formed by some laser‐induced photochemical reactions among fullerenes, oxygen and polymers.     

Cellulose/chitin films blended in NaOH/urea aqueous solution

Regenerated cellulose/chitin blend films (RCCH) were satisfactorily prepared in 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl₂ aqueous solution then treating with 1 wt % HCl. The structure, miscibility, and mechanical properties of the RCCH films were investigated by infrared, scanning electron microscopy, ultraviolet spectroscopies, X‐ray diffraction, tensile test, and differential scanning analysis. The results indicated that the blends were miscible when the content of chitin was lower than 40 wt %. Moreover, the RCCH blend film achieved the maximum tensile strength in both dry and wet states of 89.1 and 43.7 MPa, respectively, indicating that the tensile strength and water resistivity of the RCCH film containing 10–20 wt % chitin was slightly higher than that of the RC film unblended with chitin. Structural analysis indicated that strong interaction occurred between cellulose and chitin molecules caused by intermolecular hydrogen bonding. Compared to the mechanical properties of chitin film, those of the blend films containing 10–50 wt % chitin were significantly improved. This work provided a novel way to obtain directly chitin material blended in the aqueous solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1679–1683, 2002     

Thermal and thermo‐oxidative stability of thermoplastic polymer nanocomposites with arylated [60]fullerene derivatives

Nanocomposite films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were prepared by loading four variations of fullerenes such as pristine C₆₀, multiarylated [60]fullerenes with tolyl (tolyl‐C₆₀) and phenol groups (phenol‐C₆₀), and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). The TGA analysis showed no appreciable change in their thermal and thermo‐oxidative stabilities for PS/tolyl‐C₆₀ and PS/phenol‐C₆₀ films, but significant improvement up to +45°C for PS/C₆₀ and PS/PCBM films even under air. The thermo‐oxidative stability of PMMA/phenol‐C₆₀ and PMMA/PCBM, however, exhibited slightly larger improvements over that of PMMA/C₆₀. We believe that the radical‐scavenging ability of π‐conjugative fullerenes and the dispersibility of fullerene–polymer combinations play key roles in these enhancements. We also found that optimal loading occurred at a relatively low content of fullerenes (0.4–0.8 wt%) probably because larger amounts may interfere with the morphological interaction of polymer chains which is essential for the thermal persistency of polymer. POLYM. COMPOS. 37:1143–1151, 2016. © 2014 Society of Plastics Engineers     

Controlled dispersion of a porphyrin/fullerene donor‐acceptor complex in semiconducting polymer thin films: Intermolecular interactions of polymers with porphyrin and fullerene

Thin films composed of semiconducting polymers [poly(2‐vinyl naphthalene), poly(4‐diphenyl aminostyrene), poly(1‐vinyl pyrene), and poly(3‐hexyl thiophene‐2,5‐diyl)], zinc(II)?5,10,15,20‐tetra‐(2‐naphthyl)porphyrin, and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester blends were prepared to investigate the controlled dispersion of porphyrin molecules in semiconducting polymer thin films. Tailoring the intermolecular interactions between the polymer/fullerene, polymer/porphyrin, and porphyrin/fullerene systems was found to be an effective method of controlling the dispersion. When the polymer/porphyrin interactions were enhanced, intermixed porphyrin/fullerene donor–acceptor complex domains were formed, whereas under conditions where the polymer/porphyrin interactions were weakened, the complex assembled at the borders between the polymer and fullerene phases. This concept could potentially be applied to various combinations of porphyrin/fullerene systems in semiconducting polymer thin films to develop polymer solar cells with excellent performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41629.     

Synthesis and properties of hydrogen‐bonded poly(amide‐imide) hybrid films

Poly(amide‐imide), PI, hybrid films are prepared by using sol–gel techniques. First, the poly(amide amic acid) with controlled block chain length of 5000 and 10,000 g/mol and uncontrolled chain length are synthesized by condensation reaction with 4,4′‐diaminodiphenyl ether (ODA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), trimellitic anhydride chloride (TMAC) and terminated with p‐aminopropyltrimethoxysilane (APrTMOS). And then the imidization reactions of poly (amide amic acid) are proceeded to obtain the poly (amide‐imide) hybrid film. Hybrid films with 5000 g/mol block chain length possess higher storage modulus, lower glass transition temperature and damping intensity comparing to films with 10,000 g/mol block chain length. The addition of TMAC to the poly(amide‐imide) hybrids is due to the increase of toughness and intermolecular hydrogen bonding, which is the average strength of intermolecular bonding and studied by the hydrogen‐bonded fraction (f_bonded), frequency difference (Δν) and shiftment. Meanwhile, PI hybrid films containing more APrTMOS and TMAC content possess higher thermal and mechanical properties. On the other hand, hybrid films with 10,000 g/mol block chain length and more TMAC content have higher gas permeabilities than other films. The degradation temperatures of 5 wt % loss of all hybrid films are all higher than 540°C and increased as the increase of TMAC content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Phase behavior of binary and ternary blends of poly(styrene‐co‐methacrylic acid), poly(styrene‐co‐4‐vinylpyridine), and poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Poly(styrene‐co‐methacrylic acid) (PSMA) and poly(styrene‐co‐4‐vinylpyridine) (PS4VP) of different compositions were prepared and characterized. The phase behavior of these copolymers as binary PSMA/PS4VP mixtures or with poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) as PPO/PSMA or PPO/PS4VP and PPO/PSMA/PS4VP ternary blends was investigated by differential scanning calorimetry (DSC). This study showed that PPO was miscible with PS4VP containing up to 15 mol % 4‐vinylpyridine (4VP) but immiscible with PS4VP‐30 (where the number following the hyphen refers to the percentage 4VP in the polymer) and PSMA‐20 (where the number following the hyphen refers to the percentage methacrylic acid in the polymer) over the entire composition range. To examine the morphology of the immiscible blends, scanning electron microscopy was used. Because of the hydrogen‐bonding specific interactions that occurred between the carboxylic groups of PSMA and the pyridine groups of PS4VP, chloroform solutions of PSMA‐20 and PS4VP‐15 formed interpolymer complexes. The obtained glass‐transition temperatures (T_g's) of the PSMA‐20/PS4VP‐15 complexes were found to be higher than those calculated from the additivity rule. Although, depending on the content of 4VP, the shape of the T_g of the PPO/PS4VP blends changed from concave to S‐shaped in the case of the miscible blends, two T_g were observed with each PPO/PS4VP‐30 and PPO/PS4VP‐40 blend. The thermal stability of the PSMA‐20/PS4VP‐15 interpolymer complexes was studied by thermogravimetry. On the basis of the obtained results, the phase behavior of the ternary PPO/PSMA‐20/PS4VP‐15 blends was investigated by DSC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Phase behavior and density of polysulfone in binary fluid mixtures of tetrahydrofuran and carbon dioxide under high pressure: Miscibility windows

Mixtures of tetrahydrofuran (THF) and carbon dioxide (CO₂) were identified as new solvent systems for polysulfone. The miscibility and density of polysulfone in binary fluid mixtures of THF and CO₂ were investigated from 300 to 425 K at pressures up to 70 MPa. The influence of the CO₂ and polysulfone concentrations was studied, with the concentrations of the other two components kept constant. At a 4.5 wt % polymer concentration, the demixing pressures in a 10 wt % CO₂ and 90 wt % THF mixture increased with temperature (310–425 K) from 15 to 40 MPa. With increasing CO₂ concentration (from ca. 10 to 14 wt %), a significant increase (from 15 to 70 MPa at 310 K) was observed in the demixing pressures. Furthermore, with an increasing amount of CO₂, the nature of the phase boundary shifted from lower critical solution temperature behavior to upper critical solution temperature behavior. The influence of the polymer concentration was studied in the 0–5 wt % range at two CO₂ levels, with solvent compositions of 10 wt % CO₂ and 90 wt % THF and 13 wt % CO₂ and 87 wt % THF. The system with a higher level of CO₂ (13 wt %) showed highly unusual phase behavior: on pressure–composition and temperature–composition diagrams, the system displayed two distinct regions of miscibility. In the system with 10 wt % CO₂, the distinct regions of miscibility that were observed in the system with 13 wt % CO₂ partially overlapped and led to a W‐shape phase boundary. The densities of the polymer solutions were measured from the one‐phase region through the demixing point into the two‐phase region at a constant temperature. No significant change in density was found around the phase boundary; this indicated that the coexisting phases had similar densities, as is often the case with liquid–liquid phase separation in polymer solutions under high pressure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2357–2362, 2002     

Effects of the molecular structure of impact modifier and compatibilizer on the toughening of PBT/SBS/PS‐GMA blends

This work aims at studying the toughening process of poly(butylene terephthalate) (PBT) through its blends with styrene‐butadiene‐styrene block copolymers (SBS), in the presence of poly(styrene‐ran‐glicydil methacrylate) (PS‐GMA) as reactive compatibilizer. High values of impact strength were attained for PBT/SBS blends without the compatibilizer; however, this improvement is achieved for blends with SBS having similar viscosity compared to PBT, at high SBS content (40 wt %) and for blends prepared under specific processing conditions. The efficiency of the in situ compatibilization of PBT/SBS blends by PS‐GMA was found to be strongly dependent on the SBS and PS‐GMA molecular characteristics. Better compatibilizing results were observed through fine phase morphologies and lower ductile to brittle transition temperatures (DBTT) as the interfacial interaction and stability of the in situ formed compatibilizer are maximized, that is, when the miscibility between SBS and PS‐GMA and reaction degree between PBT and PS‐GMA are maximized. For the PBT/SBS/PS‐GMA blends under study, this was found when it is used the SBS with higher polystyrene content (38 wt %) and with longer PS blocks (M_w = 20,000 g mol^?1) and also the PS‐GMA with moderate GMA contents (4 wt %) and with molecular weight similar to the critical one for PS entanglements (M_c = 35,000 g mol^?1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5795–5807, 2006     

Photoinduced antimicrobial polymer blends with benzophenone as a functional additive

Benzophenone (BP)‐incorporated polymer films including polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyvinyl alcohol (PVA) films were prepared, and the structural and photoactivated properties were investigated by SEM, XRD, DSC, antimicrobial, and hydrogen peroxide (H₂O₂) production tests. When the amount of incorporated BP concentration was 0.5 wt %, the polymer films were successfully prepared without significant changes in physical properties. Also, all the BP‐incorporated polymer films showed antimicrobial abilities under UVA (365 nm) irradiation, and the effectiveness increased as the amounts of BP in the polymers are increased. On the other hand, it was observed that photoirradiated PVA/BP composite films created H₂O₂ under the atmospheric dark condition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites

A potential advantage of platelet-like nanofillers as nanocomposite reinforcements is the possibility of achieving two-dimensional stiffening through planar orientation of the platelets. The ability to achieve improved properties through in-plane orientation of the platelets is a challenge and, here, we present the first results of using forced assembly to orient graphene nanoplatelets in poly(methyl methacrylate)/polystyrene (PMMA/PS) and PMMA/PMMA multilayer films produced through multilayer coextrusion. The films exhibited a multilayer structure made of alternating layers of polymer and polymer containing graphene as evidenced by electron microscopy. Significant single layer reinforcement of 118% at a concentration of 2 wt % graphene was achieved—higher than previously reported reinforcement for randomly dispersed graphene. The large reinforcement is attributed to the planar orientation of the graphene in the individual polymer layers. Anisotropy of the stiffening was also observed and attributed to imperfect planar orientation of the graphene lateral to the extrusion flow.     

Thermal and mechanical properties of blended polyimide and amine‐functionalized poly(orthosiloxane) composites

Nanocomposite films were prepared through the blending of polyimide (PI) with octaphenyl silsesquioxane (OPS) and an amino‐functionalized analogue, octaaminophenyl silsesquioxane (OAPS), with a solution‐casting method. Although the PI–OPS composites showed visible phase separation at 5 wt %, the PI–OAPS composites were transparent with visible phase separation occurring only at 50 wt % OAPS. The interfacial interactions and homogeneity of the composites were characterized with scanning electron microscopy (SEM) and dynamic mechanical analysis. SEM analysis showed a uniform fracture surface for OAPS composites at concentrations up to 20 wt %. Interestingly, OAPS‐rich particles with sizes of less than 1 μm were formed within the PI matrix for the 50 wt % composite. The PI–OAPS composites showed higher glass‐transition temperatures (T_g's) than the pure PI. The PI–OPS composites showed a T_g lower than that of the pure PI, and this suggested poor interfacial interactions. The slightly enhanced thermal stability of PI–OAPS composites (up to 20 wt %) was attributed to the inherent thermal stability of OAPS at higher temperatures. There were small increases in the modulus and strength for the composites with respect to the base polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of fullerene functionalized poly(vinyl chloride) (PVC) and dehydrochlorinated PVC using atom Transfer Radical Addition and AIBN based fullerenation

The research presented details chemical modifications of poly(vinyl chloride) (PVC) and its derivative, dehydrochlorinated PVC (DH‐PVC) through the use of two grafting techniques, namely a normal fullerenation, using AIBN (2,2′‐Azoisobutyronitrile), and the atom transfer radical addition (ATRA). The products were characterized and the presence of new FTIR peaks at 528 and 577 cm^?1 along with new ¹H‐NMR signal at 3.9 ppm, suggested that fullerenes has been grafted to the polymer molecules. Percentage of C₆₀ in the fullerene grated products determined by UV/Visible spectroscopy initially increased with the amount of fullerene used to a maximum value (～5.66 % wt) before decreasing again. It was also determined that the C₆₀ content of the fullerene grafted PVC product prepared by using ATRA, was notably greater than that obtained using the normal fullerenation approach, regardless of the amount of C₆₀ used. When the dehydrochlorinated PVC was used as the starting polymer for fullerenation, the fullerene grafted DH‐PVC using ATRA, was markedly insoluble in many common solvents (THF and dichlorobenzene). This was not the cases for the fullerene grafted DHPVC prepared via an AIBN based fullerenation. Furthermore, the electrical conductivity values of the modified PVC products determined by using a four‐point probe method were found to increase linearly with the amount of C₆₀ present. Overall our data suggest that the suitable and efficient techniques for grafting C₆₀ onto PVC and DHPVC chains are ATRA and AIBN‐based fullerenation, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2410–2421, 2013     

Preparation of polystyrene/montmorillonite nanocomposites in supercritical carbon dioxide

The preparation of polystyrene (PS)/montmorillonite (MMT) composites in supercritical carbon dioxide (SC? CO₂) was studied. Lipophilic organically modified MMT can be produced through an ion‐exchange reaction between native hydrophilic MMT and an intercalating agent (alkyl ammonium). PS/clay composites were prepared by free‐radical precipitation polymerization of styrene containing dispersed clay. X‐ray diffraction and transmission electron microscopy indicated that intercalation of MMT was achieved. PS/clay composites have a higher thermal decomposition temperature and lower glass‐transition temperature than pure PS. The IR spectrum analysis showed that the solvent of SC? CO₂ did not change the structures of the PS molecules, but there were some chemical interactions between the PS and the clay in the composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 22–28, 2005     

Polystyrene and polyether polyurethane elastomer blends compatibilized by SMA: Morphology and mechanical properties

Blends of polystyrene (PS) and the polyether polyurethane elastomer (PU‐et) were prepared by melt mixing using poly(styrene‐co‐maleic anhydride) (SMA) containing 7 wt % of maleic anhydride as a compatibilizer. The polyurethane in the blends was crosslinked using dicumyl peroxide or sulfur. The content of maleic anhydride was varied in the blends through the addition of different SMA amounts. The morphology of the blends was analyzed by SEM and a drastic reduction of both the domain size and its distribution was observed with increase of the anhydride content in the blends. The morphology of the PU‐et blends also showed dependence on the crosslinker agent used for the elastomer, and larger domains were obtained for the elastomer phase crosslinked with dicumyl peroxide. The mechanical properties of the blends were evaluated by flexural and impact strength tests. The blend containing 0.5 wt % of maleic anhydride and 20 wt % of PU‐et crosslinked with sulfur showed the highest strength impact, which was three times superior to the PS strength impact, and the blends containing 20 wt % of PU‐et crosslinked with dicumyl peroxide showed the highest deflection at break independent of the anhydride content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 830–837, 2002     

Effect of comonomer type and concentration on the equilibrium swelling and volume phase transition temperature of N‐isopropylacrylamide‐based hydrogels

The effect of incorporating a hydrophilic monomer into poly(N‐isopropylacrylamide) (polyNIPA) hydrogels on the equilibrium swelling and the volume phase transition temperature is reported here. A nonionizable monomer (acrylamide) and three ionizable monomers (itaconic acid, 2‐ethoxyethyl monoitaconate, and 2,2‐(2‐ethoxyethyl) monoitaconate) were studied. Hydrogels with larger swelling capacity than that of the polyNIPA hydrogel were obtained. With the exception of the hydrogel containing 2,2‐(2‐ethoxyethyl) monoitaconate, which did not exhibit the de‐swelling phenomena, the rest showed a volume phase transition. The hydrogels containing 85 wt % acrylamide and 15 wt % comonomer presented the higher shrinking ratio. For some compositions, the T_c of the polyNIPA hydrogel was within the desired temperature range (38–41°C) for controlled‐drug delivery in the human body. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Making polyvinyl alcohol films iodinated at solution state before casting and its application

This research focused on the manufacture a polarizing film with PVA iodinated at solution before casting (IBC) film, which was prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.5, and 1.0 mol/L of I₂/KI aqueous solution, and I₂/KI(1:2) with 0, 5, and 10 wt % of PVA. The lights of wavelengths between 450 and 700 nm were polarized in UV analysis. The degree of polarization and transmittance of the IBC polarizing film (10 wt % I₂/KI and 0.5 mol/L boric acid) are 99.9% and 43.2%, respectively. The resistance of the heat and humidity of IBC polarizing films was higher than that of commercial polarizing films, which were elucidated by changing the transmittance of the films. This can be explained by the fact that the interaction between polyiodine molecules and PVA chains as the state of IBC is higher than that of the commercial state. The effect of boric acid may be strengthened for the resistance of heat and humidity. Crosslinking by boric acid improved thermal properties of the IBC polarizing films, resulting from the increases of degradation temperature in DSC and TG analysis. And the unit cell broadening occurred, which was caused by the intrusion of boric acid into PVA chains in X-ray analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comparison of nanoclay and carbon nanofiber particles on rheology of molten polystyrene nanocomposites under supercritical carbon dioxide

The effects of nanoparticles and high‐pressure carbon dioxide (CO₂) on shear viscosity of polystyrene (PS) were studied. Master curves of PS, PS + 5 wt % carbon nanofibers (CNFs), and PS + 5 wt % nanoclay (Southern Clay 20A) without CO₂ were created based on parallel‐plate measurements. The results showed that addition of nanoparticles increased the viscosity of the neat polymer. Steady‐state shear viscosity of PS in the presence of CO₂ and nanoparticles was measured by a modified Couette rheometer. The effect of supercritical CO₂ on these systems was characterized by shift factors. It was found that under the same temperature and CO₂ pressure, CO₂ reduced the viscosity less for both PS‐20A and PS‐CNFs than neat PS. Between the two types of nanoparticles, CNFs showed a larger viscosity reduction than 20A, indicating a higher CO₂ affinity for CNFs than 20A. However, the advantage of CNFs over 20A for larger viscosity reduction decreased with higher temperature. A gravimetric method (magnetic suspension balance) was used to measure the excess adsorption of CO₂ onto CNFs and nanoclay, thus, CO₂ showed a higher affinity for CNFs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhancement of mechanical and optical performance of commercial polystyrenes by blending with siloxane‐based copolymers

Well‐defined poly(styrene‐block ‐dimethylsiloxane) copolymers (PS‐b ‐PDMS) with low polydispersity index (M_w /M_n ) and different compositions were synthesized by sequential anionic polymerization of styrene (S) and hexamethyl(ciclotrisiloxane) (D₃) monomers. Synthesized PS‐b ‐PDMS copolymers were characterized by ¹H‐nuclear magnetic resonance, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. The physicochemical characterization determined that block copolymers have molar mass values close to ～135,000 g mol^?1, narrow M_w /M_n < 1.3, and chemical composition ranging from low to intermediate PDMS content. Blends of these copolymers with a commercial polystyrene (PS) were obtained by melt mixing and subsequently injection. Films obtained were flexible, and showed lower transparency than the original PS matrix. On the other hand, a 10 wt % incorporation of PS‐b ‐PDMS copolymers leads to better mechanical performance by enhancing elongation at break (～8.8 times higher) and opacity values (～18 times higher). In addition, UV–Vis barrier capacity of the resulting blends is also increased (up to 400% higher). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45122.