Synthesis of PMMA‐PTHF‐PMMA and PMMA‐PTHF‐PST linear and star block copolymers

Combination of cationic, redox free radical, and thermal free radical polymerizations was performed to obtain linear and star polytetramethylene oxide (poly‐THF)‐polymethyl methacrylate (PMMA)/polystyrene (PSt) multiblock copolymers. Cationic polymerization of THF was initiated by the mixture of AgSbF₆ and bis(4,4′ bromo‐methyl benzoyl) peroxide (BBP) or bis (3,5,3′,5′ dibromomethyl benzoyl) peroxide (BDBP) at 20°C to obtain linear and star poly‐THF initiators with M_w varying from 7,500 to 59,000 Da. Poly‐THF samples with hydroxyl ends were used in the methyl methacrylate (MMA) polymerization in the presence of Ce(IV) salt at 40°C to obtain poly(THF‐b‐MMA) block copolymers containing the peroxide group in the middle. Poly(MMA‐b‐THF) linear and star block copolymers having the peroxide group in the chain were used in the polymerization of methyl methacrylate (MMA) and styrene (St) at 80°C to obtain PMMA‐b‐PTHF‐b‐PMMA and PMMA‐b‐PTHF‐b‐PSt linear and star multiblock copolymers. Polymers obtained were characterizated by GPC, FT‐IR, DSC, TGA, ¹H‐NMR, and ¹³C‐NMR techniques and the fractional precipitation method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 219–226, 2004     

DOPO‐Based Phosphorus‐Containing Methacrylic (Co)Polymers: Glass Transition Temperature Investigation

A two‐step synthetic procedure is designed for preparing new flame‐retardant methacrylic monomers containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a substituent side group. DOPO and methacrylate moieties are linked by linear aliphatic hydrocarbon spacers (3 to 11 carbon atoms). Copolymerization with methyl methacrylate is carried out leading to copolymers containing between 2 and 10 wt% phosphorus. All homo‐ and copolymers exhibit a unique glass transition temperature (T_g ). A new group contribution for DOPO‐based substituent is extracted that leads to reasonable estimations of T_g s of other published polymers. The Fox equation provides a good estimation of T_g s for most copolymers and for physical blends of poly(methyl methacrylate) (PMMA) and DOPO. When using monomers having three and four carbon atoms in the hydrocarbon spacer, the T_g of copolymers remains close to that of PMMA over a wide range of composition.     

Synthesis of methyl methacrylate and N‐aryl itaconimide block copolymers via atom‐transfer radical polymerization

The paper describes the synthesis of block copolymers of methyl methacrylate (MMA) and N‐aryl itaconimides using atom‐transfer radical polymerization (ATRP) via a poly(methyl methacrylate)–Cl/CuBr/bipyridine initiating system or a reverse ATRP AIBN/FeCl₃·6H₂O/PPh₃ initiating system. Poly(methyl methacrylate) (PMMA) macroinitiator, ie with a chlorine chain‐end (PMMA‐Cl), having a predetermined molecular weight (M_n = 1.27 × 10⁴ g mol^?1) and narrow polydispersity index (PDI = 1.29) was prepared using AIBN/FeCl₃·6H₂O/PPh₃, which was then used to polymerize N‐aryl itaconimides. Increase in molecular weight with little effect on polydispersity was observed on polymerization of N‐aryl itaconimides using the PMMA‐Cl/CuBr/Bpy initiating system. Only oligomeric blocks of N‐aryl itaconimides could be incorporated in the PMMA backbone. High molecular weight copolymer with a narrow PDI (1.43) could be prepared using tosyl chloride (TsCl) as an initiator and CuBr/bipyridine as catalyst when a mixture of MMA and N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 was used. Thermal characterization was performed using differential scanning calorimetry (DSC) and dynamic thermogravimetry. DSC traces of the block copolymers showed two shifts in base‐line in some of the block copolymers; the first transition corresponds to the glass transition temperature of PMMA and second transition corresponds to the glass transition temperature of poly(N‐aryl itaconimides). A copolymer obtained by taking a mixture of monomers ie MMA:N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 showed a single glass transition temperature. Copyright © 2005 Society of Chemical Industry     

Dependence of the Morphology Development on the Kinetics of Reactive Melt Blending of Immiscible Polymers

Poly(methyl methacrylate) (PMMA) containing 50 wt% of anthracene (anth) labeled reactive PMMA chains [thus end‐capped by an anhydride (anh) or an isocyanate (NCO)] has been melt blended with polystyrene containing 33 wt% of chains end‐capped by an aliphatic amine (PS‐NH₂) at 180°C. Conversion of anth‐PMMA‐anh and anth‐PMMA‐NCO into PMMA‐b‐PS copolymers has been determined by SEC with a UV detector. The interfacial reaction mainly occurs in the initial mixing stage (?1.0 min), although at a rate which depends on the reactive groups attached to PMMA. Moreover, this interfacial reaction rate controls how the phase morphology is developed.     

Starch–acrylics graft copolymers and blends: Synthesis,characterization, and applications as matrix for drug delivery

A series of acrylic monomers–starch graft copolymers were prepared by ceric ion initiation method by varying the amount of monomers. These graft copolymers were characterized by IR and ¹³C‐NMR spectroscopy. It was seen that as the concentration of monomer [acrylic acid (AA), methacrylic acid (MA), and methyl methacrylate (MMA)] increased the percent add‐on increased in all the graft copolymers, whereas grafting efficiency increased initially but showed a slight decrease with further increase in the monomer concentration (except for MMA). The release rate of paracetamol as a model drug from graft copolymers as well as their blends was studied at two different pH, 1.2 and 7.4, spectrophotometrically. The release of paracetamol in phosphate buffer solution at pH 1.2 was insignificant in the first 3 h for St‐g‐PAA‐ and St‐g‐PMA‐graft copolymers, which was attributed to the matrix compaction and stabilization through hydrogen bonding at lower pH. At pH 7.4, the release rate was seen to decrease with increase in add‐on. The tablet containing poly(methyl methacrylate) (PMMA) did not disintegrate at the end of 30–32 h, which may be attributed to the hydrophobic nature of PMMA. These results indicate that the graft copolymers may be useful to overcome the harsh environment of the stomach and can be used as excipients in colon‐targeting matrices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Methyl methacrylate based copolymers and terpolymers: Preparation,identification, and plasticizing capability for a poly(methyl methacrylate) used in aviation

In this study, we first synthesized transparent poly(methyl methacrylate–maleic anhydride) [P(MMA–MAH)] and poly(methyl methacrylate–maleic anhydride–N‐2‐methyl‐4‐nitrophenyl maleimide) [P(MMA–MAH–MI)] via free‐radical polymerization at different monomer ratios. The synthesized polymers were characterized by titration, viscometric, spectroscopy, and thermal analyses. Higher contents of maleic anhydride (MAH) resulted in increases in the viscosity, glass‐transition temperature (T_g), and transparency. The synthesized polymers were then blended with a commercial‐grade poly(methyl methacrylate) (PMMA) used in aviation in the presence of CHCl₃. According to the free volume theory, the incorporation of 5 wt % P(MMA–MAH)s or P(MMA–MAH–MI)s into the commercial PMMA resulted in a plasticizing impact on this thermoplastic, which was confirmed by the decrease in the T_g values of the blends with almost the same transparency as the initial PMMA. In fact, the higher the content of MAH was, the lower the T_g of the blends was. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46603.     

Synthesis and characterization of diblock,triblock, and multiblock copolymers containing poly(3‐hydroxy butyrate) units

A poly[(R,S)‐3‐hydroxybutyrate] macroinitiator (PHB‐MI) was obtained through the condensation reaction of poly[(R,S)‐3‐hydroxybutyrate] (PHB) oligomers containing dihydroxyl end functionalities with 4,4′‐azobis(4‐cyanopentanoyl chloride). The PHB‐MI obtained in this way had hydroxyl groups at two end of the polymer chain and an internal azo group. The synthesis of ABA‐type PHB‐b‐PMMA block copolymers [where A is poly(methyl methacrylate) (PMMA) and B is PHB] via PHB‐MI was accomplished in two steps. First, multiblock active copolymers with azo groups (PMMA‐PHB‐MI) were prepared through the redox free‐radical polymerization of methyl methacrylate (MMA) with a PHB‐MI/Ce(IV) redox system in aqueous nitric acid at 40°C. Second, PMMA‐PHB‐MI was used in the thermal polymerization of MMA at 60°C to obtain PHB‐b‐PMMA. When styrene (S) was used instead of MMA in the second step, ABCBA‐type PMMA‐b‐PHB‐b‐PS multiblock copolymers [where C is polystyrene (PS)] were obtained. In addition, the direct thermal polymerization of the monomers (MMA or S) via PHB‐MI provided AB‐type diblocks copolymers with MMA and BCB‐type triblock copolymers with S. The macroinitiators and block copolymers were characterized with ultraviolet–visible spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, cryoscopic measurements, and thermogravimetric analysis. The increases in the intrinsic viscosity and fractional precipitation confirmed that a block copolymer had been obtained. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1789–1796, 2004     

Synthesis of polypropylene graft copolymers from a hydroxyl‐groups‐containing polypropylene precursor via atom‐transfer radical polymerization

Isotactic polypropylene graft copolymers, isotactic[polypropylene‐graft‐poly(methyl methacrylate)] (i‐PP‐g‐PMMA) and isotactic[polypropylene‐graft‐polystyrene] (i‐PP‐g‐PS), were prepared by atom‐transfer radical polymerization (ATRP) using a 2‐bromopropionic ester macro‐initiator from functional polypropylene‐containing hydroxyl groups. This kind of functionalized propylene can be obtained by copolymerization of propylene and borane monomer using isospecific MgCl₂‐supported TiCl₄ as catalyst. Both the graft density and the molecular weights of i‐PP‐based graft copolymers were controlled by changing the hydroxyl group contents of functionalized polypropylene and the amount of monomer used in the grafting reaction. The effect of i‐PP‐g‐PS graft copolymer on PP‐PS blends and that of i‐PP‐g‐PMMA graft copolymer on PP‐PMMA blends were studied by scanning electron microscopy. Copyright © 2006 Society of Chemical Industry     

Surface microphase separation in PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films

Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PMMA‐multigraft copolymers derived from linseed oil,soybean oil,and linoleic acid: Protein adsorption and bacterial adherence

Synthesis of Poly(methyl methacrylate), PMMA‐multigraft copolymers derived from linseed oil, soybean oil, and linoleic acid PMMA‐g‐polymeric oil/oily acid‐g‐poly(3‐hydroxy alkanoate) (PHA), and their protein adsorption and bacterial adherence have been described. Polymeric oil/oily acid peroxides [polymeric soybean oil peroxide (PSB), polymeric linseed oil peroxide (PLO), and polymeric linoleic acid peroxide (PLina)] initiated the copolymerization of MMA and unsaturated PHA‐soya to yield PMMA–PLO–PHA, PMMA–PSB–PHA, and PMMA–PLina–PHA multigraft copolymers. PMMA–PLina–PHA multigraft copolymers were completely soluble while PMMA–PSB–PHA and PMMA–PLO–PHA multigraft copolymers were partially crosslinked. Crosslinked parts of the PLO‐ and PSB‐multigraft copolymers were isolated by the sol gel analysis and characterized by swelling measurements in CHCl₃. Soluble part of the PLO‐ and PSB‐multigraft copolymers and completely soluble PLina‐multigraft copolymers were obtained and characterized by spectroscopic, thermal, gel permeation chromatography (GPC), and scanning electron microscopy (SEM) techniques. In the mechanical properties of the PHA–PLina–PMMA, the elongation at break is reduced up to ～ 9%, more or less preserving the high stress values at its break point (48%) when compared to PLina‐g‐PMMA. The solvent casting film surfaces were studied by means of adsorption of blood proteins and bacterial adhesion. Insertion of the PHA into the multigraft copolymers caused the dramatic increase in bacterial adhesion on the polymer surfaces. PHA insertion into the graft copolymers also increased the protein adsorption. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of poly(aryl ether sulfone)‐graft‐polystyrene and poly(aryl ether sulfone)‐graft‐[polystyrene‐block‐poly(methyl methacrylate)] through atom transfer radical polymerization

A new graft copolymers poly(aryl ether sulfone)‐graft‐polystyrene (PSF‐g‐PS) and poly(aryl ether sulfone)‐graft‐[polystyrene‐block‐poly(methyl methacrylate)] (PSF‐g‐(PS‐b‐PMMA)) were successfully prepared via atom transfer radical polymerisation (ATRP) catalyzed by FeCl₂/isophthalic acid in N,N‐dimethyl formamide. The products were characterized by GPC, DSC, IR, TGA and NMR. The characterization data indicated that the graft copolymerization was accomplished via conventional ATRP mechanism. The effect of chloride content of the macroinitiator on the graft copolymerization was investigated. Only one glass transition temperature (T_g) was detected by DSC for the graft copolymer PSF‐g‐PS and two glass transition temperatures were observed in the DSC curve of PSF‐g‐(PS‐b‐PMMA). The presence of PSF in PSF‐b‐PS or PSF‐g‐(PS‐b‐PMMA) was found to improve thermal stabilities. © 2002 Society of Chemical Industry     

Study on the synthesis of heat‐resistant PMMA

N‐cyclohexylmaleimide (CHMI) and styrene (St) were used to copolymerize with methyl methacrylate (MMA) to synthesize heat‐resistant poly(methyl methacrylate) (PMMA) by a solution copolymerization method and a suspension copolymerization method. Residual CHMI concentrations in the copolymers were analyzed by gas chromatography. Effects of styrene on residual CHMI concentration, glass transition temperature (T_g), molecular weight, and molecular weight distribution were studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1335–1339, 1999     

Preparation of PMMA–PS–PMMA via combination of anionic and photoinduced charge‐transfer polymerization

PMMA–PS–PMMA triblock copolymers were prepared by the combination of an anionic mechanism with charge‐transfer polymerization. Polystyrene with aromatic tertiary amino groups at both ends (PS_ba) was synthesized first by the reaction of a living polystyrene macrodianion with excess p‐(dimethylamino)benzaldehyde; then, the PS_ba was constituted into a binary system with benzophenone (BP) to initiate the polymerization of methyl methacrylate (MMA) under UV irradiation. The intermediate and resulting block copolymers were characterized by GPC, IR, and ¹H‐NMR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2072–2076, 1999     

Synthesis of poly(vinyl acetate) containing diblock copolymer by DPE method

Diblock copolymer poly(methyl methacrylate)‐b‐poly(vinyl acetate) (PMMA‐b‐PVAc) was prepared by 1,1‐diphenylethene (DPE) method. First, free‐radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE containing PMMA precursor with controlled molecular weight. Second, vinyl acetate was polymerized in the presence of the PMMA precursor and AIBN, and PMMA‐b‐PVAc diblock copolymer with controlled molecular weight was obtained. The formation of PMMA‐b‐PVAc was confirmed by ¹H NMR spectrum. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to detect the self‐assembly behavior of the diblock polymer in methanol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Vitamin A microencapsulation within poly(methyl methacrylate)‐g‐polyethylenimine microspheres: Localized proton buffering effect on vitamin A stability

To stabilize vitamin A in a cosmetic/dermatological formulation, we present here a new encapsulation method based on polymer microspheres having a localized “proton‐buffering” capacity. Poly(methyl methacrylate)‐g‐polyethylenimine (PMMA‐g‐PEI) was prepared by direct condensation grafting of PEI onto poly(methyl methacrylate‐co‐methyl acrylic acid). The reaction was confirmed by FT‐IR analysis showing the amide vibration at 1,550 cm^?1. Elemental analysis indicated that the weight content of the grafted PEI was 1.6% (w/w). Vitamin A was encapsulated into PMMA‐g‐PEI microspheres by using an oil‐in‐water (O/W) single emulsion method. The presence of PEI moiety dramatically improved the chemical stability of vitamin A in microspheres. Vitamin A encapsulated within PMMA‐g‐PEI microspheres maintained 91% of its initial activity after 30‐day incubation at 40°C, while only maintaining 60% within plain PMMA microspheres. This study demonstrates that proton‐buffering within hydrophobic polymer matrix is a useful strategy for stabilizing “acid‐labile” active ingredients. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 517–522, 2004     

Preparation and properties of silicone‐containing poly(methyl methacrylate) gels

Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L^?1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, W_g, and its equilibrium volume swelling ratio in benzene, q_v, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry     

Nanostructured polymer blends based on polystyrene‐b‐polybutadiene‐b‐poly(methyl methacrylate) triblock copolymers modified with polystyrene and/or poly(methyl methacrylate) homopolymers

Morphologies of polymer blends based on polystyrene‐b‐ polybutadiene‐b ‐poly(methyl methacrylate) (SBM) triblock copolymer were predicted, adopting the phase diagram proposed by Stadler and co‐workers for neat SBM block copolymer, and were experimentally proved using atomic force microscopy. All investigated polymer blends based on SBM triblock copolymer modified with polystyrene (PS) and/or poly(methyl methacrylate) (PMMA) homopolymers showed the expected nanostructures. For polymer blends of symmetric SBM‐1 triblock copolymer with PS homopolymer, the cylinders in cylinders core?shell morphology and the perforated lamellae morphology were obtained. Moreover, modifying the same SBM‐1 triblock copolymer with both PS and PMMA homopolymers the cylinders at cylinders morphology was reached. The predictions for morphologies of blends based on asymmetric SBM‐2 triblock copolymer were also confirmed experimentally, visualizing a spheres over spheres structure. This work presents an easy way of using PS and/or PMMA homopolymers for preparing nanostructured polymer blends based on SBM triblock copolymers with desired morphologies, similar to those of neat SBM block copolymers. © 2017 Society of Chemical Industry     

Synthesis and properties of liquid‐ crystalline triblock copolymers by ATRP,having electron‐transporting thiadiazole unit

ABA‐type block copolymers composed of 2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD) oligoester and poly(methyl methacrylate) (PMMA) segments (M_n = 16 200 and 23 000) were synthesized by atom‐transfer radical polymerization and their liquid‐crystalline (LC) and photoluminescence (PL) properties were examined. The structures of block copolymers were identified by Fourier transform infrared and ¹H NMR spectroscopies. Differential scanning calorimetry measurement, polarizing microscopy observation and wide‐angle X‐ray analysis revealed that the block copolymers form thermotropic LC phase (smectic C) independent of molecular weights of PMMA segments, but a model polymer (PMMA segments having the DPTD unit in the central part) has no LC melt. Solution and solid‐state PL spectra indicated that all the block copolymers display blue emission arising from the DPTD unit. Their quantum yields are 17–21%, which increase with the PMMA chain lengths. The block copolymers have good aligned structures in the LC states, but their order parameter (S) values in sheared LC states were lower than those in the sheared LC compounds. The PL properties in the LC states were independent of the LC aligned structures. Cyclic voltammetry measurements showed that these block copolymers have deep HOMO levels compared with polymers composed of oxadiazole rings. Copyright © 2007 Society of Chemical Industry     

Physical and mechanical properties of poly(methyl methacrylate)‐grafted natural rubber synthesized by methyl methacrylate photopolymerization initiated by N,N‐diethyldithiocarbamate functions previously created on natural rubber chains

Well‐defined poly(methyl methacrylate) (PMMA)‐grafted natural rubbers (NRs) were prepared to study the structure–property relationships. Syntheses were achieved by the photopolymerization of methyl methacrylate initiated by N,N‐diethyldithiocarbamate groups created beforehand in side positions on the NR chains. With this procedure, good control of the graft density and PMMA content could be obtained. Thermal, morphological, and mechanical properties of NR‐g‐PMMA copolymers were studied as a function of the NR/PMMA composition and graft density. NR‐g‐PMMAs containing 15–80% grafted PMMA showed characteristics of heterogeneous materials (characterized by two glass‐transition temperatures, those of PMMA and NR, in differential scanning calorimetry). Under these conditions, they developed the morphology of thermoplastic elastomers with PMMA nodules dispersed in the rubber matrix when the PMMA content was near 20%; conversely, they developed the morphology of softened thermoplastics with rubber nodules dispersed in PMMA when the PMMA content was near 80%. Graft copolymers containing about 20% PMMA remained essentially rubbery, but they were already different from pure NR. On the other hand, the thermal stability of NR wash improved after the introduction of PMMA grafts onto NR chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009