Synthesis and physicochemical properties of polyurethane block copolymers and their compositions with plasticizers

The synthesis of polyurethane block based on oligoesterdiols 4,4′-methylene-bis(phenylisocyanate), and various chain elongating agents was studied. The properties of these copolymers were compared (using literature data) with selected properties of polyurethanes obtained by the reactions of oligoetherdiols, viz., oligo-3,3′-bis(azidomethyl)oxetanediol and oligo-3-azidomethyl-3′-methyloxetanediol with diisocyanates. The complex of rheological and physicomechanical properties of the initial and plasticized polyurethane block copolymers was studied. Regularities of their deformation behavior were established. The process of mutual solubility was studied by the microinterference method for a wide range of systems block copolymers—plasticizers. On the basis of the data obtained, the phase diagrams were constructed for limitedly compatible systems.     

Synthesis and aqueous solution properties of hydrophobically modified anionic acrylamide copolymers

In this investigation, hydrophobically modified polyacrylamide with low amounts of anionic long‐chain alkyl was synthesized by the free radical polymerization in deionized water. This water‐soluble copolymerization method is more convenient compared with the traditional micellar copolymerization methods. The copolymers were characterized using Fourier transform infrared, ¹H NMR, and the molecular weight and polydispersity were determined using gel permeation chromatography. The solution behavior of the copolymers was studied as a function of composition, pH, and added electrolytes. As NaCl was added to solutions of AM/C₁₁AM copolymers or pH was lowered, the shielding or elimination of electrostatic repulsions between carboxylate groups of the C₁₁AM unit lead to coil shrinkage. The steady shear viscosity and dynamic shear viscoelastic properties in semidilute, salt‐free aqueous solutions were conducted to examine the concentration effects on copolymers. In addition, the shear superimposed oscillation technique was used to probe the structural changes of the network under various stresses or shear conditions. We prepared hydrophobically modified polyacrylamide with N‐alkyl groups in the aqueous medium. The advantage of this method is that the production is pure without surfactants. These results suggest that the unique aqueous solution behavior of the copolymers is different from conventional hydrophobically associating acrylamide. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2465–2474, 2008     

Synthesis of new siloxane urethane block copolymers and their properties

Siloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studies, including ESCA, EDS, and FT-IR, show well segregated block copolymers with enhanced siloxane on the surface. DSC studies show a low mp (-44°C) for the soft segment and a T_g for the hard segment above room temperature. These materials show higher thermal stability compared to polyether urethane block copolymers. These copolymers also show relatively good resistance to exposure to oxygen plasma and show improved flame retardancy compared to nonsiliconated, polyether polyurethane block copolymers. © 1994 John Wiley & Sons, Inc.     

Synthesis of polystyrene-based cationic copolymers and their colloidal properties in water

A series of polystyrene-based cationic copolymers was synthesized by two different methods: (1) solution copolymerization of styrene and vinylbenzyl trimethylammonium chloride (VBTMAC) in ethanol, and (2) surfactant-free emulsion copolymerization of styrene and vinylbenzyl chloride in water followed by reaction with trimethylamine. The results indicated that the different synthesis methods would result in different polymer structures and, therefore, affect the solubility and colloidal properties of the copolymers in water. For the copolymers prepared by method 2, partial crosslinking was observed. The copolymers made by this method are almost water-insoluble. In contrast, the copolymers made from direct copolymerization of styrene and VBTMAC in ethanol are water-soluble or dispersible, but the solubility and the particle size of microaggregates formed by these copolymers in water strongly depend on charge density and temperature. One of the important results from this study is that uniform colloidal particles with a very small particle size (30–50 nm) can be obtained by dispersing polystyrene-based cationic copolymers in water without adding any surfactants. Received: 29 July 1998 Accepted in revised form: 28 September 1998     

Calcium hydroxylapatite/methylcellulose nanocomposite: Synthesis and properties

Organomineral nanocomposites (OMCs) of calcium hydroxylapatite Ca₁₀(PO₄)₆(OH)₂ (HA) and natural methylcellulose biopolymer [C₆H₇O₂(OH)_{3 ? x} (OCH₃) _x ] _n (MC) were prepared by coprecipitation from aqueous solution in the Ca(OH)₂-H₃PO₄-[C₆H₇O₂(OH)_3?x (OCH₃) _x ] _n -H₂O system under biomimetic conditions (37°C). Synthesis products were identified by X-ray powder diffraction, IR spectroscopy, thermal analysis, scanning and transmission microscopy, and electron diffraction. The compositions and structural features of the OMCs and the crystallographic parameters, sizes, and morphology of HA nanoparticles in the OMCs were determined. The HA nanoparticles in the OMCs were found to interact with MC molecules to form agglomerates with sizes on the order of 150–200 nm.     

Synthesis of double-hydrophilic double-grafted copolymers PMA-g-PEG/PDMA and their protein-resistant properties

A series of double-hydrophilic double-grafted PMA-g-PEG/PDMA copolymers, which contained poly(methacrylate) (PMA) as backbone, poly(ethylene glycol) (PEG) and poly(N,N-dimethylacrylamide) (PDMA) as side chains synthesized successfully by using reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP), were used as physical coatings for the evaluation of protein-resistant properties by capillary electrophoresis (CE). Electroosmotic flow (EOF) measurement results showed that the PMA-g-PEG/PDMA copolymer coated capillaries could suppress electroosmotic mobility in a wide pH range (pH = 2.8–9.8) and EOF mobility decreased with the increase of copolymer molecular mass and PDMA content. At the same time, protein recovery, theoretical plate number of separation and repeatability of migration time demonstrated that antifouling efficiency was improved with the increase of molecular mass and PEG content.     

Synthesis of conjugated copolymers containing phenothiazinylene vinylene moieties and their electrooptic properties

Four different types of conjugated copolymers, consisting of alternating structures of phenothiazinylene vinylene and phenylene vinylene derivatives such as phenylene vinylene, 1,1′‐biphenyl‐4,4′‐ylene vinylene, 2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene, and 9,10‐anthrylene vinylene, were prepared by Horner–Emmons condensation between appropriate diphosphonates and dialdehydes. Single‐layer and double‐layer light‐emitting diodes were fabricated with the synthesized conjugated polymers, and their electroluminescent properties were investigated. Poly(N‐2‐ethylhexyl‐3,6‐phenothiazinylene vinylene‐alt‐9,10‐anthrylene vinylene), containing phenothiazinylene vinylene and anthrylene vinylene as repeat units, emitted a reddish‐orange color with Commission Internationale de l'Eclairage coordinates of x = 0.6173 and y = 0.3814 that was very similar to the National Television System Committee standard red, and it showed a bipolar carrier‐injection/transporting capability caused by electron‐withdrawing anthracene and electron‐donating amino groups. Poly[N‐2‐ethylhexyl‐3,6‐phenothiazinylene vinylene‐alt‐2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene], containing phenothiazinylene vinylene and dialkoxy phenylene vinylene moieties, showed excellent hole‐injection/transporting capability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2502–2511, 2003     

Styrene–isoprene block copolymers. I. Synthesis and solution properties

Copolymers with a different degree of distribution of styrene and isoprene blocks are prepared by anionic polymerization. The products are characterized by means of ¹H-NMR spectroscopy, GPC, viscometry, and light scattering. The results show that the copolymers are homogeneous in molecular weight and chain composition. In the investigated selective solvents, cyclohexane and base lubricating oil, and equilibrium exists between micelle aggregates and individual polymer coils. The influence of the copolymer structure on the micellization is more pronounced in cyclohexane.     

Synthesis and properties of propene copolymers with ether comonomers

The direct copolymerization of propene with polar comonomers using metallocene catalysts in solution was investigated. As comonomers, two ether compounds were used in comparison to 10-undecene-1-ol as well-investigated comonomer. The ether comonomers were diethylene glycol mono-10-undecenyl ether (DEGUE) and octaethylene glycol-10-undecenyl methyl ether (OEGUME). The influence of the different comonomers on the copolymerization behavior was studied. The copolymers were characterized with respect to their comonomer contents, molar masses, and thermal properties. The incorporation rate of DEGUE and OEGUME into the propene copolymers did not exceed 1.6 mol% for DEGUE and 0.31 mol% for OEGUME and was thus considerably lower than in the reference propene copolymerization with 10-undecene-1-ol. An uncompleted shielding of the oxygen atoms of the ether groups by triisobutyl aluminum (TIBA) to the metallocene catalyst is assumed to be responsible for this behavior. The crystallization kinetics in the copolymers with comparable molar masses is mainly influenced by the side chain density per 1000 propene units, n₁₀₀₀.The incorporation of hydrophilic comonomers into polypropene was expected to alter the surface properties. The slightly lowered water contact angles found on films of copolymers with higher comonomer content indicated the enhanced hydrophilicity of the polypropene copolymer surfaces compared to polypropene (PP).     

Cellulose-g-PDMAam copolymers by controlled radical polymerization in homogeneous medium and their aqueous solution properties

Water-soluble cellulose-graft-PDMAam copolymers were prepared by single-electron-transfer living radical polymerization (SET-LRP). Cellulose based macroinitiator for SET-LRP with a degree of substitution DS ≈ 2 was synthesized from softwood dissolving pulp in a homogeneous LiCl/DMAc solution. The macroinitiator was then grafted using N,N-dimethyl acrylamide (DMAam) in DMSO. Formation of cellulose-g-DMAam copolymers were confirmed by ATR–FTIR, ¹H and ¹³C NMR spectroscopy and SEC analyses. Light scattering and steady–shear viscosity measurements revealed that the studied chain length of grafts (DP_graft) had only minor effects on the solution properties of cellulose-g-PDMAam copolymers. SLS studies suggested a loose, solvent-draining architecture of the cellulose-g-PDMAam copolymer particles in H₂O.     

Structures and properties of block copolymers in solution

Structures and properties of block copolymers in solution depend on the total block length, the block length ratio, the block sequence and the solvent quality. The supramolecular structures formed by core/shell or flower-like micelles in the concentrated solution region are examined by dynamic light scattering to ascertain some of the conditions which can enhance the formation of open associated structures using a triblock copolymer in a selective solvent for the middle block.     

Synthesis and properties of Rh6- and Os3-cluster-containing monomers and their copolymers with styrene

Cluster metal-containing monomers were obtained and characterized. Mono- and disubstituted products were obtained under mild conditions via the interaction of Rh₆(CO)₁₆ with 4-vinylpyridine (4-VPy) in the presence of trimethylamin-N-oxide. Substitution of labile acetonitrile ligand in Rh₆(CO)₁₅NCMe by allyldiphenylphosphine (AlPPh₂) yields Rh₆(CO)₁₄(μ,η²-PPh₂CH₂CH=CH₂) with formation of π-complex. The structures of Rh₆(CO)₁₅(4-VPy), Rh₆(CO)₁₄(μ,η²-PPh₂CH₂CH=CH₂) and (μ-H)Os₃(μ-OCNM₂)(CO)₉PPH₂CH₂CH=CH₂ have been determined by single-crystal X-ray diffraction studies, as well as by IR-, ¹H NMR spectroscopies. The Rh - Rh bond lengths are within 2.72÷2.80 Å. The copolymerization of cluster-containing monomers synthesized with traditional monomers has been studied. It was found that Rh₆- and Os₃-containing monomers did not change either the ligand surroundings or the structure of cluster monomer framework during polymerization reaction.     

Synthesis of porous divinylbiphenyl copolymers and their sorptive properties towards phenol and its derivatives

Seven porous divinylbiphenyl polymers having the same nominal crosslinking degree (51.8 wt.%) have been synthesized using suspension polymerization method in the presence of the following inert diluents or their mixtures: toluene, heptane, dodecane, isooctane. The use of various inert diluents was aimed at changing the extent of polymeric network-diluent interactions. The obtained polymers have specific surface area in the range 50-300 m²/g depending on the type and amount of inert diluents used during polymerization. Their sorptive properties have been studied using dilute (0.5 mmol/l) aqueous solutions of phenol and its derivatives (2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,6-dimethylphenol, 4-hydroxyphenol). It has been found that sorption, at low equilibrium concentration, follows the order: 2,4,5-trichlorophenol > 2,4-dichlorophenol > 2-chlorophenol > 2,6-dimethylphenol > phenol > 4-hydroxyphenol. Full characteristic of the porous structure of polymers has been obtained by nitrogen adsorption at 77K.     

Synthesis and properties of fullerene-containing N-vinylpyrrolidone copolymers

Branched copolymers containing covalently bonded fullerene C₆₀ were synthesized by cross-linking radical copolymerization of N-vinylpyrrolidone with triethylene glycol dimethacrylate in toluene saturated with fullerene. Their composition was studied by elemental analysis and IR and electronic absorption spectroscopy. The concentration of double bonds, characteristic viscosity, and glass-transition temperature of the fullerene-containing copolymers were determined by ozonoliysis, viscosimetry, and differential scanning calorimetry. The parameters and thermal stability of the fullerene-containing copolymers were compared with those of their non-functionalized analogs.     

Composition and solution properties of fluorinated block copolymers and their surface structures in the solid state

A series of diblock copolymers composed of methyl methacrylate and 2-perfluorooctylethyl methacrylate (PMMA₁₄₄-b-PFMA _n ) with various PFMA block lengths were prepared by atom transfer radical polymerization (ATRP). The surface structures and properties of these polymers in the solid state and in solution were investigated using contact angle measurement, X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, surface tension and dynamic laser light scattering (DLS). It was found that with increasing PFMA block length, water and oil repellency decreased, the ratio of F/C increased with increasing film depth, and the degree of ordered packing of the perfluoroalkyl side chains at the surface decreased. When the number of PFMA block units reached 10, PMMA segments were detected at the copolymer surface, which was attributed to the PFMA block length affecting molecular aggregation structure of the copolymer in the solution and the interfacial structure at the air/liquid interface, which in turn affects surface structure formation during solution solidification. The results suggest that copolymer solution properties play an important role in structure formation on the solid surface. Supported by the National Natural Science Foundation of China (Grant Nos. 50573069 and 20704038) and Program for Changjiang Scholars and Innovative Research Team in University (Grant No.IRT 0654)     

Synthesis and general properties of silated-hydroxypropyl methylcellulose in prospect of biomedical use

Synthesis of grafting silane on a hydro soluble cellulose ether (HPMC) was described. In alkaline medium, this derivate is under gel form. With a decrease of the pH, a self-hardening occurs due to the silanol condensation. For potential biomedical use, we described the silated-HPMC synthesis, the gel behavior after steam sterilization and the parameters of the silanol condensation i.e. pH, silane percentage and temperature. Minimum kinetic of the condensation was observed for pH between 5.5 and 6.5. So temperature catalyzed the reaction and the self-hardening speed was increased by silane percentage.     

Chitosan-dextran branched copolymers: Synthesis and properties

Chitosan-dextran branched copolymers have been synthesized, and the rheological properties of their aqueous acetic acid solutions have been studied. On the basis of the data of FTIR spectroscopy, the formation of chemical bonds between chitosan and dextran at the nitrogen atom has been confirmed. With the use of dynamic mechanical analysis and differential scanning calorimetry, the temperatures of relaxation transitions in the resulting branched copolymers have been determined. It is shown that, along with the formation of a branched copolymer, the chemical crosslinking of chitosan macrochains can occur. Mechanical properties of films formed from solutions of the obtained polymers have been studied.     

Synthesis and properties of Pluronic-based pentablock copolymers with pendant amino groups

Amphiphilic Pluronic-based pentablock copolymers with pendant amino groups have been successfully synthesized via ring opening polymerization of γ-(carbamic acid benzyl ester)-ε-caprolactone (γCABεCL) and ε-caprolactone (εCL) using Pluronic F127 as macroinitiator and Sn(Oct)₂ as catalyst, and followed by hydrolysis of the Cbz protected groups under acidic conditions. The structure of the copolymer was confirmed by proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectroscopy spectra. In addition, gel permeation chromatography results demonstrated that the synthetic copolymer had a single and symmetrical peak. Moreover, the crystallinity and hydrophilicity could be well adjusted by the content of the functionalized monomer. Successful formation of aggregates was demonstrated by fluorescence method and transmission electron microscopy revealed that the micelles had a spherical morphology and the size was on nano scale according to the laser particle sizer results. The polymeric micelles had no obvious cytotoxicity even the micelles concentration reached 500 mg/L. Thus the Pluronic-b-poly(γ-amino-ε-caprolactone-co-ε-caprolactone) copolymers have great potential for the use in the biomedical fields.     

Synthesis and photovoltaic properties of copolymers with a fluoro quinoxaline unit

Two novel accepter units, namely, difluoroquinoxaline and monofluoroquinoxaline, were prepared and used for the synthesis of the conjugated polymers containing electron donor–acceptor pairs for use in organic photovoltaics. The introduction of a fluorine atom into the quinoxaline moiety resulted in polymers with lowered highest occupied molecular orbital (HOMO) energy levels; this increased the open circuit voltage of the devices based on the synthesized polymers. The conjugated polymers containing difluoroquinoxaline and monofluoroquinoxaline, namely, thiophene and benzodithiophene, were synthesized using the Stille polymerization reaction to produce PEHBQxF2, PEHBQxF1, PEHBDTQxF2, and PEHBDTQxF1. The HOMO energy levels of PEHBQxF2, PEHBQxF1, PEHBDTQxF2, and PEHBDTQxF1 were determined to be −5.66, −5.52, −5.54, and −5.39 eV, respectively. The device with PEHBDTQxF2/PC₇₁BM (1:2, w/w) and containing diiodooctane (3 vol %) exhibited the best photovoltaic performance, with its V_OC being 0.79 V, J_SC being 10.44 mA/cm², FF being 68%, and PCE being 5.58%. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 821–830