Synthesis and characterization of novel biodegradable poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s

Poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s were successfully synthesized by the ring‐opening copolymerization of p‐dioxanone and ethyl ethylene phosphate with triisobutyl aluminum as an initiator; this was confirmed by ¹H‐NMR and infrared spectra. The effects of the reaction conditions, such as the feeding ratio of the monomers and the reaction temperature and time, on the molecular weight of the copolymers were also studied. The in vitro degradation results showed that the introduction of phosphate segments into the backbone chains of the copolymers led to an enhancement of the degradation rate of the copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5507–5511, 2006     

Antibacterial poly{(4‐vinyl phenylboronic acid)‐co‐[2‐(dimethylamino)ethyl methacrylate]} copolymers and their application in water‐based paints

Herein, we report the synthesis of poly(4‐vinylphenylboronic acid) (PVPBA) and poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) homopolymers, copolymers, and their methyl, pentyl, and octyl quaternized forms as dopant in water‐based permanent antibacterial paints. Both quaternized and nonquaternized forms of P(VPBA‐co‐DMAEMA) copolymers have reflected higher MIC values relative to PDMAEMA homopolymers. High molecular weight copolymers were more active against Escherichia coli ATCC 25922, contrarily, lower molecular weight copolymers showed higher antibacterial activity against Staphylococcus aureus ATCC 25923. The paint films prepared with quaternized PDMAEMA homopolymers with a weight of 10% showed better antibacterial activity in water and airborne tests than the copolymers. However, it has been shown that the inadequate anti‐biofilm properties of homopolymer‐containing paint films are overcome with the VPBA content of the copolymer structure and the most effective antibacterial and anti‐biofilm properties have been obtained with paint films containing P(VPBA‐co‐5QDMAEMA) copolymers. These paint films, which can maintain antibacterial and anti‐biofilm properties for at least 1 year, have the potential to be an alternative to Ag/Cl based solid surfaces which require the active substance to be regenerated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46245.     

Vesicular and micellar self‐assembly of stimuli‐responsive poly(N‐isopropyl acrylamide‐b‐9‐anthracene methyl methacrylate) amphiphilic diblock copolymers

Dually responsive amphiphilic diblock copolymers consisting of hydrophilic poly(N‐isopropyl acrylamide) [poly(NIPAAm)] and hydrophobic poly(9‐anthracene methyl methacrylate) were synthesized by reversible addition fragmentation chain‐transfer (RAFT) polymerization with 3‐(benzyl sulfanyl thiocarbonyl sulfanyl) propionic acid as a chain‐transfer agent. In the first step, the poly(NIPAAm) chain was grown to make a macro‐RAFT agent, and in the second step, the chain was extended by hydrophobic 9‐anthryl methyl methacrylate to yield amphiphilic poly(N‐isopropyl acrylamide‐b‐9‐anthracene methyl methacrylate) block copolymers. The formation of copolymers with three different hydrophobic block lengths and a fixed hydrophilic block was confirmed from their molecular weights. The self‐assembly of these copolymers was studied through the determination of the lower critical solution temperature and critical micelle concentration of the copolymers in aqueous solution. The self‐assembled block copolymers displayed vesicular morphology in the case of the small hydrophobic chain, but the morphology gradually turned into a micellar type when the hydrophobic chain length was increased. The variations in the length and chemical composition of the blocks allowed the tuning of the block copolymer responsiveness toward both the pH and temperature. The resulting self‐assembled structures underwent thermally induced and pH‐induced morphological transitions from vesicles to micelles and vice versa in aqueous solution. These dually responsive amphiphilic diblock copolymers have potential applications in the encapsulation of both hydrophobic and hydrophilic drug molecules, as evidenced from the dye encapsulation studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46474.     

Synthesis and physicochemical characterization of amphiphilic block copolymer self‐aggregates formed by poly(ethylene glycol)‐block‐poly(ϵ‐caprolactone)

Diblock copolymers with different poly(ε‐caprolactone) (PCL) block lengths were synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG‐OH, MW 2000) as initiator. The self‐aggregation behaviors and microscopic characteristics of the diblock copolymer self‐aggregates, prepared by the diafiltration method, were investigated by using ¹H NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG–PCL block copolymers formed the self‐aggregate in an aqueous environment by intra‐ and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations of the block copolymer self‐aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The partition equilibrium constants (K_v) of pyrene, measured by fluorescence spectroscopy, revealed that the inner core hydrophobicity of the nanoparticles increased with increasing PCL chain length. The aggregation number of PCL chain per one hydrophobic microdomain, investigated by the fluorescence quenching method using cetylpyridinium chloride as a quencher, revealed that 4–20 block copolymer chains were needed to form a hydrophobic microdomain, depending on PCL block length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3520–3527, 2006     

Synthesis of Y‐shaped poly(N,N‐dimethylamino‐2‐ethyl methacrylate) and poly(trimethylene carbonate) from a new heterofunctional initiator

A new amphiphilic Y‐shaped copolymer, comprised of hydrophobic Poly(trimethylene carbonate) (PTMC) and hydrophilic Poly(N,N‐dimethylamino‐2‐ethyl methacrylate) (PDMAEMA), was designed and synthesized by a combination of atom transfer radical polymerization (ATRP) and ring‐opening polymerization (ROP) using a new heterofunctional initiator, Br‐Init‐(OH)₂, bearing one initiation site for ATRP and two for ROP. At first, a new trifunctional core molecule bearing hydroxyl group and bromine moieties, Br‐Init‐(OH)₂, was synthesized via protection followed by esterification reaction of 5‐ethyl‐5‐hydroxymethyl‐2,2‐dimethyl‐1,3‐dioxane with 2‐bromoisobutyryl bromide and deprotection. In the presence of trifunctional core molecule, Br‐Init‐(OH)₂, target Y‐shaped miktoarm star copolymers, (PTMC)₂‐ b‐PDMAEMA, were successfully synthesized by sequence conducting the ROP of TMC and ATRP of DMAEMA. The Y‐shaped copolymers were characterized by ¹H NMR and GPC measurements. Subsequently, the self‐assembly behavior of these copolymers was investigated by dynamic light scattering method and transmission electron microscopy, which indicated that these amphiphilic Y‐shaped copolymers can self‐assemble into micelles and possess distinct pH‐dependent size in aqueous milieu. The results indicate that the amphiphilic Y‐shaped copolymers had the pH‐responsive properties similar to the expected PDMAEMA. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Synthesis and association properties in water solution of random copolymers of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid and isodecyl methacrylate—potential application as surfactants in micellar‐enhanced ultrafiltration processes

Hydrophobically modified water‐soluble polymers have been prepared by copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) and isodecyl methacrylate (iDMA) in N,N‐dimethylformamide under nitrogen atmosphere, varying the composition feed. Fluorescence spectroscopy was used to further confirm the copolymers self‐aggregate in water. Critical concentration of the self‐aggregate formation (CAC) decreased by increasing the molar fraction of iDMA in the AMPS_co copolymers and varied between 1.20 and 0.04 g/L depending on the degree of hydrophobic modification. Hence, copolymer composition and charge density allowed tuning the pseudomicellar characteristics of these new amphiphilic copolymers. The addition of a salt or a low‐molecular‐weight surfactant was studied. Binding of CTAB to the AMPS_co copolymers leads to a high decrease of CAC, i.e., 0.006 g/L. Effect of the composition in the viscosimetric behavior of the hydrophobically modified copolymers AMPS_co was investigated. The removal of single metal ions, Cu²⁺, and m‐cresol from aqueous solutions by ultrafiltration with the help of the copolymers was investigated. Equilibrium dialysis experiments demonstrate that the formation of hydrophobic microdomains can be used to control the sequestration of foulants, and thus these novel copolymers have potential application as polymeric surfactants in micellar‐enhanced ultrafiltration processes for water purification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Amphiphilic 2‐ethyl hexyl methacrylate‐b‐N,N′‐dimethylacrylamide diblock copolymer monolayer behaviour at the air − water interface†

The surface activities of two amphiphilic diblock copolymers containing 2‐ethyl hexyl methacrylate‐b‐N,N′‐dimethylacrylamide (EHMA‐b‐DMA) possessing hydrophobic segments of different chain lengths were studied. Toward this end, surface pressure?area (π?A) isotherms, static and dynamic elasticities and the ν exponent of the excluded volume of polymers forming monolayers at the air?water interface were measured. The degree of hydrophobicity of the diblock copolymers was estimated by determining their surface energy values from contact angle measurements. The morphology of the monolayer at different surface pressures was studied by Brewster angle microscopy. Both copolymers were observed to form stable and elastic monolayers, and their collapse was observed to occur at similar surface pressures. Langmuir?Blodgett films were successfully deposited onto mica and silicon wafers and analysed by atomic force microscopy. © 2014 Society of Chemical Industry     

Preparation and aqueous solution behavior of a ph‐responsive branched copolymer based on 2‐(diethylamino)ethyl methacrylate

pH‐Responsive amphiphilic branched copolymers were prepared from poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2‐(diethylamino)ethyl methacrylate (DEAEMA), 2‐(tert‐butylamino)ethyl methacrylate (tBAEMA), and ethylene glycol dimethacrylate (EGDMA) utilizing a thiol‐modified free radical polymerization. The molecular structures of copolymers were confirmed by proton nuclear magnetic resonance spectroscopy (¹H NMR) and triple‐detection gel permeation chromatography (tri‐GPC). The aqueous solution behaviors of the obtained copolymers were investigated by dynamic light scattering (DLS). The DLS data showed that about 16 nm polymer particles comprising of hydrophobic poly(tert‐butylamino)ethyl methacrylate (PtBAEMA) and poly(diethylaminoethyl methacrylate (PDEAEMA) core, hydrophilic PEGMA corona were formed above pH 8. With the decrease of pH from 8 to 6, a dramatic increase in the hydrodynamic radius of polymer particles from 16 nm to 130 nm was observed resulting from the protonation of the PDEAEMA segment. Moreover, in vitro drug release behaviors of the resulting polymer assemblies at different pH values were also investigated to evaluate their potential as sustained release drug carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42183.     

Synthesis and properties of polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene triblock copolymers

A series of well‐defined and property‐controlled polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐polystyrene (PS) triblock copolymers were synthesized by atom‐transfer radical polymerization, using 2‐bromo‐propionate‐end‐group PEO 2000 as macroinitiatators. The structure of triblock copolymers was confirmed by ¹H‐NMR and GPC. The relationship between some properties and molecular weight of copolymers was studied. It was found that glass‐transition temperature (T_g) of copolymers gradually rose and crystallinity of copolymers regularly dropped when molecular weight of copolymers increased. The copolymers showed to be amphiphilic. Stable emulsions could form in water layer of copolymer–toluene–water system and the emulsifying abilities of copolymers slightly decreased when molecular weight of copolymers increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 727–730, 2006     

Self‐induced short chain branching in homopolymers and 1‐hexene copolymers of ethylene produced with amido functionalized ansa half‐sandwich complexes as catalysts

Amido ansa 3‐substituted indenyl complex precursors can be activated with methylaluminoxane and used for prepolymerization with ethylene to give a heterogeneous catalyst for olefin polymerization. Homo polymerization of ethylene with 1‐(3‐pent‐4‐enylindenylidene) dimethylsilyl'butylamidotitaniumdichloride (1), 1‐(3‐hex‐5‐enylindenylidene)dimethylsilyl'butylamidotitanium‐dichloride (2), and 1‐(3‐pent‐4‐enylindenylidene) (oct‐7‐enyl)methylsilyl'butylamidotitaniumdichloride (3) produces polyethylenes that contain ethyl branches. The ethyl branching in the polymers made with complexes 1 and 2 is barely above the ¹³C NMR detection limit, but the level observed in the polymer made with complex 3 is 17 times greater. Copolymerization of ethylene and 1‐hexene using prepolymerized 3 yields copolymers containing both ethyl and butyl branches. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 734–739, 2006     

Preparation and characterization of poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} copolymer nanoparticles

Poly{[α‐maleic anhydride‐ω‐methoxy‐poly(ethylene glycol)]‐co‐(ethyl cyanoacrylate)} (PEGECA) copolymers were prepared by radical polymerization of macromolecular poly(ethylene glycol) monomers (PEGylated) and ethyl 2‐cyanoacrylate in solvent. The structures of the copolymer were characterized by Fourier‐transform infrared (FTIR) and proton nuclear magnetic resonance (¹H‐NMR). The morphology and size of the PEGECA nanoparticles prepared by nanoprecipitation techniques were investigated by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS) methods. The results show that the PEGECA can self‐assemble into highly stable nanoparticles in aqueous media, and inner core and outer shell morphology. The size of the nanoparticles was strongly influenced by the solvent character and the copolymer concentration in the organic solvents. A hydrophobic drug, ibuprofen, was effectively incorporated into the nanoparticles, which provides a delivery system for ibuprofen and other hydrophobic compounds. Copyright © 2005 Society of Chemical Industry     

pH and thermo‐responsive poly(N‐isopropylacrylamide) copolymer grafted to poly(ethylene glycol)

pH and thermo‐responsive graft copolymers are reported where thermo‐responsive poly(N‐isopropylacrylamide) [poly(NIPAAm), poly A ], poly(N‐isopropylacrylamide‐co‐2‐(diethylamino) ethyl methacrylate) [poly(NIPAAm‐co‐DEA), poly B ], and poly(N‐isopropylacrylamide‐co‐methacrylic acid) [poly(NIPAAm‐co‐MAA), poly C ] have been installed to benzaldehyde grafted polyethylene glycol (PEG) back bone following introducing a pH responsive benzoic‐imine bond. All the prepared graft copolymers for PEG‐g‐poly(NIPAAm) [ P‐N1 ], PEG‐g‐poly(NIPAAm‐co‐DEA) [ P‐N2 ], and PEG‐g‐poly(NIPAAm‐co‐MAA) [ P‐N3 ] were characterized by ¹H‐NMR to assure the successful synthesis of the expected polymers. Molecular weight of all synthesized polymers was evaluated following gel permeation chromatography. The lower critical solution temperature of graft copolymers varied significantly when grafted to benzaldehyde containing PEG and after further functionalization of copolymer based poly(NIPAAm). The contact angle experiment showed the changes in hydrophilic/hydrophobic behavior when the polymers were exposed to different pH and temperature. Particle size measurement investigation by dynamic light scattering was performed to rectify thermo and pH responsiveness of all prepared polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Phase behavior of temperature‐ and pH‐sensitive poly(acrylic acid‐g‐N‐isopropylacrylamide) in dilute aqueous solution

Several different composition temperature‐ and pH‐sensitive poly(acrylic acid‐g‐N‐isopropylacrylamide) (P(AA‐g‐NIPAM)) graft copolymers were synthesized by free‐radical copolymerization utilizing macromonomer technique. The phase behavior and conformation change of P(AA‐g‐NIPAM) in aqueous solutions were investigated by UV–vis transmittance measurements, fluorescence probe, and fluorescence quenching techniques. The results demonstrate that the P(AA‐g‐NIPAM) copolymers have temperature‐ and pH‐sensitivities, and these different composition graft copolymers have different lower critical solution temperature (LCST) and critical phase transition pH values. The LCST of graft copolymer decreases with increasing PNIPAM content, and the critical phase transition pH value increases with increasing Poly(N‐isopropylacrylamide) (PNIPAM) content. At room temperature (20°C), different composition of P(AA‐g‐NIPAM) graft copolymers in dilute aqueous solutions (0.001 wt %) have a loose conformation, and there is no hydrophobic microdomain formation within researching pH range (pH 3 ～ 10). In addition, for the P(AA‐g‐NIPAM) aqueous solutions, transition from coil to globular is an incomplete reversible process in heating and cooling cycles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and surface properties of polydimethylsiloxane‐based block copolymers: poly[dimethylsiloxane‐block‐ (ethyl methacrylate)] and poly[dimethylsiloxane‐block‐(hydroxyethyl methacrylate)]

A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)‐terminated PDMS and 4,4′‐azobis‐4‐cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2‐(trimethylsilyloxy)ethyl methacrylate (TMSHEMA) monomers. The poly(DMS‐block‐EMA) and poly(DMS‐block‐TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and ¹H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS‐block‐HEMA) and poly(DMS‐block‐EMA) copolymer film surfaces were analysed using scanning electron microscopy and X‐ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS‐block‐EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS‐block‐HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase‐separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. Copyright © 2010 Society of Chemical Industry     

Blends containing amphiphilic polymers. V. Compatibilization of N‐alkylitaconamic acid‐co‐styrene copolymers with interacting polymers

The phase behavior of blends containing N‐alkylitaconamic acid‐co‐styrene copolymers (NAIA‐co‐S) with poly(N‐vinyl‐2‐pyrrolidone) (PVP) of two different weight average molecular weights (M _w ), poly(2‐vinylpyridine) (P2VPy) and poly(4‐vinylpyridine) (P4VPy), was analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. Copolymers containing 80% S are miscible with PVP₁₀, PVP₂₄, and P4VPy over the whole range of composition. In the case of blends with P2VPy, miscibility is observed only for the first three members of the series, i.e., NEIA‐co‐S, NPIA‐co‐S, and NBIA‐co‐S. For copolymers containing hexyl to dodecyl moieties, phase separation is observed in blends with P2VPy. Copolymers containing 50% S are miscible over the whole range of composition irrespective of the homopolymer and the length of the side chain of the itaconamic moiety of the copolymer. This behavior is interpreted in terms of steric hindrance, in the sense that the copolymers with long side chains are not able to interact with the nitrogen of P2VPy because of the position in the aromatic ring. The interactions between copolymers and homopolymers are discussed in terms of specific interactions like hydrogen bonds between the itaconamic moiety and the different functional groups of the homopolymers, together with the hydrophobic interaction, which cannot be disregarded. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2512–2519, 2006     

Synthesis,characterization, and antitumor activity of poly(maleic anhydride‐co‐vinyl acetate‐co‐acrylic acid)

The ternary copolymerization of maleic anhydride (MA), vinyl acetate (VA), and acrylic acid (AA) [P(MA‐co‐VA‐co‐AA)], which is considered to be an acceptor–donor–acceptor system, was carried out in 1,4‐dioxane with benzoyl peroxide as an initiator at 70°C under a nitrogen atmosphere. Constants of complex formation for the monomer systems in the study were determined by UV–visible (hydrogen‐bonding complex) and ¹H‐NMR (charge transfer complex) methods, respectively. The results show that polymerization of the P(MA‐co‐VA‐co‐AA) system proceeds by an alternating terpolymerization mechanism. It is shown that the synthesized copolymers have typical polyelectrolyte behavior, ability for reversible hydrolysis–anhydrization reactions, and semicrystalline structures. In these cases, including radical polymerization, and formation of semicrystalline structures, the hydrogen‐bonding effect plays a significant role. The in vitro cytotoxicities of the synthesized terpolymer and alternating copolymer were evaluated using Raji cells (human Burkitt lymphoma cell line). The antitumor activities of prepared anion‐active copolymers were studied using methyl–thiazol–tetrazolium colorimetric assay and 50% of the cytotoxic dose of each copolymer and terpolymer were calculated. Hydrolyzed P(MA‐co‐VA‐co‐AA) and P(MA‐alt‐AA) copolymers have sufficiently high antitumor activity, which depends on the amount of hydrogen‐bonding carboxylic groups and their regular distribution in the side chain of functional macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3425–3432, 2006     

Synthesis and characterization of thermo‐ and pH‐sensitive block copolymers bearing a biotin group at the poly(ethylene oxide) chain end

A poly(ethylene oxide)‐block‐poly(dimethylamino ethyl methacrylate) block copolymer (PEO‐b‐PDMAEMA) bearing an amino moiety at the PEO chain end was synthesized by a one‐pot sequential oxyanionic polymerization of ethylene oxide (EO) and dimethylamino ethyl methacrylate (DMAEMA), followed by a coupling reaction between its PEO amino and a biotin derivative. The polymers were charac terized with ¹H NMR spectroscopy and gel permeation chromatography. Activated biotin, biotin‐NHS (N‐hydroxysuccinimide), was used to synthesize biotin‐PEO‐PDMAEMA. In aqueous media, the solubility of the copolymer was temperature‐ and pH‐sensitive. The particle size of the micelle formed from functionalized block copolymers was determined by dynamic light scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3552–3558, 2006     

Synthesis and characterization of amphiphilic PMTFPS‐b‐PEO diblock copolymers

A series of new amphiphilic poly[methyl(3,3,3‐trifluoropropyl) siloxane]‐b‐poly(ethyleneoxide) (PMTFPS‐b‐PEO) diblock copolymers with different ratio of hydrophobic segment to hydrophilic segment were prepared by coupling reactions of end‐functional PMTFPS and PEO homopolymers. PMTFPS‐b‐PEO diblock copolymers synthesized were shown to be well defined and narrow molecular weight distributed by characterizations such as NMR, GPC, and FTIR. Additionally, the solution properties of these diblock copolymers were investigated using tensiometry and transmission electron microscopy. Interestingly, the critical micellization concentration increases with increasing length of hydrophobic chain. Transmission electron microscopy studies showed that PMTFPS‐b‐PEO diblock copolymers in water preferentially aggregated into vesicles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Solution behavior of two novel anionic polyacrylamide copolymers hydrophobically modified with n‐benzyl‐n‐octylacrylamide

Two novel hydrophobically modified anionic polyacrylamides (HM‐PAMs), p(AM/NaA/NaAMC₁₂S/BOAM) and p(AM/NaA/OP‐10‐AC/BOAM) have been prepared by an aqueous micellar copolymerization technique from acrylamide, sodium acrylate (NaA), sodium 2‐(acrylamido)dodecane‐1‐sulfonate (NaAMC₁₂S), octylphenol polyoxyethylene acrylate (OP‐10‐AC), and small amounts of N‐benzyl‐N‐octylacrylamide, respectively, with the objective of investigating the copolymers' rheological behaviors and surface activities under various conditions such as polymer concentration, shear rate, temperature, and salinity. As expected, the copolymers exhibit improved thickening properties due to intermolecular hydrophobic associations as the solution viscosity of the copolymers increases sharply with increasing polymer concentration. A decrease in viscosity is observed with increasing temperature, and the solution viscosity of the copolymers decreases with increasing NaCl concentration. Furthermore, the block copolymers exhibit high air–liquid surface activities as the surface tensions (STs) decrease with increasing polymer concentration. This behavior is yet another evidence of polymolecular micelles formation of the copolymers in aqueous solution, and thus the high tendency to adsorb at an interface. The ST exhibited by the copolymers was found to be relatively insensitive to the concentration of salt (NaCl). Scanning electron micrographs showed large aggregates in solutions, which is formed by the association from the hydrophobic groups of the polymers. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Novel amphiphilic poly(ester‐urethane)s based on poly[(R)‐3‐hydroxyalkanoate]: synthesis,biocompatibility and aggregation in aqueous solution

BACKGROUND: The aim of this work was to develop polyhydroxyalkanoates (PHAs) for blood contact applications, and to study their self‐assembly behavior in aqueous solution when the PHAs are incorporated with hydrophilic segments. To do this, poly(ester‐urethane) (PU) multiblock copolymers were prepared from hydroxyl‐terminated poly(ethylene glycol) (PEG) and hydroxylated poly[(R)‐3‐hydroxyalkanoate] (PHA‐diol) using 1,6‐hexamethylene diisocyanate as a coupling reagent. The PEG segment functions as a soft, hydrophilic and crystalline portion and the poly[(R)‐3‐hydroxybutyrate] segment behaves as a hard, hydrophobic and crystalline portion. In another series of PU multiblock copolymers, crystalline PEG and completely amorphous poly[((R)‐3‐hydroxybutyrate)‐co‐(4‐hydroxybutyrate)] behaved as hydrophobic and hydrophilic segments, respectively. RESULTS: The formation of a PU series of block copolymers was confirmed by NMR, gel permeation chromatography and infrared analyses. The thermal properties showed enhanced thermal stability with semi‐crystalline morphology via incorporation of PEG. Interestingly, the changes of the hydrophilic/hydrophobic ratio led to different formations in oil‐in‐water emulsion and surface patterning behavior when cast into films. Blood compatibility was also increased with increasing PEG content compared with PHA‐only polymers. CONCLUSION: For the first time, PHA‐based PU block copolymers have been investigated in terms of their blood compatibility and aggregation behavior in aqueous solution. Novel amphiphilic materials with good biocompatibility for possible blood contact applications with hydrogel properties were obtained. Copyright © 2008 Society of Chemical Industry