Release behavior of freeze‐dried alginate beads containing poly(N‐isopropylacrylamide) copolymers

Beads composed of alginate, poly(N‐isopropylacrylamide) (PNIPAM), the copolymers of N‐isopropylacrylamide and methacrylic acid (P(NIPAM‐co‐MAA)), and the copolymers of N‐isopropylacrylamide, methacrylic acid, and octadecyl acrylate (P(NIPAM‐co‐MAA‐co‐ODA)), were prepared by dropping the polymer solutions into CaCl₂ solution. The beads were freeze‐dried and the release of blue dextran entrapped in the beads was observed in distilled water with time and pH. The degree of release was in the order of alginate bead < alginate/PNIPAM bead ≈ alginate/P(NIPAM‐co‐MAA) bead < alginate/P(NIPAM‐co‐MAA‐co‐ODA) bead. On the other hand, swelling ratios reached steady state within 20 min, and the values were 200–800 depending on the bead composition. The degree of swelling showed the same order as that of release. Among the beads, only alginate/P(NIPAM‐co‐MAA‐co‐ODA) bead exhibited pH‐dependent release. At acidic condition, inter‐ and intraelectrostatic repulsion is weak and P(NIPAM‐co‐MAA‐co‐ODA) could readily be assembled into an aggregate due to the prevailing hydrophobic interaction of ODA. Thus, it could block the pore of bead matrix, leading to a suppressed release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

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     

Use of a CO2‐switchable hydrophobic associating polymer to enhance viscosity–response

A series of copolymers, poly(acrylamide)‐co‐poly(N,N‐dimethylaminoethyl methacrylate)‐co‐poly(N‐cetyl DMAEMA) (abbreviation PDAMCn), was synthesized with different monomer ratios. The resulting copolymer solution shows pronounced viscosity–response property which is CO₂‐triggered and N₂‐enabled. Electrical conductivity experiment shows that tertiary amine group on DMAEMA experiences a protonate and deprotonate transition upon CO₂ addition and its removal. In addition, different incorporation rates of DMAEMA leads to two kinds of morphological change in the presence of CO₂ and thus induces different rheological behaviors. PDAMCn incorporating longer hydrophobic monomer (C₁₈DM) show more pronounced initial viscosity and higher critical stress required to cause network deformation, which consequently enhances the viscosity–response property of the solution. The addition of NaCl could also tune the viscosity of PDAMCn solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41468.     

Synthesis and characterization of degradable copoly(trans‐4‐hydroxy‐L‐proline/ϵ‐caprolactone)

The melt polycondensation reaction of N‐protected trans‐4‐hydroxy‐L ‐proline (N‐Z‐Hpr) and ?‐caprolactone (?‐CL) over a wide range of molar fractions in the feed produced new and degradable poly(N‐Z‐Hpr‐co‐?‐CL)s with stannous octoate as a catalyst. The optimal reaction conditions for the synthesis of the copolymers were obtained with 1.5 wt % stannous octoate at 140°C for 24 h. The synthesized copolymers were characterized by IR spectrophotometry, ¹H NMR, differential scanning calorimetry, and Ubbelohde viscometry. The values of the inherent viscosity (η_inh) and glass‐transition temperature (T_g) of the copolymers depended on the molar fractions of N‐Z‐Hpr. With an increase in the trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L ‐proline (N‐CBz‐Hpr) feed from 10 to 90 mol %, a decrease in η_inh from 2.47 to 1.05 dL/g, and an increase in T_g from ?48 to 49°C were observed. The in vitro degradation of these poly(N‐CBz‐Hpr‐co‐?‐CL)s was evaluated from weight‐loss measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3176–3182, 2003     

Preparation and self‐assembly of poly(diglycidyl maleate‐co‐stearyl methacrylate)

Poly(diglycidyl maleate‐co‐stearyl methacrylate) (P(DGMA‐co‐SMA)) with reactive epoxy groups was synthesized by reaction of poly(maleic anhydride‐co‐stearyl methacrylate) (P(MA‐co‐SMA)) and epichlorohydrin. The effect of precipitant on self‐assembly behaviors of the resultant copolymer was investigated. It was found that vesicles and nanotubule liked aggregates can be obtained through self‐assembly of P(DGMA‐co‐SMA) in THF solution using CH₃CH₂OH (EtOH) as precipitant while spheral aggregates can be obtained using H₂O as precipitant. The mechanism of the self‐assembly behavior was discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Self‐assembled nanostructures: preparation,characterization, thermal,optical and morphological characteristics of amphiphilic diblock copolymers based on poly(2‐hydroxyethyl methacrylate‐block‐N‐phenylmaleimide)

A series of well‐defined amphiphilic poly[(2‐hydroxyethyl methacrylate)‐block‐(N‐phenylmaleimide)] diblock copolymers containing hydrophilic and hydrophobic blocks of different lengths were synthesized by atom transfer radical polymerization. The properties of the diblock copolymers and their ability to form large compound spherical micelles are described. Their optical, morphological and thermal properties and self‐assembled structure were also investigated. The chemical structure and composition of these copolymers have been characterized by elemental analysis, Fourier transform infrared, ¹H NMR, UV–visible and fluorescence spectroscopy, and size exclusion chromatography. Furthermore, the self‐assembly behavior of these copolymers was investigated by transmission electron microscopy and dynamic light scattering, which indicated that the amphiphilic diblock copolymer can self‐assemble into micelles, depending on the length of both blocks in the copolymers. These diblock copolymers gave rise to a variety of microstructures, from spherical micelles, hexagonal cylinders to lamellar phases. © 2013 Society of Chemical Industry     

Poly(N‐isopropylacrylamide‐co‐hydroxyethyl methacrylate) graft copolymers and their application as carriers for drug delivery system

Poly(N‐isopropylacrylamide‐co‐hydroxyethyl methacrylate) [P(NIPAM‐co‐HEMA)] copolymer was synthesized by controlled radical polymerization from respective N‐isopropylacrylamide (NIPAM) and hydroxyethyl methacrylate (HEMA) monomers with a predetermined ratio. To prepare the thermosensitive and biodegradable nanoparticles, new thermosensitive graft copolymer, poly(L ‐lactide)‐graft‐poly(N‐isoporylacrylamide‐co‐hydroxyethyl methacrylate) [PLLA‐g‐P(NIPAM‐co‐HEMA)], with the lower critical solution temperature (LCST) near the normal body temperature, was synthesized by ring opening polymerization of L ‐lactide in the presence of P(NIPAM‐co‐HEMA). The amphiphilic property of the graft copolymers was formed by the grafting of the PLLA hydrophobic chains onto the PNIPAM based hydrophilic backbone. Therefore, the graft copolymers can self‐assemble into uniformly spherical micelles ò about 150–240 nm in diameter as observed by the field emission scanning electron microscope and dynamic light scattering. Dexamethasone can be loaded into these nanostructures during dialysis with a relative high loading capacity and its in vitro release depends on temperature. Above the LCST, most of the drugs were released from the drug‐loaded micelles, whereas a large amount of drugs still remains in the micelles after 48 h below the LCST. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Toluene‐vapor sorption of chemically modified methyl methacrylate‐co‐chloromethyl styrene copolymers with N,N,‐dimethyl‐1,3‐propanediamine measured with a quartz crystal microbalance

The sorption properties of toluene vapor were measured for methyl methacrylate (MMA)‐co‐chloromethyl styrene (CMSt) copolymers chemically modified with N,N‐dimethyl‐1,3‐propanediamine (DMPDA) to develop a novel quartz crystal microbalance toluene‐vapor sensor coating. The influence of the structure of the comonomer, the composition of the copolymer, and the film thickness on the toluene sorption properties were investigated. The modified MMA–CMSt copolymers were capable of large, fast, and reversible sorption versus the modified styrene–CMSt copolymers. The largest sorption capacity was obtained for MMA–CMSt–DMPDA with a 96 mol % CMSt concentration. These behaviors were explained by a combination of the plasticization of the copolymers by the introduction of bulky DMPDA at lower CMSt concentrations and the formation of a loosely crosslinked structure at higher CMSt concentrations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of photo‐ and thermoresponsible amphiphilic copolymers having azobenzene moieties as side groups

Two series of amphiphilic copolymers, poly(HPMA‐co‐MPAP) I–V with n = 0.05–0.29 of the molar ratio of MPAP and poly(HPMA‐co‐MPAH)‐I–V with n = 0.05–0.23 of the molar ratio of MPAH, were prepared by radical copolymerization of N‐(2‐hydroxypropyl) methacrylamide (HPMA) with azo‐monomers such as 4‐(4‐methoxyphenylazo) phenyl methacrylate (MPAP) and 6‐[4‐(4‐methoxyphenylazo) phenoxy] hexyl methacrylate (MPAH) using 2,2′‐azobisisobutyronitrile as an initiator. Self‐organization of these copolymers in water was confirmed by disappearance of the proton signal of the methoxyazobenzene in ¹H‐NMR spectra measured in the solvent system of D₂O and CD₃OD. It was also found from the λ_max, located near 344 nm, that azobenzene groups self‐organized to form the dimeric chromophore type of aggregate. The aqueous solutions of poly(HPMA‐co‐MPAP) and poly(HPMA‐co‐MPAH) exhibited the lower critical solution temperature (LCST) from at 68 to 40°C and from at 70 to 52°C in the dark state, respectively, with increasing the molar ratios of azo‐monomers. On the other hand, the LCST measured in the photostationary state showed the higher temperature by 2–4°C compared with that in the dark state. It was found that the adsorption of poly(HPMA‐co‐MPAP)‐V (n = 0.29) on polystyrene microspheres was photoregulated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3056–3063, 2001     

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     

Preparation of electrorheological active ionomers from poly(2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine)

In this study, synthesis, characterization, partial hydrolysis, and salt formation of poly(2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine), (poly(HEMA)‐co‐poly‐(4‐VP)) copolymers were investigated. The copolymers were synthesized by free radical polymerization using K₂S₂O₈ as an initiator. By varying the monomer/initiator ratio, chain lengths of the copolymers were changed. The copolymers were characterized by gel permeation chromatography (GPC), viscosity measurements, ¹H and ¹³C NMR and FTIR spectroscopies, elemental analysis, and end group analysis methods. The copolymers were partially hydrolyzed by p‐toluene sulfonic acid monohydrate (PTSA·H₂O) and washed with LiOH_(aq) solution to prepare electrorheological (ER) active ionomers, poly(Li‐HEMA)‐co‐poly(4‐VP). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3540–3548, 2006     

Characterization of morphology in chemically modified styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene by solid‐state nuclear magnetic resonance

Multiphase triblock styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) copolymers chemically modified with maleic anhydride (MAH) in the presence of a radical initiator by reactive extrusion were studied by solid‐state ¹H‐NMR and ¹³C‐NMR. In the experiments performed, the concentrations of MAH and initiator were kept constant, whereas the temperature profile in the extruder was varied. Samples with known extents of grafting and crosslinking were analyzed with NMR with techniques based on proton spin diffusion to investigate the microphase structure of the modified copolymers. The ¹³C‐NMR results show that the size of the rigid domains was about 15 nm and was not significantly changed by the modification. Alterations in the rubbery phase were illustrated by measured changes in proton spin‐spin (T₂) relaxation times. The fraction of protons having intermediate mobilities increased slightly in modified SEBS with respect to that observed in unmodified copolymers. These results were found to be independent of the extruder temperature profiles used, at least in the range studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of different anchor groups on adsorption behavior and effectiveness of poly(N,N‐dimethylacrylamide‐co‐Ca 2‐acrylamido‐2‐methylpropanesulfonate) as cement fluid loss additive in presence of acetone–formaldehyde–sulfite dispersant

The impact of various anchor groups on adsorption behavior of AMPS® copolymers was studied. The anchor groups differ in anionic charge density. Copolymer adsorption and water retention of oil well cement slurries achieved from CaAMPS®‐co‐NNDMA in the presence of an acetone–formaldehyde–sulfite (AFS) dispersant were improved by incorporation of minor amounts (～ 1% by weight of polymer) of acrylic acid (CaAMPS®‐co‐NNDMA‐co‐AA), maleic acid anhydride (CaAMPS®‐co‐NNDMA‐co‐MAA), or vinyl phosphonic acid (CaAMPS®‐co‐NNDMA‐co‐VPA), respectively. Performance of these terpolymers was studied by measuring static filtration properties of oil well cement slurries at 27°C and 70 bar pressure. All fluid loss additives possess comparable molar masses and show the same adsorption behavior and effectiveness when no other admixture is present. In the presence of AFS dispersant, however, adsorption of CaAMPS®‐co‐NNDMA and hence fluid loss control is dramatically reduced, whereas effectiveness of CaAMPS®‐co‐NNDMA‐co‐AA is less influenced because of acrylic acid incorporated as additional anchor group. Even more, CaAMPS®‐co‐NNDMA‐co‐MAA combined with AFS allows simultaneous adsorption of both polymers and thus produces good fluid loss control. CaAMPS®‐co‐NNDMA‐co‐VPA no longer allows adsorption of AFS dispersant. This was also confirmed by rheological measurements. The results show that, in a binary admixture system, adsorption of the anionic polymer with anchor groups possessing higher charge density is preferred. Surface affinity of the anchor groups studied increase in the order ? SO → ? COO^? → vic‐(? COO^?)₂→ ? PO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Adsorption of surfactant by hydrophobically modified poly[2‐(diethylamino)ethylmethacrylate‐co‐N‐vinyl‐2‐pyrrolidone/octadecyl acrylate)] hydrogels and effect of surfactant adsorption on the volume phase transition

Hydrophobically modified poly[2‐(diethylamino)ethylmethacrylate‐co‐N‐vinyl‐2‐pyrrolidone/octadecyl acrylate) [P(DEAEMA‐co‐NVP/OA)] hydrogels were synthesized by free‐radical crosslinking copolymerization of 2‐(diethylamino)ethylmethacrylate (DEAEMA), N‐vinyl‐2‐pyrrolidone (NVP) with different amounts of hydrophobic comonomer octadecyl acrylate (OA) in tert‐butanol with ethylene glycole dimethacrylate (EGDMA) as a crosslinker. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). The results indicated that the swelling behavior and temperature sensitivity of the hydrogels were affected by the type and concentration of surfactant solutions. Additionally, the amount of the adsorbed SDS and DTAB molecules onto the hydrogels was determined by fluorescence measurements. An increase of OA content in the hydrogel caused an increase in the amount of adsorbed surfactant molecules in both media. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3771–3775, 2007     

Hydrophobically modified poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate): synthesis and viscosity of aqueous solution

BACKGROUND: Hydrophobically modified polyelectrolytes are widely used polymers due to their good water solubility, stretched configuration in water and strong hydrophobic association. The study reported here aimed at researching the double action of hydrophobic association and electrostatic effect of novel hydrophobically modified polyelectrolytes in solution. RESULTS: A series of novel hydrophobically modified polyelectrolytes were synthesized by micellar copolymerization with various feed ratios of sodium 2‐acrylamido‐2‐methylpropanesulfonate, N‐n‐dodecylamine and sodium dodecylsulfonate. Their structure was characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography, and the viscosities of their aqueous and salt solutions were studied. CONCLUSION: The results show that the addition of the hydrophobic comonomer results in a decrease in molecular weight (M_w). The smaller the initial number of hydrophobes in one micelle, the higher is M_w of the resulting copolymer. The viscosity of PAD‐1.73 polyelectrolyte is less sensitive to salt than those of the others. According to the zero shear viscosity and corresponding concentration, the critical cluster‐forming concentration, critical overlap concentration and critical entanglement concentration of these polymer solutions were determined. Moreover, in the dilute regime the viscosity decreases with increasing salinity, while in the semi‐dilute regime the viscosity decreases first and then increases. It is suggested that in dilute and semi‐dilute regimes, hydrophobic intramolecular association and intermolecular association dominate, respectively. Copyright © 2009 Society of Chemical Industry     

Poly(ε‐caprolactone)‐graft‐poly(N‐isopropylacrylamide) amphiphilic copolymers prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization: Synthesis,self‐assembly,and thermoresponsive property

Thermoresponsive graft copolymers of ε‐caprolactone and N‐isopropylacrylamide were synthesized by a combination of ring‐opening polymerization and the sequential atom transfer radical polymerization (ATRP). The copolymer composition, chemical structure, and the self‐assembled structure were characterized. The graft length and density of the copolymers were well controlled by varying the feed ratio of monomer to initiator and the fraction of chlorides along PCL backbone, which is acting as the macroinitiator for ATRP. In aqueous solution, PCL‐g‐PNIPAAm can assemble into the spherical micelles which comprise of the biodegradable hydrophobic PCL core and thermoresponsive hydrophilic PNIPAAm corona. The critical micelle concentrations of PCL‐g‐PNIPAAm were determined under the range of 6.4–23.4 mg/L, which increases with the PNIPAAm content increasing. The mean hydrodynamic diameters of PCL‐g‐PNIPAAm micelles depend strongly on the graft length and density of the PNIPAAm segment, allowing to tune the particle size within a wide range. Additionally, the PCL‐g‐PNIPAAm micelles exhibit thermosensitive properties and aggregate when the temperature is above the lower critical solution temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41115.     

Poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium): Synthesis,characterization, and its potential application for the removal of metal ions from aqueous solution

In the current study, poly(N‐vinylpyrrolidone‐co‐2‐acrylamido‐2‐methylpropanesulfonate sodium), poly(VP‐co‐AMPS), was prepared and used for the removal of Cu²⁺, Cd²⁺, and Ni²⁺ ions via a polymer‐enhanced ultrafiltration (PEUF) technique. The copolymer was synthesized by radical polymerization in an aqueous medium with a comonomer feed composition of 50:50 mol %. The molecular structure of the copolymer was elucidated by ATR‐FTIR and ¹H NMR spectroscopy, and the average molecular weight was obtained by GPC. The copolymer composition was determined to be 0.42 for VP and 0.58 for AMPS by ¹H NMR spectroscopy. The copolymer and homopolymers exhibited different retention properties for the metal ions. PAMPS exhibited a high retention capacity for all of the metal ions at both pH values studied. PVP exhibited selectivity for nickel ions. Poly(VP‐co‐AMPS) exhibited a lower retention capacity compared to PAMPS. However, for poly(VP‐co‐AMPS), selectivity for nickel ions was observed, and the retention of copper and cadmium ions increased compared to PVP. The homopolymer mixture containing PAMPS and PVP was inefficient for the retention of the studied metal ions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41272.     

Effects of the cosurfactant 1‐butanol and feed composition on nanoparticle properties produced by microemulsion copolymerization of styrene and methyl methacrylate

The concentration of the cosurfactant 1‐butanol (BuOH) determined the polymer weight and size for a series of poly(styrene‐co‐methyl methacrylate)s (P(St‐co‐MMA)) synthesized by the free‐radical (o/w) microemulsion technique. A factorial design established the levels of the experimental conditions for the polymerization i.e., concentration of the surfactant, sodium dodecyl sulfate (SDS); concentration of the cosurfactant, BuOH; temperature and ratio of the styrene (St) to methyl methacrylate (MMA). An increase in the weight‐average molecular weight (M_w) and number‐average molecular weight (M_n) was observed in the P(St‐co‐MMA) series with an increase in BuOH concentration from 1 to 5 wt %. These effects could arise from the micellar aggregation induced by interfacial BuOH. The unique micellar conditions could be exploited to synthesize copolymers of varying molecular weight and size. Additionally, the composition of the copolymers was virtually templates of the feed composition. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008