Thermo‐ and pH‐ responsive copolymers: Poly(n‐Isopropylacrylamide‐co‐IAM) copolymers

Poly(N‐isopropylacrylamide) (NIPAAm) is well known as a smart material with good thermal sensitivity and favorable biocompatibility. A series of new smart hydrogels, NIPAAm copolymerized with IAM (itaconamic acid; 4‐amino‐2‐methylene‐4‐oxobutanoic acid), were synthesized through radical solution polymerization in this work. Poly(NIPAAm‐co‐IAM) can respond to the changes of temperature as well as pH value. Such a characteristic is due to the fact that IAM contains not only a hydrophilic acrylic acid moiety but also an acrylamide moiety to be thermal and pH sensitive. The experimental results show that the lower critical solution temperature (LCST) of the copolymer increases as the molar fraction of IAM increases. Moreover, based on the current experimental data, 3 wt % of Poly(NIPAAm‐co‐IAM) aqueous solution in this study exhibits a phase transition temperature (37.8°C) close to the human body temperature in the buffer solution of pH 7 possibly to be useful in drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42367.     

Thermally assisted self‐healing polyurethane containing carboxyl groups

Self‐healing polymer is a kind of intelligent material with the capability to repair damage automatically. In this paper, a type of polyurethane containing carboxyl groups is reported that demonstrates thermally assisted healing effects. This polymer can be healed even 72 h after cutting and also has a repeatable healing property. The self‐healing efficiency can reach 90% when comparing the tensile strength of the healed sample to the original sample. Carboxyl content plays an important role in the self‐healing property; polyurethane with no carboxyl groups cannot be healed. The mechanism of self‐healing showed that hydrogen bonding interactions between carboxyl groups and diffusion of poly(ethylene glycol) chains contribute to the self‐healing behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45929.     

Synthesis and characterization of temperature‐responsive poly(vinyl alcohol)‐based copolymers

A poly(vinyl alcohol) (PVA)/sodium acrylate (AANa) copolymer was synthesized to improve the water solubility of PVA at the ambient temperature. Furthermore, a series of temperature‐responsive acetalyzed poly(vinyl alcohol) (APVA)‐co‐AANa samples of various chain lengths, degrees of acetalysis (DAs), and comonomer contents were prepared via an acid‐catalysis process. Fourier transform infrared and ¹H‐NMR techniques were used to analyze the compositions of the copolymers. The measurement of the turbidity change for APVA‐co‐AANa aqueous solutions at different temperatures revealed that the lower critical solution temperature (LCST) of the copolymers could be tailored through the control of the molecular weight of the starting PVA‐co‐AANa, DA, and comonomer ratios. Lower LCSTs were observed for APVA‐co‐AANa with a longer chain length, a higher DA, and fewer acrylic acid segments. In addition, the LCSTs of the APVA‐co‐AANa aqueous solutions appeared to be salt‐sensitive. The LCSTs decreased as the concentration of NaCl increased. Moreover, atomic force microscopy images of APVA‐co‐AANa around the LCST also proved the temperature sensitivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm³⁺, Nd³⁺, and La³⁺ than for Cu²⁺, Ni²⁺ and Co²⁺. The APPA–NIPAAm (10:90) copolymer/metal (Sm³⁺, Nd³⁺, or La³⁺) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu²⁺,Ni²⁺, or Co²⁺) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004     

Adsorption of Zn(II) by crosslinked acrylic copolymers with amine functional groups

Adsorption of Zn(II) ions from diluted aqueous solutions by the acrylic copolymer based on ethylacrylate : acrylonitrile : divinylbenzene matrix with different crosslinking degrees and ethylenediamine and triethylenetetramine functional groups was investigated. Adsorption experiments were carried out by batch method. The effects of the pH, initial concentration of zinc, time of contact, and the crosslinking degree of the copolymers were studied. On the basis of Langmuir and Freundlich isotherms, the parameters that characterize the adsorption were determined. The maximum Zn(II) retention capacity value (500 mg g^?1) was obtained for the acrylic copolymer with 2% crosslinking degree and ethylenediamine, as functional groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 803–808, 2004     

Facile synthesis of a triptycene-based porous organic polymer with a high efficiency and recyclable adsorption for organic dyes

Water contamination resulting from organic dyes has had severe detrimental effects on human health and environmental tolerance. To address this issue, a delicate strategy for taking host–guest function in porous organic polymers via a facile Friedel–Crafts reaction of triptycene and post-modification was achieved. By means of this route, a sulfonic acid functionalized triptycene-based porous organic polymer (TPOP–SO₃H) with a hierarchical structure and a desirable Brunauer–Emmett–Teller value of 1002 m²/g was synthesized this study. The TPOP–SO₃H material demonstrated a maximum adsorption capacity for methylene blue of 97.1 mg/g. Remarkably, an absorption efficiency of more than 90% of TPOP–SO₃H was observed even after five cycles. Therefore, such a hierarchical porous organic polymer can be highly recommended as one type of promising material for the treatment of organic dye-polluted wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47987.     

Cyclopentadiene‐functionalized polyketone as self‐cross‐linking thermo‐reversible thermoset with increased softening temperature

Self‐cross‐linkable thermo‐reversible thermosets were obtained by a two‐steps post‐functionalization of aliphatic alternating polyketones yielding two different cyclopentadiene functionalization degree of 9 and 22% (with the respect of initial 1,4‐dicarbonyl units). Thermo‐reversibility was verified by gelation experiments and differential scanning calorimetry (DSC) scans displayed a broad transition varying from 75–100°C till 160°C that can be related to retro‐Diels Alder de‐bonding of the dicyclopentadienyl moieties. The dynamic mechanical thermal (DMTA) analysis showed the complete thermo‐mechanical recovery of the material up to six thermal cycles with a softening temperature around 210°C, thereby ensuring a suitable application window for high‐temperature resistant thermosets. Independently of the exact mechanism at the molecular level and in addition to previous studies which used the same Diels‐Alder diene‐dienophile system, it must be noticed that all prepared materials retained their mechanical behavior during at least six consecutive thermal cycles, thus indicating the re‐workability of the system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42924.     

Amidohydroxylated polyester with biophotoactivity along with retarding alkali hydrolysis through in situ synthesis of Cu/Cu2O nanoparticles using diethanolamine

In this research, polyester fabric was modified through in situ synthesis of Cu/Cu₂O nanoparticles (NPs) in one single step processing using diethanolamine. This introduced amide and hydroxyl active groups on the polyester surface, adjusted pH, aminolyzed, and improved the surface activity of polyester. Copper sulfate was used as precursor, sodium hypophosphite as a reducing agent and polyvinylpyrrolidone as a stabilizer in a chemical reduction route at boil as a facile and cost‐effective approach. The central composite design was also utilized to optimize the processing conditions and study the effect of each variables on the weight gain, color change, and wettability of the treated fabrics. FESEM and mapping, EDX, XRD, and FTIR analysis confirmed effective assembling of Cu/Cu₂O NPs on the amidohydroxylated polyester surface. The optimum treated fabric showed excellent antibacterial properties on both Staphylococcus aureus and Escherichia coli. In addition, a very good photocatalytic activity towards degradation of methylene blue solution obtained after 24 h sunlight irradiation. Further, the hydrophilicity, mechanical properties and stability of the treated fabrics in concentrated sodium hydroxide improved through formation of amidohydroxyl active groups, amidoester cross‐linking and nanocross‐linking within polymeric chains through in situ synthesis of Cu/Cu₂O. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44856.     

Multi‐stimuli responsive shape memory polymers synthesized by using reaction‐induced phase separation

Thermo‐induced multishape memory polymers are a growing focus of smart materials because of its promising applications. Multishape memory effect is generally attained by using polymers with broad phase transition and multiphase polymers. The latter is of particular interest for copolymerization and polymer compositing. One requirement has to be fulfilled to achieve multishape memory effect, which is to have two reversible phase transitions. In this study, we report synthesis of polymer composite composed of strong segregated polymers by using reaction‐induced phase separation. We demonstrate the method by using polyurethane (PU) and poly(methacrylic acid) (PMAA). With adjusting the weight ratio, the polymer composites exhibit a phase spectrum from phase separation to miscible composite. The composite with PU/PMAA =3:1 demonstrated triple‐shape memory effect. Based on the results, we argued the effect of segregation on the shape memory effect for polymer composites. With the addition of PMAA, the polymer composite also exhibits pH/water‐induced shape memory effect. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43534.     

High temperature resistant silane/zirconium‐oxocluster hybrid copolymers containing “free” thiol/ene functionalities in the polymer matrix

Inorganic–organic hybrid copolymers are promising materials where the size of the inorganic/organic domains, the phase continuity and the interface between the domains play an important role in their behavior. Two types of hybrid copolymers composed of 3‐butynoate‐substituted zirconium‐oxoclusters covalently bonded to a (3‐mercaptopropyl)trimethoxysilane or a vinyltrimethoxysilane matrix are investigated in bulk. Their properties are directly correlated with the degree of condensation of the silanes and the alkyne‐3‐mercaptopropyl or alkyne‐vinyl interface. Both copolymers show storage moduli and glass‐transition temperatures (T_gG″) above 130 MPa and 230°C. However, the more impressive results are achieved with the (3‐mercaptopropyl)trimethoxysilane copolymer where a T_gG″ of about 300°C holds over six dynamical mechanical spectroscopy analyses. In addition to their excellent thermo‐mechanical proprieties, the copolymers show unreacted 3‐mercaptopropyl or vinyl groups which could be employed either in direct usage of the materials or for post‐functional modifications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Novel polyketones with pendant imidazolium groups as nanodispersants of hydrophobic antibiotics

In this work, we present a new method to nanodisperse the pH‐sensitive antibiotics oxolinic acid and flumequine by the use of a pH‐sensitive synthetic polyketone derivative with amphiphilic characteristics. The pH‐sensitive polymer bears imidazolium residues on pendant groups as weak acids, and its solvophobic properties can be tuned by changing the pH. While the antibiotics are soluble in water at pHs higher than 7.0 for flumequine and 8.4 for oxolinic acid, and the polymer is soluble in water at pHs lower than 5.5, nanoprecipitates presenting hydrodynamic radius of 35–100 nm and positive zeta potential containing both the polymer and any of the antibiotics are formed at pH 6.8 by mixing stock solutions whose pH has been adjusted to 5.4 for the polymer and higher than 10 for the antibiotics. The out‐of‐equilibrium process occurring upon mixing both solutions produces pH changing, molecular arrangement, and a controlled collapse of the system in the form of nano‐ and submicron particles. The driving forces for the arrangements are found among hydrophobic forces, long‐range electrostatic interactions, and short range aromatic–aromatic interactions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42363.     

Fabrication of photochromic hydrogels using an interpenetrating chitosan network

The synthesis of a novel interpenetrating chitosan network post‐modified with spiropyran (SP) derivatives has been used to develop photochromic hydrogels. We have synthesized succinyl chitosan polymers containing a considerable number of both amines and carboxylic groups. Their intra/inter molecular amide coupling reactions and postmodification with SP derivatives resulted in the photochromic hydrogels functionalized with chitosan‐based interpenetrating polymer network structures. In this hydrogel system, SPs undergo reversible photoresponsive structural switching between a ring‐closed colorless SP form and a ring‐opened purple merocyanine form under specific light‐irradiation conditions. Notably, the photo‐mediated wettabilities and color intensities of the hydrogels increase by the increment in the molecular weight of SP‐functionalized chitosans. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45120.     

Vinyl ether‐based polyacetal polyols with various main‐chain structures and polyurethane elastomers prepared therefrom: Synthesis,structure, and functional properties

Novel acid degradable polyacetal polyols and polyacetal polyurethanes able to controlled acid degradation were developed. Polyacetal polyols with various main‐chain structures were synthesized by polyaddition of various vinyl ethers with a hydroxyl group [4‐hydroxy butyl vinyl ether (CH₂?CH? O? CH₂CH₂CH₂CH₂? OH), 2‐hydroxy ethyl vinyl ether (CH₂?CH? O? CH₂CH₂? OH), diethylene glycol monovinyl ether (CH₂?CH? O? CH₂CH₂OCH₂CH₂? OH), and cyclohexanedimethanol monovinyl ether (CH₂?CH? O? CH₂? C₆H₁₀? CH₂? OH)] with p‐toluenesulfonic acid monohydrate (TSAM) as a catalyst in the presence of the corresponding diols [1,4‐butandiol (HO? CH₂CH₂CH₂CH₂? OH), ethylene glycol (HO? CH₂CH₂? OH), diethylene glycol (HO? CH₂CH₂OCH₂CH₂? OH), and 1,4‐cyclohexanedimethanol (HO? CH₂? C₆H₁₀? CH₂? OH)], respectively. Polyacetal polyurethanes were prepared by a two‐step polymerization, using the synthesized polyacetal polyols, 4,4′‐diphenylmethane diisocyanate (MDI), and 1,4‐butandiol (BD) as a chain extender. Depending on the main‐chain structures, these polyurethanes had different glass transition temperature (from ?44 to 19 °C) and properties such as hydrophobic or hydrophilic. Polyurethanes containing the hydrophilic main‐chain exhibited the thermoresponsiveness and had the certain volume phase transition temperature (VPTT). The polyacetal polyurethanes were flexible elastomers around room temperature (～25 °C) and thermally stable (T_d ≥ 310 °C) and additionally exhibited smooth degradation with a treatment of aqueous acid in THF at room temperature to give the corresponding raw material diols. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44088.     

Preparation and pH‐responsive performance of silane‐modified poly(methylacrylic acid)

The poly(methylacrylic acid) modified by silane [poly(methylacrylic acid‐co‐vinyl triethoxylsilane) (PMAA)] was prepared via free‐radical polymerization with different mass ratios of methylacrylic acid to vinyl triethoxylsilane (VTES). The swelling performance of the prepared PMAA in different solutions with various pH values, salt species (NaCl and CaCl₂), and concentrations was investigated in detail. The results indicated that the introduction of silane boosted the stability of the obtained PMAA in aqueous solutions in the presence of an increased quantity of VTES additive. Meanwhile, the different swelling ratios of PMAA in various pH solutions showed a high pH responsivity. In addition, we found that when the PMAA underwent a number of swelling–deswelling cycles, it demonstrated the good reversibility properties when the pH value of the swelling medium was changed from 9.0 to 1.4. Moreover, the swelling mechanism of PMAA in different solutions with different pH values was investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40403.     

Synthesis of water‐soluble thermosensitive polymers having phosphonium groups from methacryloyloxyethyl trialkyl phosphonium chlorides–N‐isopropylacrylamide copolymers and their functions

Water‐soluble thermosensitive polymers having phosphonium groups were synthesized by the copolymerization of N‐isopropylacrylamide (NIPAAm) with methacryloyloxyethyl trialkyl phosphonium chlorides (METRs) having varying alkyl lengths. The relative viscosities of the copolymer solutions increased with increasing content of phosphonium groups in the copolymers and decreased with increasing chain length of alkyl chains in the phosphonium groups. However, the copolymers of METR with octyl groups in phosphonium groups (METO) and NIPAAm became water insoluble with increasing contents of METO moieties in the copolymers. The transmittance at 660 nm of the copolymer solutions above the lower critical solution temperature (LCST) decreased gradually with increasing temperature and decreased with increasing chain length of alkyl chains in the phosphonium groups. The transmittance at 660 nm of the copolymer solutions above the LCST was greatly affected by the addition of neutral salts such as KCl. The copolymers of METR with ethyl groups in phosphonium groups and NIPAAm and those of METR with butyl groups in phosphonium groups and NIPAAm had high flocculating abilities against bacterial suspensions. The METO–NIPAAm copolymer was found to have a high antibacterial activity. The flocculating ability and the antibacterial activity of the copolymers were affected by not only the content of phosphonium groups but also the alkyl chain length in the phosphonium groups in the copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 386–393, 2003     

High temperature shape memory polyimide ionomer

In this work, a high temperature shape memory polymer based on polyimide (PI) ionomer is prepared by introducing ionic crosslinked interaction. The ionic crosslinked points are introduced to polymer networks through the reaction between polyamic acid and calcium hydroxide before thermal imidization. The crosslinked reaction, microtopography, mechanical, thermal, and shape memory properties of PI ionomers are systematically investigated. The results show the introduction of ionic crosslinked interaction could enhance the glass transition temperature, mechanical, and shape recovery performance of ODA‐ODPA, a PI. The prepared ionomers exhibit good high temperature shape memory properties around 270 °C. The shape fixation and shape recovery ratio are over 99% and 90%, respectively. This method provided a new sight of preparing high temperature shape memory polymer, which could be used in severe conditions, like aerospace industry field. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43630.     

Poly(vinyl alcohol) functionalization with aldehydes in organic solvents: Shining properties of poly(vinyl acetals)

Poly(vinyl alcohol) has been functionalized with aldehydes in tetrahydrofuran (THF) with a good control of the grafting. A wide library of poly(vinyl acetals) could be obtained in order to study some structure/property correlations. The influence of the aldehyde nature on the functionalization rates has been studied, in particular for optical properties by measurement of the shininess for further applications in the cosmetic field. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40677.     

Effect of interfacial area on heterogeneous free radical grafting of vinyl monomers in supercritical carbon dioxide: Grafting of acrylic acid on poly(vinylidenefluoride) nanoparticles

The role of the polymer interfacial area on free radical grafting of acrylic acid (AA) onto poly(vinylidenefluoride) (PVDF) was studied at 65°C using supercritical carbon dioxide (scCO₂) as a solvent and swelling agent, benzoylperoxide (BPO) as chemical initiator and PVDF nanoparticles as polymer matrix. Under adopted conditions PVDF particles do not melt neither dissolve in the reaction medium and FTIR analyses performed on carefully washed nanoparticles confirmed the achievement of high grafting levels. The mass fraction of grafted AA increased with the grafting time and the BPO concentration while it decreased when the density of the fluid phase was enhanced. Collected results suggest that the grafting level obtained by free radical grafting of vinyl monomers onto solid polymer in scCO₂ can be significantly enhanced by increasing the interfacial area of the matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41541.     

High‐performance antistatic ethylene–vinyl acetate copolymer/high‐density polyethylene composites with graphene nanoplatelets coated by polyaniline

Graphene nanoplatelets coated by polyaniline (GNP@PANI) and ethylene–vinyl acetate (EVA) copolymer–high‐density polyethylene (HDPE) were used for the first time to prepare high‐performance antistatic composites through an effective method that combined solution mixing and melt blending. GNP@PANI nanocomposites were fabricated by in situ polymerization to improve the dispersion of graphene nanoplatelets (GNPs) in the EVA–HDPE matrix and the compatibility between the GNPs and the EVA–HDPE matrix. The GNP@PANI nanocomposites and EVA were first prepared as a premix through solution mixing, and then, the premix and HDPE were prepared as highly antistatic composites through melt blending. The dispersion of the GNPs in the EVA–HDPE matrix and the compatibility between the GNPs and the EVA–HDPE matrix were confirmed by field emission scanning electron microscopy and transmission electron microscopy observations. The GNP@PANI–EVA–HDPE composites met the requirements for antistatic materials when the content of the GNP@PANI nanocomposites was 5 wt % with only about 1 wt % GNPs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45303.     

Synthesis of end‐functionalized poly(N‐isopropyl acrylamide) with zinc porphyrin and its photocatalytic activity under visible light

A series of well‐defined linear poly(N‐isopropyl acrylamide) with an asymmetrical zinc(II) porphyrin (ZnPor–PAM) end group was synthesized by atom transfer radical polymerization, wherein 5,10,15,20‐tetra(p‐bromopropanoyloxyethylphenyl) zinc porphyrin tripropionate was used as the initiator and CuBr/tris(2‐dimeoethyl)amine was used as the catalyst system. The structure of the ZnPor–PAM was characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. In addition, the polydispersity index (PDI) obtained by gel permeation chromatography indicated that the molecular weight distribution was narrow; thus, the polymerization was well controlled (1.05 < PDI < 1.21). Because of the incorporation of hydrophobic porphyrin, the lower critical solution temperature of ZnPor–PAM was lower than that of the N‐isopropyl acrylamide homopolymer. Most interestingly, the ZnPor–PAM possessed remarkable photocatalytic activity for the oxidative degradation of methylene blue in the presence of hydrogen peroxide under visible‐light radiation. Moreover, ZnPor–PAM could be reused through the uncomplicated procedure, which exploited the thermoresponsive properties of ZnPor–PAM without any significant loss in activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40523.