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Functionalized polymers with carboxylic acid groups were synthesized and used to prepare nanoparticles and nanofibers containing oxazolidine by nanoprecipitation and electrospinning, which were used as pH sensor and oil/water separator, respectively.

Different types of chain extenders in the synthesis of polyurethanes affect its structural, mechanical, and rheological properties. Effects of chain extender length, functionality, and molar ratio of the reactants on different properties of polyurethane elastomers based on poly (oxytetramethylene)glycol as the soft segment and toluene diisocyanate as the hard segment were investigated. Polyurethane samples were synthesized using different chain extenders including glycerol as the trifunctional and 1,2-propanediol, 1,4-butanediol, and 1,6-hexanediol as the bi-functional hydroxyl-containing chemicals. Fourier-transform infrared spectroscopy, X-ray diffraction, rheomechanical analysis, dynamic mechanical thermal analysis, differential scanning calorimetry, and stress–strain analysis were used for characterization of the products. By phase separation of the hard and soft segments, two different glass transition temperatures were observed. Increasing phase separation and degree of hydrogen bonding between the chain extender and diisocynates in the hard segments were resulted in higher mechanical properties. With increasing the amount of hard segment, a higher polymer toughness is determined due to higher degree of hydrogen bonding.

The development of stimuli-responsive drug nanocarriers is an increasingly important area in nanomedicine because efficient delivery of toxic drugs to targeted tissues minimizes side effects. The specific objective of this study was to synthesize and characterize a novel pH-responsive drug carrier based on halloysite nanotubes for the controlled release of the anticancer drug doxorubicin. Poly(N,N-dimethylaminoethyl methacrylate) brushes were grafted from the surface of halloysite nanotubes using the combination of mussel-inspired polydopamine surface modification and activators regenerated by electron transfer in atom transfer radical polymerization. The chemical structure and morphology of the modified halloysite nanotubes were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis as well as scanning and transmission electron microscopies. Dynamic light scattering and zeta potential analysis were carried out to evaluate the pH-responsivity of the functionalized halloysite nanotubes. The results of the drug loading and release study of pristine and functionalized halloysite nanotubes showed that grafting of poly(N,N-dimethylaminoethyl methacrylate) brushes on the polydopamine-modified halloysite nanotubes surface leads to a drastic increase in doxorubicin loading capacity and a highly pH-sensitive release behaviour. Less than 10 % of the loaded doxorubicin was released from poly (N,N-dimethylaminoethyl methacrylate)-grafted halloysite nanotubes at pH 7.4 after 24 h; in contrast, at pH 5.5 there was a continuous release of doxorubicin totalling 13 % in the first 30 min, i.e. lower than for the pristine halloysite nanotubes (32 %), but reaching 48 % after 24 h. Poly (N,N-dimethylaminoethyl methacrylate)-grafted halloysite nanotubes can hence be considered as a potential candidate for delivering highly toxic drug molecules to the acidic target sites.

The mechanical behavior of an adhesive, in neat state and reinforced with up to 0.5 wt% of reduced graphene oxide (RGO) was investigated here. Tests were done at temperatures between the ambient temperature and the glass transition temperature ( Tg[Formula: see text] of the adhesive. Using a metal mold, cured plates of the neat and RGO reinforced epoxy adhesive were prepared. The adhesive powder and the bulk dumbbell-shaped specimens, obtained from cured adhesive plates, were subjected to differential scanning calorimetry (DSC) and tensile tests, respectively, to obtain the Tg as well as mechanical properties of the adhesives. The results indicated that adding RGO up to 0.5 wt% increased the glass transition temperature, the modulus of elasticity, and the strength of the adhesive. It was found that the presence of RGO reduced the adhesive’s strain at the break at the ambient temperature. However, at high temperatures, near the Tg, the ultimate strain of RGO-reinforced adhesives decreased slightly when compared to the ultimate strain of the neat specimens. This explains the reduction in toughness at ambient temperature obtained by adding RGO and the increase at high temperatures. Finally, the failure morphology of the neat and RGO-reinforced adhesive specimens was investigated using microscopic imaging of the specimens’ failure cross-sections, which supported and justified the experimental observations.

Thermal characteristics of epoxy-modified polyurethane and novolac resins composites were investigated by using graphene oxide (GO) functionalized with hyperbranched poly(amidoamine) (PAMAM) as the curing component (GOD). The dendritic hybrid curing agent of GOD was synthesized via a divergent method and used to cure epoxy-terminated polyurethane (EPU) and epoxidized novolac resin (ENR). After preparation of the first generation of PAMAM dendrimer by using amino-functionalized GO as the core, Fourier transform infrared spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to prove the successful preparation method of GOD. TGA also showed that thermal characteristics of the hybrid EPU and ENR composites were determined by the amount of GOD and portion of the resins in the composites matrix. The hybrid composites with higher amounts of GOD and ENR matrix showed higher thermal stability and char residue. As example, the ENR-based hybrid composites with 3 wt% of GOD showed char residue of 57.2% at 600 °C and Tmax of 401.2 °C. In addition, morphological and structural study of the graphitic and hybrid samples was investigated by XRD and electron microscopies.

Carbon nanotube (CNT) grafted with hyperbranched poly(amidoamine) (PAMAM) dendrimer (CNTD) were used as a multifunctional curing and composite agent of polyurethane (PU) terminated with epoxy units. Amino-functionalized CNT was used as the core for grafting the first generation of PAMAM dendrimer by sequential addition of methyl acrylate and ethylenediamine. Two different epoxy-terminated PUs (PUB and PU-PMDA) were prepared from the reaction of poly(ethylene glycol), excess amounts of hexamethylene diisocyanate, and different chain extenders (1,4-butanediol for PUB and pyromellitic dianhydride (PMDA) for PU-PMDA), and subsequent end group transformation of the isocyanate groups to epoxy functionalities using glycidol. Fourier transform infrared spectra and thermogravimetric analysis (TGA) results showed that CNTD was successfully prepared. TGA thermograms revealed that thermal decomposition of composites were carried out in two main steps related to the soft and hard segments. In addition, char content and thermal stability of the composites were increased with increasing the CNTD content. Most importantly, the PMDA chain extender resulted in high thermal stability of the epoxy-terminated PU composites. X-ray diffraction and scanning and transmission electron microscopies presented morphological and structural properties of nanotubes and hybrid composites.

The application of photochromic materials in the development of anticounterfeiting technologies has shown a significant growth in recent years because of their advantages in displaying dual-mode security as simultaneous photochromic coloration and fluorescence emission. Photochromic copolymers based on styrene and spiropyran (5, 10, and 20 wt% with respect to styrene) with carboxylic acid chain end groups were synthesized by solution polymerization. The chemical structure, thermal behavior, and optical characteristics of the copolymers were studied using proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and UV-vis spectroscopy. The copolymer solutions in toluene and DMF were electrospun to yield photochromic nanofibers. The electrospun nanofibers from the copolymer solutions in toluene showed a well-defined morphology, a smooth surface, and a narrow size distribution in their diameter. These nanofibers were applied on cellulosic papers and banknotes for the induction of dual-mode security with a fast and facile authentication strategy. The induced security marks are virtually invisible under visible light and become visible by photochromic coloration from colorless to purple after UV irradiation. They also displayed red fluorescence emission under UV irradiation. Both the photochromic coloration and fluorescence emission showed high intensities, the security marks were rapidly authenticated upon UV irradiation, and this process was fully reversible for several cycles of UV/visible light irradiation because of the higher photofatigue resistance of the spiropyran-containing copolymers. These advantages originated from the high surface area of the photochromic nanofibers leading to higher light absorption and subsequent intense optical responses as coloration and fluorescence emission. Finally, a fast and facile anticounterfeiting strategy based on electrospun security marking was developed for the induction of dual-mode security marks on cellulosic documents and banknotes.

Invisible high-security anticounterfeiting polymeric inks exhibiting both photochromism and fluorescence emission for security marking have attracted significant interest recently. In the current study, flexible and invisible high-security anticounterfeiting inks were developed via the chemical incorporation of spiropyran into copolymer latex nanoparticles based on methyl methacrylate and butyl acrylate by semi-continuous miniemulsion polymerization. The anticounterfeiting inks are based on latex nanoparticles with various polarities and glass transition temperatures (Tg) and have spherical morphology with narrow size distribution in the range of 50–80 nm. The inks can simultaneously display photochromism (colorless to purple) and fluorescence emission (highly intense and bright red emission) upon UV irradiation in a fast and facile manner using a minimum concentration of spiropyran (about 1 wt% with respect to the polymer content). The morphology investigation and measurement of contact angles on the surface of the papers impregnated with stimuli-chromic latex samples display that the latex nanoparticles with different flexibilities have appropriate coating ability and stability on the surface of the cellulosic substrates due to the formation of hydrogen bonding. The investigation of the photochromic properties and fluorescence emission of the samples shows that the latex particles with higher polarity of the polymer chains have significant photochromic intensity and fluorescence emission as well as high photofatigue resistance, photoswitchability, and reversibility without displaying negative photochromism. Fast responsivity upon UV irradiation was observed for the sample with a Tg of about 33 °C and medium polarity, which indicated that the kinetics of the SP ↔ MC isomerization was a function of the polarity and flexibility of the polymer chains. The invisible high-security ink prepared using the photochromic and fluorescent latex nanoparticles with the highest optical properties was loaded on a stamp with different marks and used for print-marking different security documents, such as a certificate, money, and passport. The printed marks and finger-print on the security documents displayed photochromism and red fluorescence upon UV irradiation (365 nm). Spraying the latex nanoparticles on cellulosic papers induced high-resolution rewritable photopatterns on the cellulose substrate after UV illumination under different masks. Thus, the strategy developed to prepare high-security anticounterfeiting inks is an efficient, facile, and fast method for authentication applications.

Chemical incorporation of epoxy-modified graphitic layers in epoxy/novolac phenolic resin matrices was carried out through co-curing of epoxy and novolac resins using triphenylphosphine as catalyst. First, (3-glycidyloxypropyl) trimethoxysilane (GPTMS) was grafted on graphene oxide (GO) surface to obtain epoxidized GO layers. Then epoxy resin and GPTMS-modified GO were incorporated into thermosetting reaction using novolac resin in the presence of triphenylphosphine. Covalent attachment of GPTMS-modified GO to the resin matrices resulted in a hybrid composite with high thermal characteristics. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction, and Raman spectroscopy were used for approving modification of GO with GPTMS. The images resulted from scanning and transmission electron microscopies exhibited GO layers with lots of creases turning to smooth layers with a few thin ripples after modification with GPTMS. TGA results showed that thermal characteristics of resins were improved by the addition of GPTMS-modified GO. Char residue of the hybrid composites containing 0.5 and 1 wt% of GPTMS-modified GO reached 28.1 and 34.3%, respectively. Also, their maximum thermal degradation temperature was also increased by the incorporation of GPTMS-modified GO.

The simultaneous use of advantages of polysulfide polymers and epoxy resins encourages production of their blends. However, trying to introduce epoxy groups into polysulfide chains is a most interesting method to synthesis of a polymer with features of epoxy resins and polysulfide polymers. These resins can be cured by amine curing agents because of presence of epoxy groups. Herein, epoxidized polysulfide polymer/graphene nanocomposites were prepared via curing of epoxidized resin and epoxidized graphene nanosheets by diethylenetriamine. The modification of graphene oxide (GO) nanosheets with epichlorohydrin led to the formation of epoxidized GO nanosheets. Modification of GO was monitored by FT-IR and Raman spectroscopy, XRD and TGA analyses and SEM images. Dispersion of nanosheets in polymeric matrix was investigated by XRD and TEM. Thermal and thermophysical properties of nanocomposites were measured by TGA and DSC. Also, mechanical properties of nanocomposites were studied by Shore A hardness and tensile tests. Results showed that incorporation of nanosheets into polymeric matrix reduced the crystallinity of samples while Tg increased. Although XRD patterns showed no peak related to nanosheets, TEM proved that multilayer graphene nanosheets were dispersed in aggregated form. By increasing the amount of nanosheets up to 0.3 wt. %, hardness of nanocomposite samples increased due to the high modulus and aspect ratio of the nanosheets. By adding further nanosheets up to 1 wt. %, the hardness decreased associated with the formation of voids during the synthesis of nanocomposites in the high amounts of nanosheets.

Dendritic poly(amidoamine) (PAMAM)-grafted carbon nanotube (CNTD), as a multifunctional hybrid curing component of epoxy-based resins, was prepared using a divergent method. Amino-functionalized CNT was utilized as a core for grafting the first generation of PAMAM dendritic structure by sequential addition of methyl acrylate and ethylenediamine. Epoxy-terminated polyurethane (EPU) and epoxidized novolac resin (ENR) were prepared and used as the epoxy-based polymers of the hybrid composite products. Proton nuclear magnetic resonance spectroscopy was used to study the structure of EPU. Fourier transform infrared spectra were used to prove each of the modification steps during preparation of CNTD. The characteristic peaks of CNTD at 1532 cm−1 originating from combination of stretching and bending vibrations of C–N and N–H bands, respectively, and the peaks at 2930 and 2859 cm−1 assigned to the stretching vibrations of C-H band of methylene groups confirms this claim. In addition, different char residues of CNT and CNTD in thermogravimetric analysis (TGA) curves confirmed addition of the organic parts and successful preparation of CNTD. Structural properties of the hybrid composites were investigated by X-ray diffraction analysis. The hard and soft segment contents of 34.46 and 65.54 wt% were obtained from X-ray diffraction curves. Char contents of 89.6 and 85.6% at 700 °C for the CNT and CNTD shows that the PAMAM modifier content is about 4 wt%. TGA thermograms of the hybrid composites revealed that thermal characteristics of the hybrid composite composed of ENR matrix and high content of CNTD are higher than the other hybrid composites. The ENR-based hybrid composite with 4 wt% of CNTD showed the highest char residue of 55.2% and degradation peak point of 413.6 °C. Morphology of the neat and PAMAM-modified nanotubes were also studied by scanning electron microscopy and transmission electron microscopy.

Stimuli-responsive block copolymers were synthesized to detect copper ions with high limit based on a fluorescence quenching mechanism. For this purpose, poly(7-acryloyloxy 4-methylcoumarin-r-methyl methacrylate)-b-poly(dimethylaminoethyl methacrylate) in three different block ratios was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Successful synthesis of the block copolymers was confirmed by Fourier-transformed infrared and proton nuclear magnetic resonance spectroscopies. Self-assembly of the copolymers in aqueous media resulted in formation of micellar structures, as confirmed by transmission electron microscopy images and also estimated form the hydrophilic fraction of the block copolymers. Micellar size and dispersity were studied by dynamic light scattering in different conditions. In addition, dimerization kinetics of the coumarin molecules in the micellar assemblies were studied by ultraviolet–visible spectroscopy. The sample with higher molar ratio of CMA in the hydrophobic block and shorter length of PDMAEMA in the hydrophilic block showed faster dimerization reaction. The micellar assemblies formed from all the copolymers were used to sense potassium, calcium, and copper cations. All the self-assembled structures showed high sensitivity to detect copper cation, by quenching their fluorescence intensity. The copolymer sample with the highest ratio of PDMAEMA/CMA in the chain structure has the highest detection limit of 0.002 ppm for copper ion.

Stimuli-responsive block copolymers containing light-responsive coumarin moieties were synthesized using 7-(2-bromoisobutyryloxy)-4-methylcoumarin as an initiator of atom transfer radical polymerization. The resulted smart block copolymers, poly(7-acryloyloxy 4-methylcoumarin-r-methyl methacrylate)-b-poly(dimethylaminoethyl methacrylate) (P(CMA-r-MMA)-b-PDMAEMA) and poly(7-acryloyloxy 4-methylcoumarin)-b-poly(dimethylaminoethyl methacrylate) (PCMA-b-PDMAEMA), were used for pH detection by aggregation-induced fluorescence emission intensification mechanism. Calculation of hydrophilic fraction of the block copolymers by nuclear magnetic resonance spectroscopy proved micellar structure of self-assembled copolymer chains in aqueous media. Dimerization kinetics of the coumarin moieties in the micellar assemblies was investigated by ultraviolet-visible spectroscopy at different pH values. The resulted aqueous micellar dispersions of the block copolymers with different compositions were utilized for pH detection by using fluorescence spectroscopy. The copolymer containing MMA units as a spacer between coumarin moieties (P(CMA-r-MMA)-b-PDMAEMA) showed higher dimerization kinetics and applicability as a fluorescence chemosensor for detection of pH. By contraction of PDMAEMA blocks at higher pH values and consequent aggregation state of the coumarin moieties in the core, the change of fluorescence intensity was used for fluorescence sensation of pH.

Polysulfide polymers as an important class of polymers are used in different applications as sealants, adhesives, etc. They are usually synthesized by reaction of disodium polysulfides with dihalo compounds to yield liquid or solid polymers. Their most important advantages are excellent adhesion to different surfaces, creation of no defect in sealant under stress and pressure, resistance against to fuels and solvents, very low gas and steam permeability, and high resistance to ozone and UV. This article aims to review methods of synthesis, properties, and applications of polysulfide polymers. Also, polysulfide-based nanocomposites and blends are also briefly discussed.

Amine-modified graphene oxide (GO) nanosheets were used to co-cure epoxy-terminated polysulfide pre-polymer and fabrication of polysulfide polymer/graphene nanocomposites. GO was modified with ethylenediamine (EDA) to obtain amine-functionalized reduced GO-EDA nanosheets. Besides, epichlorohydrin reacted with disodium tetrasulfide (Na2S4) to prepare epoxide-terminated polysulfide prepolymer. Different amounts of GO-EDA nanosheets were used to fabricate EDA-cured nanocomposites. Different properties of nanocomposites were investigated consisting of structural, thermophysical, thermal and mechanical properties. Also, in-plane tensile properties of samples were evaluated by a peel approach where a film of nanocomposites was exerted onto the surface of aluminum and adhesion was evaluated via ASTM D3039. Results showed that glass transition temperature (Tg), melting temperature (Tm) and enthalpy of melting (ΔHm) of nanocomposites increased by increasing the amount of GO-EDA nanosheets up to 0.7 wt% whereas they were not changed significantly by more increase of nanosheets. Also, using 0.7 wt% GO-EDA led to the highest thermal stability, hardness and in-plane tensile properties of nanocomposites. In this field, variation of crystallinity of samples played the most important role in determining thermophysical and mechanical properties.

In this work, surface-initiated atom transfer radical polymerization (SI-ATRP) is used to synthesize smart copolymer-grafted Fe3O4 magnetic nanoparticles (MNPs). To do this, MNPs is modified with (3-aminopropyl)triethoxysilane (ATPES) and α-bromoisobutyryl bromide (BIBB) to yield MNPs@APTES and MNPs@BIBB nanoparticles. Then, ATRP-initiator-grafted nanoparticles are used in polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm) as stimuli-responsive monomers to obtain MNPs@PDMAEMA and MNPs@PNIPAAm respectively. Homopolymer-grafted MNPs are used as macroinitiators to produce smart copolymers-grafted MNPs named MNPs@P(DMAEMA-b-NIPAAm) and MNPs@P(NIPAAm-b-DMAEMA) those have different sequences of copolymer blocks. Successful synthesis of different structures is proved by means of different methods including FT-IR, TGA, VSM, XRD, FE-SEM, and TEM. All homopolymer- and copolymer-grafted MNPs are subjected to variation of pH and temperature to investigate stimuli-responsive behavior of hybrid structures. Although no surprising result is investigated for MNPs@PDMAEMA and MNPs@PNIPAAm nanoparticles, copolymer-grafted MNPs showed a dual pH- and temperature-sensitive behavior where copolymer sequence is important to define smart characteristic of hybrid MNPs.

Hear, three hybrid composites with high char yield and thermal stability were prepared form tetraethyl orthosilicate (TEOS)-modified epoxy resin (MER), (3-glycidyloxypropyl) trimethoxysilane (GPTES)-modified novolac resin (MNR), epoxidized novolac resin (ENR), and silica-grafted carbon nanotube (SFCNT) by a sol-gel method. The first class was prepared from MER and SFCNT. The second class was prepared from MER, MNR, and SFCNT. And the third class was prepared from MNR, ENR, and SFCNT. TEOS was used as covalent coupling agent in the sol-gel process. Results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed successful modification of epoxy and novolac resins, modification of silica nanoparticles with (3-Aminopropyl)triethoxysilane (APTES), and also functionalization of CNT with amine-modified silica nanoparticles. Results of thermogravimetric analysis confirmed that the hybrid composite containing 4 wt% of SFCNT, MNR, and ENR shows the highest char yield of 58.4%. The hybrid composite containing 4 wt% of SFCNT and MER shows the highest degradation temperature of 442.7 °C. Finally, the hybrid composite formed from 4 wt% of SFCNT, MER, and MNR shows degradation temperature of 439.0 °C and char yield of 47.2%. Microscopic images and X-ray diffraction results confirmed attachment of silica particles at the surface of CNT by chemical bonding.

Three different hybrid composites with high thermal stability and char residue were prepared from incorporation of tetraethyl orthosilicate (TEOS)-modified epoxy resin (MER), (3-glycidyloxypropyl) trimethoxysilane (GPTMS)-modified novolac resin (MNR), epoxidized novolac resin (ENR), and also furfuryl alcohol- and (3-aminopropyl) trimethoxysilane (APTMS)-modified graphene oxide (GFS) into silica/siloxane network by a sol–gel reaction. The first hybrid was composed from ENR, MNR, and GFS. The second type was prepared from MER, MNR, and GFS. The third type was prepared from MER, novolac resin, and GFS in the presence of triphenylphosphine (TPP). Results of FT-IR and XPS confirmed successful modification of epoxy and novolac resins and also functionalization of GO with furfuryl alcohol and APTMS. Results of TGA showed that GFS reaches to char residue of 37.3% at 600 °C. Char residues of 44.4, 44.0, and 34.2% were obtained for the first, second, and third hybrid composites without GFS loading. Addition of 1 wt% of GFS into the hybrid networks results in increase of char residues to 56.3, 50.0, and 34.7%, respectively. So, the first hybrid composite reaches to the highest char residue at 600 °C. These hybrid composites showed degradation temperature of 416.4, 434.5, and 424.8 °C.

In current work, nanoconfinement effect of graphene nanoplatelets on properties of matrix-grafted graphene/polysulfide polymer nanocomposites is investigated. To this end, graphene oxide (GO) is modified with (3-chloropropyl)triethoxysilane (CPTES) to be able to participate in interfacial polymerization of 1,2-dichloroethane (DCE), 1,2,3-trichloropropane (TCP) as crosslinker and disodium tetrasulfide (Na2S4). Successful modification of GO is proved by FT-IR and Raman spectroscopies, TGA, XRD, and TEM. Different amounts of modified GO (mGO) (0.0, 0.1, 0.3, 0.5, 0.7, and 1.0 wt%) are used to prepare nanocomposites. Nanoconfinement effect of graphene nanoplatelets on the crystallinity of synthesized nanocomposites is investigated by XRD and DSC. Results showed that crystallinity of nanocomposites increases by adding graphene up to 0.7 wt% while after that crystallinity decreases. Also, DSC results showed that glass transition temperature (Tg) and melting point (Tm) of nanocomposites depend strongly on the amount of used mGO and pass through a maximum by increasing graphene content. According to TGA results, all nanocomposites were more thermally stable than neat polymer and decomposed in two stages where an optimum amount of mGO exists to investigate the highest thermal stability.

Thermal stability of hybrid composites prepared from epoxy, novolac, and epoxidized-novolac resins and also modified graphene oxide (SFGO) was studied. SFGO was prepared by covering graphene oxide with silica nanoparticles and a bifunctional silane modifier. The first hybrid was prepared from SFGO and silane-modified epoxy resin. The second one was prepared from SFGO, and silane-modified epoxy and novolac resins. The third hybrid was formed from SFGO, silane-modified novolac, and epoxidized novolac resins. Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) results showed that modification of graphene oxide was carried out successfully. TGA results show that degradation temperature and char residue of resins were increased through their incorporation into hybrid network with SFGO. In addition, the most increase of char residue was observed for the hybrid composites formed from SFGO and modified novolac and epoxy resins.

Symmetric tri-block copolymer as P(DMAEMA-co-CuA)-b-PDMS-b-P(DMAEMA-co-CuA) was synthesized by atom transfer radical polymerization (ATRP) in which PDMS was used as bis-functionalized initiator. Moreover, PDMAEMA as multi-responsive hydrophilic segment was copolymerized with coumarin moieties as photocrosslinking agent. Variation of the ratio of hydrophilic/hydrophobic segments in block copolymers was resulted in different morphologies including snowman-like, hollow, spherical, and cubic structures where the morphology was affected by pH of media. The size of self-assembled tri-block copolymers was changed toward external stimuli including temperature, CO2 bubbling, and pH due to multi-responsivity of PDMAEMA block. The presence of photoactive coumarin molecules in hydrophilic PDMAEMA block was utilized for stabilizing the morphology in the self-assembled particles upon UV light irradiation (365 nm). Photocrosslinking of self-assembled particles by UV light-induced dimerization of coumarin molecules via [2π + 2π] cycloaddition reaction was investigated by spectroscopy and microscopy methods, and results indicated that morphology of the particles was stabilized after photocrosslinking. Also, the rate of coumarin dimerization was affected by its concentration, and size and morphology of the particles. According to the advantages of developed self-assembly system considering various UV-crosslinkable morphologies and multi-responsiveness, these structures have potential application in drug delivery systems for controlled release of doxorubicin (DOX).

Light-responsive polymers are of great interest today due to their various applications, especially in the field of drug delivery. In this work, poly(amidoamine) dendrimer with ethylenediamine core up to the fourth generation has been synthesized. Then, the terminal amine groups of the dendrimer have been conjugated to different amounts of 7-(carboxymethoxy)-4-methylcoumarin. 7-(Carboxymethoxy)-4-methylcoumarin has been synthesized by the reaction between 4-methylumbelliferone and ethyl bromoacetate. The synthesis of different structures has been confirmed using FTIR and 1H NMR spectroscopies. Also, the fluorescence properties of dendrimer-coumarin nanoparticles have been investigated by fluorescence microscopy. Synthesized hybrids have been exposed to self-assembly process and then crosslinked under UV light irradiation. Spherical morphology was observed for self-assembled specimens before and after crosslinking in nanometer dimensions by FE-SEM. The crosslinked samples had smaller particle sizes than the non-crosslinked samples, and the particle size was increased with increasing coumarin moieties. Moreover, dendrimer-coumarin samples were assembled in aqueous solution after crosslinking and morphologies were studied by FE-SEM images. The synthesized supramolecular structures before and after crosslinking were used as nanocarriers of DOX and release behavior was investigated at pH = 1 and 7.4 and under 254 nm-UV-light irradiation. Results showed that low pH value and irradiation of UV light resulted in more cumulative drug release.

Copper nanoparticles (CuNPs) are synthesized by chemical reduction of CuSO4·5H2O salt in presence of aniline as reducing agent. The effects of CuSO4·5H2O concentration, reaction temperature, molar ratio of [aniline]/[CuSO4·5H2O], reaction media and presence of surface capping agent of sodium dodecyl sulfate (SDS) on the morphology and size of CuNPs are investigated. The results of X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy exhibited that CuNPs tend to form cupric oxide (CuO) and cuprous oxide (Cu2O) nanoparticles in aqueous media, but choosing ethylene glycol as reaction media diminished the copper oxide formation with acting as surface capping agent. Field emission scanning electron microscopy (FE-SEM) images showed that prepared nanoparticles had morphology of almond-like and flaky-like in water and ethylene glycol whereas presence of SDS led to formation spherical particles. Also, increasing CuSO4·5H2O concentration in ethylene glycol increased the specific surface area (SSA) of CuNPs.

Herein, polyampholyte star copolymers have been prepared via a two-step reversible addition-fragmentation chain transfer (RAFT) polymerization combined with disstilation presipitation polymerization (DPP). We have used arm-first approch where poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) arms have been synthesized in three different molecular weights. Then, PDMAEMA arms have been used as macroRAFT agent in DPP of MAA to prepare crosslinked core by N,N'-methylenebisacrylamide (MBA). Nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) have been used to confirm the accuracy of the synthesized star polyampholytes. The effect of pH on the self-assembly behavior of PDMAEMA-star-PMAA star copolymers has been investigated by dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM). Also the cloud point (turbididity behavior) of the star polyampholytes has been investigated by UV–vis spectroscopy. Result indicated that, morphologies containing spherical, rod-shaped, and worm-like structures with different sizes have been obtained by chenging pH value. Also, doxorobicin (DOX) release behavior has been exmined for star polyampholytes at disparate pH values. Results showed that release amount was higher at pH = 1 than that at pH = 7 with high amount of DOX release.

Stimuli-responsive polymer nanoparticles were synthesized by surfactant-free dispersion polymerization of styrene and 2-(dimethylamino)ethyl methacrylate (DMAEMA) in three different contents of divinylbenzene intraparticle crosslinking agent. Incorporation of the hydrophilic DMAEMA comonomer during the polymerization yielded pH-responsive nanogels with a higher size than the polystyrene nanoparticles. Surface of the nanoparticles was decorated with 7-hydroxyl-4-methylcoumarin (HMC) via an esterification reaction to yield stimuli-responsive fluorescent nanogels. The monodispersed polymer nanoparticles with spherical morphology were turned into chain-like coupled structures because of interparticle cycloaddition reactions between the surface HMC moieties upon UV irradiation, as shown by scanning and transmission electron microscopies. Dimerization of the HMC-functionalized nanoparticles was investigated by ultraviolet–visible spectrophotometer and fluorescence spectroscopy. Size and its distribution for the nanoparticles before and after light irradiation were determined using dynamic light scattering. From a different view, decreasing the intraparticle crosslinking density and also purging the colloidal dispersions with CO2 were resulted in a higher mean particle size. Variation of particle size by purging CO2 and consequently at different pH values was resulted in different fluorescence characteristics. Therefore, these stimuli-responsive fluorescent nanoparticles were finally used as a pH indicator in the presence of CO2 gas or even at different pH values using fluorescence spectroscopy.

A new multi-component curing agent for epoxy resin with graphene oxide (GO) core and poly (amidoamine) (PAMAM) dendrimer-grafted silica nanoparticles was synthesized which is able to cause a considerable thermal stabilization of epoxy resins due to its dendritic amino-functionalization. Hyperbranched PAMAM-grafted silica nanoparticles (SD) were prepared and attached at the surface of GO to prepare the composite and curing agent (GSD). Then, epoxy resin was cured in the presence of different amounts of GSD and the final products were compared with ethylenediamine-cured epoxy resin (E) in their char contents. Successful functionalization of silica nanoparticles and attachment of SD at the surface of GO were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA). TGA results showed that total dendrimer content in SD and char residue of GSD are 14.4 wt % and 60.9%, respectively. Char residue and decomposition temperature are higher for composites. Covering of GO with SD was approved by scanning and transmission electron microscopies.

4th-generation poly(propylene imine) (PPI)-grafted nanocrystalline cellulose (NCC) is prepared via iterative Michael addition of acrylonitrile onto amine-functionalized NCC as initial core and homogeneous hydrogenation of nitrile groups to primary amines. Successful grafting of dendrimers onto NCCs is confirmed by TEM, FT-IR, XPS, TGA and elemental analyses. Also, peripheral primary amines of dendrimer-grafted NCCs are conjugated with folic acid (FA) to investigate bioconjugation effect on drug release behavior of nanostructures. FA-conjugated and nonconjugated nanostructures are loaded with DOX and exposed to environments with different pH values to examine release behavior. Also, drug release kinetics is studied by fitting of experimental data with release models. At different pH values, nonconjugated nanostructures show higher cumulative drug release than FA-conjugated systems while loading content was higher for conjugated systems. Drug release from nonconjugated nanostructures is modeled using Korsmeyer-Peppas model that describes release from polymeric matrix. However, in conjugated system, Higuchi model is the best one due to the better solubility of DOX in release media than cavities of grafted dendrimers.

Invisible high-security anticounterfeiting inks were developed by surface-modification of functionalized latex nanoparticles with spiropyran derivatives, which display both photochromism and fluorescence upon UV irradiation at the same time. The functionalized latex nanoparticles show different spherical, doughnut-like, and red blood cell-like morphologies depending on concentration and type of its functional groups. Microscopic investigation of the impregnated cellulosic papers with latex nanoparticles display that epoxy-functionalized spherical latex nanoparticles have considerable packing and stability on the surface of the cellulosic substrate by formation of hydrogen bonding. Epoxy-functionalized latex nanoparticles containing spiropyran were used for preparation of high-security photochromic/fluorescent anticounterfeiting inks for print-marking of different cellulosic security documents such as certificate, money, and passport with different marks. The printed marks and finger-prints on the cellulosic security documents display photochromism and red fluorescence emission upon UV irradiation with high intensity and brightness.

Dendritic-star supramolecular structure of poly(amidoamine)-g-[polystyrene-b-(2-(dimethylamino)ethyl methacrylate-co-11-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)undecyl acrylate)] (PAMAM-g-P(St-b-(DMAEMA-co-CuA))) was synthesized via grafting-from atom transfer radical polymerization (ATRP) by using PAMAM-initiator as smart drug carrier. This structure consisted of multi-responsive unites of hydrophilic PDMAEMA regarding to pH change, temperature, and CO2 gas and the coumarin molecule as photocrosslinking agent. Photocrosslinking agent is efficient for controlling DOX release after dimerization under UV light. The chemical structure of samples was confirmed by proton nuclear magnetic resonance (1H NMR) and their molecular weight was studied by gel permeation chromatography (GPC). The change of hydrophilic length of PDMAEMA and pH media resulted in various morphologies including hollow sphere, snowman- and dumbbell-like particles. The morphology of supramolecular assemblies was not changed after photocrosslinking, which confirmed the structure stabilization under UV light irradiation of 365 nm. Fluorescence microscopy was confirmed the presence of fluoresce segments in self-assembled supramolecular structures. Dynamic light scattering (DLS) indicated that the size of supramolecular assemblies was changed through the response to external stimuli such as pH, temperature, and CO2 gas. The DOX release behavior was investigated in different conditions such as pH, temperature, and after photocrosslinking under UV light of 365 nm.

Three well-tuned procedures were used for thermal improvement of epoxy resin (E). Accordingly, graphene xerogel (GX) was used as nanofiller in the matrix of E. Additionally, (3-isocyanatopropyl)triethoxysilane-modified E (IE) or tetraethyl orthosilicate (TEOS) oligomer-modified E (TE) was incorporated into a hybrid structure of graphene-containing silica/siloxane network. For this purpose, a bifunctional silane coupling agent of 1,1′-(hexane-1,6-diyl)bis(3-(3-(trimethoxysilyl)propyl)urea) (HDBTMSPU) was synthesized. GX was obtained by incorporation of HDBTMSPU-modified graphene oxide (FGO) into xerogel structure using HDBTMSPU and TEOS. Modified resins, FGO, HDBTMSPU, and TEOS were also used in preparation of hybrid products. Thermal stability and char residue of the composites were compared. GO modification was approved by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and thermogravimetric analysis results. Hybrid composite of IE, FGO, and silica/siloxane network shows higher thermal properties. Char residue is increased by 16.93 % by loading of only 1 wt% of FGO in this hybrid product.

Graphene oxide (GO) modified with furfuryl alcohol and (3-aminopropyl) triethoxysilane (GOFASi) was used in two separate ways for preparation of novolac resin nanohybrids. In the first procedure, graphene-containing silica aerogel (GA) was obtained by incorporation of GOFASi into silica aerogel network using tetraethyl orthosilicate (TEOS). Then, GA was used as an additive in novolac resin matrix. In the second procedure, the synthesis of a hybrid novolac resin was accomplished by network formation via the reaction of GOFASi with (3-glycidyloxypropyl)trimethoxysilane-modified novolac resin and TEOS. The thermal stability and the carbon yield of the hybrid resins obtained by the two procedures were compared. Fourier transforms infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis showed that both GO and the novolac resin were successfully modified. Aerogel formation was proved by Raman, X-ray diffraction, N2 adsorption and desorption isotherms, and by scanning and transmission electron microscopies.

Temperature- and carbon dioxide (CO2)-responsive block copolymers of dimethylaminoethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm) (PDMAEMA-b-PNIPAAm) with different block lengths were synthesized by atom transfer radical polymerization (ATRP). In addition, cellulose nanocrystals (CNCs) were grafted with PDMAEMA-b-PNIPAAm chains through surface initiated-ATRP. After studying self-assembly and responsivity of the free PDMAEMA-b-PNIPAAm to different stimuli, the free and CNC-grafted PDMAEMA-b-PNIPAAm chains were finally used as CO2-switched absorbents of nitrate ions from aqueous solutions. Temperature responsivity investigations showed different critical solution temperatures (CST) for the copolymers depending on the length of blocks. CO2-responsivity of the copolymers is accompanied by reduction of pH upon the purging CO2 and protonation of the tertiary amine groups of PDMAEMA block as CO2-responsive functionalities. Micellar and vesicular morphologies were estimated for the free copolymers with different ratios of hydrophilic/hydrophobic blocks. CO2-switched removal of nitrate ions was carried out at temperature below and above the CST of the copolymers (40 and 60 °C, respectively). The free copolymers with higher length of PDMAEMA block shows the highest absorption capacity of nitrate ions (490 mg/g) through the electrostatic interactions in the presence of CO2 at temperatures below the CST. N2-switched ion desorption, temperature responsivity, and filtration ability of the CNC-grafted copolymers provide the easy regeneration process.

Photodetection of originality and authentication of security documents such as money, passport, bank note, and national card have been a significant challenge in recent decade. Using of advanced optical systems could remarkably reduce copy and counterfeiting of such national and international documents. Novel ecofriendly multi-color photoluminescent inks were developed for information encryption on cellulosic papers and optical authentication of confidential/original documents by synthesis of water-based latex nanoparticles modified with photoluminescent coumarin (blue emission) and two photochromic spiropyran derivatives (red and orange emissions). Some of the latexes with higher fluorescence emission were formulated to water-based inks, and then loaded to stamps with different marks for printing of quick response code, barcode, finger print, and other marks on cellulosic documents. All of the printed marks display ultra-bright blue, red, and orange fluorescence emissions upon UV irradiation, which have potential applications in encryption, security marking and optical authentication of confidential cellulose substrates.

Hydrophobic/hydrophilic transition in multi-stimuli-responsive copolymers of N,N′-dimethylaminoethyl methacrylate and o-nitrobenzyl acrylate prepared by reversible addition-fragmentation chain transfer polymerization was studied. The smart transition was controlled by the block lengths, light irradiation, pH and temperature variation, and CO2 purging. The mechanism and kinetics of photocleavage reaction of the copolymers upon UV irradiation were investigated in various pH using UV–vis spectroscopy. The copolymers exhibited lower critical solution temperature (LCST) in a broad range (41 to about 100 °C) in water, which is readily tunable through UV irradiation and varying pH. The copolymer-coated glass surfaces were used in photolithography applications managed by altering LCST by the photocleavage reaction. Critical micelle concentration of the copolymers was determined by turbidity measurement and fluorescence spectroscopy using coumarin as the fluorescence probe. This copolymer was also used as an emulsifier to prepare stable oil-in-water emulsions and subsequent synthesis of colloidal polystyrene latex by emulsion polymerization.

In this study, self-assembly of amphiphilic thermo- and UV-sensitive block terpolymers, namely poly (methyl acrylate-b-[(7-(allyloxy)-2H-chromen-2-one)-co-(2-hydroxyethyl methacrylate(]-b-N-vinylpyrrolidone) P (MA-b-[AC-co-HEMA]-b-NVP) in water at different temperatures is studied. The synthesis of terpolymers, in three various block length for hydrophobic PMA block, is carried out by atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT)/macromolecular design by interchange of xanthate (MADIX) polymerization. Three different critical micelle temperatures (CMT) of terpolymers are calculated via UV-VIS-NIR absorptions at 600 nm. Results of self-assembly behavior of terpolymers under CMT showed spherical micelle aggregation whereas cubic-like particles with larger particle size were self-assembled at the temperatures above CMT because of second aggregation phenomena. Additionally, UV light irradiation is used to photo-crosslinking of particles owing to presence of photo-responsive coumarin derivative of AC in the middle block. The self-assembled structures are loaded with curcumin (Cur) before and after photo-crosslinking and Cur-release behavior is investigated at different temperatures of 37 and 25 °C. Drug-release behavior of samples illustrated that cumulative Cur-release above the CMT of terpolymers is higher than under CMT due to squeezing of PVP coronas and expelling of drug molecules to outside. Moreover, cumulative release of photo-crosslinked self-assembled structures was lower than before crosslinking. The cytotoxicity of terpolymers and Cur-loaded micelles was examined through culturing on the MG-63 cells which showed high cell viability after 48 h.

Dendrimers are a novel class of polymeric materials with branches ramified from a core. Their structure has a great influence on their physical and chemical properties. The unique properties of dendrimers including the similar size, the highest degree of branching, the solubility in water, and the presence of internal cavities make them attractive for pharmaceutical and biological applications. Recently, applications of dendrimers with perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) core in the fields of dye-sensitive solar cells (DSSC), sensors, and organic light-emitting diodes (OLED) have been considered. These dendrimers are usually prepared in two divergent and convergent methods. In divergent approach, dendrimers grow from the core of a multifunctional molecule. In the convergent method, dendrimer is made in a stepwise way from end groups to inside. When the dendrons are large enough, they are attached to the core of the multifunctional molecule. The use of PTCDI chromophore as the core in dendrimers enhances the photostability, thermal stability, and high fluorescent intensity of these supramolecular structures. PTCDI can be modified by dendrimers by using its two different positions consist of imide and bay positions. Both types of modifications induce different and individual properties on PTCDI.