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The dynamic covalent exchange reactions of side chains in polymer brushes on nanoparticles were successfully demonstrated, and the dispersibility of the nanoparticles after the exchange reactions was investigated in some solvents. A polymer brush with exchangeable alkoxyamine side chains was prepared by surface-initiated atom transfer radical polymerization on silica nanoparticles. Fluorinated and ionic polymers were grafted to the polymer brush via radical exchange reactions of alkoxyamine moieties. The chemical composition of the polymer brushes on nanoparticles before and after the exchange reactions was investigated by X-ray photoelectron spectroscopy (XPS). The XPS measurements indicated that the side chains of the polymer brushes were converted to the corresponding polymers. In addition, the grafted side chains could be detached from the surface of the nanoparticles through a further radical exchange process by treating with alkoxyamines. The XPS results indicate that the structure of the de-grafted polymer brush is nearly the same as the original, thus demonstrating the reversibility of the reactions. Furthermore, the dispersibility of the nanoparticles in solution could be changed by the reversible grafting reactions. A polymer brush with exchangeable alkoxyamine side chains was prepared by surface-initiated atom transfer radical polymerization on silica nanoparticles. Fluorinated and ionic polymers were grafted to the polymer brush and the grafted side chains could be detached from the surface of the nanoparticles via radical exchange reactions of alkoxyamine moieties. The chemical composition of the polymer brushes on nanoparticles before and after the exchange reactions was investigated by X-ray photoelectron spectroscopy. The dispersibility of the nanoparticles in solution could be changed by the reversible grafting reactions.

Polymer concentration-dependent aqueous lyotropic morphology transition of a double zwitterionic diblock copolymer composed of a poly(carboxybetaine methacrylate) (PCB) and poly(sulfobetaine methacrylate) (PSB) is unraveled employing small-angle X-ray scattering. Salt-free aqueous solutions of the well-defined diblock copolymer produce ordered periodic structure and the morphology transforms from hexagonally close-packed cylinder to lamellar with decreasing the polymer concentration. The morphology transition is induced by the preferential distribution of water molecules into the PCB domains below threshold polymer concentration because of the limited water capacity of the PSB network domains. The volume fraction modulation causes the instability of phase boundary curvature urging the morphology transition. The precise ordered nanostructure control of the highly biocompatible double zwitterionic block copolymers is valid for responsive biocompatible molecular design in biomaterials.

Hybrid hydrogels composed of hyaluronic acid (HA) and halloysite nanotubes (HNTs) were prepared via photocrosslinking of HA and HNTs functionalized with vinyl groups. These hybrid hydrogels showed enhanced mechanical properties without sacrificing good swelling capability, which is crucial for biomedical applications.

Light produced by synchrotron radiation (SR) is much brighter than that produced by conventional laboratory X-ray sources. The photon energy of SR X-ray ranges from soft and tender X-rays to hard X-rays. Moreover, X-rays become element sensitive with decreasing photon energy. By using a wide energy range and high-quality light of SR, different scattering and spectroscopic methods were applied to various soft matters. We present five of our recent studies performed using specific light properties of a synchrotron facility, which are as follows: (1) In situ USAXS study to understand the deformation behavior of colloidal crystals during uniaxial stretching; (2) structure characterization of semiconducting polymer thin films along the film thickness direction by grazing-incidence wide-angle X-ray scattering using tender X-rays; (3) X-ray absorption fine structure (XAFS) analysis of the formation mechanism of poly(3-hexylthiophene) (P3HT); (4) soft X-ray absorption and emission spectroscopic analysis of water structure in polyelectrolyte brushes; and (5) X-ray photon correlation spectroscopic analysis of the diffusion behavior of polystyrene-grafted nanoparticles dispersed in a polystyrene matrix.

Natural rubber (NR) films from various mixing ratios of large- (LRP) and small rubber particles (SRP) were prepared through latex and solution casting methods. Film-forming behaviours of the resulting films were investigated by monitoring their surface characteristics using atomic force microscopy (AFM). When the SRP portion was higher, the surface of the latex-cast films was found to be smoother as smaller particles protruded out of the surface less than larger ones did. AFM phase micrographs revealed a hexagonal shape of packed rubber particles (RPs) of the LRP film, while the RPs in the other samples were sphere-like. After aging under ambient conditions, the packed RPs were flattened while retaining their RP boundaries, creating a supporting framework within the rubber matrix. On the contrary, when the rubber film was cast from a toluene solution, the characteristic of RP boundaries disappeared and became aggregates of the membrane components on the film surface. The latex-cast films performed much better in mechanical strength than the solution-cast films did due to the destruction of the supporting framework arisen from the non-rubber components at the RP boundaries of the solution-cast film. An inhomogeneous density distribution produced by the non-rubber aggregates in the latex-cast films was observed in small angle X-ray scattering measurements.

This chapter covers the basic principles of reflectivity and examples of X-ray reflectivity (XR), neutron reflectivity (NR), and grazing incidence X-ray diffraction (GIXD). Reflectivity has been applied to surface and interface structure analysis, and the NR and XR are used complementary because the contrast between two given elements is different for X-rays and for neutrons. GIXD can be used as surface sensitive crystalline structure analysis.

Phosphorylated cellulose nanocrystal (P-CNC)/imogolite nanotube (natural aluminosilicate nanotube) hybrid thin films were fabricated by spin-assisted layer-by-layer assembly. Phosphorylation of CNC with diammonium hydrogen phosphate ((NH4)2HPO4) was carried out to introduce phosphate groups on the CNC surface for enhanced interaction with imogolite. Structure of the P-CNC/imogolite thin film was characterized by atomic force microscopy, scanning electron microscopy, X-ray diffraction (XRD), and grazing incidence wide-angle XRD. The film thickness increased linearly with the increment of the P-CNC/imogolite bilayer. Benefitting from the strong affinity between the phosphate group of the P-CNC and the Al-OH group of imogolite, the P-CNC/imogolite thin films were quite stable in water within a wide range of pH values, compared with the deterioration of the CNC/imogolite film under same soaking conditions.

Nature-inspired material design concepts and recent progress on anti-fouling polymer materials are reviewed, and our recent researches on anti-fouling studies with polymer brushes are summarized. Zwitterionic polyelectrolyte brush immobilized surfaces represent significant anti-fouling for bio-macromolecules, oil foulants, marine fouling organisms and pipeline foulants. The anti-fouling mechanism was considered on the basis of the wetting, lubrication, hydrated chain dimension and hydrogen-bonding structure of hydrated water in the polyelectrolyte brushes.

Repeated mechanical scission and recombination of dynamic covalent bonds incorporated in segmented polyurethane elastomers are demonstrated by utilizing a diarylbibenzofuranone-based mechanophore and by the design of the segmented polymer structures. The repeated mechanochemical reactions can accompany clear colouration and simultaneous fading.

A solvent free oxidative coupling reaction of 3-hexylthiophene (3HT) within a nanocavity is reported. It is found that 3HT can be encapsulated in nanocavities larger than 1 nm, which corresponds to the size of the molecule. In this case, the side reaction at the 4-position in 3HT is regulated.

Crystallization-induced structure fluctuations in the layer thickness direction and disordering of pre-crystallized structure in crystallized microdomain structure that consist of a strongly segregated crystalline-crystalline diblock copolymer, poly(ethylene glycol)- block -poly(perfluorooctyl ethyl acrylate) (PEG- b -PFA-C 8 ), were investigated. The structure formation process during isothermal crystallization was monitored by in-situ time-resolved simultaneous SAXS/WAXD measurements and thermal analysis. At early stage of isothermal crystallization, three dimensional growth of the PEG lamellar crystals within lamellar microphase-separated morphology induced the volume shrinkage of PEG phase, resulting in the reduction of PEG layer thickness, increase of PFA-C 8 layer thickness and disordering of pre-crystallized PFA-C 8 crystals. At late stage of isothermal crystallization, one dimensional growth, thickening of PEG lamellar crystals induced the increase of PEG layer thickness and reduction of PFA-C 8 layer thickness. The structure fluctuation in the crystallized microdomain structure depends on the crystal growth dimension.

The anti-fouling character of polymer brushes against marine organisms was investigated by performing settlement tests with barnacle cypris larvae and mussel larvae in their adhesion period, as well as a marine bacteria colonization test. The surface charge and hydration state in saline seawater appear to be important factors in the versatile anti-fouling performance of zwitterionic polyelectrolyte brushes.

Topologically ordered surfaces with a polymer brush-grafted layer were prepared by a combination of nano-imprinting (NI) and surface-initiated atom transfer radical polymerization (SI-ATRP). The molecular aggregation state and the wetting were evaluated by synchrotron radiation X-ray analyses and water droplet contact angle measurements, respectively. An ordered topography was fabricated onto a spin coated thin film of a polymethacrylate-based copolymer with polymerization initiating sites [P(MMA-co-BIEM)] by NI. Then poly{2-(perfluorooctyl)ethyl acrylate} (PFA-C8) chains were grafted onto the thin film by SI-ATRP. The surface geometry was maintained after PFA-C8 grafting when the thickness of the grafted polymer layer was sufficiently thin to a scale of the concave region. The modified P(MMA-co-BIEM) thin film surface was water repellent by a synergetic effect of the surface geometry and the low surface free energy of the grafted PFA-C8 layer.

Chain orientation of poly(glycolic acid) (PGA) induced by halloysite nanotubes (HNTs) in hybrid electrospun fibers was investigated. The well-aligned PGA/HNTs hybrid fibers were prepared by electrospinning. The influence of HNTs loading (0, 1, 5, 10 wt%) on the PGA molecular chain and crystallite orientation was characterized by polarized Fourier transform infrared spectroscopy (FT-IR) and wide angle X-ray diffraction (WAXD). The effect of HNTs loading to the thermal properties of PGA fibers was investigated by differential scanning calorimetry (DSC), and the reinforcement effect of HNTs for PGA fibers was evaluated by tensile test. High temperature FT-IR measurement revealed the presence of hydrogen bonding between PGA carbonyl groups and HNTs surface silanol groups, which induces the alignment of PGA crystallite along the HNTs long axis. At low HNTs loading, HNTs distributed and aligned along the fiber axis during electrospinning process, whereas at high HNTs loading, the aggregation and anisotropic alignment of HNTs in PGA fibers lead disordered PGA chain orientation. The PGA molecular chain and crystallite orientation achieved the highest orientation degree at 5 wt% HNT loading. Furthermore, DSC results indicated that HNTs act as nucleating agent for PGA fibers and further increase the crystallinity of PGA fibers. Besides, young's modulus of PGA fibers was enhanced significantly with the addition of HNTs, which indicates a high reinforcement effect of HNTs to PGA fibers.

Autonomously substitutable organosilane thin films based on diarylbibenzofuranone (DABBF) units were prepared, and the radical exchange reactions of the DABBF units at the surface resulted in chemi...

This chapter reviews the anti-(bio)fouling systems based on polymer brushes. Charged polymer brushes are well-hydrated in aqueous solutions to produce liquid-infused smooth interface. Because of the extremely low interfacial tension in the water-infusion soft interfaces and water, the hydrated charged polymer brushes exhibit outstanding anti-fouling capability in aqueous solutions. We present here anti-(bio)fouling properties of the charged polymer brushes to oils, asphaltenes, and marine fouling organisms including barnacle cypris larvae, mussel larvae, and marine bacteria.

The synergistic interactions between the α-amine and the carboxylic acid in an amino acid have recently been studied as bio-based zwitterions. Here, we report a new amphiphilic polymer containing glutamic acid grafted to the end of a dodecyl polymer side chain, which contains the α-amine and the γ-carboxylic acid of the glutamic acid moiety. The polymer self-assembled into a multilayered structure in the thin film, and the glutamic acid moieties in the polymer side chains were exposed to the polymer film/water interface. Annealing the sample enhanced the formation of a well-oriented lamellar structure in the films. Due to the presence of the glutamic acid moieties at the interface, the surface charge was controllable by pH in buffer solutions, resulting in zwitterionic character at neutral pH. It has been widely accepted that zwitterionic surfaces can exhibit non-fouling for proteins. Interestingly enough, the polymer film showed charge-selective protein adsorption since the synergistic interaction between the α-amine and the γ-carboxylic acid was weaker than conventional amino acid-based zwitterionic systems. This is due to the separated state of the functional groups by a three carbon spacer.

The orientation and crystallization of regioregular poly(3-dodecylthiophene) (P3DDT) in different diameter nanopores were investigated. P3DDT nanowires were prepared by a melt–wetting nonporous alumina template with P3DDT melts. The microstructure of the nanowires was analyzed by micro-Fourier transform infrared spectroscopy, grazing incidence wide angle X-ray diffraction, and differential scanning calorimetry. Although Form I modification prevails in all the nanowires, Form I crystals decrease and Form II crystals increase as the pore diameter decreases. The crystallites developed in the nanowires preferentially aligned with π–π stacking (b-axis) along the long axis of the wire and this orientation is marked as the wire diameter decreases. These results could provide guidance on designing polymeric nanomaterials for functional nanodevices in high performance organic photovoltaic cells, sensors, and electrodes.

The chain stiffness and local chain conformation of atactic poly(α-methylene-γ-butyrolactone) (PMBL), which is a side chain cyclic structural analog of poly(methyl methacrylate) (PMMA), with a weight-average molecular weight (Mw) ranging from 2.8 × 103 to 2.6 × 106 in N,N-dimethylformamide (DMF) and γ-butyrolactone (GBL) were characterized by size exclusion chromatography with a multi-angle light-scattering detector (SEC-MALS) and synchrotron radiation small-angle X-ray scattering (SAXS). Based on the Kratky-Porod worm-like chain model, the scattering functions and the Mw dependence of z-average root-mean-square radius of gyration z1/2 yielded the Kuhn segment lengths λ−1, the diameter of the PMBL chains d, and the excluded-volume strengths in DMF and GBL. The local conformation of atactic PMBL in DMF and GBL were slightly larger than those of atactic PMMA, due to the presence of the conformationally rigid lactone ring structure.

The adsorption behavior of a model compound for surface-active component of asphaltenes, N-(1-hexylheptyl)-N′-(12-carboxylicdodecyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe), and detachment behavior of asphaltene deposit films for high-density polymer brushes were investigated. Zwitterionic poly(3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (PMAPS) brushes and hydrophobic poly(n-hexyl methacrylate) (PHMA) brushes exhibit less C5Pe adsorption than poly(methyl methacrylate) (PMMA). The asphaltene deposit films on the PHMA brush detached in a model oil (toluene/n-heptane = 1/4 (v/v)), and the asphaltene films on the PMAPS brush detached in water. The antifouling character was explained by the interface free energy for the polymer-brush/asphaltenes (γSA) and polymer-brush/toluene (γSO).

The effect of α-substituent on the molecular motion and wetting behavior of poly{2-(perfluorobutyl)ethyl acrylate} [PFA-C4], poly{2-(perfluorobutyl)ethyl methacrylate} [PFMA-C4], poly{2-(perfluorobutyl)ethyl α-fluoroacrylate} [PFFA-C4], and poly{2-(perfluorobutyl)ethyl α-chloroacrylate} [PFClA-C4] films were characterized by dynamic contact angle measurement, lateral force microscopy (LFM), wide angle X-ray diffraction (WAXD), and X-ray photoelectron spectroscopy (XPS). WAXD of oriented PFClA-C4 fiber suggested the presence of rod-like chain due to the presence of bulky α-substituent. The glass transition temperature (Tg) of PFFA-C4 and PFClA-C4 were well above the room temperature. The water repellencies of PFFA-C4 and PFClA-C4 were as high as that of PFMA-C4 and their oil repellency of PFFA-C4 and PFClA-C4 was higher than the PFMA-C4. This result was originated from the low main chain mobility of PFFA-C4 and PFClA-C4 due to the presence of bulky α-substituents. The effect of molecular motion on water repellency was clarified by the results of temperature dependence studies of dynamic contact angle, LFM, and surface chemical composition measured by XPS.

Double ring-banded spherulites of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV with 12 wt% 3HV) blending with 30 wt% amorphous poly(vinyl acetate) (PVAc) were examined using polarized light optical microscopy (POM), scanning electron microscopy (SEM), atomic-force microscopy (AFM) and micro-beam X-ray diffraction. A ring-banded spherulite of PHBV/PVAc 70/30 blend was linearly scanned across the bands in 5 μm steps by means of micro-beam X-ray diffraction. Solvent-etching and fracturing were utilized for probing the interior lamellar textures of the blend samples. Detail interior lamellar orientations in bulk film of PHBV three-dimensional ring-banded spherulites were revealed. SEM and micro-beam X-ray diffraction results suggest that the PHBV lamellar orientation gradually change along the radial growth direction with right-handed rotation sense. The blending effect in band pattern (width and regularity) of PHBV/PVAc blend was discussed.

The effectiveness of energy-resolved (ER) X-ray photoelectron spectroscopy (XPS) with synchrotron radiation (SR) soft X-ray source for analysis of the outermost chemical composition of polymer materials is demonstrated. The surface molecular aggregation state of poly(ethylene glycol) (PEG)/poly(perfluorooctylethyl acrylate) (PFA-C8) was confirmed using ER-XPS. The XPS with SR soft X-ray source detect only the single bilayer structure of the PFA-C8 component, whereas the XPS with Mg Kα X-ray source detect both the PFA-C8 component at the outermost surface and PEG component at the interior.

Reversible hydrophilicity control of a radically exchangeable polymer brush with dynamic covalent linkages was successfully demonstrated. A polymer brush with alkoxyamine units was prepared via surface-initiated atom transfer radical polymerization, and reversible surface hydrophilicity control was achieved via dynamic covalent exchange reactions of alkoxyamines. Exchange reactions between alkoxyamine units in the side chains of the polymer brush and the terminal of poly(4-vinylpyridine) (P4VP) were carried out in order to prepare a side-chain functionalized polymer brush. Subsequent quaternization of P4VP chains with iodomethane was carried out to prepare a more hydrophilic surface. In addition, a de-grafting reaction of the quaternized P4VP side chains was performed to confirm reversibility of the alkoxyamine via radical exchange reactions on the surface. All the composition and wettability changes were investigated via X-ray photoelectron spectroscopy and contact angle measurements.

Reversible cross-linking reactions of alkoxyamine-appended polymers with low glass transition temperature ( T g ) were successfully carried out under bulk conditions. The low- T g polymers with alkoxyamine units in the side chains were synthesised by radical copolymerisation of 2-ethylhexyl acrylate and two kinds of alkoxyamine-containing acrylate monomers. By heating the low- T g polymers under bulk conditions at 100 °C, cross-linked polymers were formed by radical exchange reactions between alkoxyamine units, and a transition from a liquid-like flowable polymer state to a rubber-like polymer state was confirmed. A de-cross-linking reaction was also accomplished by radical exchange reactions between the cross-linked polymers and an added alkoxyamine-containing small molecule or stable nitroxyl radical, which resulted in transition to the flowable state again. The structural transition between low- T g linear polymers and cross-linked polymers were characterised by 1 H and 13 C NMR spectroscopy, Fourier transform infrared spectroscopy, rheology measurement, swelling experiment, and gel permeation chromatography measurement.

Liquid repellency of comb-shaped polyacrylates with perfluoroalkyl side-chains associates with the ordered structure of the side-chains at the surface. The molecular aggregation structure and surface properties of poly{2-[(perfluorohexylethyl)carbamate]ethyl}acrylate (PFAUr-C6) were studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), powder wide-angle X-ray diffraction (WAXD), grazing incidence wide-angle X-ray diffraction (GI-WAXD), temperature-controlled Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Poly[2-(perfluorohexyl)ethyl]acrylate (PFA-C6) was compared with PFAUr-C6 to verify the effect of carbamate linkage on the aggregation structure and surface properties. The perfluorohexyl groups in PFAUr-C6 produced a double-layered smectic structure, whereas the perfluorohexyl groups in PFA-C6 showed no ordered structure. The double-layered smectic structure in PFAUr-C6 was induced by the hydrogen bonding interaction in the carbamate linkers. PFAUr-C6 showed poor water repellency similar to PFA-C6 because of the rapid surface rearrangement. Although the perfluorohexyl groups produced smectic order structure at the film surface, the lack of positional order in the smectic layers and the low ordered structure content allowed the surface rearrangement.

Novel organic/inorganic hybrids composed of halloysite nanotubes (HNTs) and a cationic polymer were prepared through a simple mixing method. The hybrids provide more gaps for water permeation than ...

A polyacrylamide including tetra-alanine units, hydroxy groups, and hexyl groups was synthesized as a mimetic of barnacle underwater adhesive proteins. The synthesized barnacle mimetic polymer was ...

Halloysite nanotubes (HNTs) modified by a chemical vapor adsorption (CVA) process remarkably improve the thermal stability of polycarbonate nanocomposites. HNTs were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) and n-octadecyltrimethoxysilane (OTMS) using a CVA process. Both Fourier-transform infrared spectroscopy and thermogravimetric analysis showed that the modifiers were immobilized on the HNT surfaces. Polycarbonate (PC)/HNT nanocomposites were prepared with the modified HNTs by a combination of solution mixing, precipitating and compression molding. The dispersion states of modified HNTs in PC nanocomposites were observed by optical microscopy, scanning electron microscopy and transmission electron microscopy. The storage modulus (E′) and thermal stability of the PC nanocomposites were enhanced by the modified HNTs. OTMS-modified HNT/PC nanocomposites showed higher performance than AEAPS-modified HNT/PC nanocomposites due to the stronger affinity of the hydrophobic alkyl groups of OTMS for the polymer matrix. This study demonstrates a low amount of halloysite nanotubes modified by a CVA process remarkably improve the thermal stability of PC nanocomposites. The n-octadecyltrimethoxysilane modifier bearing a longer alkyl tails shows stronger affinity with the matrix than the N-(2-aminoethyl)-3-aminopropyltrimethoxysilane modifier bearing shorter alkyl tails with amino group.

This work demonstrates the anomalous crystal growth of isotactic polystyrene (iPS) in nanorod arrays with different rod sizes. At the bottom of the nanorods, the crystals in bulk film grow into nanorods along either the [110] or [100] direction parallel to the rod axis. On the top side of the nanorods, the polymer exhibits different orientations corresponding to weak or strong confinement. In the weaker confinement (bigger nanorods of 300 nm diameter), the crystals grow with the [100] direction along the nanorod, which is similar to the crystals developed in the radial of spherulite. In the stronger confinement (smaller nanorods of 65 nm diameter), the splaying of crystals in the rod is significantly suppressed, and the preferred growth direction of iPS crystals is kept in either the [110] or [100] direction. The precise control of polymer crystal orientation and crystallinity at a local scale opens important perspectives for the design of one-dimensional nanomaterials whose performance depends on the anisotropic crystal properties.

Zwitterionic polymer brushes draw increasing attention not only because of their superhydrophilic, self-cleaning capability but also due to their excellent antifouling capacity. We investigated the ion-specific modulation of the interfacial interaction potential via densely packed, uniform poly(sulfobetaine) brushes. The vertical Brownian motion of a cell-sized latex particle was monitored by microinterferometry, yielding the effective interfacial interaction potentials V(Δh) and the autocorrelation function of height fluctuation. The potential curvature V″(Δh) exhibited a monotonic increase according to the increase in monovalent salt concentrations, implying the sharpening of the potential confinement. An opposite tendency was observed in CaCl2 solutions, suggesting that the ion specific modulation cannot be explained by the classical Hofmeister series. When the particle fluctuation was monitored in the presence of free sulfobetaine molecules, the increase in [sulfobetaine] resulted in a distinct increa...

Based on efforts to develop synthetic materials with novel properties similar to the ingenious mussel adhesive, we present a structural study of gels with different cross-linking approaches, using a catechol-bearing polystyrene system. Prior studies have shown that catechol affords a dual cross-linking system based on Fe3+–catechol complexes and oxidative coupling. In this study, the structures of gels with different cross-linking ratios were investigated by field-emission scanning electron microscopy (FE-SEM), small angle X-ray scattering (SAXS), Raman spectroscopy, and dynamic viscoelastic measurements. These results revealed that Fe3+–catechol cross-linking leads to a more compact structure, which increased the gel rigidity. In addition, Fe3+–catechol cross-links could be removed from the hybrid cross-linking system by an acidifying process, yielding a catechol–catechol cross-linked gel with stable covalent bonds. A structure in which a continuous network of loosely folded poly(styrene-co-DOPMAm) chains is combined, with a cross-linking density varying from high (coordinative) to low (covalent), was achieved by balancing both oxidation and coordination. The work presented here will provide inspiration for those designing new classes of synthetic materials with advanced properties, biomimicking extensible byssal threads.

The development of macroscopic nanofiber orientation and microscopic crystallite and molecular chain orientation have been investigated during uniaxial stretching of electrospun poly(vinyl alcohol) (PVA) non-woven nanofiber mats. Scanning electron microscopy and stress-strain/small-angle X-ray scattering show that the macroscopic nanofiber orientation significantly increases during the initial stage of deformation, and approaches a plateau on the way of stretching. Detailed analyses of the stress-strain/wide-angle X-ray diffraction measurement and polarized Fourier transform infrared spectroscopy indicate that the microscopic crystallite and molecular chain orientation rapidly increase at the initial stage of stretching due to macroscopic nanofiber orientation. At higher deformation, the microscopic modes of orientation continuously develop as a result of the nanofiber stretching. The complicated deformation process of non-woven nanofiber mats is discussed in terms of macroscopic nanofiber orientation and the microscopic crystallite and molecular chain orientation.

We have demonstrated the growth of polymer brushes from a surface-textured thin urushiol film. Thermal imprinting was done on an initiator-immobilized thin urushiol film, and surface-initiated atom...

International audience; The direct surface modification of poly(vinylidene fluoride-co-trifluoroethylene) (VDF-co-TrFE) copolymerfilms via surface-initiated atom transfer radical polymerization (ATRP) is presented. The surface-initiatedATRP of tert-butyl acrylate (tBA) and styrene was carried out on poly(VDF-co-TrFE) films containing 75mol% VDF at 383 K. Such a reaction was monitored by 1H and 19F NMR, attenuated total reflectanceFourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and by watercontact angle measurements. First, the 19F NMR spectra of poly(VDF-co-TrFE)-g-poly(tBA) graftcopolymers revealed a reduction in the signal intensity at 123 ppm compared with that of the poly(VDFco-TrFE) copolymer, indicating that the polymerization of tBA occurred exclusively by fluorine abstractionfrom the TrFE units. ATR-FTIR spectra of the resulting poly(VDF-co-TrFE)-g-poly(tBA) and poly(VDF-co-TrFE)-g-polystyrene (PS) films evidenced the characteristic absorption frequencies assigned to carbonyl andaromatic C–H stretching. The atomic ratio on the surface of polymer-grafted poly(VDF-co-TrFE) filmobserved by XPS well agreed with theoretical value of poly(tBA) and PS hompolymers. These resultsindicated that poly(tBA) and PS were successfully grafted onto the poly(VDF-co-TrFE) film surfaces forminggrafting layers, the thickness of which was over 10 nm. The poly(VDF-co-TrFE)-g-poly(tBA) film wassubsequently treated with p-toluenesulfonic acid and sodium hydrogen carbonate to modify the graftedchains into poly(acrylic acid sodium salt). Surface-grafted polystyrene was also converted to poly(styrenesulfonic acid sodium salt) by treatment with sulfonic acid. Each reaction step was characterized by ATR-IRand XPS. The static water contact angle of poly(VDF-co-TrFE) copolymer was remarkably reduced from 91to 15 by hydrolysis of the tBA chains, sulfonation of the styrene chains and their neutralization. Ahydrophilic surface was successfully achieved on the poly(VDF-co-TrFE) film by direct surface-initiatedpolymerization fromthe outermost surface of the TrFE unitwithout any change in the bulk physical properties.

Imogolite is a naturally occurring aluminosilicate nanotube consisting of a single-walled with a composition of (OH)3Al2O3SiOH, with Al–OH and Si–OH groups distributed on the external and internal surfaces of the tube wall, respectively. The recent progress in surface modification of imogolite utilizing specific interaction between Al–OH and phosphonic acid is reported in this chapter, and the preparation procedures of novel imogolite-based polymer nanocomposites are introduced.

Programmed thermodynamic formation of star-like nanogels from designed diblock copolymers with thermally exchangeable dynamic covalent bonds in their side chains and structure analysis of the nanogels were performed. Linear diblock copolymers that consist of poly(methyl methacrylate) block and random copolymer block of methyl methacrylate (MMA) and methacrylic esters with alkoxyamine moiety were prepared by atom transfer radical polymerization (ATRP). By heating the diblock copolymers in anisole, a cross-linking reaction occurred as a result of the radical crossover reaction of alkoxyamine moieties to afford star-like nanogels. Kinetic studies have revealed that the cross-linking behavior reaches equilibrium at a given reaction time, with characteristic reaction behaviors for thermodynamic reactions being observed. The equilibrium structures of the star-like nanogels were controlled by the initial concentrations of diblock copolymers as well as their compositions and molecular weights. Furthermore, by heating the star-like nanogels with excess alkoxyamine, linear polymers were successfully regenerated. The molecular weights and sizes of the nanogels were evaluated by gel permeation chromatography-multiangle laser light scattering (GPC-MALLS) and small-angle X-ray scattering (SAXS) measurements, respectively, and the morphologies of the nanogels were directly observed by scanning force microscopy (SFM).

Dynamic covalent polymers incorporating thermally reversible alkoxyamine units in the main chain were synthesized, and their thermal structural reorganization behavior was systematically investigated. The model reaction using alkoxyamine derivatives clearly revealed that the exchange reaction between the derivatives occurred upon heating over 60 °C, and the degree of exchange strongly depended on the reaction temperature, time, and concentration. Polycondensation from alkoxyamine-based diol and adipoyl chloride at room temperature successfully afforded the corresponding poly(alkoxyamine ester) without any decomposition of the alkoxyamine units. Their molecular weight can be readily estimated by conventional gel permeation chromatography (GPC). In contrast, their thermal reorganization behavior was completely different from common polymers; for instance, the peak in the GPC profiles of the fractionated polymer with a narrow molecular weight distribution broadened to 1.6−2.0 upon heating. Furthermore, the m...

A facile synthetic strategy for well-defined multiblock copolymers utilizing ‘living’ free-radical polymerization macroinitiator has been presented. Polyurethane composed of alkoxyamine initiating units and poly(tetramethylene oxide) (PTMO) segments was prepared by polyaddition of tolylene 2,4-diisocyanate terminated PTMO with an alkoxyamine-based diol. Polymerization of styrene with the polyurethane macroinitiator was carried out under nitroxide-mediated free-radical polymerization (NMRP) condition. GPC, NMR, and IR data revealed that the polymerization was accurately controlled and well-defined polystyrene chains were inserted in the main chain of macroinitiator to give the poly(tetramethylene oxide)-b-polystyrene multiblock copolymers. The synthesized multiblock copolymers were characterized by tensile test, differential scanning calorimetry, and dynamic mechanical analysis. Mechanical properties of the multiblock copolymers can be tuned by the sufficient molecular weight control of PS chains. Soft segment of PTMO and hard segment of PS were apparently compatible due to the multiblock structure of low molecular weight segments and polar urethane groups.

The synthesis of a macrocycle with alkoxyamine-based dynamic covalent bonds and its dynamic polymerization behavior are described. The macrocyclic alkoxyamine was synthesized by condensation of an alkoxyamine-based diol with adipoyl chloride under high-dilution conditions. Spectroscopic measurements revealed that one of the obtained macrocyclic compounds was a [2 + 2] adduct. The [2 + 2] macrocyclic compound acted as a monomer for “ring-crossover” polymerization to afford the corresponding polymer with Mn = 2000−18 000 due to the intermolecular radical crossover reaction. The polymerization behavior strongly depended on concentration, time, and temperature. Furthermore, under high-dilution conditions, the obtained poly(alkoxyamine) depolymerized to the monomer or oligomers mainly by the intramolecular radical exchange process.