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Zwitterionic methacrylate polymers with either choline phosphate (CP) (poly(MCP)) or phosphorylcholine (PC) (poly(MPC)) side groups were analyzed to characterize the bound hydration water molecules as nonfreezing water (NFW), intermediate water (IW), or free water (FW). This characterization was carried out by differential scanning calorimetry (DSC) of polymer/water systems, and the enthalpy changes of cold crystallization and melting were determined. The electron pair orientation of CP is opposite to that of PC, and the former binds the alkyl terminal groups at the phosphate esters. The numbers of NFW and IW molecules per monomer unit of poly(MCP) with an isopropyl terminal group were estimated to be 10.7 and 11.3 mol/mol, respectively, which were slightly greater than those of the poly(MCP) bearing an ethyl terminal group. More NFW and IW molecules hydrated the phosphobetaine polyzwitterions, poly(MCP) and poly(MPC), compared with carboxybetaine and sulfobetaine polymers. Moreover, the hydration states of polyelectrolytes were compared with the zwitterionic polymers. Finally, we discuss the relationship between the amount of hydration water and bio-inert properties.

Time evolution of the microscopic wetting velocity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or water on a micrometer-scale line-patterned surface with a poly(3-sulfopropyl methacrylate) brush and a hydrophobic perfluoroalkyl monolayer was precisely measured by direct observation using optical microscopy and a selective dyeing method over a long period (178 days). When a liquid droplet was placed on the dyed line-patterned brush surface, the liquid penetrated and spread into the polymer brush layer, forming a precursor thin film that extended beyond the macroscopic contact line. The elongation proceeded in two stages by an adiabatic process followed by a diffusive process. The elongation distance X increased with time in proportion to t2.6 for water and t0.81 for EMI-TFSI during the adiabatic process. In a diffusive process, the advancing velocity of the precursor film was markedly reduced to be expressed as X ∝ t0.66 for water and X ∝ t0.21 for EMI-TFSI, indicating that the diffusive process was affected by the energy dissipation of the wetting system. The high viscosity and the strong molecular interaction of EMI-TFSI with the polymer brush gave a large entropy change during the wetting process to result in a slower spreading velocity.

Anionic polymerization of methacrylate-functionalized ionic monomers, 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTAC) and 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate...

The atom transfer radical polymerization (ATRPs) of para-substituted styrenes bearing nitro, cyano, acetoxy, acetoxymethyl, and methoxy groups were performed to elucidate the effects of these substituents in terms of the Hammett equation. 4-Cyanostyrene (4CS) polymerized rapidly in acrylonitrile at 80 °C and afforded polymers with a narrow molecular weight distribution, while the ATRP of 4-acetoxystyrene (4AS) proceeded very slowly and gave the corresponding polymer in a low yield. The apparent polymerization rate constants (kpapp) of 4CS and 4-acetoxymethyl styrene were consistent with the Hammett equation with ρ = 1.52; however, the rate constant for the polymerization of 4AS did not follow the Hammett relation. The polymerization rate of 4AS was increased by the addition of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP); however, the NMR and MALDI-TOF-MS spectra of the resulting polymer revealed that a chain transfer radical polymerization took place to give a polymer with relatively low molecular weight. On the other hand, 4-methoxystyrene was immediately polymerized in 2,2,2-trifluoroethanol (TFE) and pentafluorophenol (PFP) by a cationic mechanism because of the electron-donating methoxy group, whereas 4AS did not polymerize in TFE and PFP. The deviant and irregular polymerization behavior of 4AS has been discussed in comparison with the reactivities of various para-substituted styrenes bearing electron-withdrawing and electron-donating groups. The deviant and irregular polymerization behavior of 4-acetoxystyrene was found through the detailed study on the ATRP of various para-substituted styrenes bearing electron-withdrawing and electron-donating groups. The relationship between the rate constant for polymerization rate and the Hammett parameter was discussed.

Polyzwitterions have emerged as a new class of antifouling materials alternating poly(ethylene glycol). The exemplary biopassivation and lubrication behaviors are often attributed to the particular chemical structure of zwitterions, which involve a large dipole moment of the charged groups and a neutral net charge, while the hydration state and dynamics also associate with these characteristics. Polymer brushes composed of surface-tethered polyzwitterion chains produced by surface-initiated controlled radical polymerization have been developed as thin films which exhibit excellent antifouling and lubrication properties. In past decades, numerous studies have been devoted to examining the structure and dynamics of polyzwitterion brush chains in aqueous solutions. This feature article provides an overview of recent studies exploring the hydration state of polyzwitterion brushes with specular neutron reflectivity, highlights some newly published work on the nonuniform equilibrium structure, ion concentration dependence, ion specificity, and the effects of charge spacer length in the zwitterions, and discusses future perspective in this field.

The adhesion force of the tentacle of a live cypris on a glass surface covered with polymer brush was directly measured by scanning probe microscopy. Polymer brushes were prepared on the cover glass and silicon wafers by surface-initiated atom transfer radical polymerization of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MAPS) or 2-hydroxyethyl methacrylate (HEMA). A small amount of glue was placed at the edge of a tipless cantilever supported by the piezo motion control system of the scanning probe microscope and monitored by using an optical microscope. A live cypris swimming in seawater was held down on the slide glass by the cantilever for 30 min until the glue cured. The tentacles of the live cypris immobilized on the cantilever were forced to make contact with the surface-modified cover glass. The adhesion force was determined by the torsion of the cantilever when the tentacle was detached from the cover glass surface. The adhesion force between the cypris and the propylsilane-modified glass surface increased from 1.6 to 40 μN with the increase in age of the cypris larva from 3 to 21 days after metamorphosis from the nauplius larva. Poly(MAPS) and poly(HEMA) brush surfaces exhibited extremely low adhesion to the cypris larva during 21 days in seawater, indicating the effective antifouling property of hydrophilic polymer brushes. The adhesion force between the tentacle of a live cypris and polymer brushes on the sidewall of cover glass was directly measured by scanning probe microscopy in seawater. The cypris was immobilized on the cantilever with glue, and then forced to make contact with the modified surface. When the tentacle was detached by moving the cantilever away from the surface, the torsion of the cantilever caused the laser deflection on the photodiode corresponding to the adhesion force. Polymer brush surfaces exhibited extremely low adhesion to the cypris larva.

Holmium (Ho), one of the lanthanide elements, shows a high magnetic moment. Here we present a simple, yet highly potential approach for preparing polymer-based magnetic materials from a three-dimensional polymer network composed with poly(acrylic acid) and Ho showing trivalent nature. We have successfully prepared a magnetic polymer network that reacts directly to a magnet by three-dimensionally immobilizing Ho in the polymer matrix. The present method allowed a preparation of wide range of magnetic materials using polymeric scaffolds, e.g., polymer-grafted particles and cross-linked polymer gels. As a result of the high Ho content, these materials responded quickly to the magnet. The discovery of a method to prepare magnetic materials will provide flexibility in materials design and greatly expand the scope of application of magnetic materials.

The microscopic wetting behavior of a water film on the line-patterned surface of a polyelectrolyte brush was directly visualized using an optical microscope by dyeing procedures. Surface line patterns of 5 and 5 μm width or 10 and 5 μm width for the polyelectrolyte brush and hydrophobic monolayer, respectively, were prepared by a photolithography process, chemical vapor adsorption method, and surface-initiated polymerization. A droplet of water containing dye was placed on the line-patterned surface. In front of the contact line, a water film with a nanometer-scale thickness, referred to as a precursor film, elongated along the polymer brush line with time. The elongation velocity at the first stage increased as the brush line width increased. On the other hand, at the second stage after the macroscopic contact line stopped moving, the precursor film continued to elongate in proportion to the 0.6 power of time, independent of the brush thickness, line width, and droplet volume.

Direct surface modification of polymer fibers and films by surface-initiated polymerization has been investigated. The introduction of initiating sites on polymer materials and their successive polymerization produce surface-tethered polymer chains on the polymer surface. The surface-selective modification controls the surface properties, such as wetting, lubrication and anti-fouling, without sacrificing bulk performance. Among the various procedures for introduction of initiating groups and subsequent polymerization proposed to date, this focused review article highlights our studies on polymer brush grafting to electrospun polymer fibers and polymer films through surface-initiated polymerization. We review studies focusing on grafting polymer chains to five different types of solid polymers: poly(methyl methacrylate)-based copolymers, Br-containing polyolefins, poly(vinylidene fluoride-co-trifluoroethylene), poly(butylene terephthalate), and poly(ether-ether ketone). Direct surface modification of polymer fibers and films by surface-initiated polymerizations has been investigated. The introduction of initiating sites on the polymer materials and successive polymerization produce surface-tethered polymer chains on the polymer surface. The surface-selective modification controls the surface properties such as wetting, lubrication and anti-fouling without sacrificing the bulk performances. Researches on grafting polymer chains to five types of polymers, poly(methyl methacrylate)-based copolymer, Br-containing polyolefins, poly(butylene terephthalate), poly(vinylidene fluoride-co-trifluoroethylene) and poly(ether-ether ketone) are reviewed.

Polymer brushes having proton donor and acceptor type functional groups were prepared on silicon wafers by surface-initiated atom transfer radical polymerization of 2-hydroxyethyl methacrylate (HEMA), 4-hydroxystyrene (4HS), 2-vinylpyridine (2VP), and 4-vinylpyridine (4VP), respectively. Two silicon wafers, one prepared with a poly(HEMA) brush and one with a poly(4VP) brush, were jointed in a 1-cm 2 contact area using 5-μL of methanol under a pressure of 120 N at room temperature and successively air-dried to form hydrogen bonds at the brush interface, yielding a lap shear adhesion strength of 337 kPa. Furthermore, poly(4HS) and poly(4VP) brushes also adhered more firmly with 5-μL of methanol to yield a lap shear adhesion strength of 843 kPa due to the phenolic OH group with a larger dipole moment compared to aliphatic OH. In addition, the adhered specimens smoothly debonded in methanol within 20 min at 298 K. The two separated substrates adhered again with a small amount of methanol. Repeatable adhesion and debonding was successfully achieved by proton donor and acceptor type polymer brushes.

High-performance soft interfaces were designed by tethering various polyelectrolyte brushes with anionic, cationic, and zwitterionic functional groups on substrate surfaces using a surface-initiated controlled radical polymerization technique. Ion-containing polymer brushes afforded superhydrophilic surfaces inducing antifouling properties in water. Repeatable adhesion systems without organic solvents were achieved through oppositely charged polyelectrolyte brushes by controlling the electrostatic attractive interaction between the brushes. Environmentally friendly water lubrication systems were also demonstrated by the high-density ion-containing polymer brushes.

Surface grafting of polyelectrolytes on materials brings about various significant changes in surface properties such as wettability, adhesion, and friction, because of their excellent hydrophilicity and unique intermolecular interactions that depend on the ionic strength of the solution. This review paper describes the characterization of the swollen structure and electrostatic interaction of polyelectrolyte brushes in aqueous solution by use of optical tweezers and neutron reflectivity, in order to discuss the dissociation of ionic groups and charge distribution in the polyelectrolyte brush. In addition, the spreading and structure of water on the polyelectrolyte brush surface were characterized by high spatial resolution IR spectroscopy.

Surface-initiated atom transfer radical copolymerization of hexyl methacrylate (HMA) and 3-ethyl-3-oxetanylmethyl methacrylate (OxMA) was carried out on the surfaces of block- and ring-type steel pieces covered with silicon-incorporated diamond-like carbon (DLC-Si) in order to generate an oleophilic copolymer brush layer at the outermost surface. The sample was then immersed in a 1% BF3OEt2 solution to form cross-linkages between oxetane groups in the polymer brush chains. The thickness of the polymer brush layer was confirmed to be 50 nm through transmission electron microscope images of the focused ion beam (FIB)-fabricated cross section. The friction properties of the composite films were evaluated using block-on-ring tests under a load of 49 N (130 MPa), using a base oil at 353 K for 30 min. Although the brush layer was partially scratched from the substrate surface during the friction test, the polymer brush-immobilized DLC-Si exhibited a low friction coefficient of 0.02, while the friction coefficient of the non-modified steel substrate was 0.12. It is supposed that the oleophilic polymer brush was swollen in the oil to form a stable lubrication layer, thus preventing the direct contact of the DLC-Si substrate. The dependency of the tribological properties on normal load, sliding velocity, wear depth, and the silicon content of the DLC-Si substrate was also investigated.

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.

Choline phosphate (CP) is a phosphobetaine-type zwitterionic functional group, referred to as inverse phosphorylcholine (PC) due to the reverse orientation of a positively charged quaternary amine and anionic phosphate in contrast to PC lipids in nature. The A unique dipole paring between CP and PC groups has attracted much attention in the biointerface research field. Herein, to evaluate the molecular interaction between the CP and PC groups in water, force-distance curve measurements using scanning probe microscopy (SPM) with a PC-group-functionalized cantilever was carried out on the surface of polymer brushes bearing the CP groups. Three types of methacrylate monomers bearing CP with ethyl (Et), methoxyethyl (MOE), and isopropyl (iPr) phosphates were synthesized in 42-71% yields, and polymerized by surface-initiated atom transfer radical polymerization to form polymer brushes on silicon wafers. The surface free energy of CP-polymer brushes with Et, MOE, and iPr was estimated to be 64.0, 61.4, and 57.4 mN m

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.

A series of zwitterionic polyelectrolytes poly[3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate] (PMAPS) with a wide range of weight-average molecular weight (Mw) between 5.5 × 103 and 1.6 × 106 g mol–1 with narrow molecular weight distribution (Mw/Mn = 1.07–1.19) were thoroughly characterized in aqueous NaCl solutions for salt concentration (Cs) over a range from theta Cs (0.074 M) to 1.0 M by synchrotron radiation small-angle X-ray scattering (SAXS), light scattering, and viscometry at 25 °C. To determine the chain stiffness parameter (λ–1) and the excluded-volume strength (B) of PMAPS in an aqueous NaCl solution, SAXS profiles and the Mw dependences of the radius of gyration, the second virial coefficient, the interpenetration function, the hydrodynamic radius, and the intrinsic viscosity for PMAPS were analyzed on the basis of the (un)perturbed cylindrical wormlike chain model. The experimental λ–1 value for PMAPS chains in aqueous NaCl solutions barely decreased but was almost consta...

For practical applications of poly(l-lactic acid) (PLLA), PLLA crystallization with keeping transparency is preferable. As one method to keep transparency without inhibiting crystallization, we prepared SiO2 nanoparticles which were modified with poly (methyl methacrylate) (PMMA-g-SiO2). FT-IR and TG–DTA measurement indicated that PMMA was grafted on SiO2 surface successfully. TG–DTA and GPC measurement of free PMMA cleaved from PMMA-g-SiO2 determined graft density of PMMA as 0.039 chains/nm2. The effect of PMMA-g-SiO2 on PLLA crystallization was characterized by DSC measurement and POM observation. Although PMMA-g-SiO2 could not promote PLLA crystallization significantly like commercial crystal nuclear agents, it did not inhibit PLLA crystallization. By UV measurement and Haze meter, it was indicated that crystallized PLLA with PMMA-g-SiO2 generated 3.5–5.3 times higher transparency than crystallized PLLA with/without commercial nucleating agent. TEM observation indicated that the aggregation size of PMMA-g-SiO2 was 21.7 ± 13.9 nm which was smaller than visible wavelength. Transparency improvement likely resulted from size-reduced aggregation of PMMA-g-SiO2 in PLLA matrix. On the other hand, PMMA-g-SiO2 made size of generated spherulite smaller but increased its number in PLLA matrix, which inhibited transparency improvement.

The water lubrication behavior of a polyelectrolyte brush was investigated by using double-spacer-layer ultra-thin-film interferometry to determine the thickness of the aqueous lubrication layer present at the interface between the brush and a spherical glass lens. A hydrophilic poly{[2-(methacryloyloxy)ethyl]trimethylammonium chloride} brush was prepared on an optical glass disk coated with layers of semireflective chromium and silica. The thickness of the hydrodynamic lubrication layer was estimated interferometrically. On increasing the sliding velocity from 10(-5) to 10(-1) m·s(-1), the gap between the rotating disk and loading sphere glass lens showed a marked increase to 130 nm at 2×10(-2) m·s(-1), and the friction coefficient simultaneously decreased to 0.01-0.02, indicating that the polyelectrolyte brush promoted the formation of a fluid lubrication layer that separates the rubbing surfaces, preventing direct contact and providing a low friction coefficient.

Due to their light weight, low corrosion and good tribological properties, polymer films have been widely studied in dry condition as well as recently in aqueous environment. Though the presence of water can further reduce the friction, it promotes the wear rate of the polymer films. As a remedy to decrease the wear rate of polymer films under aqueous condition, in this study, we used PMMA brush which is chemically anchored to a substrate and compared its friction and wear properties with those of conventional PMMA spin-cast film. Ellipsometry, contact angle measurements and atomic force microscopy are used to study the surface properties, e.g., wear mechanisms and wear depths of PMMA films. Under different sliding speeds and applied loads, PMMA brush showed lower friction than PMMA spin-cast film in aqueous. Moreover, it was shown that the swelling of water molecules is a dominant factor in determining the wear durability of PMMA films in which PMMA brush showed better wear performance than PMMA spin-cast film.

Chain diffusion at the polyphenylene oxide/polystyrene (PPO/PS) interface of bilayer films were investigated using nanothermal analysis (nano-TA) and time-of-flight secondary ion mass spectrometry (TOF–SIMS). An ultralow-angle slicing technique by the surface and interfacial cutting analysis system (SAICAS) was used to expand the size of the interfacial region effectively. The glass-transition temperature (Tg) at the interface was directly evaluated by nano-TA. The gradient of Tg at the PPO/PS interface became broad after annealing. An increase in annealing time caused an increase in the Tg of the initial PS layer, indicating that the PPO diffused across the interface. Since PPO/PS is a compatible blend system, the local chemical compositions were evaluated by Fox equation. The methodology presented here is useful for interfacial analyses of various polymer composite systems and is beneficial because the isotope labeling is not necessary.

Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in the presence of organic chloride salts, imidazolium chlorides, using alkyl bromide initiator was carried out in 2,2,2-trifluoroethanol (TFE) at 333 K. The ATRP using a sufficient large amount of chloride salts proceeded in a controlled manner to produce polymers with narrow molecular weight distributions (Mw/Mn < 1.2). The model reaction using an alkyl bromide and the imidazolium chloride indicated that a halogen exchange reaction occurred during the ATRP in TFE to form a chloride-terminated propagating species from the alkyl bromide. ATRP of MMA in TFE using an alkyl chloride initiator and CuCl catalyst, however, gave low initiation efficiency and loss of control over the polymerization. The combination of the alkyl bromide initiator, CuBr, and a sufficient amount of organic chloride salts was very effective to improve the control of ATRP in protic solvents, especially in fluoroalcohols. A methacrylate monomer bearing imidazolium...

A series of poly[2-(methacryloyloxy)ethyltrimethylammonium chloride] (PMTAC) in aqueous NaCl solutions with a weight-average molecular weight (Mw) of between 6.0 × 103 and 1.5 × 105 were characterized by synchrotron radiation small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements at 298 K. The hydrodynamic radius (RH) of PMTAC initially decreased with increasing salt concentration (Cs) and then leveled off at Cs = 0.5–1.0 M. The values of z-average root-mean-square radius of gyration (⟨S2⟩z1/2) simply increased with a decrease in Cs for Mw > 2 × 104 g/mol. In contrast, the values of ⟨S2⟩z1/2 for Mw < 2 × 104 g/mol increased with an increase in Cs probably because of a change in local conformation of PMTAC chain. To study local chain conformation of PMTAC, scattering functions and Mw dependences of ⟨S2⟩z1/2 and RH for PMTAC were analyzed in terms of the helical wormlike chain (HW) model which is a simple continuous elastic wire model with bending and torsional energies. The cha...

The wetting behavior of superhydrophilic polyelectrolyte brushes was investigated. Reflection interference contrast microscopy demonstrated that the contact angles of water on the polyelectrolyte brushes were extremely low but remained finite in the range of

An acrylamide-type copolymer containing hydroxyl, amino, and ortho-nitrobenzyl protected catechol groups was synthesized as a functional mussel adhesive protein (MAP) mimetic. The resulting copolymer was stable even in the oxidative condition. Light irradiation to aqueous solution of the copolymer induced deprotection of a caged compound to give a native catechol group and triggered an oxidative cross-linking reaction to afford the adhesive gel. Two glass plates were adhered through light-activated gelation of the polymer solution in a humid air atmosphere. A novel type of light-activated adhesive with excellent stability and light controllable activation properties was successfully fabricated by modification of the MAP mimetic copolymer.

The surfaces of polyethylene and polypropylene sheets were modified by grafting with polymeric brushes formed from a phosphobetaine monomer. Pressed sheets of bromo-functionalized polyethylene or polypropylene macroinitiators (PE-MIs and PP-MIs, respectively) were used to initiate the atom-transfer radical polymerization of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) under mild conditions to form a superhydrophilic grafted surface layer. The grafted polyolefin sheets showed excellent wettability and oil-detachment behaviour in water. Even three years after surface grafting had been performed, the PMPC-g-PP sheet retained a water contact angle of less than 10°. Furthermore, the water contact angle of the PMPC-g-PP sheet remained as low as 12° after it had been annealed at 373 K for 60 min under reduced pressure. Dynamic friction tests performed on the PMPC-g-PE sheet by sliding it against a glass ball revealed a marked reduction in the friction coefficient in water at sliding velocities in the range of 10−5 to 10−1 m s−1, possibly as a result of lubrication by water.

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.

The effect of the Molecular weight dispersity (MWD) on the interfacial width between a hPS brush and unbound dPS matrix has been investigated by NR measurement. The intermixing between hPS brush with narrow MWD and dPS matrix hardly occurred even after thermal annealing at 398 K because of dry-brush regime. In contrast, the intermixing of hPS brush with broad MWD and free dPS proceeded to increase the interfacial width like a wet-brush condition, in spite of high grafting density.

Novel horizontal-type time-of-flight neutron reflectometer SOFIA (SOFt Interface Analyzer) was installed in BL 16 of Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex (J-PARC). The design and performance of SOFIA reflectometer was described based on the preliminary results of the neutron reflectivity (NR) measurements of deuterated polystyrene (d-PS) thin films, Langmuir–Blodgett film and at deuterium oxide/ polymer brush interfaces. Time-resolved in-situ NR measurement at 1-min intervals was also demonstrated to observe interfacial mixing of d-PS on the PS brush surface during annealing.

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.

Surface-initiated atom transfer radical polymerization (ATRP) of (2-methacryloyloxyethyl)trimethylammonium chloride (MTAC), 3-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatopropanesulfonate) (MAPS), and 2-methacryloyloxyethyl phosphorylcholine (MPC) was carried out in 2,2,2-trifluoroethanol (TFE) containing a small amount of 1-hexyl-3-methylimidazolium chloride at 60 °C to produce well-defined ionic polymer brushes and the corresponding free polymers with predictable number-average molecular weight (Mn, 1×104−3×105 g mol−1) and narrow molecular weight dispersity (Mw/Mn

In gelation chemistry, catechol groups are used as cross-linking points. Both oxidation and coordination effects of catechol were investigated for their unique features in chemistry by spectroscopic measurements. Polystyrene copolymers containing catechol groups were synthesized by free radical copolymerization of styrene and N-2-(3′,4′-ditriethylsilyloxyphenyl)ethyl methacrylamide, and the successive deprotection reaction was catalyzed by tetra-n-butylammonium fluoride. The copolymer containing catechol units afforded a dual cross-linking system based on completely different coordination and oxidation chemistries, and the competing cross-linking mechanisms are discussed. These findings are useful and important for paving the way for designing a novel bioinspired artificial adhesive surface coating and curing system.

The relationships between the molecular aggregation states and water repellency of the perfluoroalkyl (Rf) groups of poly{2-(perfluorooctyl)ethyl acrylate} (poly(FA-C8)) brush thin films with broad and narrow molecular weight dispersities (MWDs) were analyzed by grazing incidence wide-angle X-ray diffraction (GI-WAXD) and water contact angle measurements. MWD-controlled-poly(FA-C8) brush thin films were prepared by surface-initiated atom transfer radical polymerization on a flat silicon substrate in the absence and presence of an ionic liquid. In-plane diffraction profiles of poly(FA-C8) brush films with narrow MWD had peaks corresponding to the periodic lengths of bilayer lamellae at qxy = 2–6 nm–1. This indicated that the orientation of Rf groups were parallel to the surface of the silicon substrate. In contrast, the peak of the in-plane GI-WAXD for brush films with broad MWD brush was confirmed at qxy = 12.5 nm–1, indicating that the Rf groups were oriented perpendicular to the surface of the silicon s...

The dimensions and intermolecular interactions of surface-grafted and unbound, free polyampholytes, poly[3-(N-2-methacryloyloxyethyl-N,N-dimethyl) ammonatopropanesulfonate] (PMAPS) and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), were estimated in an aqueous NaCl solution over a wide range of salt concentrations (Cs). The free PMAPS and PMPC fractionated by a recycling preparative size-exclusion chromatography system were characterized in aqueous NaCl solutions for Cs over a range from 0 to 5.0 M by static light scattering and dynamic light scattering (DLS) measurements. The hydrodynamic radius (RH) and the concentration coefficient of the diffusion coefficient (kD) for PMPC were independent of Cs, whereas those for PMAPS were strongly dependent on Cs. Monodisperse silica nanoparticles immobilized with PMAPS (SiNP-PMAPS) and PMPC (SiNP-PMPC) by surface-initiated atom transfer radical polymerization were characterized in aqueous NaCl solutions for Cs over a range from 0 to 5.0 M by DLS and synchrotron radiation small-angle X-ray scattering (SAXS) measurements. The SAXS profiles from SiNP-PMAPS and SiNP-PMPC solutions were well described by the core-shell model, taking into account interacting self-avoiding chains and assuming a Schulz-distributed core with two fitting parameters. The chain dimension of surface-grafted poly[3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate)] brush on silica nanoparticles in aqueous NaCl solution was precisely estimated by dynamic light scattering and synchrotron radiation small-angle X-ray scattering measurements to reveal large dependency on salt concentration. On the other hand, we confirmed that the chain dimension of poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous solution was hardly affected by salt concentration.