Search

Small-angle X-ray scattering (SAXS) was measured from the aqueous solutions of polyion complexes (PICs), prepared with isoelectrical mixing oppositely charged two block copolymers MAPTAC-b-PMPC and AMPS-b-PMPC. The ratio (R_p) of the polymerization degree of the cationic to the neutral chains was changed from 0.27 to 9.5. When R_p is 0.27, 4.7 and 9.5, PICs took a star-like spherical, a cylindrical and vesicle-like shape, respectively. We found how tethered PMPC chains are crowded on the shell, and this parameter was much smaller than those of PEG in spherical core-shell polymeric micelles.

Amphiphilic diblock copolymers (M₉₈E_n) composed of hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and hydrophobic poly(2-methoxyethyl acrylate) were synthesized via controlled radical polymerization. M₉₈E_n formed micelles in water, which can encapsulate hydrophobic guest molecules into the core. The micelles did not interact with proteins in an aqueous solution due to the PMPC shells.

Thermo-responsive liquid marbles can be prepared using poly(N-isopropylacrylamide) powder and Na₂SO₄ aqueous solution, which were transferred to the surface of bulk water containing Na₂SO₄ aqueous solution. They remained stable at room temperature. When the bulk aqueous solution was cooled, the liquid marbles disintegrated because powder wettability increased. Thus, the remote triggering of chemical reactions using liquid marbles can be achieved by cooling.

The influence of polymer formation in liquid crystals (LCs) was investigated using several analytical techniques. The monomers 4,4′-dimethacryloyloxy-biphenyl (4,4′-DMOB) and 3,3′-dimethacryloyloxy-biphenyl (3,3′-DMOB) were used. The results indicated that the orientation of the LC affects the rate constant of polymerization. Moreover, the structures of the monomers affected the orientation of the LC.

Side-chain typed POSS-based polynorbornenes connecting with a short spacer exhibiting optical transparency owing to prevention of POSS crystallization to provide amorphous character. In addition, the resulting amorphous polymers exhibited excellent thermal stability.

pH- and thermoresponsive polymer bearing pendant tertiary amino groups was grafted onto the surface of Resovist (PDMA@Rv). At pH 5.4, the grafted-polymer became hydrophilic, and the size of PDMA@Rv remained constant, irrespective of temperature. PDMA@Rv formed aggregates and showed lower critical solution temperature behavior above pH 7. PDMA@Rv contained a larger number of core particles of iron oxide than Resovist, which reduced the initial magnetic susceptibility due to the interaction of the core magnetic particles inside PDMA@Rv.

Random pH-responsive copolymers, P(A/AaU) have been prepared from a pH-responsive pendant fatty acid-containing monomer (AaU) and a pendant sulfonate-containing monomer (AMPS). In water, P(A/AaU) formed unimer micelles under acidic conditions. Under basic conditions, the P(A/AaU) polymer chains expand due to the electrostatic repulsions. Although pH-responsive sunscreen shows waterproof properties under neutral conditions, it disperses under weakly basic conditions such as soap water. pH-responsive diblock copolymers with a pendant fatty acid-containing block were prepared. This review also discusses pH-responsive gelling agents based on ABA triblock copolymers.

Hydrophilic alternating copolymers (P(11EO/MA)_m) of methoxy poly(ethylene glycol) allyl ether (11EO) and maleic anhydride (MA) were prepared via controlled radical polymerization. The MA units in P(11EO/MA)_m were hydrolyzed to prepare pendant carboxylic acid group-containing polymers (P(11EO/MH)_m). Furthermore, an amphiphilic diblock copolymer (P(11EO/MH)_m-PS_n) was prepared via block copolymerization of styrene using P(11EO/MH)_m as a macro-chain transfer agent. The association behavior of P(11EO/MH)_m-PS_n in water was also investigated.

Poly(sodium styrenesulfonate)-block-poly(ethylene glycol)-block-poly(sodium styrenesulfonate) (PSS–PEG–PSS) and poly(methacrylic acid) (PMA) homopolymer were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. When aqueous solutions of PSS–PEG–PSS and PMA were mixed below pH 5, water-soluble PSS–PEG–PSS/PMA complexes were formed due to hydrogen bonding interactions between the PEG block and the pendant carboxylic acids in PMA.

pH-responsive poly(6-(acrylamido)hexanoic acid)-grafted silica particles (PAaH-SiO₂) were prepared via reversible addition-fragmentation chain transfer (RAFT)-controlled radical polymerization using the chain transfer agent immobilized silica particles. Millimeter-sized ‘liquid marbles’ can be prepared using the pH-responsive PAaH-SiO₂ particles. The ‘liquid marble’ can be transferred intact onto the surface of neutral or acidic water pool, which exhibited long-term stability. When pH of the water pool was changed to alkaline, ‘liquid marble’ burst immediately on the surface of the water pool.

Random copolymers (P(M_100-m/T _m )) composed of 2-methacryloyloxyethyl phosphorylcholine, which suppresses protein fouling, and 3-(triethoxysilyl)propyl methacrylate, which can react covalently to the glass surface, were prepared via photoinitiated radical polymerization. Coating of the glass with P(M_100-m/T _m ) was confirmed by red fluorescence from Rhodamine 6G. The protein antifouling properties of the P(M_100-m/T _m ) coating on glass were confirmed using fluorescence-labeled proteins.

Amphiphilic incompletely condensed polyhedral oligomeric silsesquioxanes possessing various substituents and poly(ethylene glycol)s of different chain lengths have been developed. It has been elucidated that their self-association behaviors in water are dependent on the substituents and chain lengths of poly(ethylene glycol)s. Precise molecular design, excellent thermal stability, and good dispersibility have been realized at once.

Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-block-poly(cholesteryl 6-methacryloyloxyhexanoate) (PMPC₈₂-b-PChM_n) with different PChM block lengths was prepared via controlled/living radical polymerization. To prepare the aqueous solution, the diblock copolymer was dissolved in an organic solvent and then subject to dialyze against pure water. These diblock copolymers formed spherical and rod-like micelles in water depending on the composition of cholesteryl (Chol) group in the polymer. The morphology of the polymer aggregates could be controlled from spherical to rod-like micelles with increasing amount of Chol groups in the polymer.

Fullerenes (C₆₀ and C₇₀) and water-soluble poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) were mixed by physical means to prepare water-soluble fullerene/PMPC complexes. PMPC can solubilize large amounts of fullerenes in water. The complexes can generate singlet oxygen upon visible light irradiation.

Dual thermoresponsive diblock copolymers comprising poly(di(ethylene glycol) ethyl ether acrylate) (PeDEGA) and poly(N-isopropylacrylamide) (PNIPAM) blocks with different lower critical solution temperatures (LCST_A and LCST_B) were prepared via organotellurium-mediated living radical polymerization. The LCST_A of the PeDEGA was lower than the LCST_B of PNIPAM. At T < LCST_A, the diblock copolymers dissolve in a unimer state. When the LCST_A ≤ T < LCST_B, polymer micelles with a PeDEGA core and PNIPAM shells formed. Above the LCST_B, intermicellar aggregates formed owing to hydrophobic interactions between the PNIPAM shells.

A series of amphiphilic diblock copolymers (PVA_m-b-PVPi_n: m/n = 82/6, 72/26, and 70/74) with different block lengths of hydrophilic poly(vinyl alcohol) (PVA) and hydrophobic poly(vinyl pivalate) (PVPi) blocks were prepared. PVA_m-b-PVPi_n was synthesized from poly(vinyl acetate)-b-PVPi (PVAc_m-b-PVPi_n) diblock copolymer via selectively hydrolysis. In water, PVA_m-b-PVPi_n formed spherical polymer micelles with a PVPi core and a PVA shell. The hydrodynamic radius, light scattering intensity, and aggregation number of PVA_m-b-PVPi_n increased with increasing PVPi block length. In contrast, the critical micelle concentration was reduced because of stronger hydrophobic interactions.

Complex formation of pendant lysine residue-containing zwitterionic random copolymer with copper (II). To remove excess copper in the body, a copolymer (P(MPC/LysA)) comprising 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and l-lysinylacrylamide (LysA) was synthesized via controlled radical polymerization. The copolymer exhibited a zwitterionic structure under physiological conditions due to the pH-independent neutral charge of MPC. The LysA residues were found to form a complex with copper (II) ion (Cu²⁺) under neutral-basic conditions, with two pendant l-lysine residues forming a complex with one Cu²⁺ molecule. P(MPC/LysA) has potential for use in removing excess Cu²⁺ in the body by forming water-soluble aggregates with Cu²⁺ at physiological pH.

A pair of the oppositely charged diblock copolymer was used to prepare the polyion complex (PIC) micelle by mixing them in an aqueous medium using electrostatic, hydrophobic, and π–π interactions. The PIC micelles attained the maximum size and aggregation number when the charges of the cationic and anionic blocks were neutralized. The PIC micelle was stable against NaCl because the core was formed by electrostatic, hydrophobic, and π–π interactions. The micelle can encapsulate charge and hydrophobic guest molecules.

This study presents a facile method for preparation of water-soluble molecular complexes between carboxylic acid-functionalized multiwalled carbon nanotube and poly(2-methacryloyloxyethyl phosphorylcholine) (MWCNTs/PMPC) by hand grinding. MWCNTs could be solubilized in aqueous environment with higher suspended concentrations when increasing polymer concentration and pH of the solution. MWCNTs/PMPC adsorbed light and induced heat generation to reach the temperature required for photothermal therapy (PTT) when the complexes were irradiated by near-infrared (NIR) at a wavelength of 808 nm. The water-soluble MWCNT complex covered by biocompatible PMPC is a promising candidate for PTT application.

The generation of singlet oxygen (¹O₂) by sonicating a water-soluble complex of fullerene/poly(2-methacryloyloxyethyl phosphorylcholine) (C₆₀/PMPC) was investigated for sonodynamic therapy (SDT). ¹O₂ was generated from C₆₀/PMPC under ultrasonic irradiation, and the amount of ¹O₂ increased with increasing solubilized C₆₀ concentration and irradiation time. In cell viability tests, after 3 h of incubation, the cell viabilities were 10% and 84% in the presence of C₆₀/PMPC with and without sonication, respectively. This result suggests that C₆₀/PMPC shows a sonodynamic effect, which demonstrates its potential application in SDT.

Gold was vacuum deposited on one side of 6-μm-diameter silica-gel particles to prepare Janus particles (JPs). Thiol-terminated pH-responsive poly(sodium 6-acrylamidohexanoate) (pAaH-SH) was immobilized onto the gold surface of JPs. pH-responsive flocculation and dispersion behavior of pAaH-grafted JPs can be observed with optical and fluorescence microscopy measurements.

The pH-responsive behavior of a core-crosslinked multiarm star polymer with an ionic poly(acrylic acid) (PAA) block segment in the arm was greatly affected by the arm chain sequence. Two types of star polymers with opposite block sequences was shown to differ sharply in the balance of hydrogen bonding and ionic repulsion between arm polymers, resulting in the different pH-responsive aggregation behaviors. The fundamental understanding gained by the present study deepens the insight into the solution properties of branched polyelectrolytes, which would expand the possibility for various applications.

A melittin-targeting drug carrier was synthesized by the grafting of sodium alginate to an oligopeptide. The melittin-loading onto oligopeptide–alginate nanoparticles at 0.1:1 unit ratio was more than double that onto alginate nanoparticles, suggesting the specific interaction of melittin with the oligopeptide-side chain in the oligopeptide–alginate nanoparticles. More than 80% of Caco-2 cells did not survive under the dose of 2.5 μM melittin-loaded oligopeptide–alginate nanoparticles. The results confirm that the derivation of an oligopeptide-side chain in alginate offers a specific binding site for melittin and effectively works in cancer chemotherapy.

The friction properties of a dilute solution of block copolymer additives in a base lubricant oil confined between mica surfaces were investigated using the surface forces apparatus. Friction force, sliding film thickness, and contact geometry were evaluated in detail, and the results were compared to those of the solutions of a different block copolymer additive having similar molecular structure. The relationship between the chemical structure of additives, confined structures between surfaces, and friction mechanisms were discussed, which shed new light of the design of low-friction surfaces in oil-based lubrication.