Search results for "copolymer"

Double stimuli-responsive polysaccharide block copolymers as green macrosurfactants for near-infrared photodynamic therapy

2019

The NIR absorbing photosensitizer phthalocyanine zinc (PC(Zn)) was stabilized in aqueous media as water-dispersible nanoparticles with a reduction- and pH-responsive full polysaccharide block copolymer. A cellular uptake and also photo switchable intracellular activity of the cargo upon irradiation at wavelengths in the near infrared region were shown. The block copolymer was synthesized by applying a copper-free click strategy based on a thiol exchange reaction, creating an amphiphilic double-stimuli-responsive mixed disulfide. The dual-sensitive polysaccharide micelles represent a non-toxic and biodegradable green macrosurfactant for the delivery of phthalocyanine zinc. By encapsulation i…

Thermodynamically Controlled Morphological Disorder in a Microphase-Separated Cylindrical Block Copolymer

1996

Shape Changes of Statistical Copolymacromonomers:  From Wormlike Cylinders to Horseshoe- and Meanderlike Structures

2002

Microphase separation in ternary ABC block copolymers: Ordering control in molten diblock AB copolymers by attaching a short strongly interacting C b…

1997

Some specific features of the microphase separation in molten ternary ABC triblock copolymers (in particular, modifications of the molten AB diblock copolymers by attaching a short third block C strongly incompatible with both A and B blocks) are studied rigorously within the framework of the weak segragation approach. It is shown that via such a modification one can control both the stability as to the microphase separation transition (i.e., the corresponding spinodal temparatures) and the smoothness of such a transition. Two modes of such modifications for every composition are studied in detail:  (i) those resulting in the minimal spinodal temperatures and (ii) those that result in the s…

Morphology evolution in mesoporous titania block copolymer composite films with increasing Sol-Gel reaction time

2013

A morphology evolution of thin films of titania from spherical mesopores to worm-shaped mesopores was realized by simply varying the sol–gel reaction time from 46 min to 25 h in the quadruple system consisting of polystyrene–block-poly(ethylene oxide) (PS–b-PEO), 1,4-dioxane, concentrated HCl, and titanium tetraisopropoxide (TTIP). Imaging techniques including scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to investigate the local structure change of the as-prepared, calcined, and UV-degraded composite films. Grazing incidence small angle X-ray scattering (GISAXS) experiments prove that the structure change in local areas is representative of that over the…

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

2020

ortho-Metalated Dirhodium(II) Catalysts Immobilized on a Polymeric Cross-Linked Support by Copolymerization. Study of their Catalytic Activity in the…

2008

Chiral ortho-metalated dirhodium(II) compounds containing the phosphine P(p-CH2═CHC6H4)3 have been efficiently immobilized by radical copolymerization with styrene and 1,4-divinylbenzene. Their cat...

Topologically Controlled Interpolyelectrolyte Complexes

2008

The complexation of a cylindrical polyelectrolyte−brush−surfactant complex (PMMPSS−C12) and an oppositely, highly charged cylindrical polyelectrolyte−brush (PMMPEI−PEO) in dimethylformamide (DMF) l...

Bridging rigidity and flexibility : modulation of supramolecular hydrogels by metal complexation

2021

The combination of complementary, noncovalent interactions is a key principle for the design of multistimuli responsive hydrogels. In this work, an amphiphilic peptide, supramacromolecular hydrogelator which combines metal-ligand coordination induced gelation and thermoresponsive toughening is reported. Following a modular approach, the incorporation of the triphenylalanine sequence FFF into a structural (C3EG ) and a terpyridine-functionalized (C3Tpy ) C3 -symmetric monomer enables their statistical copolymerization into self-assembled, 1D nanorods in water, as investigated by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the presence of a terpyridine …

Synthesis of Linear and Star-Shaped Block Copolymers of Isobutylene and Methacrylates by Combination of Living Cationic and Anionic Polymerizations

1998

A new synthetic route for the preparation of polyisobutylene (PIB)-based linear and star-shaped block copolymers was developed by combining living carbocationic and anionic polymerizations. Living PIB chains were quantitatively endcapped with 1,1-diphenylethylene, leading to 1,1-diphenyl-1-methoxy (DPOMe) or 2,2-diphenylvinyl (DPV) termini, or both. Both the DPOMe- and DPV-terminated PIBs, and the mixtures of both endgroups were quantitatively metalated with K/Na alloy, Cs metal, or Li dispersion in THF at room temperature. The resulting stable macrocarbanion obtained by metalation with K/Na alloy was used to initiate living anionic polymerization of tert-butyl methacrylate (tBMA) yielding …