Papers by Keyword: Amphiphilic Block Copolymer

Abstract: Lactide (LA) and PEG as raw materials, 2,2-Dimethylol Propionic Acid (DMPA) as initiator, hexamethylene diisocyanate (HDI) as coupling agent, amphiphilic block copolymer PLA-PEG with side carboxyl group was synthesized. A novel PLA-PEG-PTX pro-drug was prepared through the esterification reaction between the side carboxyl group on copolymer and hydroxyl group on paclitaxel. Its structure was characterized with ¹H-NMR and FT-IR. The pro-drug micelles were prepared by solvent evaporation method. The particle size of the micelles was determined by nanoparticle tracking analyzer, the micro structure of the micelles was determined by TEM, and the drug release properties were investigated by dialysis experiments. Results showed that the pro-drug micelles are spherical with core-corona structure and major particles size in 55-85nm. The PLA-PEG750-PTX (molar ratio of LA to DMPA as 40 to 1) pro-drug micelles released paclitaxel slowly and steadily without obvious burst release in buffer solution with pH=7.0, and its cumulative release rate reached to 36% in 10 hours. PLA-PEG750-PTX pro-drug micelles have a certain sustained-release effect, which is beneficial to improve the anti-tumor effect of paclitaxel.

Abstract: Novel chiral amphiphilic diblock copolymers bearing L-phenylalanine was synthesized using a “click” reaction of N3-L-phenylalanine and MPEO-b-PGPE. The structure and composition of copolymers were characterized by 1H-NMR and elemental analysis. Additionally, the self-assembly behavior of these chiral copolymers was investigated in sodium dihydrogen phosphate buffer (pH 4.5): the CMC of copolymer MPEO-b-PGTP determined by the measurement of surface tension was 2.1 mg/mL; the size and morphology of the micelles were studied using TEM; the specific optical rotation ([α]25D) of the micellar solutions was also measured; the result indicated that the copolymers can form chiral micelles in sodium dihydrogen phosphate buffer (pH =4.5).In recent years, the synthesis, structure and properties of optically active polymer have been paid attention by scientists owing to its potential applications in chiral separation, asymmetric adsorption, chiral synthesis[1]. The amphiphilic block polymers bearing amino acid possess not only the characteristics of the conventional amphiphilic block copolymer, but also good optically activity and biocompatibility. So it can be employed as nanoreactors for asymmetrical catalysis and materials for drug delivery. But there have been few reports published on the synthesis of chiral amphiphilic copolymers bearing amino acid. Sutthira Sutthasupa reported the synthesis of amino acid-based norbornene block copolymer with ester and carboxyl groups as hydrophobic and hydrophilic units[2]. O’Reilly group synthesized the amino acid-based chiral amphiphilic block copolymers using RAFT technique, and elucidated its self-assembly into spherical micelles with optically active hydrophobic core[3]. In the present work, chiral amphiphilic diblock copolymers bearing L-phenylalanine (L-Phe) pendants poly(ethylene oxide)-b-poly (glycidyl triazolyl-L-phenylalanine) (MPEO-b-PGTP) have been synthesized by the modification of poly(ethylene oxide)-b-poly (propargyl glycidyl ether) (MPEO-b-PGPE) with L-phenylalanine.

Abstract: A series of amphiphilic block copolymers mPEO-b-PCL with different PCL molecular weight were successfully prepared by combination of anionic ring-opening polymerization with coordination-insertion ring-opening polymerization. Firstly, the linear mPEO was prepared by anionic ring-opening copolymerization of EO with 2-(2-methoxyethoxy) ethoxide potassium as the small molecule initiators, then the mPEO as the macroinitiator was used to initiate the ring-opening polymerization of CL, in the absence of Sn(Oct)₂ as the catalyst, and amphiphilic block copolymers mPEO-b-PCL were obtained. By changing the ratio of monomer and macroinitiator, prepared a series of different molecular weight mPEO-b-PCL. The structure of intermediates and final products were characterized by ¹H NMR and GPC. The critical micelle concentration (cmc) of the final copolymer was measured. In addition, the sizes and morphologies of the obtained micelles at different PCL chains were studied with Laser nano-particle size analyzer and transmission electron microscopy (TEM).

Abstract: The behavior of amphiphilic block copolymers in solution has attracted considerable attention in recent years. In this paper, the self-assembly behaviors of the amphiphilic fluorinated ABC-type triblock copolymer (MeOPEO16-PSt220-PFHEA22) in different mixed solutions were studied. Also, the effect of ionic concentration on the self-assembly aggregates of the copolymer in toluene-ethanol-water was studied.

Abstract: Photografting of bifunctional photolinker on biocompatible amphiphilic copolymers, such as PCL-b-PEGs and PLGA-b-PEGs, has been developed as a practical and versatile strategy for the materials functionalisation. Depending on the copolymer nature (block length, % of crystallinity) and the experimental conditions we could selectively direct the grafting on the hydrophilic PEG segments. The resulting copolymers were further derivatized with molecules of interest (RGD-peptides, LDV-peptides, “home-made”peptidomimetics, mannose derivatives,…) by substitution of the O-succinimidyl ester of the photolinker. The derivatization rates were controlled by radiolabelling, colorimetric assay and XPS spectroscopy. The functionalized copolymers were used in the formulation of nanoparticles displaying the ligands on their outer-shell. This nanoparticulate system was successfully employed for the oral vectorisation of antigen and for the targeted delivery of an anticancer drug.

Abstract: A2BA2-type amphiphilic liquid crystalline block copolymers containing azobenzene were synthesized by atom transfer radical polymerization (ATRP). The macroinitiator prepared by the esterification reaction between poly(ethylene glycol) (PEG) and 2,2-dichloroacetyl chloride was used to initiate the ATRP of 6-[4-(4-ethoxyphenylazo)phenoxy]hexyl methacrylate (M6C). The resulting macroinitiator and block copolymers were characterized by 1H NMR, gel permeation chromatography (GPC). Polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) preliminarily revealed the liquid crystalline property of these block copolymers. These novel amphiphilic liquid crystalline block copolymers are promising in some areas, such as optical data storage, optical switch, and molecular devices.

Abstract: Photo- and temperature-responsive amphiphilic block copolymers, poly(ethylene glycol)-b-poly{(N-isopropylacrylamide-co-6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate), denoed as PEO-b-P(NIPAM-co-MAZO), were designed and synthesized by atom transfer radical polymerization (ATRP). The macroinitiator based on poly(ethylene glycol) (PEG, Mn = 2000 Da) was utilized to initiate the copolymerization of N-isopropylacrylamide (NIPAM) and 6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate (MAZO). The resultant copolymers, combining photo-responsive moieties with thermal-responsive moieties, possess photo- and temperature- dual-responsive property, among of which, PNIPAM shows lower critical solution temperature (LCST) and PMAZO exhibits reversible trans-cis isomerization under UV/vis irradiation. In selective solution they can form selective micro-tunnel with excellent controlled release, and can be used as drug carrier and controllable membrane.

Abstract: Atom transfer radical polymerization (ATRP) has been employed for the synthesis of a novel amphiphilic fluorinated triblock copolymer PEG-b-PS-b-PFHEM for anti-fouling coatings. The macroinitiator based on poly(ethylene oxide) monomethyl ether was used to prepare an amphiphilic diblock copolymer PEG-b-PSt-Br, which was then utilized to initiate the ATRP of fluorinated monomer perfluorohexylethyl acrylate (FHEA), resulting in an amphiphilic triblock copolymer. These copolymers were characterized by means of 1H NMR and GPC. The amphiphilic triblock copolymer surface composes of fluorinated and PEGylated blocks, and the fluorinated surface has critical surface energy, while the PEGylated surface is expected to have a relatively low interfacial energy when in contact with water. Microphase-separation of both blocks could take place and result in the reduction of protein adsorption and cell adhesion. The amphiphilic fluoropolymer has the potential application as excellent antifouling coatings and antifouling membranes.

Abstract: In this study, block copolymers of PS-b-PMSMA with various molecular weight were synthesized by atom transfer radical polymerization (ATRP). GPC analysis showed that the molecular weight distribution of the prepared PS-b-PMSMA could be controlled to be lower than 1.3 for the case of molecular weight less than 30,000. The chemical structures of the amphiphilic block copolymers of PS-b-PMSMA were well identified by FTIR. SEM showed that the spherical micelles and compound micelles were produced in hybrid films. The EDX analysis indicated that the nano-sized CdS particles have been successfully prepared in the PS-b-PMSMA composite films. The diameter of CdS particles calculated from Brus formula was about 4-5 nm. PL analysis revealed that the λmax of emission of the prepared composite materials had a red-shift as the CdS particle size increased.

Abstract: Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding was existed between the colloidal silica nanoparticles and PS-b-P2VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P2VP led to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. The TEM and AFM studies showed that the uniform pore morphology with pore size 10-15nm was prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.