Triblock Copolymer Nanoparticles Research Articles

Usefulness of percutaneous estradiol-loaded PLGA-PEG-PLGA nanoparticles for the treatment of osteoporosis

Compared with poly (dl-lactide-co-glycolide) (PLGA) nanoparticles, triblock copolymer (PLGA-PEG-PLGA) nanoparticles composed of PLGA and polyethylene glycol (PEG) may improve the skin permeability of drugs. In this study, the usefulness of estradiol-loaded (E2-loaded) PLGA-PEG-PLGA nanoparticles in the treatment of osteoporosis was investigated by comparison with E2-loaded PLGA nanoparticles. The cumulative E2 permeation of each nanoparticle through rat skin was quantified using a Franz cell. The results showed that PLGA-PEG-PLGA nanoparticles had significantly higher permeation than PLGA nanoparticles. Next, in vivo treatment experiments were conducted using an ovariectomized rat model of osteoporosis. Nanoparticles were administered once per week in combination with iontophoresis. At 6 weeks after the initiation of treatment, significant improvement in bone density was observed in the treated group compared with the untreated group. The improvement in bone density tended to be greater in the PLGA-PEG-PLGA nanoparticle group versus the PLGA nanoparticle group. This may be attributed to the higher hydrophilicity of the particle surface of PLGA-PEG-PLGA nanoparticles compared with PLGA nanoparticles and the improved skin permeability of the particles through the trans-adnexal pathway.

Ursolic acid loaded tri-block copolymer nanoparticles based on triphenylphosphine for mitochondria-targeted cancer therapy

A novel biodegradable amphiphilic triblock copolymer, polyphosphate, polyethylene glycol, and polylactic acid (PAEEP-PEG-PLLA), was synthesized by twice ring-opening polymerization and triphenylphosphine (TPP) was grafted onto the block copolymer to synthesize a carrier material TPP-PAEEP-PEG-PLLA, which was identified by 1H-nuclear magnetic resonance (1H-NMR) spectroscopy. The TPP-PAEEP-PEG-PLLA nanoparticles encapsulated with ursolic acid (UA) were prepared by the emulsion-solvent evaporation method and characterized by dynamic light scattering. The mitochondrial targeting ability of fluorescently labeled nanoparticles was evaluated by laser confocal microscopy. The average particle size and surface charge of the UA -loaded nanoparticle solution were 180.07 ± 1.67 nm and +15.57 ± 1.33 mV, respectively. The biocompatibility of nanoparticles was briefly evaluated by erythrocyte hemolysis assay. In vitro cell proliferation assay and scratch migration assay were performed to compare the difference in anti-tumor effect between UA and UA nanoparticles. The results showed that TPP-modified triblock copolymers had good mitochondrial targeting and improved the low bioavailability of UA, and UA nanoparticles exhibited more pronounced anti-tumor capabilities. In summary, the results suggested that our UA nanoparticles were a promising drug-targeted delivery system for the treatment of tumors.

ABC or ACB triblock copolymers? Changing the RAFT group position in diblock copolymer macro-RAFT agents leads to different PISA behaviors in RAFT dispersion polymerization

ACB and ABC triblock copolymer nanoparticles were prepared by reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization using diblock copolymer macromolecular RAFT (macro-RAFT) agents with different RAFT group positions.

Highly hydrophobic cellulose acetate mats modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymer and TiO2 nanoparticles by electrospinning

Cellulose acetate (CA) mats modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO or EPE) and sol–gel synthesised titanium oxide (TiO2) nanoparticles were successfully fabricated by using electrospinning technique. Under the same preparation conditions, higher spinnability was achieved for EPE triblock copolymers modified mats. All fabricated mats showed a micrometric multilayer structure, which enabled layer-by-layer peeling. The addition of TiO2 nanoparticles facilitated the peeling process. The diameter of the fibres was ~ 3 times lower after the incorporation of sol–gel synthesised TiO2 nanoparticles. TEM images confirmed that under electrospinning conditions the PPO block domains were able to microphase separated from the PEO block/CA phase. Additionally, the introduction of sol–gel synthesised TiO2 nanoparticles led to an inorganic network formation with nanoparticle size equal to ~ 8 nm in diameter. Moreover, the addition of TiO2 nanoparticles increased the hydrophobicity of the mats and their self-cleaning ability, being more effective for TiO2/CA than for TiO2-EPE/CA due to the partial absorption of water by EPE triblock copolymer. Young’s modulus of fabricated mats improved drastically with the addition of TiO2 nanoparticles, as well as their physical integrity in polar and nonpolar solvents. Fabricated mats with enhanced spinnability, which maintain CA mat features as well as the properties associated with sol–gel synthesised TiO2 nanoparticles, can find a wide range of applications.

Sensitization of glioblastoma cancer cells to radiotherapy and magnetic hyperthermia by targeted temozolomide-loaded magnetite tri-block copolymer nanoparticles as a nanotheranostic agent

AimsRecently, the development of new strategies in the treatment and diagnosis of cancer cells such as thermo-radiation-sensitizer and theranostic agents have received a great deal of attention. In this work, folic acid-conjugated temozolomide-loaded SPION@PEG-PBA-PEG nanoparticles (TMZ-MNP-FA NPs) were proposed for use as magnetic resonance imaging (MRI) contrast agents and to enhance the cytotoxic effects of hyperthermia and radiotherapy. Main methodsNanoparticles were synthesized by the Nano-precipitation method and their characteristics were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). To evaluate the thermo-radio-sensitization effects of NPs, C6 cells were treated with nanoparticles for 24 h and then exposed to 6-MV X-ray radiation. After radiotherapy, the cells were subjected to an alternating magnetic field (AMF) hyperthermia. The therapeutic potential was assessed using clonogenic assay, ROS generation measurement, flow cytometry assay, and qRT-PCR analysis. Also, the diagnostic properties of the nanoparticles were assessed by MRI. Key findingsMRI scanning indicated that nanoparticles accumulated in C6 cells could be tracked by T2-weighted MR imaging. Colony formation assay proved that TMZ-MNP-FA NPs enhanced the anti-proliferation effects of AMF by 1.94-fold compared to AMF alone (P < 0.0001). Moreover, these NPs improved the radiation effects with a dose enhancement factor of 1.65. All results showed that the combination of carrier-based chemotherapy with hyperthermia and radiotherapy caused a higher anticancer efficacy than single- or two-modality treatments. SignificanceThe nanoparticles advanced in this study can be proposed as the promising theranostic and thermo-radio-sensitizer platform for the diagnosis and tri-modal synergistic cancer therapy.

Folic acid-conjugated magnetic triblock copolymer nanoparticles for dual targeted delivery of 5-fluorouracil to colon cancer cells

BackgroundIn the current study, folic acid-conjugated PEG-PCL-PEG triblock copolymer were synthesized and loaded with 5-fluorouracil and magnetite nanoparticles (5-FU-SPION-PEG-PCL-PEG-FA) for targeted delivery of drug to HT29 human colon cancer cells and CT26 mouse colon cancer model. The nanoparticles were synthesized and characterized by nuclear magnetic resonance spectroscopy (NMR) and transmission electron microscopy (TEM). The cellular uptake of nanoparticles was assessed in vitro (on HUVEC and HT29) and in vivo (on CT26 colon tumor tissues). The cytotoxic effect of nanoparticles was assessed on human colon cell lines (HT29, Caco-2, HTC116, and SW480) and normal HUVEC cells. In addition, antitumor effects of nanoparticles were investigated based on tumor volume, survival time and protein expression of Bax and Bcl-2 on CT26 tumor-bearing BALB/c mice.ResultsCharacterization of nanoparticles showed 5-FU-SPION-PEG-PCL-PEG-FA (5-FU-NPs-FA) nanoparticles had spherical shape with hydrodynamic diameter of 85 nm. The drug-release profile exhibited sustained pH-responsive release with cumulative release reaching approximately 23% after 24 h. Cellular uptake studies revealed that HT29 cancer cells absorb higher amount of 5-FU-NPs-FA as compared to HUVEC normal cells (P < 0.05). In addition, 5-FU-NPs-FA was found to be more antitumor efficient in comparison to free 5-FU based on Bax/Bcl2 ratio, survival rate of tumoral mouse and inhibitory tumor volume (P < 0.05).ConclusionsThe results suggested that 5-FU-NPs-FA could be considered as promising sustained drug delivery platform for in vitro and in vivo conditions, which may provide selective treatment of tumor cancer cells.Graphical Abstarct

Radio-sensitivity enhancement in HT29 cells through magnetic hyperthermia in combination with targeted nano-carrier of 5-Flourouracil

Normal tissue complication and development of radioresistance in cancer cells are known as the main challenges of ionizing radiation treatment. In the current study, we intended to induce selective radiosensitization in HT29 cancer cells by developing folic acid modified magnetic triblock copolymer nanoparticles as carrier of 5-Flourouracil (5-FU) which was further used in combination with hyperthermia. The aforementioned nanoparticles were synthesized and characterized by differential scanning calorimetric analysis (DSC), UV–visible spectroscopy, dynamic light scattering (DLS), zeta sizer, and transmission electron microscopy (TEM). These nanoparticles were also assessed to determine drug loading capacity (DLC %) and drug release profile. The cytotoxicity of nanoparticles was evaluated on two different cell lines: HUVEC and HT29. Furthermore, radiosensitivity induction of the nanoparticles with and without exposure of alternative magnetic field was investigated. MTT-based cytotoxicity assay demonstrated that the therapeutic ratio was enhanced in response to using 5-FU-loaded nanoparticles as compared to 5-FU. Various characterizations including gene expression study, measurement of reactive oxygen species (ROS) generation, Annexin V/PI staining, and clonogenic assay revealed that ionizing radiation in combination with hyperthermia in the presence of the synthesized nanoparticles led to maximal anti-cancer effects as compared to other single (P < 0.001) and combined treatments (P < 0.01). Our results suggested that combined treatment based on using folic acid modified magnetic copolymer nanoparticle as carrier of 5-FU accompanied with hyperthermia could be proposed as an efficient approach to enhance radiation effects in cancer cells.

Synthesis of ABA triblock copolymer nanoparticles by polymerization induced self-assembly and their application as an efficient emulsifier

ABA triblock copolymer nanoparticles of PHPMA-b-PS-b-PHPMA were synthesized by PISA and demonstrated to be an efficient emulsifier.

A Multistage Cooperative Nanoplatform Enables Intracellular Co-Delivery of Proteins and Chemotherapeutics for Cancer Therapy.

Combining intracellularly active proteins with chemotherapeutics represents a promising strategy for synergistic cancer therapy. However, the lack of nanocarrier systems for delivery into cancer cells and controlled intracellular release of both physicochemically very distinct cargos significantly impedes the biomedical translation of this combination strategy in cancer therapy. Here, a well-designed triblock copolymer, mPEG-b-PGCA-b-PGTA, is reported for application in a multistage cooperative drug delivery nanoplatform that accomplishes effective intracellular co-delivery of hydrophilic ribonuclease A (RNase A) and hydrophobic doxorubicin (DOX). RNase A bioreversibly modified with phenylboronic acid groups via a ROS-cleavable carbamate linker is incorporated into the triblock copolymer nanoparticles with high efficiency through a pH-reversible phenylboronic acid-catechol linkage. The reversible covalent conjugations between RNase A and the triblock copolymer endow the nanoparticles with high stability under normal physiological conditions. Upon cellular internalization, the cooperative release of DOX and RNase A from the triblock copolymer nanoparticles is triggered at multiple stages by endosomal acidic environment and subsequent DOX-enhanced intracellular ROS environment. This leads to enhanced synergistic anticancer effects as demonstrated both in vitro and in vivo. Given the versatility of dynamic covalent conjugations, this work provides a universal and stable platform for intracellular co-delivery of various combinations of proteins and chemotherapeutics.

Nanoparticle-enhanced chemo-immunotherapy to trigger robust antitumor immunity.

Mounting evidence suggests that immunotherapies are a promising new class of anticancer therapies. However, the immunosuppressive tumor microenvironment (TME), poor immunogenicity, and off-target toxicity hinder the broader implementation of immunotherapies. Here, we describe a novel strategy combining chemotherapy and immunotherapy to modulate the TME by systemically and concurrently delivering the chemotherapeutic agent SN38 (7-ethyl-10-hydroxycamptothecin) and the STING agonist DMXAA (5,6-dimethylxanthenone-4-acetic acid) into tumors using triblock copolymer nanoparticles, named PS3D1@DMXAA, which enhances antigen cross-presentation and induces the conversion of the immunosuppressive TME to immunogenic TME through the newly found synergistic function between SN38 and STING activation. PS3D1@DMXAA thus shows potent therapeutic efficacy in three mice tumor models and elicits remarkable therapeutic benefit when combined with anti-PD-1 therapy. Our engineered nanosystem offers a rational design of an effective immunotherapy combination regimen to convert uninflamed "cold" tumors into "hot" tumors, addressing the major challenges immunotherapies faced.

Construction of triblock copolymer-gold nanorod composites for fluorescence resonance energy transfer via pH-sensitive allosteric

To explore the effects of microenvironmental adjustments on fluorescence, a pH-sensitive nanocomposite system based on fluorescence resonance energy transfer (FRET) was constructed. The model system included a modified triblock copolymer (polyhistidine-b-polyethylene glycol-b-polycaprolactone) and gold nanoparticles. A near-infrared dye was used as the donor, and spectrally matched gold nanorods, attached after C-terminus modification with α-lipoic acid, were used as the receptor to realize control of the FRET effect over the fluorescence intensity for two polymer configurational changes (i.e., “folded” and “stretched” states) in response to pH. After synthesis and characterization, we investigated the self-assembly behavior of the system. Analysis by quartz crystal microbalance revealed the pH sensitivity of the polymer, which exhibited “folding” and “stretching” states with changes in pH, providing a structural basis for the FRET effect. Fluorescence spectrophotometry investigations also revealed the regulatory impact of the assembled system on fluorescence.

Dual-Targeting Temozolomide Loaded in Folate-Conjugated Magnetic Triblock Copolymer Nanoparticles to Improve the Therapeutic Efficiency of Rat Brain Gliomas

In order to conduct an effective chemotherapy session as a treatment modality for glioblastoma tumors, a nanocarrier platform is required for the drug to cross the blood brain barrier (BBB) successfully and properly target glioma cells. Dual-targeting Temozolomide (TMZ) loaded triblock polymer coated magnetic nanoparticles (MNPs) were synthesized with a SPION core and by conjugating the surface with folic acid (FA), which were shown to effectively pass the BBB and target tumor cells. Two principal methods, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were employed for characterization of the synthesized nanoparticles. TMZ-loaded MNP-FA nanoparticles presented with a size of 58.61 nm, a zeta potential of -29.85 ± 0.47 mV, and a drug loading content of 6.85 ± 0.46%. Data gathered from inductively coupled plasma optical emission spectrometry (ICP-OES) and Prussian blue staining indicated effective dual-targeting, which subsequently led to an appreciably enhanced penetration through the BBB and accumulation of MNPs-FA in rat glioma cells. The anticancer effect of the dual-targeting MNPs-FA was also indicated by the increased survival time (>100%, p < 0.001) and decreased tumor volume (p < 0.001). In conclusion, the dual-targeting TMZ-loaded MNPs-FA are able to improve therapeutic efficiency toward brain gliomas in rats.

Block Copolymer Nanoparticles Prepared via Polymerization-Induced Self-Assembly Provide Excellent Boundary Lubrication Performance for Next-Generation Ultralow-Viscosity Automotive Engine Oils.

Core cross-linked poly(stearyl methacrylate)–poly(benzyl methacrylate)–poly(ethylene glycol dimethacrylate) [S31–B200–E20] triblock copolymer nanoparticles were synthesized directly in an industrial mineral oil via polymerization-induced self-assembly (PISA). Gel permeation chromatography analysis of the S31–B200 diblock copolymer precursor chains indicated a well-controlled reversible addition–fragmentation chain transfer dispersion polymerization, while transmission electron microscopy, dynamic light-scattering (DLS), and small-angle X-ray scattering studies indicated the formation of well-defined spheres. Moreover, DLS studies performed in THF, which is a common solvent for the S and B blocks, confirmed successful covalent stabilization because well-defined solvent-swollen spheres were obtained under such conditions. Tribology experiments using a mini-traction machine (MTM) indicated that 0.50% w/w dispersions of S31–B200–E20 spheres dramatically reduce the friction coefficient of base oil within the boundary lubrication regime. Given their efficient and straightforward PISA synthesis at high solids, such nanoparticles offer new opportunities for the formulation of next-generation ultralow-viscosity automotive engine oils.

Highly photostable rylene-encapsulated polymeric nanoparticles for fluorescent labeling in biological system

Rylene dyes exhibit superior photophysical properties including outstanding chemical and photochemical stabilities as well as high fluorescence quantum yields (FQYs). However, the rylene chromophores have some limitations, such as high hydrophobicity and low solubility in aqueous solution, as a fluorescent tag for biological system. Herein, we present a general method to load the rylene dyes into triblock copolymer nanoparticles (NPs) and stabilize the core. The rylene dyes in confined hydrophobic core fairly preserve their FQYs in aqueous environment. Lumogen probe nanoparticles (PNPs) were prepared with four different commercial rylenes (Lumogen Violet, Yellow, Orange and Red) in the spectral region of visible and infrared (400–750nm) and their photophysical properties were characterized. They exhibited enhanced photostability compared to commercial fluorescent dyes. Also the internalization of Lumogen PNPs in HeLa cell was confirmed by cell uptake test. These results indicate the Lumogen PNPs can be widely applicable in fluorescence detection and imaging such as flow cytometry and fluorescence microscopy.

Tri-block copolymer nanoparticles modified with folic acid for temozolomide delivery in glioblastoma.

In the present study, Folic Acid (FA) ligand was used to functionalize Temozolomide-loaded Poly (ethylene Glycol)-Poly (Butylene Adipate)-Poly (ethylene Glycol)-coated magnetite nanoparticles (TMZ-SPION-PEG-PBA-PEG) for targeted chemotherapy of glioma cells. Four types of nanoparticles were synthesized with the hydrodynamic diameters of 24-49 nm. Using MTT, Prussian blue, and ICP-OES assays, the cytotoxicity effect and cellular uptake of nanoparticles were evaluated in C6 cancer cells and OLN-93 normal cells. Moreover, in vitro anti-tumor efficacy of nanoparticles was evaluated through colony formation, quantitative real-time PCR, and flow cytometry analysis. As compared to OLN-93 cells TMZ-SPION-PEG-PBA-PEG-FA nanoparticles showed an increase in the cytotoxicity of the loaded TMZ in C6 cells within 24 and 48 h treatment (P < 0.0001), while such effect was not observed in the case of non-targeting nanoparticles. The colony formation, flow cytometry, and real-time PCR assays showed that TMZ-SPION-PEG-PBA-PEG-FA led to the enhancement of inhibitory effects to C6 cells compared to TMZ alone (P < 0.05). These results suggested that TMZ-SPION-PEG-PBA-PEG-FA could effectively slow down cell proliferation, due to the targeting effect and the high accumulation of TMZ in C6 cells via an FA-receptor mediated endocytosis. In conclusion, TMZ-loaded magnetite FA-conjugated PEG-PBA-PEG NPs could be used as a targeted drug delivery system for targeted therapy of brain glioma.

Interfacial crosslinking of self‐assembled triblock copolymer nanoparticles via alkoxysilane hydrolysis and condensation

ABSTRACTThe use of amphiphilic triblock copolymers bearing a reactive alkoxysilane middle block as polymeric stabilizers is reported in this work. A series of poly(ethylene glycol) methyl ether methacrylate‐b‐(3‐trimethoxysilyl)propyl methacrylate‐b‐benzyl methacrylate (PEGMA‐b‐MPS‐b‐BzMA) triblock copolymers were prepared by RAFT solution polymerization and polymerization‐induced self‐assembly (PISA), respectively, where the various block lengths and overall composition were varied. The copolymers prepared by solution polymerization were employed as oil‐in‐water stabilizers where upon application of a catalyst, the 3‐(trimethoxysilyl)propyl methacrylate (MPS) block at the droplet interface was crosslinked to yield capsule‐like structures. The effectiveness of interfacial crosslinking was validated by dynamic light scattering and electron microscopy. In situ self‐assembly by the PISA method resulted in spherical nanoparticles of controllable size that were readily crosslinked by addition of base, with significant enhancement of colloidal stability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1897–1907

Formulation of temozolomide by folic acid-conjugated tri-block copolymer nanoparticles for targeted drug delivery

Introduction: Glioblastoma multiforme (GBM) is the most frequent primary malignant tumor of the brain. But, the treatment of GBM is one of the most problems in cancer therapy because of poor drug penetration across the blood-brain barrier (BBB). Targeting drug delivery system and conjugating targeting moieties was recognized to overcome the poor penetration of chemotherapy drugs into tumor cells. In the present study, folic acid- conjugated magnetite tri-block copolymer was utilized to targeted chemotherapy of the glioma cells. Materials and Methods: The characterization and morphology of NPs (SPION-PEG-PBA- PEG, SPION-PEG-PBA-PEG-FA, TMZ-SPION-PEG-PBA-PEG, and TMZ-SPION-PEG-PBA-PEG- FA) were determined by Dynamic Light Scattering (DLS) analysis and transmission electron microscope (TEM). The in vitro release behaviors of TMZ from NPs were evaluated with an equilibrium dialysis bag diffusion method. Additionally, to identify the targeting effect of FA- conjugated NPs, C6 glioblastoma cells and OLN-93 glial cells were used. The cytotoxicity effect of NPs was determined by the MTT assays in both cell lines. Results: DLS analysis showed that all nanoparticles had mean diameters of 24-49 nm. In our study, TMZ entrapment efficiency of TMZ-SPION-PEG-PBA-PEG-FA and TMZ-SPION-PEG- PBA-PEG nanoparticles were 52.8 and 50%, respectively, with the drug loading capacity of 6.65 and 6.3%, respectively. It was found that nearly 90% of TMZ in stock solution was released within the first 2 h. However, TMZ-loaded NPs generated only 75% leakage within the 48 h and revealed a sustained release feature, which might be described by that drug was gradually released with the dissolution of polymers. The results from the MTT assay indicated that TMZ-SPION-PEG-PBA-PEG-FA NPs revealed the highest anti-proliferation effect on the C6 cells compared with OLN-93 cells (P < 0.0001). Also, compared with unmodified NPs, conjugation with FA-ligand could further elevate the cytotoxicity effect on C6 cells (P < 0.0001) which demonstrated a satisfactory drug delivery system. Conclusion: TMZ-SPION-PEG-PBA-PEG-FA NPs served as a potential system for the transport of TMZ across the GBM cells through receptor-mediated endocytosis. The results revealed that proposed system could be exploited as potential carrier for delivery of drugs to the brain.

Thin Film Nanocomposites Based on SBM Triblock Copolymer and Silver Nanoparticles: Morphological and Dielectric Analysis

Hybrid organic/inorganic thin film nanocomposites based on poly(styrene)‐b‐poly(butadiene)‐b‐poly(methyl methacrylate) triblock copolymer and silver nanoparticles are prepared and characterized. In order to improve the compatibility of nanoparticles with the polymeric matrix, their surface is modified with dodecanethiol surfactant, which enables a good dispersion of nanoparticles through the triblock copolymer, without the formation of aggregates. By atomic force microscopy (AFM), the dispersion level of nanoparticles is analyzed, together with their effect on the thin film surface morphology, for nanocomposites up to 15 wt% of nanoparticles. Dielectric properties of nanocomposites are studied by dielectric relaxation spectroscopy (DRS), analyzing the effect of nanoparticles on dielectric properties. Even if conductivity and permittivity of composites increase with nanoparticle content, percolation threshold is found to be at around 15% in volume. Morphologically analyzed nanocomposites are, in this way, below the threshold.

Synthesis of Multicompartment Nanoparticles of ABC Triblock Copolymers through Intramolecular Interactions of Two Solvophilic Blocks

A new strategy to synthesize multicompartment block copolymer nanoparticles (MCBNs) of poly(4-vinylpyridine)-block-polystyrene-block-poly(4-hydroxystyrene) (P4VP-b-PS-b-P4HS) combining the polymerization-induced self-assembly (PISA) of linear ABC triblock copolymers and the intramolecular complexation through hydrogen bonding between the poly(4-vinylpyridine) (P4VP) and poly(4-hydroxystyrene) (P4HS) blocks is proposed. These MCBNs contain a polystyrene (PS) core of about 30 nm and the dispersed 3–5 nm microdomains of the P4VP/P4HS complexes on the solvophobic PS core, in which the size of the dispersed P4VP/P4HS microdomains increases with the polymerization degree (DP) of the P4HS block. The successful synthesis of MCBNs is ascribed to the intramolecular interactions via hydrogen bonding between the P4HS and P4VP blocks confined within the triblock copolymer nanoparticles. The strategy affords the efficient synthesis of MCBNs and avoids the application of the ABC miktoarm terpolymers and the fluorinated ...

The doubly thermo-responsive triblock copolymer nanoparticles prepared through seeded RAFT polymerization

The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly(N-isopropylacrylamide)-block-poly[N,N-(dimethylamino) ethyl methacrylate] (PS-b-PNIPAM-b-PDMAEMA) are successfully prepared through the seeded RAFT polymerization in situ by using the PS-b-PNIPAM-TTC diblock copolymer nanoparticles as the seed. The seeded RAFT polymerization undergoes a pseudo-first-order kinetics procedure, and the molecular weight increases with the monomer conversion linearly. The hydrodynamic diameter (Dh) of the triblock copolymer nanoparticles increases with the extension of the PDMAEMA block. In addition, the double thermo-response behavior of the PS-b-PNIPAM-b-PDMAEMA nanoparticles is detected by turbidity analysis, temperature-dependent 1H-NMR analysis, and DLS analysis. The seeded RAFT polymerization is believed as a valid method to prepare triblock copolymer nanoparticles containing two thermo-responsive blocks.