Triblock Copolymer Poly Research Articles

Vat photopolymerization of poly(styrene-b-isoprene-b-styrene) triblock copolymers

Vat photopolymerization (VPP) additive manufacturing (AM) produces complex geometries with micron-scale resolution and smooth surface finish from a wide range of photocrosslinkable polymeric precursors. However, mass transport limitations typically constrain VPP amenable precursors to viscosities less than 10 Pa·s. Reactive oligomers and monomers comprise the majority of VPP polymeric precursors, which result in highly crosslinked and brittle 3D objects upon printing. This work describes colloidal high molecular weight ABA triblock copolymers, or latex, as a feedstock for aqueous photoreactive compositions to enable AM of thermoplastic elastomers (TPE). Photorheological analysis determined 15 wt% aqueous reactive monomers and oligomers generated a structural scaffold that achieved sufficiently high modulus to maintain feature fidelity for iterative layer formation. Subsequent thermal post-processing removed water and promoted polymeric particle coalescence throughout the scaffold resulting in an interpenetrating network (IPN) that exhibited an isotropic dimensional shrinkage of 25 %. Small-angle X-ray scattering (SAXS) confirmed microphase-separated morphologies typical of triblock copolymers, revealing a characteristic length scale of 30 nm. Using commercially available VPP printers, ABA triblock copolymer poly(styrene-b-isoprene-b-styrene) latex yielded printed elastomers with precise feature fidelity and tensile extensibility exceeding 800 %.

Mechanical properties of melt-fabricated, drawn films of A–B–A triblock copolymers of poly(l-lactide) (A) and two types of polyethers (B)

Mechanical properties of melt-fabricated, drawn films of A–B–A triblock copolymers of poly(l-lactide) (A) and two types of polyethers (B)

Synthesis of novel conducting triblock copolymer poly(thiophene-co-pyrrole-co-aniline) by chemical oxidative polymerization method for gas sensor application

The conducting triblock copolymer P(Th-co-Py-co-Ani) of thiophene (Th), pyrrole (Py), and aniline (Ani) has been synthesized by chemical oxidative polymerization method using anhydrous iron (III) chloride (FeCl3) as an oxidizing agent in presence of acetonitrile solvent at 0–8°C. Characterizations of the synthesized copolymer were performed by Attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction analysis (PXRD), UV-Vis spectroscopy, elemental analysis (CHNS), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). Notably, UV-Vis spectroscopy revealed that triblock copolymers exhibit highly conjugated conducting polymer backbone, essential for its electrical conductivity and suitability for various applications. The prepared P(Th-co-Py-co-Ani) material was investigated for the gas sensing property of several gases such as ammonia, acetone, carbon monoxide, ethanol and methane. The gas sensing study revealed that P(Th-co-Py-co-Ani) demonstrates promising gas sensing capabilities, particularly at room temperature.

Stereocomplex-Driven Morphological Transition of Coil-Rod-Coil Poly(lactic acid)-Based Cylindrical Nanoparticles.

The stereocomplexation of poly(lactic acid) (PLA) enantiomers opens up an avenue for the formation of new materials with enhanced performance, specifically regarding their mechanical and thermal resistance and resistance to hydrolysis. Despite these useful features, the study of the stereocomplexation between block copolymers based on PLA in solution is limited, and a comprehensive understanding of this phenomenon is urgently needed. Herein, triblock copolymers of poly(N-hydroxyethyl acrylamide) and PL(or D)LA in which PLA was midblock (PHEAAmy-b-PL(D)LAx-b-PHEAAmy) were synthesized and assembled into cylindrical micelles via crystallization-driven self-assembly . The stereocomplexation between enantiomeric micelles facilitates the morphological transition, and the transformation process was investigated in detail by varying the aging temperature, block composition, and solvent. It was found that the solubility of the copolymers played a vital role in determining the occurrence and the speed of the chain exchange between the micelles and the unimers, which thereafter has a significant impact on the shape transition. These results lead to a deeper understanding of the stereocomplex-driven morphological transition process and provide valuable guidance for further optimization of the transition under physiological conditions as a new category of stimuli-responsive systems for biomedical applications.

Thermo-tunable Injectable Thermosensitive Hydrogel and its Application as Protein Carriers

It is known that polymer chemistries determine mechanical and physical properties of hydrogels and thus its drug delivery performance. In order to achieve desired drug release behavior, triblock copolyester PCT-PEG-PCT with proper hydrogel formulation has to be synthesized. This research has demonstrated a way to adjust hydrogel mechanical and gelation properties by simply physically mixing amphiphilic copolymers with different composition to achieve desired protein carriers. Tri-block copolymer poly (CL-co-TOSUO)-PEG-poly (CL-co-TOSUO), briefed as (PCT-PEG-PCT) with different composition have been successfully synthesized. These copolymers are thermosensitive and can form hydrogels in aqueous solution. Copolymers with higher percentage hydrophobic PCT blocks show higher mechanical stiffness and yet lower solubility. To reduce the crystallinity of the hydrophobic block and soften the hydrogel, the copolymer with long PCT blocks was physically mixed with ones with shorter PCT blocks. The polymer mixture demonstrated a moderated mechanical stiffness and desired solubility. The polymer mixture also achieved a gelation temperature at 37°C, which is desirable for drug delivery. Macromolecular drug, bovine serum albumin (BSA) was used as model drug for its release study. This protein drug was successfully loaded into the polymer mixture, and the drug release study shows the polymer mixture is able to extend a stable drug release for over 48 hours. This result confirms physical mixing of PCT-PET-PCT thermosensitive copolymers can tune gel properties and improve drug delivery performance without redesigning and synthesizing new polymers.

Toward understanding polymeric micelle stability regulated by diverse physico-chemical strategies and their stabilized mechanism

Despite polymeric micelles as a kind of promising drug delivery system (DDS), their unsatisfactory stability in physiological environment remains a barrier to clinical translation. Thus, the present study aims at understanding the factors and underlying mechanism to stabilize micelles. Accordingly, we designed triblock copolymers poly(2-phenoxyethyl methacrylate)-b-poly(2-oxopropyl methacrylate)-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PPOEMA-b-POPMA-b-PPEGMA), and prepared cross-linked polymeric micelles (CPM) self-assembled by these copolymers. Förster resonance energy transfer (FRET) fluorescence test showed cross-linked structure was more stable in diluted environment. Meanwhile, cross-linking and higher proportion of hydrophilic shell retarded the dissociation of micelles after incubating with protein. Experiment and simulation results revealed stabilized mechanism of micelles regulated by different strategies. Firstly, Van der Waals interaction between benzene rings would be the driving force of micelle stability. Secondly, cross-linking reshaped micelle structure, thereby evoking π-π stacking effect and simultaneously limiting movement of polymer segments, resulting in the more rigid micelle structure. Then, longer hydrophilic branch chain led to better coverage of hydrophilic shell, conducive to micelle stability in thermodynamics. In addition, doxorubicin (DOX)-loaded micelles possessed pH-responsive property and remarkably inhibited the growth of tumor cells. These findings are of significance in further understanding of polymeric micelle stability, and provide new insight for the design of stable and long-circulating materials for drug delivery.

Single-Micelle-Templated Synthesis of Hollow Barium Carbonate Nanoparticle for Drug Delivery

A laboratory-synthesized triblock copolymer poly(ethylene oxide-b-acrylic acid-b-styrene) (PEG-PAA-PS) was used as a template to synthesize hollow BaCO3 nanoparticles (BC-NPs). The triblock copolymer was synthesized using reversible addition-fragmentation chain transfer radical polymerization. The triblock copolymer has a molecular weight of 1.88 × 104 g/mol. Transmission electron microscopy measurements confirm the formation of spherical micelles with a PEG corona, PAA shell, and PS core in an aqueous solution. Furthermore, the dynamic light scattering experiment revealed the electrostatic interaction of Ba2+ ions with an anionic poly(acrylic acid) block of the micelles. The controlled precipitation of BaCO3 around spherical polymeric micelles followed by calcination allows for the synthesis of hollow BC-NPs with cavity diameters of 15 nm and a shell thickness of 5 nm. The encapsulation and release of methotrexate from hollow BC-NPs at pH 7.4 was studied. The cell viability experiments indicate the possibility of BC-NPs maintaining biocompatibility for a prolonged time.

Fluorine-Free, Highly Durable Waterproof and Breathable Fibrous Membrane with Self-Clean Performance.

Lightweight, durable waterproof and breathable membranes with multifunctional properties that mimic nature have great potential for application in high-performance textiles, efficient filtering systems and flexible electronic devices. In this work, the fluoride-free triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) fibrous membrane with excellent elastic performance was prepared using electrospinning. According to the bionics of lotus leaves, a coarse structure was built onto the surface of the SBS fiber using dip-coating of silicon dioxide nanoparticles (SiO2 NPs). Polydopamine, an efficient interfacial adhesive, was introduced between the SBS fiber and SiO2 NPs. The hydrophobicity of the modified nanofibrous membrane was highly improved, which exhibited a super-hydrophobic surface with a water contact angle large than 160°. The modified membrane retained super-hydrophobic properties after 50 stretching cycles under 100% strains. Compared with the SBS nanofibrous membrane, the hydrostatic pressure and WVT rate of the SBS/PDA/SiO2 nanofibrous membrane improved simultaneously, which were 84.2 kPa and 6.4 kg·m-2·d-1 with increases of 34.7% and 56.1%, respectively. In addition, the SBS/PDA/SiO2 nanofibrous membrane showed outstanding self-cleaning and windproof characteristics. The high-performance fibrous membrane provides a new solution for personal protective equipment.

Double Stimuli-Responsive di- and Triblock Copolymers of Poly(N-isopropylacrylamide) and Poly(1-vinylimidazole): Synthesis and Self-Assembly.

For the first time, double stimuli-responsive properties of poly(N-isopropylacrylamide) (PNIPA) and poly(1-vinylimidazole) (PVIM) block copolymers in aqueous solutions were studied. The synthesis of PNIPA60-b-PVIM90 and PNIPA28-b-PVIM62-b-PNIPA29 was performed using reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were characterized by size exclusion chromatography and 1H NMR spectroscopy. The conformational behavior of the polymers was studied using dynamic light scattering (DLS) and fluorescence spectroscopy (FS). It was found that PNIPA and block copolymers conformation and ability for self-assembly in aqueous medium below and above cloud point temperature depend on the locus of hydrophobic groups derived from the RAFT agent within the chain. Additionally, the length of PVIM block, its locus in the chain and charge perform an important role in the stabilization of macromolecular micelles and aggregates below and above cloud point temperature. At 25 °C the average hydrodynamic radius (Rh) of the block copolymer particles at pH 3 is lower than at pH 9 implying the self-assembling of macromolecules in the latter case. Cloud points of PNIPA60-b-PVIM90 are ~43 °C and ~37 °C at a pH of 3 and 9 and of PNIPA28-b-PVIM62-b-PNIPA29 they are ~35 °C and 31 °C at a pH of 3 and 9. Around cloud point independently of pH, the Rh value for triblock copolymer rises sharply, achieves the maximum value, then falls and reaches the constant value, while for diblock copolymer, it steadily grows after reaching cloud point. The information about polarity of microenvironment around polymer obtained by FS accords with DLS data.

Mechanism of regulating pore structure of polyethyleneimine modified mesoporous silica foam

A novel mesoporous silica foam (MCF) with a specific surface area of 712.5 m<sup>2</sup>/g and a pore volume of 2.44 cm<sup>3</sup>/g is synthesized by using triblock copolymer poly (ethylene oxide, polypropylene oxide and ethylene oxide, P123) as template and TEOS (C<sub>8</sub>H<sub>20</sub>O<sub>4</sub>Si) as silicon source. The effect of polyethylenimide (PEI) modified MCF on nanoscale pore structure is studied by positron annihilation lifetime spectroscopy (PALS) and conventional characterization methods, such as N<sub>2</sub> adsorption desorption, transmission electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The results show that the synthesized MCF has an obvious disordered mesoporous structure, and a continuous porous network with window connection between the pores is formed. Meanwhile, it can be seen directly that PEI is successfully introduced into MCF pore channels. In order to evaluate the pore size and its distribution more comprehensively, the mechanism of positron annihilation which is highly sensitive to nanometer scale open volumes in PEI loaded MCF is studied. It is found that there are two long life components <i>τ</i><sub>3</sub> and <i>τ</i><sub>4</sub>, indicating the micropores and mesopores co-existing in the sample. Furthermore, the introduction of PEI molecules results in a significant decrease in <i>τ</i><sub>3</sub> and <i>τ</i><sub>4</sub>, and the lifetime values are then corrected by using the positron annihilation rate formula in pure gas to calculate the pore size. The results show that the pore size gradually decreases with the filling of the organic molecule PEI. This provides a new insight into the mechanism of regulating the pore structure of MCF by polyethyleneimine modification, as well as the characterization of pore structure in organic-modified mesoporous molecular sieves.

Thermoresponsive Self-Healing Zwitterionic Hydrogel as an In Situ Gelling Wound Dressing for Rapid Wound Healing.

It is highly desired yet challenging to fabricate biocompatible injectable self-healing hydrogels with anti-bacterial adhesion properties for complex wounds that can autonomously adapt to different shapes and depths and can promote angiogenesis and dermal collagen synthesis for rapid wound healing. Herein, an injectable zwitterionic hydrogel with excellent self-healing property, good cytocompatibility, and antibacterial adhesion was developed from a thermoresponsive ABA triblock copolymer poly[(N-isopropyl acrylamide)-co-(butyl acrylate)-co-(sulfobetaine methacrylate)]-b-poly(ethylene glycol)-b-poly[(N-isopropyl acrylamide)-co-(butyl acrylate)-co-(sulfobetaine methacrylate)] (PZOPZ). The prepared PZOPZ hydrogel exhibits a distinct thermal-induced sol-gel transition around physiological temperature and could be easily applied in a sol state and in situ gelled to adapt complex wounds of different shapes and depths for complete coverage. Meanwhile, the hydrogel possesses a rapid self-healing ability and can recover autonomously from damage to maintain structural and functional integrity. In addition, the CCK-8 and 2D/3D cell culture experiments revealed that the PZOPZ hydrogel dressing shows low cytotoxicity to L929 cells and can effectively prevent the adhesion of Staphylococcus aureus and Escherichia coli. In vivo investigations verified that the PZOPZ hydrogel could increase angiogenesis and dermal collagen synthesis and shorten the transition from the inflammatory to the proliferative stage, thereby providing more favorable conditions for faster wound healing. Overall, this work provides a promising strategy to develop injectable zwitterionic hydrogel dressings with multiple functions for clinic wound management.

Improvement of the self‐assembly of low χABA triblock copolymers with the addition of an ionic liquid

AbstractSelf‐assembly of high molecular weight commercially available low χ ABA triblock copolymers with ionic liquids (ILs) was observed after solvent casting without the implementation of an additional annealing step. Here, the addition of an IL to a triblock copolymer poly(methyl methacrylate‐b‐butyl acrylate‐b‐methyl methacrylate) (MAM) with an elastomeric central block and rigid end blocks is proposed to tune the self‐assembled morphology. Two different compositions of this copolymer with different initial microstructures (ill‐defined morphology without long‐range order and a lamellar morphology) were selected. The selectivity of the IL addition in one of the block phases was studied through the evolution of the glass transition of both blocks. The impact of the IL weight concentration on the morphology as well as the domain spacing is presented. Adding IL to the first copolymer detected a lyotropic disorder–order transition towards a gyroid morphology, observed even for a high molecular weight copolymer due to the low χ parameter, and for higher IL content a second transition to a lamellar morphology was observed. For the second copolymer, only an order–order transition (lamellae to cylinders) could be detected at high IL content. IL also enhanced the long‐range ordering of the MAM morphology obtained through solvent casting without additional annealing steps, compared with the same composition without IL. © 2022 Society of Industrial Chemistry.

Effect of triblock copolymers on the lipase catalytic behavior at the interface of conventional O/W emulsions

The ‘interfacial quality’ is the key influencing factor for lipase activities at interfaces, and thus, interfacial engineering has become an effective strategy to modulate lipase catalysis. In the current research, the triblock copolymers poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO) were adopted to form conventional oil-in-water (O/W) emulsion systems. The results showed the different effects of PEO-PPO-PEO molecules on the spatial barriers, emulsion particle size, and ultimately interfacial adsorption properties of lipases. Since the molecular weight of Candida antarctica lipase B (CALB) is approximately half that of Candida rugosa lipase (CRL), it can more easily pass through the triblock copolymer adsorption layer, resulting in a higher adsorption ratio. The results confirmed that the catalytic efficiency of CALB at the emulsion interfaces was much lower than that of CRL due to its lack of a typical ‘lid’ structure. Both the effective amount of lipase molecules at the interfaces (controlled by the interfacial adsorption ratio) and the effective catalytic interface area (influenced by the specific surface area controlled by the average particle size of the O/W emulsion) impacted the catalytic activities of CRL. Na+ ions were found to have a certain inhibitory effect on the catalytic activity of CRL.

Gentamycin-loaded halloysite-based hydrogel nanocomposites for bone tissue regeneration: fabrication, evaluation of the antibacterial activity and cell response

Biocompatible hydrogels are promising approaches for bone repair and engineering. A novel therapeutic nanocomposite hydrogel was designed based on triblock copolymer poly e-caprolactone (PCL)-polyethylene glycol-PCL and natural gelatin (PCEC/GEL) and reinforced with halloysite nanotube (HNT). Gentamicin (GM) loaded HNT was immobilized in polymeric hydrogel matrix to fabricate scaffolds using the freeze-drying method. Scaffolds were characterized via Fourier transform infrared (FT-IR), x-ray powder diffraction, and scanning electron microscope (SEM) methods. The swelling ratio, density, porosity, degradation, and mechanical behavior were evaluated to investigate the effects of HNT on the physicochemical properties of the composite. Cell viability and cell attachment were investigated by microculture tetrazolium (MTT) assay and SEM. Cell proliferation was observed without any cytotoxicity effect on human dental pulp-derived mesenchymal stem cells (h-DPSCs). Alizarin red staining and real-time reverse transcription polymerase chain reaction (QRT-PCR) assay were carried out to monitor the osteoconductivity of scaffolds on h-DPSCs which were seeded drop wise onto the top of scaffolds. The quantification of the messenger RNA (mRNA) expression of osteogenic marker genes, bone morphogenetic protein 2, SPARK, bone gamma-carboxyglutamate protein and runt-related transcription factor 2 over a period of 21 d of cell seeding, demonstrated that cell-encapsulating PCEC/GEL/HNT-GM hydrogel scaffolds supported osteoblast differentiation of h-DPSCs into osteogenic cells through the up-regulation of related genes along with moderate effects on cell viability. Moreover, the antibiotics loading reduced bacterial growth while maintaining the osteogenic properties of the scaffold. Therefore, the bactericidal PCEC/GEL/HNT-GM hydrogel nanocomposite, with enhanced durability, maintenance the functionality of seeded cells in vitro that can be a remarkable dual-functional candidate for hard tissue reconstruction and customized bone implants fabrication via the direct incorporation of bactericidal drug to prevent infection.

Role of modified silica nanoparticles in enhancing the properties of flexible solid electrolytes

With the aim of developing solid electrolytes with high ionic conductivity, PVdF-HFP has been blended with a triblock copolymer (poly(propylene glycol)-block-poly(ethylene glycol)-poly(propylene glycol) bis(2-aminopropyl ether); ED2003), SiO2 nanoparticles (with modified morphology) and electrolyte solution (1 M LiBF4 in EMIMBF4) in different proportions. The addition of ED2003 has resulted in enhancing the porosity of the polymer matrix and eventually the ionic conductivity. Electrolyte films with SiO2 nanoparticles having a modified morphology enhance both the polymer-filler interface and the electrochemical properties as compared to the films with the spherical SiO2 nanoparticles, thus enhancing the ion conduction. Ionic conductivity of ∼0.274 mScm−1(at 30ºC) has been obtained for the electrolyte film with 30 wt.% of electrolyte solution and a minimal amount (1 wt.%) of modified SiO2 nanoparticles. Also, 1H and 13C NMR studies of the electrolyte films have been done to understand the chemical surrounding and the interaction of ionic liquid's cation (EMIM+) with the other constituents of the matrix.

Improvement in dispersion stability of alumina suspensions and corresponding chemical mechanical polishing performance

The dispersion stability of alumina suspensions is an obstacle to its large-scale application for chemical mechanical polishing (CMP) since the aggregation of particles will cause scratches on the wafer surface during polishing. Therefore, this study was devoted to improving the physicochemical properties of alumina suspensions using different polymeric dispersants, including polyethylene glycol (PEG) with nonionic properties, sodium polyacrylate (PAAS) with anionic properties, and their triblock copolymer poly(acrylic acid)-b-PEG-b-poly(acrylic acid) (PAEG). The characterization results of dispersion stability showed that, compared with PEG and PAAS, the suspensions containing a suitable dosage of PAEG exhibited the advantages of low-viscosity (Viscosity < 3 mPa·s), good-stability (Zeta potential < -50 mV), and monodisperse (Polydispersity index < 0.1). The adsorption isotherm indicated that the adsorption of dispersants on alumina particles was consistent with Langmuir model. Furthermore, the total potential energy between particles in suspension was calculated for theoretical analysis of the inter-particle interactions. Besides, the dispersion mechanisms of PEG, PAAS, and PAEG were proposed as steric stabilization, electrostatic stabilization and electrosteric stabilization, respectively. Finally, CMP experiments showed that the suspension prepared by using PAEG as a dispersant to polish SiC substrates resulted in better removal rates (382 nm/h) and lower surface roughness (Ra: 1.85 nm).

Preparation of stereocomplex and pseudo-polyrotaxane with various cyclodextrins as wheel components using triblock copolymer of poly(ethylene glycol) and polylactide

The ABA-type triblock-copolymers (BCPs) of polylactide (PLA) and poly(ethylene glycol) (PEG) were synthesized as axle components for rotaxane formation. It is known that α-cyclodextrin (CD) exists near the PEG moiety in pseudo-polyrotaxane (PPRX), and the PLA moiety can form a stereocomplex (SC), by mixing with L- and D-isomers. In this study, various CDs, including β-CD and γ-CD, were used as wheel components, and effects of CD structures on both PPRX and SC formations were studied. The solubility of CDs is influenced to form the PPRX, resulting in differing numbers of CDs in the axle. PPRX structures were investigated by 1H NMR, NOESY, and DOSY, and SC structures were investigated by FT-IR and XRD. Their thermal properties were also evaluated by DSC and TGA, to consider the physical properties of the simultaneous formation of PPRX and SC. This study gave insight into the complicated host-guest and polymer-polymer interactions.

Glasses‐shaped triblock copolymer prepared by combination of atom transfer radical polymerization and ring opening polymerization

AbstractA glasses‐shaped triblock copolymer of poly(ε‐caprolactone)‐b‐polystyrene‐b‐poly(ε‐caprolactone) (PCL‐b‐PS‐b‐PCL) is prepared by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). Polystyrene (PS) star polymers are prepared via ATRP using a tetra‐functional initiator, followed by azidation to yield azide end‐functionalized star polymers. An alkyne‐functionalized coupling agent, 2,2‐bis[(2‐propyn‐1‐yloxy)methyl]‐1‐propanol is employed to produce hydroxy 8‐shaped PS via copper(I)‐catalyzed alkyne‐azide cycloaddition. Herein, hydroxy 8‐shaped PS with high purity is obtained through preparative size exclusion chromatography (Prep SEC) and high‐performance liquid chromatography, followed by the characterizations using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS), size exclusion chromatography (SEC), infrared, and proton nuclear magnetic resonance (1H NMR) spectroscopy. The hydroxy groups of the 8‐shaped PS are utilized as initiators for the ROP of ε‐caprolactone to obtain linear chains attached to the 8‐shaped architecture. After SEC fractionation, the glasses‐shaped triblock copolymer is characterized using 1H NMR and SEC. This unprecedented topology possesses two free chain‐ends and two cycles; thus, both the properties of linear and cyclic polymers may be expected to be observed.

Nanostructure of PMMA/MAM Blends Prepared by Out-of-Equilibrium (Extrusion) and Near-Equilibrium (Casting) Self-Assembly and Their Nanocellular or Microcellular Structure Obtained from CO2 Foaming.

Blends of poly(methyl methacrylate) (PMMA) and a triblock copolymer poly(methyl methacrylate)-b-poly(butyl acrylate)-b-poly(methyl methacrylate) (MAM) have been obtained following both out-of-equilibrium (extrusion) and near-equilibrium (solvent casting) production routes. The self-assembly capability and the achievable nanostructures of these blends are analyzed by transmission electron microscopy (TEM) regarding their production route and potential for the achievement of nanocellular foams by CO2 gas dissolution foaming. The influence of the initial nanostructure of the solids on the obtained cellular structure of bulk and film samples is determined by high-resolution scanning electron microscopy (HRSEM) for diverse foaming conditions (saturation pressure, saturation temperature, and post-foaming stage), taking into account the required use of a foaming mold to achieve foams from films. Moreover, the influence of the nanostructuration on the presence of solid outer layers, typical of the selected foaming process, is addressed. Finally, consideration of a qualitative model and the obtained results in terms of nanostructuration, cellular structure, and foaming behavior, allow proposing a detailed cell nucleation, growth, and stabilization scheme for these materials, providing the first direct evidence of the cell nucleation happening inside the poly(butyl acrylate) phase in the PMMA/MAM blends.

Engineering of anticancer drugs entrapped polymeric nanoparticles for the treatment of colorectal cancer therapy

Traditional chemotherapeutic agents have been successfully used to treat cancers, although their many disadvantages include poor solubility, high dosage needs, severe side effects, low therapeutic indices, development of multiple drug resistance, and non-specific targeting of cancer cells. In this study, Methotrexate (MEX) and curcumin (CUR) were incorporated into the triblock copolymer poly(lactic-co-glycolic acid) (PLGA)–poly(ethylene glycol) (PEG)–PLGA to achieve synergism in the treatment of colorectal cancer. Nanoparticle-based combination treatments for colorectal cancer can be developed using this remarkably symmetric synthetic strategy. The particles were visualized by high-resolution transmission microscopy (HR-TEM), and their size and polydispersity were determined using dynamic light scattering. Without a blast of impact, MEX and CUR were released gently from the polymeric nanoparticle system. CUR/MEX@NPs also demonstrated dose-dependent cytotoxic effects on SW1417 and CL40 cell lines, with a higher apoptosis ratio than free MEX and CUR. According to the in vitro cellular uptake analysis, cancer cells absorbed the polymeric nanoparticles more readily. From the fluorescence experiment, nanomaterials promoted cell death in the SW1417 and CL40 cell lines. Additionally, in vivo systemic toxicity and in vitro findings support the biocompatibility of CUR/MEX@NPs. Furthermore, these nanomaterials cause apoptosis in cancer cells. From these findings, CUR/MEX@NPs exhibit the potential to be successfully utilized to treat colorectal cancer.