Copolymer Concentration Research Articles

Photo-curable carboxymethylcellulose composite hydrogel as a promising biomaterial for biomedical applications

A series of carboxymethylcellulose (CMC) functionalized with glycidyl methacrylate (GMA) was successfully synthesized for producing of CMC-g-GMA copolymer. Water-soluble CMC-g-GMA copolymer was photo-crosslinked while Irgacure-2959 was used as a UV-photo-initiator at 365 nm. On the other hand, cellulose nanocrystals (CNCs) from sugarcane were graft-copolymerized in an aqueous solution utilizing cerium ammonium nitrate (CAN) as an initiator in a redox-initiated free-radical approach. CNCs were grafted with GMA to enhance their physicochemical and biological characteristics. Factors affecting hydrogel formation, e.g. CMC-g-GMA copolymer concentration, irradiation time and incorporation of different concentration of CNCs-g-GMA nano-filler, were discussed in dependance on the swelling degree and gel fraction of the produced hydrogels. Notably, the addition of CNCs-g-GMA nanofillers increased progressively thermal stability of the prepared hydrogel. CMC-g-GMA filled with CNCs-g-GMA composite hydrogel showed antimicrobial activity against multidrug resistance pathogens. Thus, CMC-g-GMA filled with CNCs-g-GMA composite hydrogel could be endorsed as compatible biomaterials for versatile biomedical applications.

Luminescence of Terbium Ions in Aqueous Solutions of Sodium Styrene Sulfonate Copolymers with 4-Methacrylamidosalicylic Acid

Water-soluble copolymers of sodium styrene sulfonate and 4-methacrylamidosalicylic acid of 93.7 mol % composition have been synthesized, and their interaction with terbium and gadolinium ions has been investigated to fabricate luminescent probes promising for their visualization in biomedical research. It has been shown that, in aqueous solutions in the copolymer concentration range 0.15–1.7 mg mL–1 and at the ratio [Tb3+]/[COO–] = 1, water-soluble luminescent metal polymer complexes with a luminescence lifetime of 823 µs are formed. When Tb3+ ions are partially replaced in the complex by Gd3+ ions, bimetallic complexes with intense luminescence are formed.

Synthesis and application of a temperature sensitive poly(N-vinylcaprolactam-co-N,N-diethyl acrylamide) for low-temperature rheology control of water-based drilling fluid

During deepwater drilling operation, the wellbore temperature decreases with the increase of water depth, and increases rapidly with the increase of formation depth. Temperature sensitive polymers can change the molecular conformation with temperature, and then change its hydrophobicity, to adjust the network structure between solid particles and polymer in drilling fluid. In this paper, a novel temperature sensitive copolymer poly(N-vinylcaprolactam-co-N,N-diethyl acrylamide) (PNVDE) was synthesized. Its molecular structure, molecular weight and molecular weight distribution were characterized. The effects of salinity, pH value and copolymer concentrations on lower critical solution temperature (LCST) were studied. Based on the temperature sensitive property of the copolymer, the ability to control the low-temperature rheology of water-based drilling fluid (WBDF) was studied. The results showed that PNVDE can effectively control the rheology of deepwater WBDF in the range of 4~ 60 ℃. At the same time, the experiments of temperature and salt resistance showed that the copolymer has strong ability of temperature resistance and salt resistance, and can withstand the temperature alternation of drilling fluid. The synergistic effect of PNVDE and bentonite made the rheology of deepwater drilling fluid stable, which can be explained by “SASA Hydrogen Bond Network”.

Tunable and scalable fabrication of block copolymer-based 3D polymorphic artificial cell membrane array

Owing to their excellent durability, tunable physical properties, and biofunctionality, block copolymer-based membranes provide a platform for various biotechnological applications. However, conventional approaches for fabricating block copolymer membranes produce only planar or suspended polymersome structures, which limits their utilization. This study is the first to demonstrate that an electric-field-assisted self-assembly technique can allow controllable and scalable fabrication of 3-dimensional block copolymer artificial cell membranes (3DBCPMs) immobilized on predefined locations. Topographically and chemically structured microwell array templates facilitate uniform patterning of block copolymers and serve as reactors for the effective growth of 3DBCPMs. Modulating the concentration of the block copolymer and the amplitude/frequency of the electric field generates 3DBCPMs with diverse shapes, controlled sizes, and high stability (100% survival over 50 days). In vitro protein–membrane assays and mimicking of human intestinal organs highlight the potential of 3DBCPMs for a variety of biological applications such as artificial cells, cell-mimetic biosensors, and bioreactors.

Antifouling improvement of a polyacrylonitrile membrane blended with an amphiphilic copolymer

Abstract The amphiphilic copolymer polyacrylonitrile-co-poly(hydroxyethyl methacrylate) (PAN-co-PHEMA) was readily blended with polyacrylonitrile (PAN) to fabricate a flat-sheet blending membrane through non-solvent induced phase separation (NIPS). In the membrane-forming process, the hydrophilic PHEMA chains are uniformly distributed on the surface, as revealed by the energy-dispersive X-ray tests. The sponge-like sub-layer embedded with droplet-shaped structures is formed at the cross-sections of membranes, because of the high viscosity of the casting solution. With the increase of copolymer concentration, the mean pore size of the blending membranes increases from 26.9 to 99.8 nm, leading to the increase of membrane flux from 93.6 to 205.4 l/(m2h). The incorporation of PAN-co-PHEMA copolymer endows the blending membrane with a rough surface microstructure and enhanced hydrophilicity. The rejection ratio of membranes for emulsified pump oil reaches 99.9%, indicating a prominent separation performance. In the cycle permeation experiments, the flux recovery ratio of the blending membranes is as high as 99.6%, which is much higher than those of PAN membrane. The irreversible fouling of blending membranes induced by oil adsorption is alleviated, and converted into reversible fouling, owing to the reduction of the adhesion force between foulant and membrane surface. These results suggest that the anti-fouling property of PAN membranes has been dramatically strengthened via the addition of PAN-co-PHEMA copolymer.

Self-Assembled Amphiphilic Fluorinated Random Copolymers for the Encapsulation and Release of the Hydrophobic Combretastatin A-4 Drug.

Water-soluble amphiphilic random copolymers composed of tri(ethylene glycol) methacrylate (TEGMA) or poly(ethylene glycol) methyl ether methacrylate (PEGMA) and perfluorohexylethyl acrylate (FA) were synthesized by ARGET-ATRP, and their self-assembling and thermoresponsive behavior in water was studied by dynamic light scattering (DLS) and UV-vis spectroscopy. The copolymer ability to self-fold in single-chain nano-sized structures (unimer micelles) in aqueous solutions was exploited to encapsulate Combretastatin A-4 (CA-4), which is a very hydrophobic anticancer drug. The cloud point temperature (Tcp) was found to linearly decrease with increasing drug concentration in the drug/copolymer system. Moreover, while CA-4 was preferentially incorporated into the unimer micelles of TEGMA-ran-FA, the drug was found to induce multi-chain, submicro-sized aggregation of PEGMA-ran-FA. Anyway, the encapsulation efficiency was very high (≥81%) for both copolymers. The drug release was evaluated in PBS aqueous solutions both below and above Tcp for TEGMA-ran-FA copolymer and below Tcp, but at two different drug loadings, for PEGMA-ran-FA copolymer. In any case, the release kinetics presented similar profiles, characterized by linear trends up to ≈10–13 h and ≈7 h for TEGMA-ran-FA and PEGMA-ran-FA, respectively. Then, the release rate decreased, reaching a plateau. The release from TEGMA-ran-FA was moderately faster above Tcp than below Tcp, suggesting that copolymer thermoresponsiveness increased the release rate, which occurred anyway by diffusion below Tcp. Cytotoxicity tests were carried out on copolymer solutions in a wide concentration range (5–60 mg/mL) at 37 °C by using Balb/3T3 clone A31 cells. Interestingly, it was found that the concentration-dependent micro-sized aggregation of the amphiphilic random copolymers above Tcp caused a sort of “cellular asphyxiation” with a loss of cell viability clearly visible for TEGMA-ran-FA solutions (Tcp below 37 °C) with higher copolymer concentrations. On the other hand, cells in contact with the analogous PEGMA-ran-FA (Tcp above 37 °C) presented a very good viability (≥75%) with respect to the control at any given concentration.

Tuning the size of all-HPMA polymeric micelles fabricated by solvent extraction

The size of polymeric micelles crucially affects their tumor accumulation, penetration and antitumor efficacy. In the present study, micelles were formed based on amphiphilic poly(N-2-hydroxypropyl methacrylamide)-block-poly(N-2-benzoyloxypropyl methacrylamide) (p(HPMAm)-b-p(HPMAm-Bz)) via the solvent extraction method, and factors impacting micelle size were systematically studied, including the molecular weight of the polymers, homopolymer content, and processing methods (i.e., batch process versus continuous microfluidics). The formation of core-shell structured micelles was demonstrated by light scattering, sedimentation velocity and electron microscopy analysis. Micellar size and aggregation number increased with decreasing the molecular weight ratio of the hydrophilic/hydrophobic block. The presence of hydrophobic p(HPMAm-Bz) homopolymer and high copolymer concentration increased micelle size, while the presence of hydrophilic p(HPMAm) homopolymer did not affect micellar size. Regarding processing conditions, it was found that the use of tetrahydrofuran and acetone as solvents for the polymers resulted in larger micelles, likely due to their relatively high water-solvent interaction parameters as compared to other solvents tested, i.e., dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Among the latter, only dimethylformamide led to micelles with a narrow polydispersity. Addition of dimethylformamide to an aqueous solvent and faster mixing of two solvents using microfluidics favored the formation of smaller micelles. In conclusion, our results show that the size of all-HPMA polymeric micelles can be easily tailored from 40 to 120 nm by varying the formulation properties and processing parameters.

Ground Tire Rubber Modified by Elastomers via Low-Temperature Extrusion Process: Physico-Mechanical Properties and Volatile Organic Emission Assessment.

In this paper, low-temperature extrusion of ground tire rubber was performed as a pro-ecological waste tires recycling method. During this process, ground tire rubber was modified with constant content of dicumyl peroxide and a variable amount of elastomer (in the range: 2.5–15 phr). During the studies, three types of elastomers were used: styrene-butadiene rubber, styrene-ethylene/butylene-styrene grafted with maleic anhydride and ethylene-octene copolymer. Energy consumption measurements, curing characteristics, physico-mechanical properties and volatile organic compounds emitted from modified reclaimed GTR were determined. The VOCs emission profile was investigated using a passive sampling technique, miniature emission chambers system and static headspace analysis and subsequently quantitative or qualitative analysis by gas chromatography. The VOCs analysis showed that in the studied conditions the most emitted volatile compounds are dicumyl peroxide decomposition by-products, such as: α-methylstyrene, acetophenone, α-cumyl alcohol, methyl cumyl ether, while the detection level of benzothiazole (devulcanization “marker”) was very low. Moreover, it was found that the mechanical properties of the obtained materials significantly improved with a higher content of styrene-butadiene rubber and styrene-ethylene/butylene-styrene grafted with maleic anhydride while the opposite trend was observed for ethylene-octene copolymer content.

A Biofouling Resistant Zwitterionic Polysulfone Membrane Prepared by a Dual-Bath Procedure.

This study introduces a zwitterionic material to modify polysulfone (PSf) membranes formed by a dual bath procedure, in view of reducing their fouling propensity. The zwitterionic copolymer, derived from a random polymer of styrene and 4-vinylpyrridine and referred to as zP(S-r-4VP), was incorporated to the PSf solution without any supplementary pore-forming additive to study the effect of the sole copolymer on membrane-structuring, chemical, and arising properties. XPS and mapping FT-IR provided evidence of the modification. Macrovoids appeared and then disappeared as the copolymer content increased in the range 1–4 wt%. The copolymer has hydrophilic units and its addition increases the casting solution viscosity. Both effects play an opposite role on transfers, and so on the growth of macrovoids. Biofouling tests demonstrated the efficiency of the copolymer to mitigate biofouling with a reduction in bacterial and blood cell attachment by more than 85%. Filtration tests revealed that the permeability increased by a twofold factor, the flux recovery ratio was augmented from 40% to 63% after water/BSA cycles, and irreversible fouling was reduced by 1/3. Although improvements are needed, these zwitterionic PSf membranes could be used in biomedical applications where resistance to biofouling by cells is a requirement.

Atypical vesicles and membranes with monolayer and multilayer structures formed by graft copolymers with diblock side-chains: nonlamellar structures and curvature-enhanced permeability.

Graft copolymers with diblock side-chains Am(-graft-B3Ay)n in a selective solvent have been reported to self-assemble into vesicles, but the structure is expected to differ distinctly from those of lipid bilayers. Surprisingly, the number of alternating hydrophobic A-block and hydrophilic B-block layers in the vesicle can vary from a monolayer to multilayers such as the hepta-layer, subject to the same copolymer concentration. The area density of the copolymer layer is not uniform across the membrane. This structural difference among different layers is attributed to the neighboring environment and the curvature of the layer. Because of the unusual polymer conformations, nonlamellar structures of polymersomes are formed, and they are much more intricate than those of liposomes. In fact, a copolymer can contribute to a single or two hydrophilic layers, and it can provide up to three hydrophobic layers. The influence of the backbone length (m) and side-chain length (y) and the permeation dynamics are also studied. The thickness of hydrophobic layers is found to increase with increasing side-chain length but is not sensitive to the backbone length. Although the permeation time increases with the layer number for planar membranes, the opposite behavior is observed for spherical vesicles owing to the curvature-enhanced permeability associated with Laplace pressure.

Radical reaction extrusion copolymerization mechanism of MMA and N-phenylmaleimide and properties of products.

Using the method of bulk reactive extrusion radical copolymerization, N-phenyl maleimide (N-PMI) and styrene (St) and methyl methacrylate (MMA) were copolymerized. Through multi-detection gel permeation chromatography, bulk copolymerization kinetic analysis, UV-Vis spectroscopy, elemental analysis, and 1H NMR and 13C NMR analysis, it was found that, contrary to the classical free radical copolymerization theory, N-PMI and MMA could not only achieve copolymerization, but could even reach the level of azeotropic copolymerization. The factor that caused this change turned out to be the viscosity of the system. Secondly, through DSC, TG and GC-MS analysis, it was found that N-PMI units were randomly inserted into the molecular chain of PMMA, which greatly improved the stiffness of its molecular segments and the Tg of the copolymer; at the same time, the insertion of N-PMI units also very effectively blocked the zipper-style de-end group degradation that often occurs in PMMA. When the mass content of the N-PMI copolymer reached 10%, the Tg, initial degradation temperature and semi-degradation temperature of the copolymer increased by 19 °C, 58 °C and 47 °C, respectively. In addition, St, N-PMI can also significantly improve the processing fluidity of the PMMA copolymer, and after St participates were introduced in the copolymerization, the melt flow rate can be increased by 3.5 times. Furthermore, the copolymer not only had good mechanical properties and transparency, but also had excellent antibacterial properties against E. coli and S. aureus with only the effect of trace residual N-PMI in the copolymer. This provides an excellent reference for the preparation of antibacterial PMMA with high heat resistance, good mechanical properties and high transparency.

Silica nanoparticle-loaded thermoresponsive block copolymer vesicles: a new post-polymerization encapsulation strategy and thermally triggered release.

A thermoresponsive amphiphilic diblock copolymer that can form spheres, worms or vesicles in aqueous media at neutral pH by simply raising the dispersion temperature from 1 °C (spheres) to 25 °C (worms) to 50 °C (vesicles) is prepared via polymerization-induced self-assembly (PISA). Heating such an aqueous copolymer dispersion from 1 °C up to 50 °C in the presence of 19 nm glycerol-functionalized silica nanoparticles enables this remarkable ‘shape-shifting’ behavior to be exploited as a new post-polymerization encapsulation strategy. The silica-loaded vesicles formed at 50 °C are then crosslinked using a disulfide-based dihydrazide reagent. Such covalent stabilization enables the dispersion to be cooled to room temperature without loss of the vesicle morphology, thus aiding characterization and enabling the loading efficiency to be determined as a function of both copolymer and silica concentration. Small-angle X-ray scattering (SAXS) analysis indicated a mean vesicle membrane thickness of approximately 20 ± 2 nm for the linear vesicles and TEM studies confirmed encapsulation of the silica nanoparticles within these nano-objects. After removal of the non-encapsulated silica nanoparticles via multiple centrifugation–redispersion cycles, thermogravimetric analysis indicated that vesicle loading efficiencies of up to 86% can be achieved under optimized conditions. Thermally-triggered release of the silica nanoparticles is achieved by cleaving the disulfide bonds at 50 °C using tris(2-carboxyethyl)phosphine (TCEP), followed by cooling to 20 °C to induce vesicle dissociation. SAXS is also used to confirm the release of silica nanoparticles by monitoring the disappearance of the structure factor peak arising from silica–silica interactions.

Polymerization-induced self-assembly and disassembly during the synthesis of thermoresponsive ABC triblock copolymer nano-objects in aqueous solution.

Polymerization-induced self-assembly (PISA) has been widely utilized as a powerful methodology for the preparation of various self-assembled AB diblock copolymer nano-objects in aqueous media. Moreover, it is well-documented that chain extension of AB diblock copolymer vesicles using a range of hydrophobic monomers via seeded RAFT aqueous emulsion polymerization produces framboidal ABC triblock copolymer vesicles with adjustable surface roughness owing to microphase separation between the two enthalpically incompatible hydrophobic blocks located within their membranes. However, the utilization of hydrophilic monomers for the chain extension of linear diblock copolymer vesicles has yet to be thoroughly explored; this omission is addressed for aqueous PISA formulations in the present study. Herein poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (G-H) vesicles were used as seeds for the RAFT aqueous dispersion polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Interestingly, this led to polymerization-induced disassembly (PIDA), with the initial precursor vesicles being converted into lower-order worms or spheres depending on the target mean degree of polymerization (DP) for the corona-forming POEGMA block. Moreover, construction of a pseudo-phase diagram revealed an unexpected copolymer concentration dependence for this PIDA formulation. Previously, we reported that PHPMA-based diblock copolymer nano-objects only exhibit thermoresponsive behavior over a relatively narrow range of compositions and DPs (see Warren et al., Macromolecules, 2018, 51, 8357–8371). However, introduction of the POEGMA coronal block produced thermoresponsive ABC triblock nano-objects even when the precursor G-H diblock copolymer vesicles proved to be thermally unresponsive. Thus, this new approach is expected to enable the rational design of new nano-objects with tunable composition, copolymer architectures and stimulus-responsive behavior.

DEPOSITION OF SILVER PARTICLES ON THE SOLID SURFACES WITH THE PARTICIPATION OF BLOCK COPOLYMER OF POLYSTYRENE AND POLYETHYLENE GLYCOL

Earlier the ability of obtaining of stabilized organosols in such systems as «toluene-water», «toluene-methanol» in presence of block copolymer of polystyrene and polyethylene glycol has been shown. In present investigation these disperse systems have been used in a mixture with precursor of silver nanoparticles (silver salt) and reducing agent (sodium citrate or hydrazine hydrate). Thus obtained silver sols have been put on a glass or graphite surfaces with subsequent removal of block copolymer by heating of samples in air to 500 °C. The dimension of obtained silver sols particles has been determined by means of sedimental turbidimetry (ST) and dynamic light scattering (DLS) methods. It has been shown that in silver sols obtained in the system «toluene-water-citrate» with the copolymer content of 0.25 and 1 g/100 ml have particle diameters of 800 and 1100 nm correspondingly. According to scanning electron microscopy (SEM) data the silver particles have spheric form. Their size does not depend much on the concentration of silver, but with an increase in the concentration of the copolymer, their size heterogeneity increases. The formation of spatial ordered structures of silver particles on the glass surface is noted, while the particles on the graphite surface are distributed more evenly. Using the system "toluene-methanol-block copolymer-silver salt-hydrazine hydrate" on the basis of thermally expanded graphite (TEG), a composite with a silver content of 130 mg/g was obtained and its effect on the activity of yeast fungi was evaluated. In comparison with the control samples (TEG and TEG treated with a similar dispersed system without the participation of a block copolymer), a decrease in foam formed in the column during fermentation of sucrose at 35 °C was found. Thus, it is shown that the block copolymer of polystyrene and polyethylene glycol promotes a more uniform deposition of silver particles from sols on the surface of graphite and can be used, in particular, to create materials with potential biological activity.

Preparation and characterisation of graphene oxide containing block copolymer worm gels.

This paper reports a generic method for preparing reinforced nanocomposite worm-gels. Aqueous poly(glycerol monomethacrylate)-b-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) and methanolic poly(glycerol monomethacrylate)-b-poly(benzyl methacrylate) (PGMA-PBzMA) worm gels were prepared by RAFT-mediated polymerisation-induced self-assembly (PISA). The former system undergoes a reversible worm-to-sphere degelation transition upon cooling to 5 °C whilst the latter system undergoes the same transition on heating to 56 °C. This transition allows these copolymer dispersions to be readily mixed with graphene oxide (GO) whilst in a low viscosity state and form nanocomposite gels on returning to room temperature via a sphere-to-worm transition. Various quantities of GO were added to the studied copolymer dispersions at a fixed copolymer content of 15% w/w. A general trend was observed whereby relatively small quantities of GO caused the gel strength of the nanocomposite gel to be higher than that of the pristine worm-gel, as determined by oscillatory rheology. Additional quantities of GO resulted in gel weakening or prevented gel-reformation altogether. For instance, 15% w/w PGMA52-PHPMA130 worm gels had a storage modulus (G') of approximately 1.5 kPa. The addition of 1.5% w/w GO based on the copolymer caused G' to increase to approximately 4.0 kPa but >1.5% w/w GO resulted in gel strengths <1.0 kPa. A combination of aqueous electrophoresis and transmission electron microscopy measurements were used to investigate the mechanism of nanocomposite gel formation. It was observed that the PGMA-based copolymers readily absorb onto the surface of GO. Thus, the role of GO is both to strengthen the worm-gels when an optimal concentration of GO is used, but also prevent worm-reformation if too much copolymer becomes absorbed on the surface of the sheets.

Effect of Ethylmethacrylate and Isobutylmethacrylate on Surface Hardness and Surface Roughness of Heat-Cure Ocular Acrylic Resins

Background Acrylic resin is a commonly utilized material in clinical practice, including: maxillofacial prosthesis Interim prostheses, repair dentures, reline, orthodontic equipment, and record bases are only a few examples of possible applications. However, these materials have some drawbacks, for example low mechanical properties. To improve the performance of the acrylic resins, various materials have been incorporated. Purpose: The purpose of this research is to assess the effects of adding different concentrations of copolymers of Ethyl methacrylate (EA) and Isobutyl methacrylate (IBMA) monomers on some of the mechanical properties of acrylic resin such as surface hardness and surface roughness. Approach: 100 samples were made of acrylic resin and were divided into three groups (a control group and two experimental groups). Twenty samples were used for the control group and these samples were divided into ten samples for each group based on the tests performed. While 40 samples per experimental group (IBMA, EMA) were divided into two groups according to the added concentration (1% and 2%). Then, according to the tests performed, each group was divided into two groups with ten samples for each group. Acrylic samples were fabricated with dimensions of 65 mm x 10 mm x 2.5 lengths, width and thickness respectively according to (ADA specification, No.12, 1999). Each specimen was subjected to the surface hardness test and surface roughness test. All data were analyzed using SPSS version 20, One –way ANOVA, LSD and Post Hoc -Tukey test were utilized for detecting the significant differences and multiple comparisons. Results: The control group had the greatest mean value of hardness compared with the experimental group while the EMA 1% group showed the lowest mean value of roughness test compared with the control and other experimental groups. Conclusion: The incorporation of experimental groups (IBMA, EMA) in different concentrations by weight in MMA and PMMA had a decrease slightly of surface hardness of acrylic resins, and the incorporation of EMA 1% by weight in MMA and PMMA had improved surface roughness. In added EMA2%, IBMA 2% enhanced slightly the surface roughness of acrylic resins.

Investigation into the effect of resin finish on the functional characteristics of plain fabrics using different curing methods

PurposeCellulosic fabric and plain weave are the most commonly used material in home textiles. The poor wrinkling, dimensional stability and pilling are some of the problems faced during usage. The textile industries apply resin finish to improve these characteristics. The purpose of this study is to improve pilling resistance, dimensional stability and smoothness appearance (SA) of rayon and rayon/cotton plain fabrics using different concentrations of dimethyloldihydroxyethylene urea (DMDHEU) and acrylic copolymer. The finish was fixed using two different fixation methods.Design/methodology/approachThree concentrations, 40, 100 and 150 g/l of Arkofix NF (DMDHE based) and Appretan N9211 (acrylic copolymer), were taken. The finish was applied at normal and shock cure. The effects of finish on pilling resistance, dimensional stability, smoothness, tear strength, light fastness, Berger whiteness and yellowness index of plain fabrics were investigated.FindingsThe changes in the characteristics of the finished fabrics were compared with unfinished fabrics. This study revealed that at 40 g/l of Arkofix NF and Appretan N9211 using a normal cure would improve the pilling resistance, dimensional stability and SA of the plain fabrics. Whereas, there was no adverse effect observed on tear strength, light fastness, Berger whiteness and yellowness index of plain fabrics at these conditions.Originality/valueUnlike the previous studies, this paper proposed the single finish formulation where the functional characteristics of the plain rayon and rayon cotton fabrics meet the general requirement of a customer.

The preparation of cross-linkable polyethylene via coordination copolymerization of ethylene with alkene-derived chlorosilane

A facile and controllable way to prepared silane-crosslinked polyethylene by coordination polymerization was proposed in this article. Four alkene-derived chlorosilanes, trichloro(oct-7-en-1-yl)silane (Oct-TriSi), dichloro(methyl)(oct-7-en-1-yl)silane (Oct-DiSi), chlorodimethyl(oct-7-en-1-yl)silane (Oct-MoSi) and (2-(bicyclo[2.2.1]hept-5-en-2-yl)ethyl)dichloro(methyl)silane (Nor-DiSi) were first synthesized by hydrosilylation and copolymerized with ethylene to prepare cross-linkable polyethylene. The copolymerization results of ethylene/octenyl-silanes indicated monochloro-substituted silane showed lowest crosslinking ability while trichloro-substituted silane showed the lowest copolymerization ability, therefore, their ability to prepare cross-linkable polyethylene was: Oct-DiSi > Oct-TriSi > Oct-MoSi, moreover, Nor-DiSi outcompeted Oct-DiSi as comonomer to obtain higher copolymerization activity, comonomer proportion in copolymer, comonomer conversion and gel content. The crosslinking process was simply finished via alcoholysis with methanol and subsequent hydrolysis catalyzed with DBTDL. Even with a slight addition of Nor-DiSi, the polyethylene was able to be crosslinked, with the gel content ranging from 42.0 to 98.0%. The TGA and DMA tests demonstrated the crosslinked copolymers showed better thermal stability and heat deformation resistance than polyethylene. After crosslinking, the copolymers with an appropriate gel content would have higher yield stress, tensile modulus and tensile stress.

Amphiphilic star block copolymer micelles in saline as effective vehicle for quercetin solubilization

There has been an enormous interest in improving the therapeutic efficacy of hydrophobic flavonoids through enhancement of their bioavailability. A carrier capable to effectively solubilize flavonoids is expected to support the chemical/structural integrity of flavonoid molecule, and hence, its antioxidant properties. In this paper, the effectiveness of saline solutions of an amphiphilic star block ethylene oxide-propylene oxide copolymer (Tetronic®T904) has been investigated for solubilizing quercetin (QN). T904 self-assembles in aqueous solution above its critical micellization temperature (CMT) that depends on solution concentration, temperature, pH and presence of salt. We have studied the solubilization of QN in T904 micelles at different temperature, concentration and salt (sodium chloride) concentration using scattering and spectral techniques. Our findings suggest that, at a given temperature, QN solubility is influenced by the concentration of salt and copolymer. When compared to its linear counterparts (the Pluronics®), T904 solutions offered superior solubilization. 2D NOESY NMR observations revealed that QN occupied the periphery of the hydrophobic core of micelles. Such an environment can protect the drug against oxidation in aqueous phase.

Swelling studies on poly(n, n-dimethyl acrylamide-co-acrylic acid) hydrogels

Hydrogel copolymers based on N, N-dimethyl acrylamide (DMA) and acrylic acid (АAc) were synthesized with different molar composition ratios ([DMA-AAc] = 30÷70, 50÷50 and 70÷30) using ammonium peroxydisulfate as a free radical initiation system and in the presence of various amounts of N, N’-methylene bis (acrylamide) as a crosslinker agent (0.05, 0.1 and 0.3 mol. %) and water as reactant medium. The swelling technique characterized the obtained copolymer by different amounts to added of the crosslinking agent. While a large amount of crosslinking agent in the poly (DMA-co-AAc) hydrogels was reduced the swelling degree in the water medium, a smaller amount in the gel indicated the tendency of the gel to burst. Absorption studies were made using on different concentrations of copper sulphate (CuSO4). Poly (DMA-co-AAc) hydrogels absorption capacity is competitive when there is more N, N-dimethyl acrylamide content in copolymer than others. The swelling ratios of low concentration of Cu (II) ion are higher than those of higher concentration of Cu (II) ion. Hydrogel gave the highest swelling ratio for the solution containing the lowest Cu (II) ion concentration than for the solution containing the highest Cu (II) ion.