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1.
Carbohydr Polym ; 229: 115461, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826390

RESUMO

Low molar mass (LMM) biopolymers are highly required to design functional nanomaterials, which mainly find application in biomedical fields. However, the synthesis of LMM polymer is a challenging task. In this work, we report a partial enzymatic depolymerization process which allows to produce a series of LMM hydroxypropylmethyl cellulose (HPMC) polymer, with a weight average molar mass (Mw) under and over 10,000 g mol-1 and low dispersity (Ɖ < 1.5). Variation of the starting HPMC grade, reaction time, and enzyme concentration were the key parameters to control the Mw and yield of the target molecules. This approach provides a versatile way of producing LMM HPMCs with varying degrees of substitution, and having a single reactive aldehyde function at one chain extremity. LMM HPMC can find for instance application as building blocks for the development of new functional molecular architectures.

2.
Membranes (Basel) ; 9(12)2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31779174

RESUMO

Sweeping gas membrane distillation (SGMD) is a useful option for dehydration of aqueous solvent solutions. This study investigated the technical viability and competitiveness of the use of SGMD to concentrate aqueous solutions of 1,3-dimethyl-2-imidazolidinone (DMI), a dipolar aprotic solvent. The concentration from 30% to 50% of aqueous DMI solutions was attained in a bench installation with Liqui-Cel SuperPhobic® hollow-fiber membranes. The selected membranes resulted in low vapor flux (below 0.15 kg/h·m2) but were also effective for minimization of DMI losses through the membranes, since these losses were maintained below 1% of the evaporated water flux. This fact implied that more than 99.2% of the DMI fed to the system was recovered in the produced concentrated solution. The influence of temperature and flowrate of the feed and sweep gas streams was analyzed to develop simple empirical models that represented the vapor permeation and DMI losses through the hollow-fiber membranes. The proposed models were successfully applied to the scaling-up of the process with a preliminary multi-objective optimization of the process based on the simultaneous minimization of the total membrane area, the heat requirement and the air consumption. Maximal feed temperature and air flowrate (and the corresponding high operation costs) were optimal conditions, but the excessive membrane area required implied an uncompetitive alternative for direct industrial application.

3.
Carbohydr Polym ; 211: 133-140, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824073

RESUMO

AB2-type amphiphilic (HPMC)2-PLA copolymers with various hydrophilic block lengths were synthesized using a three step procedure: ring-opening polymerization of L-lactide initiated by propynol, amination reduction of the aldehyde endgroup of HPMC, and thiol-click reaction. The resulted copolymers were characterized by NMR, DOSY-NMR, SEC and FT-IR. The cloud point (CP) was determined by UV-vis spectrometer. Data show that the HPMC block length has little effect on the Cp of the copolymers which is lower than that of HPMC. The self-assembly behavior of the copolymers was investigated from DLS, TEM, and critical micelle concentration (CMC) measurements. Spherical micelles are obtained by self-assembly of copolymers in aqueous solution. The micelle size and the CMC of copolymers increase with increasing HPMC block length. It is concluded that biobased and biodegradable (HPMC)2-PLA copolymers could be promising as nano-carrier of hydrophobic drugs.


Assuntos
Derivados da Hipromelose/química , Poliésteres/química , Micelas
4.
Environ Sci Pollut Res Int ; 26(32): 32687-32697, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30547338

RESUMO

The shortage of drinking water is a major problem in the rural areas of the Mekong Delta, especially, when surface water, a main local direct drinking water source is being threatened by pesticide pollution and salinity intrusion. A hybrid process coupling electrodialysis (ED) and nanofiltration (NF) is proposed as an effective process easy to setup in a small plant to treat complex matrix with high salinity and pesticide concentration as is the Mekong Delta surface water. Performance of the ED-NF integration was evaluated with synthetic solutions based on the comparison with a single NF step generally used for pesticide removal. Both energy consumption and water product quality were considered to assess process efficiency. The ED stage was designed to ensure a 50% removal of salinity before applying NF. As expected, the NF rejection is better in the hybrid process than in a case of a single NF step, especially for pesticide rejection. The integration of a NF stage operated with NF270 membrane consumes less energy than that with NF90 membrane but its efficiency was observed not high enough to respect the Vietnamese guidelines. Using NF90, the optimal recovery rate of the NF stage varies from 30 to 50% depending on the salt content in the feed.


Assuntos
Praguicidas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Filtração , Membranas Artificiais , Salinidade , Águas Residuárias , Água
5.
Polymers (Basel) ; 10(7)2018 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-30960658

RESUMO

The preparation of well-arranged nano-porous thin films from an ABA triblock copolymer of polystyrene-block-poly(sodium 4-styrenesulfonate)-block-polystyrene (PS-PNaSS-PS) is reported. This copolymer was self-assembled in a N,N-dimethylformamide (DMF)/water mixture and the resulting micellar solution was used to prepare thin films via the compact packing of the flower-like micelles using spin coating method. The films were characterized by several microscopy techniques such as TEM, AFM, and SEM. Permeation test was performed to highlight the interconnected porous nature of the polymeric network obtained. Under applied water pressure, the micellar morphology was altered and a partial fusion of the micelles was observed that resulted in a change in the water permeability. Such hydrophilic nanoporous thin films with negatively charged interface could find applications in membrane filtration.

6.
Soft Matter ; 13(38): 6689-6693, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28948266

RESUMO

Herein, a membrane prepared from the self-assembly of poly(styrene-co-acrylonitrile)-b-poly(ethylene oxide)-b-poly(styrene-co-acrylonitrile) micelles is found to exhibit translocation of nano-objects dispersed in aqueous solution. With the water flow as a driving force, temporary pores are created in between the micelles to facilitate the passage of nano-objects. These temporary pores close afterwards through a self-healing mechanism. As main results, polystyrene and silica nanoparticles exhibited a selective translocation directly influenced by their size and applied pressure.

7.
Langmuir ; 33(8): 1914-1926, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28147481

RESUMO

Cationic vectors are ideal candidates for gene delivery thanks to their capability to carry large gene inserts and their scalable production. However, their cationic density gives rise to high cytotoxicity. We present the proper designed core-shell polyplexes made of either poly(ethylene imine) (PEI) or poly(2-dimethylamino ethyl methacrylate) (PDMAEMA) as the core and zwitterionic poly(acrylic acid)-block-poly(sulfobetaine methacrylate) (PAA-b-PSBMA) diblock copolymer as the shell. Gel retardation and ethidium bromide displacement assays were used to determine the PEI/DNA or PDMAEMA/DNA complexation. At neutral pH, the copolymer serves as a protective shell of the complex. As PSBMA is a nonfouling block, the shell reduced the cytotoxicity and enhanced the hemocompatibility (lower hemolysis activity, longer plasma clotting time) of the gene carriers. PAA segments in the copolymer impart pH sensitivity by allowing deshielding of the core in acidic solution. Therefore, the transfection efficiency of polyplexes at pH 6.5 was better than at pH 7.0, from ß-galactosidase assay, and for all PAA-b-PSBMA tested. These results were supported by more favorable physicochemical properties in acidic solution (zeta potential, particle size, and interactions between the polymer and DNA). Thus, the results of this study offer a potential route to the development of efficient and nontoxic pH-sensitive gene carriers.


Assuntos
Polímeros/química , DNA , Técnicas de Transferência de Genes , Concentração de Íons de Hidrogênio , Iminas/química , Metacrilatos/química , Nylons/química , Polietilenos/química
8.
Macromol Biosci ; 16(1): 57-62, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26222768

RESUMO

Amphiphilic diblock copolymer containing randomly distributed positive and negative charged monomers are synthesized using RAFT polymerization technique to be used as anti-bioadhesion coatings for hydrophobic surfaces. Quaternized 2-(dimethylamino) ethyl methacrylate and potassium 3-sulfopropyl methacrylate (P[qDMAEMA-co-KSPMA]) are randomly polymerized to yield an anti-bioadhesion block which is, in one pot, copolymerized with styrene as an anchoring block. This copolymer has demonstrated high anti-bioadhesion properties to avoid the blood clotting in medical devices through a simple and facile approach to preparation of pseudozwitterionic copolymers.


Assuntos
Sangue , Polímeros/química , Adsorção , Materiais Revestidos Biocompatíveis , Humanos , Metacrilatos/química , Polimerização , Estireno/química
9.
Int J Pharm ; 495(1): 154-161, 2015 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-26264166

RESUMO

This work aims to evaluate the potential of reverse micelles prepared from amphiphilic polylactide-b-poly(ethylene glycol) (PLA-b-PEG) block copolymers for controlled release of hydrophilic drugs. Different PLA-b-PEG diblock and triblock copolymers were synthesized by ring-opening polymerization of D- or L-lactide in the presence of a PEG macroinitiator. Reverse micelles were prepared by self-assembly of copolymers in a solvent/co-solvent/water system. Toluene was used as solvent, and ethanol as co-solvent to solubilize appropriate amount of water. The resulting nano-sized reverse micelles were able to encapsulate heparin in the hydrophilic core. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to determine the size and morphology of reverse micelles. The results show that reverse micelles are spherical in shape with sizes below 100 nm. Drug loaded reverse micelles were embedded in biocompatible membranes by mixing with 10% PLA solution in toluene with 1:3 volume ratio. In vitro release studies were realized in phosphate buffer saline (PBS) at 37°C. Heparin was almost totally released within 24h. Triblock copolymer reverse micelles exhibited faster drug release than diblock ones probably due to the more compact micelle structure of the latter. Therefore, PLA-b-PEG reverse micelles could be promising for applications as carrier of hydrophilic drugs when embedded in biocompatible membranes.


Assuntos
Preparações de Ação Retardada/química , Liberação Controlada de Fármacos , Heparina/química , Lactatos/química , Micelas , Polietilenoglicóis/química , Sistemas de Liberação de Medicamentos , Heparina/análise , Interações Hidrofóbicas e Hidrofílicas , Polímeros/química
10.
Adv Mater ; 25(27): 3739-44, 2013 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-23754442

RESUMO

A zipper-assembly of micelles into 2D/3D coatings is reported. Block copolymer micelles that incorporate a poly(n-octadecyl methacrylate) block are zipped and unzipped on demand onto a PMMA surface. The mechanism implies an interdigitation of molecular brushes enabling 15 nm micelles to be assembled into monolayers or multilayers.


Assuntos
Polímeros/química , Micelas , Tamanho da Partícula , Propriedades de Superfície
11.
Biomacromolecules ; 13(9): 2849-58, 2012 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-22838402

RESUMO

"Schizophrenic" diblock copolymers containing nonionic and zwitterionic blocks were prepared with well-controlled molecular weights via atom-transfer radical polymerization (ATRP). In this work, we report a systematic study of how morphological changes of poly(N-isopropylacrylamide)-block-poly(sulfobetaine methacrylate) (PNIPAAm-b-PSBMA) copolymers affect hemocompatibility in human blood solution. The "schizophrenic" behavior of PNIPAAm-b-PSBMA was observed by (1)H NMR, dynamic light scattering (DLS), and turbidity measurement with double morphological transition, exhibiting both lower critical solution temperature (LCST) and upper critical solution temperature (UCST) in aqueous solution. Below the UCST of PSBMA block, micelles were obtained with a core of insoluble PSBMA association and a shell of soluble PNIPAAm, whereas the opposite micelle structure was observed above the LCST of PNIPAAm block. In between the UCST and LCST, unimers with both soluble blocks were detected. Hydrodynamic size of prepared polymers and copolymers is determined to illustrate the correlations between intermolecular nonionic/zwitterionic associations and blood compatibility of PNIPAAm, PNIPAAm-b-PSBMA, and PSBMA suspension in human blood. Human fibrinogen adsorption onto the PNIPAAm-b-PSBMA copolymers from single-protein solutions was measured by DLS to determine the nonfouling stability of copolymer suspension. The new nonfouling nature of PNIPAAm-b-PSBMA copolymers was demonstrated to show extremely high anticoagulant activity and antihemolytic activity in human blood over a wide range of explored temperatures from 4 to 40 °C. The temperature-independent blood compatibility of nonionic/zwitterionic block copolymer along with their schizophrenic phase behavior in aqueous solution suggests their potential in blood-contacting applications.


Assuntos
Acrilamidas/química , Acrilamidas/síntese química , Materiais Biocompatíveis/síntese química , Eritrócitos/efeitos dos fármacos , Metacrilatos/síntese química , Polímeros/química , Acrilamidas/farmacologia , Resinas Acrílicas , Adsorção , Materiais Biocompatíveis/farmacologia , Eritrócitos/citologia , Fibrinogênio/química , Hemólise/efeitos dos fármacos , Humanos , Luz , Espectroscopia de Ressonância Magnética , Metacrilatos/farmacologia , Micelas , Peso Molecular , Nefelometria e Turbidimetria , Polimerização , Espalhamento a Baixo Ângulo , Soluções , Temperatura , Água
12.
Angew Chem Int Ed Engl ; 51(29): 7166-70, 2012 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-22696305

RESUMO

When pressure is applied to dynamic interactive membranes consisting of micelles composed of a triblock copolymer, their morphologies can be fine-tuned. Membranes with a range of porosities are accessible which can regulate and thereby control filtration performance and also display effective autonomous healing.

13.
Langmuir ; 26(4): 2574-83, 2010 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-19810684

RESUMO

The thin active layer (TAL) of seven nanofiltration (NF) membranes was studied using differential scanning calorimetry, and the membranes were classified into two groups according to the polymer physical state (amorphous or semicrystalline). NF membrane performance in terms of permeate volume flux density and rejection of neutral solutes was investigated in temperature cycles. The modeling of rejection using a hindered transport theory showed irreversible and opposite pore size changes for the two groups of NF membranes when the maximum operating temperature of the cycle exceeded the glass-transition temperature of the TAL. A mechanism of pore deformation is proposed to explain the variation of the solute transport properties as a function of the temperature and the polymer physical state in the TAL.

14.
Chemistry ; 16(7): 2309-16, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-20033966

RESUMO

The synthesis and characterisation of new arborescent architectures of poly(L-lysine), called lysine dendrigraft (DGL) polymers, are described. DGL polymers were prepared through a multiple-generation scheme (up to generation 5) in a weakly acidic aqueous medium by polycondensing N(epsilon)-trifluoroacetyl-L-lysine-N-carboxyanhydride (Lys(Tfa)-NCA) onto the previous generation G(n-1) of DGL, which was used as a macroinitiator. The first generation employed spontaneous NCA polycondensation in water without a macroinitiator; this afforded low-molecular-weight, linear poly(L-lysine) G1 with a polymerisation degree of 8 and a polydispersity index of 1.2. The spontaneous precipitation of the growing N(epsilon)-Tfa-protected polymer (GnP) ensures moderate control of the molecular weight (with unimodal distribution) and easy work-up. The subsequent alkaline removal of Tfa protecting groups afforded generation Gn of DGL as a free form (with 35-60% overall yield from NCA precursor, depending on the DGL generation) that was either used directly in the synthesis of the next generation (G(n+1)) or collected for other uses. Unprotected forms of DGL G1-G5 were characterised by size-exclusion chromatography, capillary electrophoresis and (1)H NMR spectroscopy. The latter technique allowed us to assess the branching density of DGL, the degree of which (ca. 25%) turned out to be intermediate between previously described dendritic graft poly(L-lysines) and lysine dendrimers. An optimised monomer (NCA) versus macroinitiator (DGL G(n-1)) ratio allowed us to obtain unimodal molecular weight distributions with polydispersity indexes ranging from 1.3 to 1.5. Together with the possibility of reaching high molecular weights (with a polymerisation degree of ca. 1000 for G5) within a few synthetic steps, this synthetic route to DGL provides an easy, cost-efficient, multigram-scale access to dendritic polylysines with various potential applications in biology and in other domains.


Assuntos
Anidridos/química , Dendrímeros/síntese química , Lisina/síntese química , Substâncias Macromoleculares/síntese química , Polilisina/síntese química , Polímeros/síntese química , Dendrímeros/química , Lisina/química , Substâncias Macromoleculares/química , Espectroscopia de Ressonância Magnética , Modelos Químicos , Polilisina/química , Polímeros/química , Solubilidade , Temperatura , Água
15.
J Hazard Mater ; 170(1): 111-7, 2009 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-19497667

RESUMO

The wastewaters resulting from different baths of a dyeing factory specialized in denim fabric are collected and treated by an activated sludge plant. This study investigated the coupling of activated sludge treatment with either nanofiltration (NF) or reverse osmosis (RO) to recycle water and reuse it in the process. We first conducted NF experiments with a HL membrane in different configurations: dead end and cross-flow for flat sheets and also in spiral wound form. Results on water permeation and salt rejection show that performances are configuration dependent. Then, for the study of the NF/RO textile wastewater treatment, experiments were conducted with spiral wound membranes in order to be closest to the industrial configuration. After analyzing the removal efficiencies of suspended solids and chemical oxygen demand (COD) of the treatment plant, we conducted NF experiments using an HL2514TF spiral wound membrane preceded by ultrafiltration (UF) treatment. We used as well an RO membrane (AG2514TF) to compare performances in water yield and quality for the same pumping costs. The results show that NF allows higher yield, while respecting the Tunisian standard of water reuse (COD<90 mg L(-1)). Above 9bar, the TDS rejection reaches 60% and the hardness is lower than the factory constraint (100 mg L(-1) CaCO(3)), allowing the reuse of the water in the process.


Assuntos
Resíduos Industriais/prevenção & controle , Indústria Têxtil , Purificação da Água/métodos , Carbonato de Cálcio , Conservação dos Recursos Naturais/métodos , Filtração/métodos , Membranas Artificiais , Nanotecnologia , Osmose , Tunísia
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