Partial Hydrolysis Of Poly Research Articles

Development of novel self-assembled polymeric micelles from partially hydrolysed poly(2-ethyl-2-oxazoline)-co-PEI-b-PCL block copolymer as non-viral vectors for plasmid DNA in vitro transfection

A new efficient, non-viral gene delivery cationic polymeric micellar system was developed by partial hydrolysis of poly(2-ethyl-2-oxazoline) (PEtOx) with two different hydrolysis percentages of PEtOx (30% and 60%) to reduce the disadvantages of the PEI. These self-assemble amphiphilic cationic micelles prepared from poly(2-ethyl-2-oxazoline)30%-co-poly(ethyleneimine)-block-poly(ɛ-caprolactone) (PEtOx30%-co-PEI-b-PCL) (PPP30) and poly(2-ethyl-2-oxazoline) 60%-co-poly(ethyleneimine)-block-poly(ɛ-caprolactone) (PEtOx60%-co-PEI-b-PCL) (PPP60) block copolymers were successfully condensed with pEGFP-C3 plasmid DNA via electrostatic interactions to form micelle/DNA complexes with desirable particle sizes. All formulations showed low critical micelle concentration (CMC) values that means highly stable in serum containing medium. Polymeric micelles were also evaluated for their stability in the presence of serum and nuclease as well as cytotoxicity and transfection efficiency. All our results proved that our novel polymeric micellar system prepared by PPP60 block copolymer offer to be an efficient promising carrier for gene delivery applications. Moreover, these findings contribute to design and development of novel gene vectors with tunable and functionality features and also to reduce the cytotoxicity of PEI by partial hydrolysis of PEtOx an alternative synthesis method to produce linear PEI.

Sizes of Macromolecules of Copolymers of N-Methyl-N-Vinylacetamide and N-Methyl-N-Vinylamine Hydrochloride with Low Charge Linear Density

Series of copolymers of N-methyl-N-vinylacetamide and N-methyl-N-vinylamine hydrochloride containing from 1.5 to 17% mol % of charged units were obtained by partial hydrolysis of poly(N-methyl-N-vinylacetamide). A complex of hydrodynamic investigations of their diluted solutions (viscous flow, velocity sedimentation, translational diffusion) was performed in 0.2 M NaCl in order to determine the molecular characteristics of copolymers. Viscosimetric investigations were performed in salt-free solution (ionic strength ~10–6 M) to study intrachain electrostatic interactions; the influence of charge linear density on the sizes of polyelectrolyte macromolecules was studied under these conditions. The examination of hydrodynamic volumes, equilibrium rigidity, and/or swelling coefficients of charged chains was performed.

Full and partial hydrolysis of poly(2-oxazoline)s and the subsequent post-polymerization modification of the resulting polyethylenimine (co)polymers

This review discusses the full and partial hydrolysis of poly(2-oxazoline)s as well as the synthetic methods that have been reported to modify the resulting secondary amine groups.

Developing Porous Honeycomb Films Using Miktoarm Star Copolymers and Exploring Their Application in Particle Separation

This paper reports for the first time the synthesis and application of miktoarm star copolymers to produce highly ordered honeycomb films using the breath figure technique. Miktoarm star copolymer containing a cross-linked core and two arm species, e.g., polystyrene and poly(t-butyl acrylate), is successfully synthesized using ATRP in a one-pot arm-first method. Various experimental parameters, including polymer architectures, solvents, polymer concentrations, and substrates, are explored to investigate their effects on the structure of the honeycomb films. It is found that miktoarm star copolymers with high molecular weight and spherical shape could readily produce ordered honeycomb films in a broader range of concentrations and humidity than linear block copolymers with similar chemical compositions but lower molecular weight. Partial hydrolysis of poly(t-butyl acrylate) arm species in the honeycomb film transforms the surface property from hydrophobic to hydrophilic while maintaining the film's mechanical stability in water. This porous monolayer film with uniform pore size distribution and inter-connected pore channels is successfully applied for separation of microparticles with different sizes.

Linear polyethylenimine produced by partial acid hydrolysis of poly(2-ethyl-2-oxazoline) for DNA and siRNA delivery in vitro

Polyethylenimines (PEIs) are the most efficient synthetic vectors for gene delivery available to date. With its high charge density and strong proton-buffering effect, PEI has an ability to condense DNA and small interfering RNA at physiologic pH. However, the polymer suffers from the disadvantage of high cellular toxicity. To reduce its cellular toxicity, we synthesized linear PEIs by partial hydrolysis of poly(2-ethyl-2-oxazoline). Three linear PEIs with different hydrolysis percentages (30%, 70%, and 96%, respectively) were produced as PEI30, PEI70, and PEI96. PEI30 and PEI96 cannot be considered as suitable transfection agents because of low transfection efficiency (PEI30) or high cellular toxicity (PEI96). PEI70 displayed very weak cell toxicity. The charge density of this polymer (PEI70) was strong enough to condense DNA and small interfering RNA at a physiologic pH of 7.4. Our results also show that PEI70 was highly efficient in DNA delivery and small interfering RNA-mediated knockdown of target genes. Thus, polymers such as PEI70 appear to be very promising vectors for gene delivery.

Partial Hydrolysis of Poly(2‐ethyl‐2‐oxazoline) and Potential Implications for Biomedical Applications?

The hydrolysis of PEtOx is studied to evaluate the potential toxicity of partially hydrolyzed polymers that might interfere with its increasing popularity for biomedical applications. The hydrolysis of PEtOx is studied in the presence of digestive enzymes (gastric and intestinal) and at 5.8 M hydrochloric acid as a function of temperature (57, 73, 90, and 100 °C). It is found that PEtOx undergoes negligible hydrolysis at 37 °C and that thermal and solution properties are not altered when up to 10% of the polymer backbone is hydrolyzed. Mucosal irritation and cytotoxicity is also absent up to 10% hydrolysis levels. In conclusion, PEtOx will not decompose at physiological conditions, and partial hydrolysis will not limit its biomedical applications.

Thermal Cloud Point Fractionation of Poly(vinyl alcohol-co-vinyl acetate): Partition of Nanogels in the Fractions

Poly(vinyl acetate-co-vinyl alcohol) (PVA), well-known as emulsion stabilizers, are obtained by partial hydrolysis of poly(vinyl acetate) (PVAc). Their thermal cloud point fractionation was performed in aqueous medium between 40 and 75 °C. This fractionation was carried out in order to get an insight in the partition of the initially present nanogels in the different fractions. All the fractions were characterized by size exclusion chromatography (SEC), NMR and dynamic light scattering (DLS) giving access to average degree of polymerization , DPw average degree of hydrolysis DH, average sequence lengths of vinyl acetate VAc, volume fraction and average size diameter (Dv) of nanogels and “free PVA chains”. The polydispersity of the samples in DPw, DH and VAc could be confirmed. The nanogels characterized by the highest values of volume fraction and Dv, in the range of 40–43 nm, were separated in the first coacervate fraction, whereas the most soluble fraction with low VAc content does not contain nanogels but only “free chains” of a Dv value of around 7–8 nm. The nanogels in the various fractions could further be disaggregated into “free chains” by complex formation with sodium dodecyl sulfate (SDS).

Determination of %polyvinyl alcohol in vinyl acetate‐alcohol resins by quantitative near infrared spectroscopic analysis

AbstractA number of vinyl acetate‐alcohol resins (VAAR) samples were collected during partial hydrolysis of poly(vinyl acetate) at different conversions levels (<30%). Using these VAAR samples with known OH (hydroxyl) content, it has been demonstrated that near infrared (NIR) spectroscopic data produced a near perfect fit for the calibration of OH content. A 4‐factor partial least‐squares method was employed and gave the best results. Further work also confirmed that NIR, operating at a well‐controlled environment, is able to quantify, with great precision, the OH content of the selected model compound. In the case for the OH content analysis of VAAR resins, solvent mix ratio (methyl acetate: methanol) and temperature have been identified to be the two most influential factors on the analytical results. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:1–10, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20166

On‐line acoustic attenuation spectroscopy of emulsions stabilized by vinyl alcohol–vinyl acetate copolymers: a model system for the suspension polymerization of vinyl chloride

AbstractBACKGROUND: Poly[(vinyl alcohol)‐co‐(vinyl acetate)] (PVA) copolymers obtained by partial hydrolysis of poly(vinyl acetate) are currently used as industrial stabilizers in the suspension polymerization of vinyl chloride monomer (VCM). Their molecular characteristics, mainly the average degree of hydrolysis (DH) and average degree of polymerization (DPw), have a major influence on the monomer droplet size and the properties of the final poly(vinyl chloride) resin.RESULTS: The average droplet size and size distribution of chlorobutane/water emulsions, as a model system for VCM/water emulsions, were studied using acoustic attenuation spectroscopy on‐line with an agitated laboratory reactor. The emulsions were stabilized by PVA with DH values between 73 and 88 mol% and DPw values between 450 and 2500. The effects of agitation speed, stirring time and concentration of the PVA copolymers were investigated. An attempt was made to correlate the interfacial tension and the droplet size.CONCLUSION: On‐line acoustic spectroscopy appears to be a suitable technique for the real‐time control of the droplet size of monomer suspensions. The advantages and limitations of the technique are outlined. The validity and the application limits of the commonly cited correlation between the droplet size and the Weber number are established for polymeric surfactant‐stabilized emulsions. Copyright © 2009 Society of Chemical Industry

The Synthesis of High Molecular Weight Partially Hydrolysed Poly(vinyl alcohol) Grades Suitable for Nanoparticle Fabrication

Poly(vinyl alcohol) (PVA) is a highly versatile synthetic polymer that is formed by full or partial hydrolysis of poly(vinyl acetate) (PVAc). A wide range of PVA partially hydrolysed grades are commercially available, but the amphiphilic grades of the polymer (30-60% hydrolysis), which probably the most interesting in terms of drug delivery, are not readily available. As a consequence few studies have assessed the application of low hydrolysis PVA polymers to form nanocarriers. The aims of this study were to synthesise amphiphilic grades of PVA on a laboratory scale, analyse their chemical properties and determine whether these grades could be used to form nanoparticles. PVA 30%, PVA 40%, PVA 50% and PVA 60% were synthesised via direct saponification of PVAc. All grades of PVA synthesised had degrees of hydrolysis close to those predicted from the stoichiometry of the saponification reaction. The PVA grades displayed <1.5% batch to batch variability (n=3) in terms of percentage hydrolysis, demonstrating the manufacture process was both reproducible and predictable. Analysis of the polymer characteristics using 13C nuclear magnetic resonance and differential scanning calorimetry revealed that all PVA grades contained block distributions (i.e., eta <1) of vinyl alcohol monomers (eta ranged from 0.33-0.45) with a high probability of adjacency calculated for the hydroxylated units (P(OH) ranged 0.926-0.931). All the grades of PVA formed nanoparticles using a precipitation technique with a trend towards smaller particle size with increasing degree of PVA hydrolysis; PVA 30% resulted in significantly larger nanoparticles (225 nm) compared to PVA 40-60% (137-174 nm).

Synthesis and Anticoagulant Properties of a Novel Heparinoid N-Sulfate-Bearing Vinylpolymer

A novel heparinoid polymer was prepared with an N-sulfate side chain group by sulfation of poly( N-vinylacetamide-co-vinylamine) [poly(NVA-co-VAm)] which was obtained by the partial hydrolysis of poly( N-vinylacetamide) [poly(NVA)]. The hydrolysis of poly(NVA) was controlled by reaction time and temperature and the sulfation of poly(NVA-co-VAm) was performed with chlorosulfonic acid. Poly( N-vinylacetamide-co-vinylamine-co-vinylsulfamic acid) [poly(NVA-co-VAm-co-VSA)] was confirmed by means of IR spectroscopy, and the degree of sulfation of poly(NVA-co-VAm-co-VSA) was estimated by elemental analysis. The anticoagulant properties of poly(NVA-co-VAm-co-VSA) were evaluated using the Lee-White clotting test and activated partial thromboplastin time (APTT) test. The human whole blood clotting time in the presence of poly(NVA-co-VAm-co-VSA) was prolonged compared with poly(NVA) and poly(NVA-co-VAm). The clotting time was prolonged with increased N-sulfate groups on the polymer. APTT tests of the polymer were also prolonged with N-sulfate increases. The results suggest that the N-sulfate components on the polymer can endow anticoagulant activity to synthetic polymers.

Vinyl polymerization, 366. Polymerization of methyl methacrylate initiated with a hydrolyzed product of poly[bis(2‐chloroethyl) vinylphosphonate

AbstractPVPA, a simulated terpolymer from vinylphosphonic acid, 2‐hydroxyethyl hydrogen vinylphosphonic acid and 2‐chloroethyl hydrogen vinylphosphonic acid, was prepared by partial hydrolysis of poly[bis(2‐chloroethyl) vinylphosphonate] (2). In aqueous solution, PVPA was found to be able to polymerize methyl methacrylate (MMA) without any further initiator by a radical mechanism. The effects of the masses of water, PVPA and MMA on the polymerization were studied. The overall activation energy was found to be 77,7 kJ.mol−1. The Michaelis‐Menten equation could be applied for the relationship between the mass of MMA and the rate of polymerization (Rp). The plots of pH of aqueous solution against Rp gave a downward bell‐type curve. An initiation mechanism of the polymerization process is discussed.

Comportement hydrophile-hydrophobe de copolymeres d'acide acrylique et de N-(sec-butyl)- N-methyl-acrylamide en solution aqueuse

A series of amide-acid copolymers were obtained by partial hydrolysis of poly N-(sec-butyl)- N-methyl-acrylamide (PAAm). In aqueous solution, their hydrophobic character decreased as the mole fraction of acidic groups increased. Total hydrolysis led to poly(acrylic acid) (PAA). Hydrophobic character was studied by potentiometric titrations of salt-free solutions and is discussed in terms of “conformational transition” as for poly(methacrylic acid) (PMA). The free energy change of the transition is described as the sum of the partial contributions of the main chain and of the lateral groups. The N- N-disubstituted amide groups give rise to a hydrophobic contribution as compared to the solubility of hydrocarbons in water. The viscometric titrations of the copolymer with 55·1 per cent of acidic groups and of PMA in presence of Ca 2+ ions are compared. The relation between the hydrophilic hydrophobic behaviour and the distribution of the hydrophilic and hydrophobic moieties of these polyelectrolytes is discussed.