Interaction Between an Ethoxylated Alkylphenol Polymer with Formaldehyde and Triblock polyEO–polyPO–polyEO Copolymer in Aqueous Solutions

The interaction between an ethoxylated alkylphenol polymer with formaldehyde (EAPPF) and a triblock polyEO–polyPO–polyEO copolymer (TBCP) in aqueous solutions has been investigated in detail by means of surface tension, steady-state fluorescence, dynamic light scattering (DLS) measurements and computer simulations. For comparison, the ethoxylated alkylphenol oligomer (EAPO), which is the monomer unit of EAPPF, and another nonionic water-soluble polymer PEG were also selected to get more information about the interaction between different types of surfactants and polymers. The surface properties of mixed systems at the air/water surface were evaluated from surface tension measurements. Information about the hydrophobic microenvironment and size of the aggregates was obtained from steady-state fluorescence using pyrene as a hydrophobic probe and DLS measurements, respectively. The dissipative particle dynamics simulation method was applied to simulate the interaction between EAPPF (or EAPO) and TBCP (or PEG) in aqueous solutions. The synergetic interaction between EAPPF (or EAPO) and TBCP in binary mixed solution enhanced the adsorption of surfactant molecules (EAPPF or EAPO) at the interface, while no obvious interaction between EAPPF (or EAPO) and PEG was observed.     

Thermal behaviour of polyethylene‐block‐poly(methyl methacrylate) block copolymer: effect of multiple heating and cooling rates versus mathematical artefact

The melting and crystallization behaviours of a polyethylene‐block‐poly(methyl methacrylate) (PE‐b‐PMMA) diblock copolymer and a PE homopolymer were investigated using multiple heating and cooling rate differential scanning calorimetry (DSC) experiments, and modelling of the crystallization kinetics and lamellar thickness distribution. This new model was first validated applying literature and experimental data. The model‐predicted morphology (n = 3.2) closely matched the spherulitic morphology (n = 3), which was determined using polarized optical microscopy. For each experimental cooling rate, the model predicted diblock copolymer crystallinity that well matched the entire DSC crystallinity curve, notably for an Avrami–Erofeev index of n = 2; and apparent crystallization activation energy that hardly varied with the cooling rates used, relative crystallinity (α), and crystallization temperature or time. This disfavours the concept of variable activation energy. The use of the right crystallization model and parameter estimation algorithm is important for addressing the mathematical artefact. Under non‐isothermal cooling, the PE‐b‐PMMA diblock copolymer, as per the model prediction, crystallized without confinement (n ≠ 1), preserving the cylindrical structure. From the characteristic shapes of the crystallization function f(α(T)) versus 1/T and crystallization rate versus α plots, the resulting T_cmax and narrow α_max range can guide the search for an appropriate crystallization model. The overall treatment illustrated in this study is not restricted to a PE homopolymer and a PE‐b‐isotactic PMMA block copolymer. It can be generally applied to crystalline homopolymers and copolymers (alternating, random and block), as well as their blends. The block copolymers and blends can be crystalline–amorphous as well as crystalline–crystalline. © 2014 Society of Chemical Industry     

Self-Assembled Glucose and Thermo Dual-Responsive Micelles of an Amphiphilic Graft Copolymer

Amphiphilic copolymers P(PBA)-g-P(PEG) containing poly(phenylboronic acid) (PPBA) and poly(ethylene glycol) (PEG) side chains were synthesized by copolymerization of 4-vinylphenylboronic acid (PBA) and poly(ethylene glycol) methyl ether methacrylate. The surface tension results showed that the critical micelle concentration (CMC) of P(PBA)-g-P(PEG) was 0.09 g/L. TEM revealed that these copolymers self-assembled into regular sphere micelles above CMC. The photon correlation spectroscopy suggested that they had unique performance of thermo-induced self-assembly. Above critical micelle temperature, they self-assembled into monodisperse micelles with thermosensitivity. Hydrodynamic diameters of these micelles increased dramatically in the presence of glucose. The glucose-regulated drug release behavior was observed through UV-vis spectroscopy.     

Synthesis of Artificial Membrane of Copolymer (Acrylic Acid/Butyl Acrylate) PAA-PBA for the Design of Polymersomes

Polymersomes are synthetic vesicles that imitate biological membrane functions. The purpose of this work is to develop an artificial copolymer (acrylic acid/butyl acrylate) PAA-PBA membrane by random synthesis. A factorial design 2^k was applied to determine the conditions for this reaction. The Fourier transform infrared spectrometer indicated that the polymerization reaction was complete without a –C=C-absorption peak. The Gordon-Taylor equation showed that the hydrophilic part of the PAA-PBA composition is 20–40% and the hydrophobic part 60–80%. The authors selected the copolymers with low molecular weight, within the range of 3134.49 ± 994.21 g/mol and a polydispersity of 1.40.     

Heteroarm Star-Shaped Poly (N-isopropylacryamide-co-itaconic acid) Copolymer Prepared by Glucose Core as ATRP Initiator

Star-shaped temperature- and pH-sensitive poly (N-isopropylacryamide-co-itaconic acid) copolymer is synthesized by atom transfer radical polymerization (ATRP) using 1,2,3,4,6-penta-O-Isobutyrylbromide-α-D-glucose as 5-Arm ATRP Initiator. For ATRP of itaconic acid (IA), carboxylic groups of IA are protected via silylation by hexamethyldisilazane (HMDS) using Fe₃O₄ as a magnetic catalyst. The polymerization is carried out in 2-propanol/toluene 50:50 (v/v) mixed solvent at 90°C. Structure of copolymers is studied with FT-IR, ¹H NMR, glass transition temperature (Tg), and scanning electron microscopy (SEM). Results of temperature, pH, and percentage variation on polymer structure and the effects on lower critical solution temperature (LCST), which is investigated with potentiometery and conductometry, show that LCST of copolymer is around body temperature and demonstrate the ability of this polymer in the design of controlled drug delivery systems. According to the obtained results from naltrexone release, the investigated star-shaped copolymer may have potential applications in the controlled release of drugs.     

A Novel Light-Cured Dental Material Based on Maleic Copolymer Functionalized With Urethane Derivative for Dental Applications

The purpose of this work was to obtain a polymeric material aimed at being easily applied in a thin film on an organic substrate for dental applications. A maleic anhydride copolymer functionalized with a urethane derivative bearing methacrylate groups was synthesized, and by its mixing with commercial dental monomers, two light-curing formulations were prepared and investigated. The surface morphology and physicochemical properties of the obtained materials are affected by their composition. An increase of the diffusion coefficient from 0.38 at 3.58 µm²/s (estimated by fluorescence recovery after photobleaching) could ensure minimal moisture of an organic injectable paste situated under this polymer film.     

2-HEMA-g-Na-PCMS: A Novel Polymeric Matrix for the Controlled Release of Paracetamol

2-hydoxyethyl methacrylate (2-HEMA) was graft copolymerized with sodium salt of partially carboxymethylated starch (Na-PCMS). Thus prepared, graft copolymer (2-HEMA-g-Na-PCMS) was used as a polymeric matrix for preparing controlled-release tablets of paracetamol. Tablets of standard specification were prepared using the wet granulation method. Ingredients utilized for tablet preparation were 2-HEMA-g-Na-PCMS graft copolymer, paracetamol and excipients. Tablets were characterized for disintegration time (min), hardness, angle of repose and percent friability. It was found that tablets prepared by the compression of graft copolymer, excipients and drug in specified ratios resulted in an excellent controlled-release tendency of paracetamol.     

The 31 Helix-Coil Transition for Polypeptides.: Circular Dichroism Studies

Abstract

Circular dichroism has become a popular method for following conformational transitions induced in optically active polymers. Recent refinement of experimental spectra obtained from model polypeptides by computer fitting to spectra obtained from solutions of proteins of known conformation has verified the applicability of the models chosen for the α helical and β conformations. However, the spectrum required for disordered regions was in conflict with much of the literature and agrees with our assignment based on studies of collagen and collagen models at elevated temperature. This spectrum consists of two troughs, one at ~225 nm and the other at ~200 nm. The latter had previously been associated with random polypeptides and we have shown the former to be sensitive to disorder in polymers approaching the 3₁ helical conformation. This paper presents the results from a study of three polypeptides which undergo a 3₁ helix → disorder transition.     

Synthesis and Characterization of Biodegradable Polymer – Used as a Pour Point Depressant for Lubricating Oil

Additives based on polymers of alkyl methacrylate used in lubricant composition improve the viscometric and rheological properties of the lubricant and provide fuel economy. They are also looked upon to provide additional performance characteristics such as improved low temperature fluidity, dispersancy and thickening. However, the recent demand for eco-friendly technology guided us to incorporate the sunflower chemistry into the acrylate skeleton through the process of copolymerization in anticipation of getting an ideal blend of performance as well as eco-friendly chemistry. The present investigation comprises the homo and copolymerization of sunflower oil with different mass fraction of methyl methcrylate (MMA), decyl acrylate (DA) and styrene, characterizations and their evaluations as a pour point depressant in base oils.