Design of Polyurethane Composed of Only Hard Main Chain with Oligo(ethylene glycol) Units as Side Chain Simultaneously Achieved High Biocompatible and Mechanical Properties

In order to create a novel rigid polymer material for biomedical application, we designed the polymer structure of polyurethane, bearing oligo­(ethylene glycol) (OEG) as the side chain, which was synthesized by only hard main chain using diisocyanate and short diol monomers. We investigated the effect of the graft structure of OEG units on polymer properties using pentaethylene glycol (OEG₅) or propanediol (PDO) in the main chain as the other diol monomers. Furthermore, the rigid 4,4′-methylene­bis­(cyclohexyl isocyanate) (HMDI) and symmetric hexamethylene diisocyanate (HDI) were selected for the isocyanate monomers. As a result, there is a significant difference in various properties, depending on both the existence and the position of OEG units in the polymer structure. For example, differential scanning calorimetry (DSC) showed that the graft structure of OEG caused a decrease in the glass transition temperature from 73 to 35 °C in the case of using HMDI as well as a disappearance of the melting point in the case of using HDI. The Fourier transform infrared (FT-IR) spectra showed that the ordered hydrogen bonding of CO stretching vibration at 1682 cm^–1 was not observed in the polyurethane grafted with OEG. In the mechanical test of polyurethane composed of HMDI, the sample grafted with OEG exhibited excellent values of elastic modulus of 1.7 GPa and elongation at break of 184%, while that with OEG₅ and PDO in the main chain showed 115 MPa with 370% and 739 MPa with 19%, respectively. The polyurethane grafted with OEG showed around 0.6 μg/cm² of protein adsorption, almost the same as that with OEG₅ in the main chain, while that using PDO in the main chain showed more than 3.0 μg/cm². Therefore, the polyurethane design bearing OEG as the side chain provides excellent rigidity, toughness, and biocompatibility simultaneously

Thermosensitive Biodegradable Homopolymer of Trimethylene Carbonate Derivative at Body Temperature

A thermosensitive biodegradable homopolymer with a lower critical solution temperature (LCST) at body temperature was developed, with a poly­(trimethylene carbonate) (PTMC) backbone and oligoethylene glycol (OEG). The novel monomer was designed by the direct connection of OEG into trimethylene carbonate (TMC), and no other functional groups exist in the polymer structure. Such a well-defined monomer unit contributed to its homogeneous characteristics. Three units of ethylene glycol in the TMC derivative resulted in a water-soluble nature at room temperature, and the solution became cloudy at higher temperatures. The LCST ranged from 31 to 35 °C and was influenced by the molecular weight and polymer concentration. Four units of ethylene glycol, however, increased the LCST temperature to 72 °C. It is noteworthy that the present characteristics, thermosensitivity at body temperature, biodegradablility, and a well-defined homopolymer structure, are promising for biomedical applications as an essential material

Hydrogen-Bonded Multilayer Films Based on Poly(<i>N</i>‑vinylamide) Derivatives and Tannic Acid

Layer-by-layer (LbL) assembly based on hydrogen-bonding interactions is generating great interest for biomedical applications because it is composed of neutral polymers, while LbL assembly based on electrostatic interaction requires polycations which may induce toxicity issues. As a neutral polymer, poly­(<i>N</i>-vinylamide), which has low toxicity compared to poly­(acrylamide), has the potential to fabricate LbL thin films via hydrogen-bonding interactions. Herein we report interpolymer complexes of poly­(<i>N</i>-vinylamide)­s and natural polyphenol tannic acid to form the multilayered thin film. Poly­(<i>N</i>-vinylformamide) and poly­(<i>N</i>-vinylacetamide), which are water-soluble and insoluble in acetonitrile, could not form complexes with TA in water. On the other hand, <i>N</i>-alkylated poly­(<i>N</i>-vinylamide) such as poly­(<i>N</i>-ethyl-<i>N</i>-vinylformamide) and poly­(<i>N</i>-methyl-<i>N-</i>vinylacetamide) was soluble in acetonitrile and allowed the LbL assembly to proceed with TA. Furthermore, the QCM frequency shift with films composed of poly­(<i>N</i>-ethyl-<i>N-</i>vinylformamide) and TA were stable in water, while those of poly­(<i>N</i>-methyl-<i>N</i>-vinylacetamide) and TA were instable in water, possibly because formamide has lower steric hindrance compared to acetamide to allow stronger hydrogen-bonding interactions to take place. Thus, LbL assembly reactions with alkylated poly­(<i>N</i>-vinylamide)­s and TA were investigated and revealed that poly­(<i>N</i>-ethyl-<i>N</i>-formamide) and TA, which are water-soluble, effectively interacted with one another to generate water-stable hydrogen-bonded multilayered films

Development of a rapid <i>in vitro</i> tissue deadhesion system using the thermoresponsive sol-gel transition of hydroxybutyl chitosan

<p>In regenerative medicine, it has become increasingly important to collect cultured tissues using non-invasive methods. Enzymatic deadhesion is normally used to collect cells, but this method cannot be used when trying to collect whole tissues in order to avoid damaging cell–cell interactions. In order to resolve this issue, a thermoresponsive culture dish with poly(<i>N</i>-isopropyl acrylamide) (PNIPAAm) has been employed. This system can change its hydrophobicity depending on temperature. Thus, tissues can attach above 37 °C and be detached below 20 °C. However, the PNIPAAm system has some issues related to cost and detachment time. In this study, we developed a novel thermoresponsive detachment system using a polysaccharide derivative. We chose hydroxy butyl chitosan (HBC) as the thermoresponsive polymer because of its high biocompatibility and rapid phase transition. We developed a novel method of HBC synthesis in conditions that were milder than previously reported. We used spin-coating to make a thin coating on two kinds of culture dishes with various concentrations of HBC solution. Seeded cells attached to the surface at less than 0.5 mg/ml HBC coating concentration, and they could be successfully detached by simply lowering the temperature of the suspension dishes without enzymatic treatment; the cells took only 5–20 min to detach. To evaluate this system, we measured three metrics related to cell culturing on culture dishes: initial attachment rate, detachment rate and tissue detachment time. The study revealed that tissues could be detached faster on the suspension dishes used in this study than on PNIPAAm grafted dishes when HBC was coated at 0.5 mg/ml. We successfully developed a novel tissue detachment system using HBC. These results suggest that smart polymers may be useful in regenerative medicine.</p

Layer-by-Layer Assembly of Partially Sulfonated Isotactic Polystyrene with Poly(vinylamine)

The stereoregular synthetic polymer isotactic polystyrene bearing partially sulfonated groups (SiPS) was used as a layer-by-layer assembled thin film for the first time. When a low molecular weight compound was employed as the pair for the alternative layer-by-layer (LbL) assembly, the frequency shift was very small using quartz crystal microbalance (QCM) analysis, whereas poly­(vinylamine) (PVAm) formed an effective pair for the construction of LbL films with SiPS. When it was neutralized, SiPS was not assembled, probably due to the loss of effective polymer–polymer interactions. The ionic strength conditions revealed a slight difference of the assembly behavior on the isotactic polymer as compared to the atactic one. The assembled LbL film showed the same peaks over the range from 1141 to 1227 cm^–1 and 700 cm^–1 in the FT-IR/ATR spectra as the bulk complex of SiPS/PVAm, and the thickness on one side was calculated at 76 nm by QCM analysis. The surface roughness of the film was also observed by AFM

Near-Ultraviolet Circular Dichroism of Achiral Phenolic Termini Induced by Nonchromophoric Poly(l,l‑lactide) and Poly(d,d‑lactide)

Herein, we present the first induced chirality of vanillin and its phenolic analogs attached to the chain ends of poly­(l,l-lactide) and poly­(d,d-lactide). Vanillin analogs were used as chromophoric and luminophoric, but achiral, ring-opening initiators of corresponding chiral cyclic lactides. Induced chirality was evident from clear circular dichroism bands at 270–320 nm due to π–π* and n−π* transitions at the vanillin moiety. However, no circularly polarized luminescence band was detected. Density functional theory (DFT) and time-dependent DFT calculations suggested the existence of multiple through-space intramolecular CH/O interactions between the <i>ortho</i>-methoxy moiety of vanillin and nearest-neighbor lactic acid units. The terminus sensitively indicated whether the main-chain chirality was l or d

Stereocomplex Film Using Triblock Copolymers of Polylactide and Poly(ethylene glycol) Retain Paxlitaxel on Substrates by an Aqueous Inkjet System

The stereocomplex formation of poly­(l,l-lactide) (PLLA) and poly­(d,d-lactide) (PDLA) using an inkjet system was expanded to the amphiphilic copolymers, using poly­(ethylene glycol) (PEG) as a hydrophilic polymer. The diblock copolymers, which are composed of PEG and PLLA (MPEG-<i>co</i>-PLLA) and PEG and PDLA (MPEG-<i>co</i>-PDLA), were employed for thin-film preparation using an aqueous inkjet system. The solvent and temperature conditions were optimized for the stereocomplex formation between MPEG-<i>co</i>-PLLA and MPEG-<i>co</i>- PDLA. As a result, the stereocomplex was adequately formed in acetonitrile/water (1:1, v/v) at 40 °C. The aqueous conditions improved the stereocomplex film preparation, which have suffered from clogging when using the organic solvents in previous work. The triblock copolymers, PLLA-<i>co</i>-PEG-<i>co</i>-PLLA and PDLA-<i>co</i>-PEG-<i>co</i>-PDLA, were employed for square patterning with the inkjet system, which produced thin films. The amphiphilic polymer film was able to retain hydrophobic compounds inside. The present result contributed to the rapid film preparation by inkjet, retaining drugs with difficult solubility in water, such as paclitaxel within the films

Synthesis and Characterization of Modified Aliphatic Polycarbonates as Environmentally Friendly Oilfield Scale Inhibitors

Oilfield scale inhibitors have been used for many decades, mostly to fight carbonate and sulfate scaling. Many inhibitors are known, but only a few show good biodegradation to make them environmentally acceptable in areas with strict regulations, such as offshore Norway. Often high biodegradation is at the expense of other useful properties, such as thermal stability for high-temperature squeeze applications. We have now synthesized and investigated a new class of polycarbonate polymers with pendant anionic functional groups (carboxylate and phosphonate) as potential oilfield scale inhibitors. These polymers have a carbonate group in the backbone. Polymers with carboxylate and phosphonate side groups were prepared. We report here the scale inhibition performance of these polymers at 100 °C against both calcite and barite scaling at typical North Sea conditions in dynamic tube-blocking equipment, both before and after aging at 130 °C. The phosphonated copolymer gave very good performance against calcite scaling and showed good thermal stability. This polymer also gave a biodegradation of 36% in 28 days in seawater by the OECD 306 test

Sustainable Coating Materials: Exploring the Influence of Adjuvants on Kaolinite Suspension with Insights from Five Local Mining Clays

Herein, we presented a comprehensive case study on the kaolin suspension derived from mining powder, with a specific emphasis on its mineral constituents within the size range of 2–5 μm and its suitability in spray applications. We have systematically investigated the influence of adjuvants, existing in both organic molecules and polymers, on the sedimentation behavior of clay suspensions. The investigations included the analysis of turbidity, dispersion weight, pH, and surface charge as key parameters. Our findings revealed that the specific presence of PEG–PPG-PEG, PAA, and PSAMA had a notable effect on delaying the suspension of sedimentation by the actual sediment weight as well as enhancing the uniformity of clay coating by the reflection efficiency of coating materials in PPFD units. To enhance sustainability in coating materials, it was essential to elucidate the optimal amounts of adjuvants and the pH levels as they are closely related to the efficacy of tree-coated spraying and soil conditions

Additional file 1: of Aggregation Control by Multi-stimuli-Responsive Poly(N-vinylamide) Derivatives in Aqueous System

Supporting information. (DOCX 343 kb