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In recent times, there has been a significant surge in research interest surrounding thermo-responsive water-soluble polyacrylamides, primarily due to their intriguing capability to undergo significant solubility changes in water. These polymers exhibit the remarkable ability to shift from a soluble to an insoluble state in response to temperature variations. The capacity of these polymers to dynamically respond to temperature changes opens up exciting avenues for designing smart materials with tunable properties, amplifying their utility across a spectrum of scientific and technological applications. Researchers have been particularly captivated by the potential applications of thermo-responsive water-soluble polyacrylamides in diverse fields such as drug delivery, gene carriers, tissue engineering, sensors, catalysis, and chromatography separation. This study reports the construction and functionalization of polymer gels consisting of a polymer network of polyacrylamide derivatives with nano-sized structural units. Specifically, thermo-responsive polymer gels were synthesized by combining well-defined star-shaped polymers composed of polyacrylamide derivatives with a multifunctional initiator and linking method through a self-accelerating click reaction. The polymerization system employed a highly living approach, resulting in polymer chains characterized by narrow molecular weight distributions. The method’s high functionality facilitated the synthesis of a temperature-responsive block copolymer gel composed of N-isopropyl acrylamide (NIPA) and N-ethyl acrylamide (NEAA). The resulting polymer gel, comprising star-shaped block copolymers of NIPA and NEAA, showcases smooth volume changes with temperature jumps.

In this work, an innovative ionic liquid functionalized star-shaped polymer is synthesized by coupling star-polycaprolactone with benzimidazolium (star-PCL-Bim), and statically coated into a capillary column for gas chromatographic (GC) separations. The fabricated star-PCL-Bim capillary column with moderate-polar nature reveals a high column efficiency of 3598 plates/m for n-dodecane at 120 °C, and advantageous distinguishing ability (R > 1.5) for 9 aromatic isomer mixtures and 12 cis-/trans-isomers. Its excellent resolving capacity can be credited to the architecture of star-PCL-Bim, the PCL arms, and π-electron-rich benzimidazolium cations, and it results in a quite different retention behavior of star-PCL-Bim from that of star-PCL and commercial HP-35 columns, with "dual-nature" selectivity in separating a mixture including 29 compounds. These favorable chromatographic characteristics demonstrate the great application potential of this material in GC, and provide a prospective strategy to obtain high-performance stationary phases. [ABSTRACT FROM AUTHOR]

In this paper, we propose one-step synthetic strategies for obtaining well-defined linear and star-shaped polyvinylpyrrolidone (linPVP and starPVP). The produced macromolecules and a commercial PVP K30 with linear topology were investigated as potential matrices for suppressing metronidazole (MTZ) crystallization. Interestingly, during the formation of binary mixtures (BMs) containing different polymers and MTZ, we found that linear PVPs exhibit maximum miscibility with the drug at a 50:50 weight ratio (w/w), while the star-shaped polymer mixes with MTZ even at a 30:70 w/w. To explain these observations, comprehensive studies of MTZ-PVP formulations with various contents of both components were performed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained results clearly showed that the polymer's topology plays a significant role in the type of interactions occurring between the matrix and MTZ. Additionally, we established that for MTZ-PVP 50:50 and 75:25 w/w BMs, linear polymers have the most substantial impact on inhibiting the crystallization of API. The star-shaped macromolecule turned out to be the least effective in stabilizing amorphous MTZ at these polymer concentrations. Nevertheless, long-term structural investigations of the MTZ-starPVP 30:70 w/w system (which is not achievable for linear PVPs) demonstrated its complete amorphousness for over one month. [ABSTRACT FROM AUTHOR]

A search and analysis has been carried out of English-language 2005–2020 scientifi c literature devoted to methods of obtaining branched (co)polymers of acrylamide, acrylic acid and (met)acrylates in order to obtain novel materials with valuable properties. It has been found that modern methods of controlled radical polymerization are mainly used for this purpose, namely, atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT) and group transfer polymerization (GTP). In most cases, original synthesized compounds were the chain transfer agents in RAFT. Depending on the order of synthesis, a distinction is made between the “core–arms” and “arms–core” approaches. The prospects of using branched polymers of acrylamide, acrylic acid and (met)acrylates for bioconjugation, surface immobilization, tissue engineering, oil production enhancement, and fl occulation are estimated.

Blending hydrogel with an amphiphilic polymer can increase the hydrophobic drug loading and entrapment efficiency of hydrogel-based formulations. In this study, a hydrogel formulation with star-shaped polycaprolactone-b-poly(ethylene glycol) (PCL-b-PEG) as the hydrophobic drug cargo is produced. The 4-arm and 6-arm star-shaped PCL are synthesized with different molecular weights (5000, 10,000, 15,000 g/mol) via ROP and MPEG as the hydrophilic segment is attached via the Steglich esterification. FTIR and 1H-NMR analysis showed the presence of all functional groups for homopolymers and copolymers. Mn for all synthesized polymers is close to the theoretical value while GPC spectra showed a monomodal peak with narrow molecular weight distribution (PDI:1.01–1.25). The thermal degradation temperature and crystalline melting point of synthesized polymers increase with the increase in molecular weight and number of arms. All formulations possess high drug loading and entrapment efficiency (>99%) and increase with increasing molecular weight, number of arms, and amount of polymer in the formulations. All formulations showed a sustained drug release pattern with no initial burst, which follows the Korsmeyer–Peppas kinetic model. The polymer hydrogel formulations showed antibacterial activity against E. coli and S. aureus. The hydrogel containing 4-arm PCL15k-PEG is chosen as the best formulation due to its high drug release, good antimicrobial activity, and morphology. [ABSTRACT FROM AUTHOR]

• For the first time, a polymer star with functional groups in the core with a controlled spatial arrangement of the arms and functional groups relative to the plane of the cyclic core (strictly on different sides and statistically) was synthesized. • For their synthesis, a synthetic approach recently developed by us was used, associated with the sequential use of hydrothiolation and hydrosilylation reactions of polyfunctional organosilicon compounds. • It was shown that the core with alkoxy groups suppresses crystallization as effectively as the cores without alkoxy groups, studied in earlier works for similar systems. • It was shown that the structure of the core (ordered/disordered) does not affect the thermal properties of the polymer star. • The study of monolayers of the obtained functional polymer stars in a Langmuir bath, combined with the study of the zeta potential and microscopy at the Brewster angle, showed that the isomerized star is characterized by a lower order, larger areas of the onset of the surface pressure isotherm and a higher surface pressure of the conformational transition compared to the stereoregular one. Siloxane star-shaped polymers have been obtained by sequential hydrothiolation and hydrosilylation of vinyl- and hydride-containing tetracyclosilsesquioxane. The mild conditions of these reactions avoid ring isomerization, opening the way to star-shaped polymers based on a stereoregular silsesquioxane ring. Monofunctional telechelic PDMS and a mixture of polymer star-shaped stereoisomers were synthesized as reference materials. All resulting compounds bore the same functional groups and were analyzed by GPC, TGA, DSC and NMR. The study of monolayers of these compounds on the Langmuir trough allowed to evaluate the influence of stereoregularity and pre-organization of the star PDMS on the parameters of the formed monolayers. [Display omitted] [ABSTRACT FROM AUTHOR]

A star-shaped polymer (Star-PEG-PCL2) was synthesized to with PCL and PEG, and used as a stationary phase for gas chromatography. The statically coated Star-PEG-PCL2 column exhibited an efficiency of 2260 plates/m determined by naphthalene at 120 °C and moderate polarity. The Star-PEG-PCL2 column showed high resolution performance for isomers of a wide ranging polarity, including methylnaphthalenes, halogenated benzenes, nitrobenzene, phenols, and anilines, and displayed dual-nature selectivity for a mixture of 17 analytes. Also, the Star-PEG-PCL2 column exhibited good separation performance and column inertness for Grob test mixture and a series of cis-/trans-isomers. In addition, it exhibited advantageous separation performance over the commercial HP-35 and PEG-20M columns for chloroaniline and bromoaniline isomers through its unique three-dimensional framework. In conclusion, it has good potential as a new stationary phase for separating a variety of analytes because of its special structure and excellent separation performance. [ABSTRACT FROM AUTHOR]

Star-shaped poly(ethylene glycol) (PEG) chain termini were functionalized with alendronate to create transient networks with reversible crosslinks upon addition of calcium ions. The gelation ability of alendronate-functionalized PEG was greatly dependent on the number of arms and arm molecular weight. After mixing polymer and calcium solutions, the formed hydrogels could be cut and then brought back together without any visible interface. After 2 minutes of contact, their connection was strong enough to allow for stretching without tearing through the previous fracture surface. Oscillatory rheology showed that the hydrogels recovered between 70 and 100% of the original storage and loss modulus after rupture. Frequency sweep measurements revealed a liquid-like behavior at lower frequencies and solid-like at high frequencies. Shifting frequency curves obtained at different calcium and polymer concentrations, all data collapsed in a single common master curve. This time-concentration superposition reveals a common relaxation mechanism intrinsically connected to the calcium-bisphosphonate complexation equilibrium.

To study the self-assembly and hydrogel formation of the star-shaped graft copolypeptides with asymmetric topology, star-shaped poly(L-lysine) with various arm numbers were synthesized by using asymmetric polyglycerol dendrimers (PGDs) as the initiators and 1,1,3,3-tetramethylguanidine (TMG) as an activator for OH groups, followed by deprotection and grafting with indole or phenyl group on the side chain. The packing of the grafting moiety via non-covalent interactions not only facilitated the polypeptide segments to adopt more ordered conformations but also triggered the spontaneous hydrogelation. The hydrogelation ability was found to be correlated with polypeptide composition and topology. The star-shaped polypeptides with asymmetric topology exhibited poorer hydrogelation ability than those with symmetric topology due to the less efficient packing of the grafted moiety. The star-shaped polypeptides grafted with indole group on the side chain exhibited better hydrogelation ability than those grafted with phenyl group with the same arm number. This report demonstrated that the grafted moiety and polypeptide topology possessed the potential ability to modulate the polypeptide hydrogelation and hydrogel characteristics. [ABSTRACT FROM AUTHOR]

To study the self-assembly and hydrogel formation of the star-shaped graft copolypeptides with asymmetric topology, star-shaped poly(L-lysine) with various arm numbers were synthesized by using asymmetric polyglycerol dendrimers (PGDs) as the initiators and 1,1,3,3-tetramethylguanidine (TMG) as an activator for OH groups, followed by deprotection and grafting with indole or phenyl group on the side chain. The packing of the grafting moiety via non-covalent interactions not only facilitated the polypeptide segments to adopt more ordered conformations but also triggered the spontaneous hydrogelation. The hydrogelation ability was found to be correlated with polypeptide composition and topology. The star-shaped polypeptides with asymmetric topology exhibited poorer hydrogelation ability than those with symmetric topology due to the less efficient packing of the grafted moiety. The star-shaped polypeptides grafted with indole group on the side chain exhibited better hydrogelation ability than those grafted with phenyl group with the same arm number. This report demonstrated that the grafted moiety and polypeptide topology possessed the potential ability to modulate the polypeptide hydrogelation and hydrogel characteristics.

This study presents a novel approach by utilizing poly(vinylpyrrolidone)s (PVPs) with various topologies as potential matrices for the liquid crystalline (LC) active pharmaceutical ingredient itraconazole (ITZ). We examined amorphous solid dispersions (ASDs) composed of ITZ and ( i ) self-synthesized linear PVP, ( ii ) self-synthesized star-shaped PVP, and ( iii ) commercial linear PVP K30. Differential scanning calorimetry, X-ray diffraction, and broad-band dielectric spectroscopy were employed to get a comprehensive insight into the thermal and structural properties, as well as global and local molecular dynamics of ITZ-PVP systems. The primary objective was to assess the influence of PVPs' topology and the composition of ASD on the LC ordering, changes in the temperature of transitions between mesophases, the rate of their restoration, and finally the solubility of ITZ in the prepared ASDs. Our research clearly showed that regardless of the PVP type, both LC transitions, from smectic (Sm) to nematic (N) and from N to isotropic (I) phases, are effectively suppressed. Moreover, a significant difference in the miscibility of different PVPs with the investigated API was found. This phenomenon also affected the solubility of API, which was the greatest, up to 100 μg/mL in the case of star PVP 85:15 w/w mixture in comparison to neat crystalline API (5 μg/mL). Obtained data emphasize the crucial role of the polymer's topology in designing new pharmaceutical formulations.

The ring opening polymerization reactions of ε-caprolactone and L-lactide in the presence of the initiator dipentaerythritol, generated the hydroxy-terminated 6-armed star-shaped ε-caprolactone and L-lactide oligomers (H6CLO and H6LAO), respectively. The disulfide-containing polyester-urethane networks (PN-LCxy-DSz, weight ratios of H6LAO/H6CLO: x/y = 1/0, 3/1, 1/1, 1/3, and 0/1, BHEDS/(H6LAO + H6CLO) molar ratios: z = 0, 1, and 3) were produced by reacting H6LAO, H6CLO and bis(2-hydroxyethyl)disulfide (BHEDS) with hexamethylene diisocyanate (HDI). Fourier-transform infrared (FT-IR) spectroscopy and gel fraction analyses were conducted, which revealed that the urethanization reaction proceeded smoothly to generate the polymer networks. The differential scanning calorimetry (DSC) experiments with the PN-LCxy-DSz networks revealed that the oligocaprolactone (CLO) segments were crystallized, while the oligolactide (LAO) segments were not. The dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) techniques were used to reveal the high compatibility of the LAO and CLO segments in the PN-LC31-DS1 network. The compatibility of the co-networks decreased with increasing CLO fraction. The cut lines in the PN-LCxy-DS1 (xy = 10, 31, 11, and 31) films self-healed at room temperature within 24 h. The PN-LC31-DS1 film exhibited the highest healing efficiency on the tensile strength (98.5%). In contrast, the cut lines in the PN-LC10-DS0 and PN-LC01-DS0 films, devoid of disulfide bonds, did not exhibit the self-healing property. [ABSTRACT FROM AUTHOR]

Recently due to the exclusive rheological properties and a highly branched structure, star-shaped polymers have received more attention. In the first section of the present work, the polyethylene glycol (PEG)-based star-shaped polymer systems were prepared from the reaction of methoxypolyethylene glycols with various molecular weight as arm and trimesoyl chloride (TMC) as a core. The structure of the synthesized star-shaped polymers confirmed using the Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The solubility test showed that the synthesized polymers are soluble in water, dimethyl sulfoxide, dimethylformamide, and chlorinated solvents. In the second part of this work, the crosslinked PEGs preparation possibility in the melt state by using the trimesic acid (TMA) and TMC as a crosslinker was investigated. Evaluation of the swelling and solubility behavior of the prepared systems showed that the prepared crosslinked systems with TMA are soluble in most of the organic solvents, while the crosslinked systems with TMC as a crosslinker are insoluble in all of the organic solvents and show the swellability characteristics. From the obtained results it is concluded that the TMC is a better crosslinker for the crosslinking of PEG in the melt state. [ABSTRACT FROM AUTHOR]

Linear and calix[4]arene based star-shaped poly-2-ethyl-2-oxazines have been explored in saline solutions at NaCl concentration of 0.0050 g cm−3. The calix[4]arene core promotes an aggregation in solutions of the star-shaped polymer and a decrease in its phase separation temperature. Poly-2-ethyl-2-oxazine is more sensitive to the presence of NaCl in solution than the known poly-2-isopropyl-2-oxazolines. [ABSTRACT FROM AUTHOR]

Highlights • A water-based silsesquioxane (POSS)-containing polymer, POSS-PAA, was synthesized by interfacial polymerization. • The pollution of leather tanning wastewater can be reduced by this star-shaped polymer. • The hydrothermal stability and fullness properties of leather can be improved by POSS-PAA. Abstract A water-based silsesquioxane (POSS)-containing polymer, POSS-PAA, was synthesized by using octavinyl-POSS (V-POSS) and acrylic acid (AA) via interfacial polymerization. The TEM of POSS-PAA showed that the polymer formed a core-shell structure in aqueous solution and was well-dispersed. The star-shaped POSS-PAA and linear PAA were both tanned with 3.5% chromium tanning agent, and leather hide was tanned with 3.5% chromium tanning agent as a control. The results showed that the shrinkage temperature of wet-blue leather treated by POSS-PAA was increased by 3.5 °C than that of the control. The thickening rate of the POSS-PAA treated wet-blue leather samples was increased by 21% and 96% than the linear PAA-treated leather and the control leather, respectively. The EDS results suggested that the POSS-PAA pre-treated leather had a higher chromium content than the others, and the chromium distribution from the leather flesh side to the grain side was uniform. Moreover, the Cr 2 O 3 content in both the POSS-PAA and the PAA pre-treated tanning waste water was reduced by about 50%, compared to the control waste. The COD and BOD of the POSS-PAA pre-tanning waste were decreased compared to the others. Therefore, POSS-PAA appeared to be promising for promoting the development of cleaner leather production. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research focuses on the crystallizability and melt flow property of linear poly(L-lactide) (1-PLL) by blending with star-shaped 16-arm PLL (16-PLL). The 1-PLL/16-PLL blends were chain extended during melt blending using an epoxy-based chain extender. The crystallinities of the 1-PLL/16-PLL blends increased with the 16-PLL blend ratio and chain extension reaction. The 16-PLL enhanced formation of branched PLL during chain extension was confirmed by thermogravimetry, and improved the melt flow property of the blends. Stresses at break of the compressed blend films were improved slightly by the 16-PLL blending and chain extension. In conclusion, the 16-PLL could be used as a nucleating agent and a melt strength enhancer for linear PLL. [ABSTRACT FROM AUTHOR]

Enantiomeric hydroxy-terminated 4-armed star-shaped lactide oligomers (H4LLAO15 and H4DLAO15) with the degree of polymerization per arm, n = 15 and a hydroxy-terminated 4-armed star-shaped ε-caprolactone oligomer (H4CLOn) with n = 7 or 15 were crosslinked with methylenediphenyl 4,4′-diisocyanate at a weight ratio of H4LLAO15/H4DLAO15 = 1/0 or 1/1 produced conetworks (MH-4LLAO15/4CLOns or MH-4scLAO15/4CLOns) with the weight ratios of (H4LLAO15 + H4DLAO15)/H4CLOn of 75/25, 50/50 and 25/75 in addition to the homonetworks (MH-4LLAO15, MH-4scLAO15 and MH-4CLOn). The conetwork with a higher oligolactide (LAO) fraction and longer arm length of the oligocaprolactone segment possessed a better compatibility. Stereocomplex (sc) crystallites of the LAO segments were dominantly formed for MH-4scLAO15 and all MH-4scLAO15/4CLOns, which were regenerated during cooling and subsequent heating processes after melt. However, LAO homo-crystallites for MH-4LLAO15/4CLOns were not regenerated at all. MH-4LLAO15/4CLO15s and MH-4scLAO15/4CLO15s exhibited higher tensile toughnesses than MH-4LLAO15/4CLO7s and MH-4scLAO15/4CLO7s, respectively. Especially, the tensile toughness (25.8 MJ m−3) of MH-4scLAO15/4CLO15 75/25 was much higher than that (14.6 MJ m−3) of MH-4LLAO15/4CLO15 75/25. [ABSTRACT FROM AUTHOR]

A combination of ring-opening polymerization and atom-transfer radical polymerization was used to synthesize a four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate). The structure of obtained copolymer was determined by Fourier transform infrared,1H and13C NMR spectroscopies. The uniform electroactive nanofibers consisting blend of four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) copolymer and polyaniline were produced using electrospinning technique. The electroactivity of prepared nanofibers was investigated using cyclic voltammetry measurement. The morphologies of electrospun nanofibers produced from four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) and their blends with polyaniline were investigated by the scanning electron microscopy. The presence of polyaniline resulted in significant decrease of sticking fibers. [ABSTRACT FROM AUTHOR]

The reactions of a hydroxy-terminated 8-armed star-shaped ɛ-caprolactone oligomer (H8CLO), which was prepared by the ring opening polymerization of ɛ-caprolactone initiated by tripentaerythritol, with furfuryl isocyanate and (4-maleimidophenyl)isocyanate at the OH/NCO ratios of 1/1.5 and 1/1.2 produced furan- and maleimide-functionalized star-shaped oligomers (F8CLO and M8CLO), respectively. Furthermore, the same reactions except that the OH/NCO ratios are 1/0.75 and 1/0.6 produced half furan- and maleimide-functionalized star-shaped oligomers (H4F4CLO and H4M4CLO). By the furan/maleimide Diels-Alder (DA) reaction and/or OH/NCO urethanization reaction with 1,6-hexamethylene diisocyanate, a DA network (DA8CLO), polyurethane/DA network (PU4DA4CLO) and polyurethane network (PU8CLO) were synthesized. The differential scanning calorimetric analysis revealed that the endothermic peak temperature (113 and 143 °C) due to retro DA reaction of PU4DA4CLO was lower than that (157 °C) of DA8CLO. The conversion (87%) of DA reaction for PU4DA4CLO was a little higher than that (77%) for DA8CLO, and their DA conversions decreased with increasing annealing temperature over the range of 90–150 °C by the progression of retro DA reaction. The decrease of crosslinking density by the retro DA reaction was confirmed by the swelling test. When partially overlapped cut-films of DA8CLO, PU4DA4CLO and PU8CLO were stood at 70 °C for 24 h, the PU8CLO film was not self-repaired, but the DA8CLO and PU4DA4CLO films were self-healed. Especially, the self-repaired PU4DA4CLO film maintained the original shape during the treatment at 70 °C, while the self-repaired DA8CLO film considerably deformed by softening. [ABSTRACT FROM AUTHOR]

This research focuses on the crystallizability and melt flow property of linear poly(L-lactide) (1-PLL) by blending with star-shaped 16-arm PLL (16-PLL). The 1-PLL/16-PLL blends were chain extended during melt blending using an epoxy-based chain extender. The crystallinities of the 1-PLL/16-PLL blends increased with the 16-PLL blend ratio and chain extension reaction. The 16-PLL enhanced formation of branched PLL during chain extension was confirmed by thermogravimetry, and improved the melt flow property of the blends. Stresses at break of the compressed blend films were improved slightly by the 16-PLL blending and chain extension. In conclusion, the 16-PLL could be used as a nucleating agent and a melt strength enhancer for linear PLL. [ABSTRACT FROM AUTHOR]

ABSTRACT Solvent-free isothermal tuning of viscoelasticity of polymer materials is important for an emerging photochemical molding technology and photoreversible adhesives. In this study we designed a four-armed star-shaped poly(butyl acrylate, BA) oligomer having four coumarin end groups. The irradiation of UV at the wavelength of 365 nm (UV365) to the viscous poly(BA) oligomer under a solvent-free condition produced a solid network material along with the progress of dimerization reaction with coumarin end groups. The subsequent irradiation of UV at the wavelength of 254 nm (UV254) caused dimer dissociation reaction to attain change in the mixing degree of star and network architectures in the material. Moreover, viscoelasticity of the network material was tunable by repetitive UV365 and UV254 irradiations. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 9-15 [ABSTRACT FROM AUTHOR]

It is important to develop tailor-made biodegradable/biocompatible polymer networks usable for biomaterials whose thermal and mechanical properties are easily controlled by changing the composition. We synthesized sugar-alcohol-based polymer networks (SPN-mscLAO/3CLO, m = 4, 5 or 6) by the crosslinking reactions of erythritol, xylitol or sorbitol-based m-armed star-shaped L-lactide and D-lactide oligomers (HmSLLAO and HmSDLAO), a glycerol-based 3-armed star-shaped "-caprolactone oligomer (H3SCLO) and hexamethylene diisocyanate (HDI) at the weight ratios of HmSLLAO/HmSDLAO = 1/1 and (HmSLLAO + HmSDLAO)/H3CLO = 100/0, 75/25, 50/50, 25/75 or 0/100). The influence of the arm number on the crystallization behavior, thermal and mechanical properties of SPN-mscLAO/3CLOs were systematically investigated by comparing with those of sugar-alcohol-based homochiral polymer network (SPN-mLLAO, m = 4, 5 or 6) prepared by the reaction of HmSLLAO and HDI. Stereocomplex (sc) crystallites are dominantly formed for SPN-mscLAO/3CLOs 100/0-25/75, whereas SPN-mLLAOs were amorphous. The higher order of melting temperature of sc-crystals for SPN-mscLAO/3CLOs 100/0-25/75 was m = 5 > m = 6 > m = 4. The sc-crystallinities of SPN-4scLAO/3CLOs 100/0-50/50 were significantly lower than those of SPN-mscLAO/3CLOs 100/0-50/50 (m = 5 and 6). The larger order of the sc-spherulite size at crystallization temperature of 110 °C was m = 5 > m = 6 > m = 4 for SPN-mscLAO/3CLO 100/0. The size and number of sc-spherulites decreased with increasing crystallization temperature over the range of 110-140 °C and with increasing CLO fraction. Among all the networks, SPN-5scLAO/3CLOs 75/25 and 50/50 exhibited the highest and second highest tensile toughnesses (21.4 and 20.3 MJ·m-3), respectively. [ABSTRACT FROM AUTHOR]

Hydroxy-terminated 4-armed star-shaped ɛ-caprolactone and l -lactide oligomers (H4CLO n and H4LAO n ) with a degree of polymerization per arm (n = 5, 10 or 15) were reacted with furfuryl isocyanate and (4-maleimidophenyl)isocyanate to produce furan- and maleimide-functionalized 4-armed star-shaped ɛ-caprolactone and l -lactide oligomers (F4CLO n and M4LAO n ), respectively. The Diels-Alder (DA) reaction of F4CLO n and M4LAO n from room temperature to 40 °C in 1,2-dichloroethane produced conetworks (F4CLO n -M4LAO n ) in which the two star-shaped oligomer units are alternatingly arranged. The conversion of DA reaction for F4CLO n -M4LAO n decreased with increasing n value. F4CLO 10 -M4LAO 10 exhibited a higher degree of swelling in chloroform than F4CLO 5 -M4LAO 5 in agreement with the difference in crosslinking density. F4CLO 15 -M4LAO 15 dissolved in chloroform because of the insufficient crosslinking reaction. All the F4CLO n -M4LAO n s exhibited endothermic peaks due to retro-DA reactions on the first heating differential scanning calorimetric scans, whereas the corresponding peaks considerably weakened on the second heating scans due to phase separation. The cut films of F4CLO n -M4LAO n (n = 5 and 10) were self-repaired by heating the partially superposed pieces at 70 °C. [ABSTRACT FROM AUTHOR]

The reactions of diglycerol-based 4-armed enantiomeric lactide oligomers (DG4LLAO and DG4DLAO, DGDLAO/DGLLAO = 1/1) and a 1,3-propanediol-based 2-armed rac-lactide oligomer (PD2racLAO) with hexamethylene diisocyanate produced bio-based polyesterurethane networks (PEU-DG4scLAO/PD2racLAOs) with different feed ratios of stereocomplex (sc) lactide oligomer (DG4scLAO = DG4DLAO + DG4LLAO) and PD2racLAO. Crystallization behavior and physical properties of PEU-DG4scLAO/PD2racLAOs were compared with those of the corresponding pentaerythritol- and glycerol-based polyesterurethane networks (PEU-PE4scLAO and PEU-GC4scLAO) with no PD2racLAO fraction. The X-ray diffraction analysis revealed that sc crystallites were formed without any homo-crystallization for PEU-DG4scLAO/PD2racLAOs 100/0-25/75 in a similar manner to PEU-PE4scLAO or PEU-GC3scLAO. Differential scanning calorimetric analysis for PEU-DG4scLAO/PD2racLAOs 100/0-25/75 revealed that the sc crystallites were not regenerated during a cold crystallization process of the quenched samples, but regenerated by isothermal crystallization from the melt. This result was a marked contrast to the previous result that sc crystallites were almost completely regenerated by the cold crystallization for PEU-PE4scLAO and PEU-GC3scLAO. Polarized optical microscopic analysis revealed that the incorporation of 25% of PD2racLAO enhanced the sc-nucleation efficiency, and further addition caused the reduction of overall crystallization. PEU-DG4scLAO/PD2racLAO 100/0 exhibited a higher elongation at break and tensile toughness than PEU-PE4scLAO and PEU-GC3scLAO. Tensile strength and elongation at break for PEU-DG4scLAO/PD2racLAOs decreased with increasing feed of PD2racLAO. [ABSTRACT FROM AUTHOR]

Copyright of Kobunshi Ronbunshu is the property of Society of Polymer Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Poly[2-(Dimethylamino) ethyl acrylate] (PDMAEA) based polymers have been studied as potential gene delivery system. However, few reports emerging in literature suggesting that star-shaped PDMAEA based polymers are performing better in polyplexation with DNA, cytotoxicity and transfection, as compared to linear counterparts. Nonetheless, little evidences exist on direct comparison between the linear and star-shaped polymer structures. To address this, a series of new star-shaped PDMAEA polymers with linear counterparts were synthesised and directly compared their polyplexation with DNA and cytotoxicity in culture cell lines. The star-shaped PDMAEA polymers were synthesised using pentaerythritol tetrakis [2-(dodecylthiocarbonothioylthio)-2-methylpropionate] (4-arm DDMAT) RAFT agent in a “core-first” approach, whereas 2-(dodecylthiocarbonothioylthio)-2-methylpropionate was used to synthesise linear PDMAEA polymers. In order to investigate the effect of molar mass, both star-shaped and linear PDMAEA were synthesised in low (10 kDa) and high (20 kDa) molar mass. It must be noted here that the overall molar mass of the star-shaped polymer was equal to that of the linear counterparts. Interestingly, we found that the star-shaped polymer has slightly smaller hydrodynamic diameter (more compact) relative to linear counterparts, and importantly, star-shaped PDMAEA binds to DNA at much lower nitrogen to phosphate ratio (N/P ratio). However, the cytotoxicity studies in cultured 3T3 murine cell lines demonstrated that both star-shaped and linear counterparts have no toxicity at low 10 kDa, but significantly toxic at higher 20 kDa molar mass, this finding confirmed that the molar mass of PDMAEA play a key role in cytotoxicity effect, not variable polymer structures. Taken together, star-shaped PDMAEA binds more effectively to DNA than linear counterparts and showed no toxicity at 10 kDa molar mass at variable polymer concentrations. [ABSTRACT FROM AUTHOR]

The reactions of enantiomeric glycerol-based 3-armed lactide oligomers (H3DLAO and H3LLAO) and a diethylene glycol-based 2-armed ɛ-caprolactone oligomer (H2CLO) with hexamethylene diisocyanate (HDI) produced polyesterurethane copolymer networks (PEU-3scLAO/2CLOs 100/0, 75/25, 50/50, 25/75 and 0/100) with different feed ratios of stereocomplex (sc) lactide oligomer (H3scLAO = H3DLAO + H3LLAO, H3DLAO/H3LLAO = 1/1) and H2CLO. Thermal and mechanical properties of the copolymer networks were compared with those of a simple homochiral (hc) network (PEU-3DLAO) produced by the reaction of H3DLAO and HDI. X-ray diffraction and differential scanning calorimetric analyses revealed that sc crystallites are formed without any hc crystallization for PEU-3scLAO/2CLOs, and that PEU-3DLAO is amorphous. The melting temperatures of sc crystallites for PEU-3scLAO/2CLOs were much higher than that of hc crystallites of H3DLAO. The polarized optical microscopic analysis revealed that the nucleation efficiency is enhanced with increasing feed of H3scLAO fraction, whereas the spherulite growth rate is accelerated with increasing feed H2CLO fraction over 100/0-50/50 networks. PEU-3scLAO/2CLO 100/0 (i.e., PEU-3scLAO) exhibited a higher tensile strength and modulus than PEU-3DLAO. The elongation at break and tensile toughness for PEU-3scLAO/2CLOs increased with an increasing feed amount of H2CLO. [ABSTRACT FROM AUTHOR]

The reactions of methylenediphenyl 4,4’-diisocyanate (MDI) with hydroxy-terminated 4-armed star-shaped l -lactide oligomer (H4LAO n ) and 4-armed star-shaped ε-caprolactone oligomer (H4CLO n ) with the degree of polymerization per one arm, n = 3, 5 or 10 produced conetworks [MH4(LA/CL)O n s] with the feed H4LAO n /H4CLO n weight ratios of 75/25, 50/50 and 25/75. The formation of conetwork structures with different crosslinking densities was confirmed by the swelling test and FT-IR spectral analysis. Scanning electron microscopic analysis revealed that the oligolactate (LAO) and oligocaprolactone (CLO) segments are compatibilized for all the conetworks except for MH4(LA/CL)O 10 25/75. Differential scanning calorimetry and dynamic mechanical analyses revealed that all the conetworks are substantially amorphous, and that only one glass transition temperature ( T g ) was observed for each of the conetworks except for MH4(LA/CL)O 10 25/75. Tensile properties of MH4(LA/CL)O n s were largely affected by the influence of the T g value which changes according to the LAO/CLO ratio. MH4(LA/CL)O 5 50/50 ( T g : 33.3 °C) exhibited the highest tensile toughness among all the conetworks. [ABSTRACT FROM AUTHOR]

ABSTRACT The combination of living/controlled cationic cyclopolymerization and crosslinking polymerization of bifunctional vinyl ethers (divinyl ethers) was applied to the synthesis of core-crosslinked star-shaped polymers with rigid cyclized arms. Cyclopolymerization of 4,4-bis(vinyloxymethyl)cyclohexene ( 1), a divinyl ether with a cyclohexene group, was investigated with the hydrogen chloride/zinc chloride (HCl/ZnCl2) initiating system in toluene at 0 °C. The reaction proceeded quantitatively to give soluble poly( 1)s in organic solvents. The content of the unreacted vinyl groups in the produced polymers was less than ∼3 mol%, and therefore, the degree of cyclization of the polymers was determined to be ∼97%. The number-average molecular weight ( Mn) of the polymers increased in direct proportion to monomer conversion and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that living cyclopolymerization of 1 occurred. The chain linking reactions among the formed living cyclopolymers with 1,4-bis(vinyloxy)cyclohexane ( 3) as a crosslinker in toluene at 0 °C produced core-crosslinked star-shaped cyclopoly( 1)s [star-poly( 1)s] in high yield (100%). Dihydroxylation of the cyclohexene double bonds of star-poly( 1) gave hydrophilic water-soluble star-shaped polymers with rigid arm structure [star-poly( 1)-OH] with thermo-responsive function in water. Tgs of star-poly( 1) and star-poly( 1)-OH were 135 °C and 216 °C, respectively; these values are very high as vinyl ether-based star-shaped polymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1094-1102 [ABSTRACT FROM AUTHOR]

Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) were successfully synthesized. One of them is an (A-b-B)4 type star polymer [(PCL-b-PEG)4] and the other one is a Y-shaped PEG-(PCL)2. A star-shaped polymer (PCL-b-PEG)4 was prepared by ring-opening polymerization (ROP) of ε-caprolactone continued by click reaction of (PCL-azide)4 and PEG-alkyne. The synthesis of Y-shaped PEG-(PCL)2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI) with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB). However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three- and four-arm star shaped polymers, as well as diblock copolymers, are synthesized via acyclic diene metathesis (ADMET) polymerization. This is accomplished by using an asymmetric α,ω-diene containing a terminal double bond and an acrylate, which is polymerized in the presence of multifunctional acrylates as selective and irreversible chain transfer agents using Hoveyda-Grubbs second generation catalyst. High cross-metathesis selectivities are achieved at low temperatures enabling good control over molecular weights. Furthermore, additional polyethyleneglycol (PEG) blocks are attached to these polymers via Heck coupling of the acrylate end-groups of these polymers with aryl iodide functionalized PEG, obtaining three- and four-arm star shaped di- and triblock copolymers with molecular weights up to 31 kDa. [ABSTRACT FROM AUTHOR]

Abstract: In order to develop the effective vectors that had high gene transfection capability and low cytotoxicity in the neuronal cells, we tested the star-shaped polymer consisting of β-cyclodextrin core and poly(amidoamine) (PAMAM) dendron arms [β-CD-(D3)7] as the vector to transfect the human neuroblastoma SH-SY5Y cells. The physicochemical properties of the β-CD-(D3)7/plasmid DNA (pDNA) complexes were characterized by using gel electrophoresis, dynamic light scattering, transmission electron microscopy and zeta-potential experiments. Among the human neuroblastoma SH-SY5Y cells, β-CD-(D3)7/pDNA complex demonstrated a lower toxicity compared to those of PAMAM (G =4, with an ethylenediamine core)/pDNA complex. When the N/P ratio was over 20, it was observed that PAMAM had a faster increment in toxicity compared to β-CD-(D3)7. Fluorescent image, confocal microscopy image and flow cytometry showed that β-CD-(D3)7/pDNA complexes had significantly higher transgene activity than that of PAMAM/pDNA complexes. For example, the transfection efficiency was 20% and 7.5% for β-CD-(D3)7/pDNA and PAMAM/pDNA complexes, respectively. These results indicated that β-CD-(D3)7 might be a promising candidate for neurotypic cells gene delivery with the characteristics of good biocompatibility, relatively high gene transfection capability and potential in vivo gene delivery ability. [Copyright &y& Elsevier]

Conventional block copolymers are able to self-assemble in bulk, resulting in a microphase separation or formation of aggregates in solution. Polypeptides show secondary structure effects and specific non-covalent interactions, which can cause a specific aggregation behavior and result in interesting supramolecular structures. Conjugation of polypeptides with simple synthetic polymers combines these phenomena with the advantages of synthetic polymers like solubility and processability. Various chemical strategies have been developed for conjugating different synthetic polymers with smaller and larger peptides. Here, we emphasize conjugation methods for peptides prepared by solid phase peptide synthesis having a controlled sequence as well as for polypeptides consisting of only one or two amino acids, which can be prepared by polymerization of the corresponding N-carboxyanhydride. By consecutive polymerization using a macroinitiator, block copolymers as conjugates are accessible. Different methods using this approach are highlighted. Furthermore, examples of conjugation of peptides with preformed polymers by ˵click″ chemistry are presented. [ABSTRACT FROM AUTHOR]

A well-defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties with an alkyne terminal group is prepared (P(S- co-CMS), $\overline{M}_{\rm n}$ = 5500 Da, PDI = 1.13). The chloromethyl groups are converted into Hamilton wedge (HW) entities (P(S- co-HWS), $\overline{M}_{\rm n}$ = 6200 Da, PDI = 1.13). The P(S- co-HWS) polymer is subsequently ligated with tetrakis(4-azidophenyl)methane to give HW-functional star-shaped macromolecules (P(S- co-HWS))4, $\overline{M}_{\rm n}$ = 25 100 Da, PDI = 1.08). Supramolecular star-shaped copolymers are then prepared via self-assembly between the HW-functionalized four-arm star-shaped macromolecules ( P(S- co-HW)) 4 and cyanuric acid (CA) end-functionalized PS (PS-CA, $\overline{M}_{\rm n}$ = 3700 Da, PDI = 1.04), CA end-functionalized poly(methyl methacrylate) (PMMA-CA, $\overline{M}_{\rm n}$ = 8500 Da, PDI = 1.13) and CA end-functionalized polyethylene glycol (PEG-CA, $\overline{M}_{\rm n}$ = 1700 Da, PDI = 1.05). The self-assembly is monitored by 1H NMR spectroscopy and light scattering analyses. [ABSTRACT FROM AUTHOR]

Precision and efficient star-shaped polymer synthesis using fast living cationic polymerization was achieved with FeCl3, SnCl4, or GaCl3 in the presence of an added base. Addition of FeCl3 following the addition of a divinyl compound into living poly[isobutyl vinyl ether (VE)] mixture accelerated the polymer-linking reaction significantly and yielded a star polymer with narrow molecular weight distribution (MWD) and high yield (Mw/Mn = 1.21, yield = 99%) within only 15 s. This system also accelerated the synthesis of star-shaped polymers containing polar functional pendants, e.g., poly(VE)s with malonate groups were linked efficiently using SnC14 in conjunction with THF in 30 min. Furthermore, heteroarm star polymers containing two types ofpoly(VE)s with malonate- and oxyethylene-pendants were prepared using SnCl4 in the presence of THF, rapidly and efficiently. [ABSTRACT FROM AUTHOR]

Star-shaped poly(methyl acrylate) (PMA) was synthesized using tri(2-bromopropionate) glyceride as the initiator and methyl acrylate as the monomer via atom transfer radical polymerization (ATRP). The structures of tri(2-bromopropionate) glyceride and PMA were characterized by IR, GC-MS, H NMR, and C NMR. The reinforcing effects of this star-shaped PMA on polyvinylchloride (PVC) in various PMA/PVC blends were evaluated. The results indicated that a blend containing 1% star-shaped PMA exhibits an 18% increase in the elastic modulus and a 10% increase in tensile strength compared to PVC. Moreover, the impact resistance of the blend was 30% higher than that for PVC. The blend also exhibited high thermal stability. SEM images showed that the star-shaped PMA and PVC are highly compatible when blended, which causes the enhanced elasticity of the blend. [ABSTRACT FROM AUTHOR]

Abstract: One new three-arm star-shaped polymer was synthesized by the core-first way using atom transfer radical polymerization (ATRP) method. This polymer contained charged iridium (Ir) complex as the luminescent core and 2-(carbazol-9-yl) ethyl methacrylate as the arm repeat unit. Its structure was confirmed by elemental analysis, nuclear magnet resonance (NMR) and photoluminescence (PL). The polymer has a relatively low polydispersity index (PDI) of 1.30 with excellent thermal stability. It also possesses significant redox behavior with a HOMO level of −5.21eV, which will be of benefit to hole-injection. The PL spectrum of the polymer in film state has a stable peak at 565nm, however, its PL in dichloromethane solution varied with its concentration. It demonstrated effective energy transfer from the arm unit to the core in the host–guest system. This indicated that when the length of the arm is properly designed, highly luminescent materials can be achieved with emission at 565nm. [Copyright &y& Elsevier]

Abstract: The separation and sequencing of DNA are the main objectives of the Human Genome Project, and this project has also been very useful for gene analysis and disease diagnosis. Capillary electrophoresis (CE) is one of the most common techniques for the separation and analysis of DNA. DNA separations are usually achieved using capillary gel electrophoresis (CGE) mode, in which polymer gel is packed into the capillary. Compared with a traditional CGE matrix, a hydrophilic polymer matrix, which can be adsorb by the capillary wall has numerous advantages, including stability, reproducibility and ease of automation. Various water-soluble additives, such as linear poly(acrylamide) (PAA) and poly(N,N-dimethylacrylamide) (PDMA), have been employed as media. In this study, different star-shaped PDMA polymers were designed and synthesized to achieve lower polymer solution viscosity. DNA separations with these polymers avoid the disadvantages of high viscosity and long separation time while maintaining high resolution (10bp between 271bp and 281bp). The influences of the polymer concentration and structure on DNA separation were also determined in this study; higher polymer concentration yielded better separation performance, and star-like polymers were superior to linear polymers. This work indicates that modification of the polymer structure is a potential strategy for optimizing DNA separation. [Copyright &y& Elsevier]

Abstract: In this feature article, we present a short review on the recent development in the construction of structurally perfect red and blue light-emitting materials and highlight such research in our group. We focus mainly on the three-dimensional conjugated structures such as dendrimers, hyperbranched polymers, star polymers, spirobifluorene-based polymers, and spiro-bridged ladder-type oligomers and polymers. Results indicated three-dimensional conjugated structures can efficiently decrease the aggregation of materials, resulting in the improving of the light-emitting efficiency. [Copyright &y& Elsevier]