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We show the remarkable effect of using static (DC) and alternating (AC) electric fields to control the free-radical polymerization of methyl methacrylate (MMA). The magnitude and/or frequency of the applied electric field (up to 154 kV cm−1) were found to control the molecular weight, dispersity, and stereochemistry of the produced polymers. [ABSTRACT FROM AUTHOR]

Star-shaped glycopolymers due to the attractive combination of the physicochemical, morphological, self-assembly properties along with biological activity have gained increased attention as innovative agents in novel cancer therapies. Unfortunately, the production of these highly desirable biomaterials remains a challenge in modern macromolecular chemistry. The main reason for that is the low polymerizability of ionic glycomonomers originated from their steric congestion and the occurrence of ionic interactions that generally negatively influence the polymerization progress and hinder controllable reaction pathway. In this work, the new ionic sugar monomer was (co)polymerized for the first time via Activator Generated by Electron Transfer Atom Transfer Radical Polymerization (AGET ATRP) using a three-arm resveratrol-based core to obtain star-like (co)polymers. The obtained products were examined in terms of their physicochemical properties and morphology. Aside from the synthesis of these new glycopolymers, also a thorough description of their thermal properties, ability to self-assembly, the formation of stable superstructures was studied in detail. It was found that examined (co)polymers did not show any heterogeneities and phase separation, while their variation of glass transition temperature (Tg) was strictly related to the change in the number of glycomonomer. Also, the stability and shapes of formed superstructures strictly depend on their composition and topology. Finally, we have shown that synthesized carbohydrate-based polymers revealed high antiproliferative activity against several cancer cell lines (i.e., breast, colon, glioma, and lung cancer). The cytotoxic activity was particularly observed for star-shaped polymers that were systematically enhanced with the growing concentration of amine moieties and molecular weight. The results presented herein suggest that synthesized star-shaped glyco(co)polymers are promising as drug or gene carriers in anticancer therapies or anti-tumor agents, depending on their cytotoxicity. [ABSTRACT FROM AUTHOR]

We report, for the first time, the metal-free green synthesis of linear poly(vinyl pyrrolidone) (PVP) homopolymers of molecular weight higher than 100 kg mol−1 and narrow dispersities via thermal and photo-induced free radical polymerisation carried out within alumina nanoporous membranes acting as “nanoreactors”. [ABSTRACT FROM AUTHOR]

[Display omitted] Modified oligosaccharides with cyclic topology seem to be promising excipients for the preparation of Amorphous Solid Dispersions (ASDs), especially with those Active Pharmaceutical Ingredients (APIs), which have a strong crystallization tendency from the amorphous/glassy state. Herein, the usefulness of two acetylated cyclodextrins (ac-α-CD and ac-β-CD) with various molecular weights (M w) as stabilizers for the supercooled metronidazole (Met) has been discussed. X-ray diffraction (XRD) studies carried out on Met-acCDs mixtures (prepared in molar ratios from 1:2 to 5:1) showed that the system with ac-α-CD containing the highest amount of API (5:1 m/m) crystallizes immediately after preparation, whereas all Met-ac-β-CD ASDs remain stable. What is more, long-term XRD measurements confirmed that the Met-ac-α-CD 2:1 m/m system crystallizes after 100 days of storage in contrast to the same system containing ac-β-CD. The non-isothermal calorimetric data revealed that the activation barrier for crystallization (E c r) in ASDs with the oligosaccharide having a greater M w (i.e., composed of seven acGLU molecules) is slightly higher. Finally, to explain the differences in behavior between the mixtures with both acCDs, infrared studies, DFT calculations and Molecular Dynamics simulations were performed. All methods excluded the scenario of API incorporation inside the acCDs' core. On the other hand, obtained results suggested that in comparison to ac-α-CD, the greater amount of Met molecules might be bounded on the outside surface of ac-β-CD. Therefore, this modified saccharide is a better stabilizer of the examined API. [ABSTRACT FROM AUTHOR]

This work demonstrates the effect of a high dc bias field (up to 160 kV/cm) on the polyaddition reaction of the modeled epoxy resin system. Polymerization of bisphenol A diglycidyl ether (DGEBA) supported by high electric field results in obtaining epoxides with significantly increased molecular weight, which is seven-fold higher than the zero-field reference (M n = 4.7 kg/mol). We also found a markedly reduced dispersity (Ð = 1.52 at 0 kV/cm, Đ = 1.21 at 160 kV/cm). The molecular weight and dispersity of obtained polymers change almost linearly with the reaction time. By following polymerization kinetics in the real-time of the experiment, via dielectric spectroscopy, we observe slowing down the reaction progress at dc fields of E = 160 kV/cm, compared to the zero-field case, E = 0 kV/cm. The polymer materials obtained in the presence/absence of static electric fields exhibit distinctly different glass transition temperatures. Our study highlights a better control over the reaction and product properties attained by using only the magnitude of the applied field as the control variable. Thus, a high electric field could provide an alternative pathway in synthesizing and developing advanced polymer materials using simpler, "green", less-expensive, and technologically demanding approaches. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we report 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) supported high-pressure approach enforcing Ring-Opening Polymerization (ROP) of γ-butyrolactone (GBL), that due to unfavorable thermodynamics and low ring strain, is considered as a hardly polymerizable monomer. Application of Broadband Dielectric Spectroscopy (BDS) allowed us to find optimal thermodynamic conditions to perform well-controlled and notably fast polymerization (even within 1 h!), avoiding undesired crystallization process. It was shown that by varying pressure and temperature conditions, we could control molecular weight, dispersity of recovered macromolecules, as well as rate and efficiency of the reaction that are significantly altered with respect to the reference process carried out at ambient conditions. Experiments performed at respectively very low temperature T = 233 K and low/moderate pressure (p = 75–250 MPa) and much higher temperatures (T = 248–268 K) and compressions (p = 1000 MPa) yielded poly(γ-butyrolactone) (PGBL) of tailored absolute molecular weight in moderate range M n = 2.8–15.0 (up to 30.3) kg/mol and narrow/moderate dispersity ranging from Đ = 1.12–1.89. What is more, the implementation of MALDI-TOF, GPC and DSC analyses, clearly indicated that as i) the time of reaction gets longer, ii) the amount of catalyst increases, iii) the temperature lowers, the content of cyclic products in produced polymers grows. This phenomenon influences the rheological properties (viscosity), foil formation ability (films) and cell culture proliferation features of the recovered macromolecules. Presented results open a highly effective and repeatable route to produce PGBL via pressure-assisted ROP and indicate the possibility of tuning properties of this polymer by varying concentration of cycles or eventual block copolymerization with other biorelevant monomers to meet the expectations of the biotechnological industry. [Display omitted] • Organocatalyzed high-pressure assisted γ-butyrolactone Ring-Opening Polymerization. • Well-defined macromolecules (M n up to 30.3 kg/mol; low to moderate Đ = 1.12–1.89). • External catalytic effect of high pressure: reduced reaction time; increased yield. • Monitoring the polymerization progress in situ using BDS technique. • Analysis: NMR, GPC, MALDI, DSC, SEM, rheology, cytotoxicity, cell proliferation. [ABSTRACT FROM AUTHOR]

• There is an anomalous narrowing of the α -peak with compression in acTRE and silTRE. • The temperature-pressure superpositioning is not satisfied in these systems. • The reason for that is probably a change in local structure of molecules at high p. • α-relaxation in silTRE is characterized by extremely high sensitivity to compression. In this paper, broadband dielectric spectroscopy (BDS) was applied to study the molecular dynamics of the methyl, acetyl, and silyl derivatives of trehalose, TRE (metTRE, acTRE, and silTRE, respectively) at high pressure (p). Unexpectedly, our investigations indicated a breakdown of the temperature–pressure superpositioning (TPS) in acTRE and silTRE since the α -loss peak got narrower during compression. Importantly, a similar finding has been reported earlier only for one low-molecular weight compound, i.e., tris(dimethylsiloxy)phenylsilane. Additional X-ray diffraction (XRD) measurements carried out on the ordinary and pressure densified glasses of acTRE indicated that the changes in the width of the α -process in this saccharide (and probably silTRE) are rather due to variations in the supramolecular structure and enhanced local ordering occurring at high p. What is more, we also thoroughly characterized the structural dynamics of three TRE derivatives at different thermodynamic conditions. It was found that the sensitivity of the α -relaxation to compression, reflected in the pressure coefficient of the glass transition temperature (d T g /d p) and activation volume for the α -process, Δ V α (at T = T g), increases with increasing molecular weight (M w) of the modified carbohydrate. Interestingly, for silTRE both d T g /d p and Δ V α were extremely high, reaching the following values: 453 K/GPa and 1049 cm3/mol, respectively. Our data clearly revealed a link between the local structure of compressed van der Waals liquids and peculiar anomalous variations in the shape of the structural process upon densification. [ABSTRACT FROM AUTHOR]