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Understanding the kinetics and mechanisms of polymerization, particularly the role of a catalyst or initiator used, allows for the manipulation and control of the fabrication of new materials by the most convenient, straightforward routes. The kinetics of the bulk ring‐opening polymerization (ROP) of d‐lactide, a useful monomer employed to control the properties of poly(l‐lactide), have been studied herein to identify a relatively quick (1 h), controlled, yet convenient route to moderately high molecular weight poly(d‐lactide). Tin(II) octoate (Sn(Oct)2), Sn(Oct)2/n‐butanol (nBuOH) and liquid tin(II) butoxide (Sn(OnBu)2) as initiating systems were investigated by non‐isothermal differential scanning calorimetry (DSC). Isoconversional methods were employed to determine the activation energy (Ea) for each reaction. The results showed that liquid Sn(OnBu)2 was a more efficient initiator than the commonly reported initiating systems of Sn(Oct)2 and Sn(Oct)2/nBuOH in terms of producing higher polymerization rates and polymer molecular weights. High‐molecular‐weight poly(d‐lactide) (1.8 × 105 Da) with moderate dispersity (Ð = 1.3) was obtained using 0.1 mol% liquid Sn(OnBu)2 as the initiator at 120 °C. This work describes the applications of non‐isothermal DSC and isoconversional methods in comparing the effectiveness of different initiators in the bulk ROP of d‐lactide for the first time. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This work investigates the high catalytic activity of bi‐functional lithium N‐heterocyclic carbene (bisLiNHCs) complexes in bulk ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) monomer at room temperature. The study employs a bulk ROP technique using tetramethylene‐tethered bis[N‐(N′‐alkyl/arylimidazolium)] bishexafluorophosphate (bis[Bim][PF6]), benzyl alcohol (BnOH), and n‐butyl lithium (nBuLi) in molar ratios of 1:2:4. The results show that 1,4‐bisLiNHC (3a) has the highest catalytic capability, producing the highest molecular weight of PCL with acceptable dispersity in only 93 s (59 361 g mol−1, Đ = 1.8). However, longer and aromatic linker chains (3b‐3g) are found to be less effective due to the increased steric effect for complex formation with the monomer, leading to longer reaction times and lower molecular weight PCL with wider dispersity. Additionally, the study conducts a mechanistic analysis using the DFT method with B3LYP (6‐31G(d,p)) as the basis set. The most plausible mechanism proposed involves continuous and coordinated insertion with low energy barriers. [ABSTRACT FROM AUTHOR]

This work investigates the thermal and rheological properties of the poly(L‐lactide‐co‐ε‐caprolactone), PLC, tapered block copolymer synthesized by ring‐opening polymerization (ROP) using stannous octoate (Sn[Oct]2) as an initiator. The PLC copolymer (LL: CL = 48.9:51.1 mol% from 1H‐NMR) was obtained as a transparent, elastomeric material with a tapered monomer sequencing (R = 0.38 from 13C‐NMR data) due to randomizing effect of transesterification. The Mn, Mw, and ĐM of the PLC copolymer from GPC are 8.04 × 104, 1.36 × 105, and 1.69 respectively. The obtained moduli of the copolymer at 100% and 300% strain are rather low at 0.91 and 1.16 MPa. The rheological properties of the PLC melt are studied in terms of steady and oscillatory shear flow. The master curves at a reference temperature of 150°C with 5% and 100% strain suggest that the copolymer melt may contain some regular microstructures, such as small crystalline domains of poly(L‐lactide), which remained intact at high strain deformation. The flow curve of the PLC melt at 150°C constructed from a cross model shows a Newtonian viscosity (η0) of 6754 Pa‐s, a consistency index (k) of 0.59, and a Power Law index of 0.35 where the onset of Power Law behavior is observed at around 10 s−1. For the fabrication of the PLC nerve tubes, the best result is observed from the extruded PLC tubes with a combination of PEG porosifying agent leaching and phase immersion precipitation at 2°C using DMF/1,4‐dioxane (1:1) as a mixed solvent and ethanol/chloroform (9:1) as a non‐solvent. The porous tube obtained under this condition has a pore diameter and pore depth of approximately 2.3–2.5 and 30 μm respectively. [ABSTRACT FROM AUTHOR]

A facile and green one‐pot synthesis of 2,3‐dihydroquinazolinones, using microwave irradiation, has been developed. Dihydroquinazolinones were synthesized from 2‐aminobenzamide derivatives and various aldehydes in aqueous solution under base and catalyst free reaction conditions. The desired products, from aliphatic and aromatic aldehydes substrates, were obtained in 5 minutes with up to 99 % isolated yields. [ABSTRACT FROM AUTHOR]

The focus of this study was the development of a new synthetic method for quinazolinones based on the principles of Green Chemistry. Quinazolinones were synthesized from 2‐aminobenzamide using methanol as both the C1 source and a green solvent in the presence of base Cs2CO3. Additionally, a commercially available, economical copper complex was used as a catalyst in the reaction. The desired products were achieved in moderate to high yield with up to 99 % isolated yield. [ABSTRACT FROM AUTHOR]

Understanding the underlying role of microstructural design in polymers allows for the manipulation and control of properties for a wide range of specific applications. As such, this work focuses on the study of microstructure–property relationships in l‐lactide/ϵ‐caprolactone (LL/CL) copolymers. One‐step and two‐step bulk ring‐opening polymerization (ROP) procedures were employed to synthesize LL/CL copolymers of various compositions and chain microstructures. In the one‐step procedure, LL and CL were simultaneously copolymerized to yield P(LL‐stat‐CL) statistical copolymers. In the two‐step procedure, poly(l‐lactide) (PLL) and poly(ϵ‐caprolactone) (PCL) prepolymers were synthesized in the first step before CL and LL respectively were added in the second step to yield P[LL‐b‐(CL‐stat‐LL)‐b‐LL] and P[CL‐b‐(LL‐stat‐CL)‐b‐CL] block copolymers as the final products. The findings reveal that, in addition to the copolymerization procedure employed, the length and type of the prepolymer play important roles in determining the chain microstructure and thereby the overall properties of the final copolymer. Moreover, control over the degree of crystallinity and the type of crystalline domains, which is controlled during the polymer chemistry process, heavily influences the physical and mechanical properties of the final polymer. In summary, this work describes an interesting approach to the microstructural design of biodegradable copolymers of LL and CL for potential use in biomedical applications. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The cover image is based on the Research Article Use of non‐isothermal DSC in comparative studies of tin(II) systems for the ring‐opening polymerization of D‐lactide by Sawarot Phetsuk et al., https://doi.org/10.1002/pi.6517. [ABSTRACT FROM AUTHOR]

ABSTRACT The kinetics of the ring-opening polymerization (ROP) of ε-caprolactone ( ε-CL) initiated by soluble aluminum tri- sec-butoxide (Al(O secBu)3) has been investigated by the differential scanning calorimetry (DSC). The DSC polymerizations were carried out under nonisothermal and isothermal conditions to obtain three-arms poly( ε-caprolactone) (PCL). From nonisothermal DSC, the polymerization rate (d α/d t) increased with increasing heating rates. The values of Ea were determined from Kissinger ( [ABSTRACT FROM AUTHOR]

ABSTRACT Norbornene macromonomers 2 and 3 bearing 10- and 20-mers of lactide were synthesized by ring-opening polymerization of lactide using 5-norbornene-2, 3- exo-exo-dimethanol as an initiator and DBU as a catalyst. Macromonomers 2 and 3 were copolymerized with amino acid derived norbornene monomer 1, using the Grubbs 2nd generation ruthenium catalyst. The random and block copolymers with Mn's ranging from 28,000 to 180,000 were obtained almost quantitatively where the Mn's of the block copolymers were higher than those of the random ones. Three-dimensional macroporous structure polymers with average pore size of 10 µm could be found in poly( 1) and the block co-polymer of 1 and 2 or 1 and 3 at the high ratio of 1. Meanwhile, poly( 2) and poly( 3) along with block and random copolymers with low ratio of 1 exhibit much larger pores in the range of 50-300 µm. The porosity increased with increase in the unit ratio of 1. The compressive strength of the porous structure of poly( 2) and poly( 3) was improved by the copolymerization with 1. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1660-1670 [ABSTRACT FROM AUTHOR]

ABSTRACT The main objective of this work has been to study the effects of copolymer microstructure, both chemical and physical, on the microporosity, in vitro hydrolytic degradability and biocompatibility of electrospun poly( l-lactide- co-ε-caprolactone), PLC, copolymer tubes for potential use as absorbable nerve guides. PLC copolymers with L : C compositions of 50 : 50 and 67 : 33 mol % were synthesized via the ring-opening copolymerization of l-lactide (L) and ε-caprolactone (C) at 120°C for 72 h using stannous octoate (tin(II) 2-ethylhexanoate) and n-hexanol as the initiating system. Electrospinning was carried out from solution in a dichloromethane/dimethylformamide (7 : 3 v/v) mixed solvent at room temperature. The in vitro hydrolytic degradation of the electrospun PLC tubes was studied in phosphate buffer saline over a period of 36 weeks. The microporous tubes were found to be gradually degradable by a simple hydrolysis mechanism leading to random chain scission. At the end of the degradation period, the % weight retentions of the PLC 50 : 50 and 67 : 33 tubes were 15.6% and 70.2%, respectively. Pore stability during storage as well as cell attachment and proliferation of mouse fibroblast cells (L929) showed the greater potential of the PLC 67 : 33 tubes for use as temporary scaffolds in reconstructive nerve surgery. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4357-4366, 2013 [ABSTRACT FROM AUTHOR]