A systematic study of macrodiols and poly(ester-urethanes) derived from α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH) with different ether [CH2CH2O]m groups. Synthesis and characterization

Experimental Design (24) to Improve the Reaction Conditions of Non-Segmented Poly(ester-urethanes) (PEUs) Derived from α,ω-Hydroxy Telechelic Poly(ε-caprolactone) (HOPCLOH)

Aliphatic unsegmented polyurethanes (PUs) have garnered relatively limited attention in the literature, despite their valuable properties such as UV resistance and biocompatibility, making them suitable for biomedical applications. This study focuses on synthesizing poly(ester-urethanes) (PEUs) using 1,6-hexamethylene diisocyanate and the macrodiol α,ω-hydroxy telechelic poly(ε-caprolactone) (HOPCLOH). To optimize the synthesis, a statistical experimental design approach was employed, a methodology not commonly utilized in polymer science. The influence of reaction temperature, time, reagent concentrations, and solvent type on the resulting PEUs was investigated. Characterization techniques included FT-IR, 1H NMR, differential scanning calorimetry (DSC), gel permeation chromatography (GPC), optical microscopy, and mechanical testing. The results demonstrated that all factors significantly impacted the number-average molecular weight (Mn) as determined by GPC. Furthermore, the statistical design revealed crucial interaction effects between factors, such as a dependence between reaction time and temperature. For example, a fixed reaction time of 1 h, with the temperature varying from 50 °C to 61 °C, did not significantly alter Mn. Better reaction conditions yielded high Mn (average: 162,000 g/mol), desirable mechanical properties (elongation at break > 1000%), low levels of unreacted HOPCLOH in the PEU films (OH/ESTER response = 0.0008), and reduced crystallinity (ΔHm = 11 J/g) in the soft segment, as observed by DSC and optical microscopy. In contrast, suboptimal conditions resulted in low Mn, brittle materials with unmeasurable mechanical properties, high crystallinity, and significant amounts of residual HOPCLOH. The best experimental conditions were 61 °C, 0.176 molal, 8 h, and chloroform as the solvent (ε = 4.8).

Monodisperse oligo(ε-caprolactones) with terpenes and alkyl end-groups: synthesis, isolation, characterization, and antibacterial activity

Linear aliphatic oligoesters derived from ε-caprolactone (CL) were synthesized by ring-opening polymerization (ROP) using terpene alcohols that have antibacterial activity as initiators (nerol, geraniol, β-citronellol and farnesol). Ammonium decamolybdate (NH4)8[Mo10O34] was used as a catalyst. From previous oligoesters, monodisperse species of monomers, dimers, and trimers were isolated by flash column chromatography (FCC). Poly(ε-caprolactone) (PCL) oligoesters [oligo(CLs)] and monodisperse oligomeric species were characterized by different analytical techniques, such as nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization quadrupole time-of-flight mass spectrometry (ESI/MS-QTOF), and Fourier-transform infrared (FTIR) spectroscopy to determine the chemical nature of the samples. The thermal properties were analyzed by differential scanning calorimetry (DSC), which showed significant differences between the olefin and alkyl terminal groups. The end-groups affected crystalline domains according to the crystallization temperatures (T c), melting temperatures (T m), and glass transition temperature (T g) of the oligo(CLs) and monodisperse oligomeric species. In addition, the results of thermogravimetric analysis (TGA) suggest that the thermal degradation in the case of the monomer and dimer species with olefin terminal groups is similar compared to that with the alkyl terminal group. Due to the antimicrobial properties of olefinic initiators, microbiological tests were carried out on the monodisperse oligomeric species through studies of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiograms. This is the first time in the literature that monodisperse oligomers derived from PCL functionalized with terpenes and alkyl end-groups were tested in terms of their antibacterial properties. The results indicated that these monodisperse species could lead to new antibiotic compounds with potential applications.

Monodisperse oligo(δ-valerolactones) and oligo(ε-caprolactones) with docosyl (C22) end-groups

Two different families of monodisperse oligoesters with α-hydroxyl-ω-docosyl (C₂₂) terminal groups [oligo(δ-valerolactone) and oligo(ϵ-caprolactone)] were isolated by flash column chromatography (FCC).