Block Copolyesters Research Articles

Solvent-Dependent Sequence-Controlled Copolymerization of Lactones: Tailoring Material Properties from Robust Plastics to Tough Elastomers.

Copolymerization stands as a versatile and potent method for tailoring polymer properties by adjusting structural unit composition and sequence distribution. However, achieving sequence-controlled copolymerization in a one-step and one-pot process remains challenging. This study introduces a solvent-dependent sequence-controlled copolymerization strategy to produce block and statistical copolyesters from 4-phenyl-2-oxabicyclo[2.1.1]hexan-3-one (4Ph-BL) and ε-caprolactone (ε-CL). The distinct kinetics of the two monomers enable the facile synthesis of diblock and triblock copolyesters, PCL-b-P(4Ph-BL) and P(4Ph-BL)-b-PCL-b-P(4Ph-BL), in non-coordinating solvents, such as dichloromethane and toluene. Conversely, coordinating solvents like tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 1,4-dioxane, and 1,2-dimethoxyethane facilitate frequent transesterifications, yielding statistical copolyesters P[CL-stat-(4Ph-BL)] with varying ratios of heterosequences. Density functional theory (DFT) calculations confirmed that coordinating solvents stabilize the transition state for transesterification, thereby validating their role in triggering this process. By varying the microstructures and compositions, the resultant copolyesters display tunable thermal and mechanical properties, evolving from robust plastics with an ultimate tensile strength of up to 46.3 ± 3.1 MPa to tough elastomers with >99.3% elastic recovery. All the copolyesters exhibit remarkable thermal stability (Td,5% = 376 °C) and maintain desirable chemical circularity (>92%), supporting a closed-loop life cycle for sustainable material economy.

Solvent‐Dependent Sequence‐Controlled Copolymerization of Lactones: Tailoring Material Properties from Robust Plastics to Tough Elastomers

Copolymerization stands as a versatile and potent method for tailoring polymer properties by adjusting structural unit composition and sequence distribution. However, achieving sequence‐controlled copolymerization in a one‐step and one‐pot process remains challenging. This study introduces a solvent‐dependent sequence‐controlled copolymerization strategy to produce block and statistical copolyesters from 4‐phenyl‐2‐oxabicyclo[2.1.1]hexan‐3‐one (4Ph‐BL) and ε‐caprolactone (ε‐CL). The distinct kinetics of the two monomers enable the facile synthesis of diblock and triblock copolyesters, PCL‐b‐P(4Ph‐BL) and P(4Ph‐BL)‐b‐PCL‐b‐P(4Ph‐BL), in non‐coordinating solvents, such as dichloromethane and toluene. Conversely, coordinating solvents like tetrahydrofuran, 2‐methyltetrahydrofuran, 2,5‐dimethyltetrahydrofuran, 1,4‐dioxane, and 1,2‐dimethoxyethane facilitate frequent transesterifications, yielding statistical copolyesters P[CL‐stat‐(4Ph‐BL)] with varying ratios of heterosequences. Density functional theory (DFT) calculations confirmed that coordinating solvents stabilize the transition state for transesterification, thereby validating their role in triggering this process. By varying the microstructures and compositions, the resultant copolyesters display tunable thermal and mechanical properties, evolving from robust plastics with an ultimate tensile strength of up to 46.3 ± 3.1 MPa to tough elastomers with >99.3% elastic recovery. All the copolyesters exhibit remarkable thermal stability (Td,5% = 376 °C) and maintain desirable chemical circularity (>92%), supporting a closed‐loop life cycle for sustainable material economy.

Metalloporphyrin catalyzed self-switchable terpolymerization of propene oxide, phthalic anhydride and lactide for one-pot prepare block copolyesters

The copolymerization of polylactic acid with other monomers or polymers can enhance its performance and expand its range of applications. In this work, a range of metalloporphyrin catalysts featuring diverse substituents and metal coordination centers were synthesized and employed in conjunction with co-catalyst bis(triphenylphosphoranylidene) ammonium chloride (PPNCl) for the terpolymerization of phthalic anhydride (PA), propylene oxide (PO), and lactide (LA) ester without the use of initiators. The catalytic activity of the porphyrin ligand is significantly influenced by its substituents and different metal centers. Under optimal conditions, catalyst TOMePP-CoCl exhibits the most outstanding reactivity among all catalysts. In particular, this terpolymerization is a one-pot self-switching polymerization catalyzed by the metalloporphyrin/PPNCl system. PA selectively undergoes ring-opening copolymerization with PO first, while LA remains inert until PA totally consumed. Through continuous feeding experiments, a multiblock copolymer with fine structure controllability was successfully synthesized, which has been verified by DOSY NMR analysis.

Self-switchable terpolymerization of cyclic anhydrides, epoxides and lactide catalyzed by C2v-symmetric cobaltoporphyrins

The urgency for biodegradable plastics free from crude oil-based chemicals is currently paramount. These materials should be easily recyclable and capable of undergoing degradation at the end of their useful life. Herein, a series of C2v-symmetric cobaltoporphyrins featuring different substituents were synthesized, and evaluated for their catalytic performance in the self-switchable terpolymerization of epoxides, cyclic anhydrides and lactide in coordination with a co-catalyst bis(triphenylphosphoranylidene) ammonium chloride (PPNCl), under initiator-free conditions. These cobaltoporphyrin homogeneous catalysts exhibit promising chemical selectivity in the multicomponent copolymerization, resulting in kinetic differentiation between the ring-opening copolymerization of epoxides with cyclic anhydrides and the ring-opening polymerization of lactide. Lactide only participates in polymerization after complete conversion of cyclic anhydrides, leading to sequence-regulated block copolyesters. The substituents on the porphyrin ligand have significant influence on its catalytic activity. Among all catalysts tested, DOMePP-CoCl exhibited the most outstanding reactivity under optimal conditions. Furthermore, by utilizing different cyclic anhydrides and epoxide monomers, the DOMePP-CoCl/PPNCl catalytic system still exhibited excellent reaction activity, allowing for the high-yielding and high-selectivity transformation into corresponding multiblock copolyesters.

Marriage of Organic and Grubbs Catalysts for Tandem Synthesis of Bottlebrush Polyesters.

Bottlebrush polymers (BBPs) have gained wide attention for their special characters, such as rigid main/side chains, stemming from the exceedingly high graft density. This study aims to provide a simple synthetic approach to BBPs with polyester side chains by merging ring-opening alternating copolymerization (ROAP) and ring-opening metathesis polymerization (ROMP). A simple phosphazene base (tBuP1) is employed for the ROAP of phthalic anhydride and epoxide, after which Grubbs third-generation catalyst (G3) is added to in situ switch on ROMP of the macromonomer, i.e., norbornenyl-ended alternating polyester. The compatibility of tBuP1 with G3 and well-controlled ROMP is evidenced by DOSY-NMR of mixed catalysts, characterization of BBPs, and side-chain degradation. The method can also be extended to BBPs with one-step synthesized block copolyesters side chains. These results highlight the strength of the non-nucleophilic organobase catalyst for convenient construction of complex (degradable) polymers with compositional diversity.

Study on tensile stress fluctuation of poly(butylene succinate) (PBS) and its bicrystalline block copolyesters (PBSEG)

AbstractBased on the stress fluctuation during the tensile process of poly(butylene succinate) (PBS), the tensile behavior of biodegradable bicrystalline block copolyesters (PBSEG) synthesized using polycondensation of poly(ethylene glycol) (PEG) and poly(butylene succinate) (PBS) was further studied. The effects of tensile rate and temperature test conditions on the stress–strain behavior of bicrystalline block copolymer PBSEG were investigated by conducting tensile tests. The experimental results showed that when the mass content of polyethylene glycol in PBSEG was 60%, the material did not show obvious periodic stress fluctuation during the “cold drawing” stage of the stress–strain curve, but showed different and more complicated periodic curve changes. The stress fluctuation of PBSEG copolyester had the characteristics of small amplitude and short period. The elongation at break increased obviously, and the maximum elongation at break was more than 2000%. The analysis of morphology and structure showed that the surface morphology of PBSEG dumbbell bars did not show obvious alternating changes in structure, characterized by light and dark. Craze was the main cause of ductile fracture for PBS and PBSEG copolyesters. The tensile fracture of the two materials occurred in the stress fluctuation region.Highlights Small‐amplitude and short‐period stress fluctuation for PBSEG copolyester. There was no alternating light and dark on the surface of the PBSEG stretched spline. Craze was the main cause of ductile fracture for PBS and PBSEG copolyesters. Tensile fracture of the materials occurred in the stress fluctuation region.

(R/S)-lactate/2-hydroxybutyrate dehydrogenases in and biosynthesis of block copolyesters by Ralstonia eutropha

Bacterial polyhydroxyalkanoates (PHAs) are promising bio-based biodegradable polyesters. It was recently reported that novel PHA block copolymers composed of (R)-3-hydroxybutyrate (3HB) and (R)-2-hydroxybutyrate (2HB) were synthesized by Escherichia coli expressing PhaCAR, a chimeric enzyme of PHA synthases derived from Aeromonas caviae and Ralstonia eutropha. In this study, the sequence-regulating PhaCAR was applied in the natural PHA-producing bacterium, R. eutropha. During the investigation, (R/S)-2HB was found to exhibit strong growth inhibitory effects on the cells of R. eutropha. This was probably due to formation of excess 2-ketobutyrate (2KB) from (R/S)-2HB and the consequent l-valine depletion caused by dominant l-isoleucine synthesis attributed to the excess 2KB. Deletion analyses for genes of lactate dehydrogenase homologs identified cytochrome-dependent d-lactate dehydrogenase (Dld) and [Fe-S] protein-dependent l-lactate dehydrogenase as the enzymes responsible for sensitivity to (R)-2HB and (S)-2HB, respectively. The engineered R. eutropha strain (phaCAR+, ldhACd-hadACd+ encoding clostridial (R)-2-hydroxyisocaproate dehydrogenase and (R)-2-hydoroxyisocaproate CoA transferase, ∆dld) synthesized PHA containing 10 mol% of 2HB when cultivated on glucose with addition of sodium (RS)-2HB, and the 2HB composition in PHA increased up to 35 mol% by overexpression phaCAR. The solvent fractionation and NMR analyses showed that the resulting PHAs were most likely to be block polymers consisting of P(3HB-co-3HV) and P(2HB) segments, suggesting that PhaCAR functions as the sequence-regulating PHA synthase independently from genetic and metabolic backgrounds of the host cell.Key points(R/S)-2-hydroxubutyrates (2HB) caused l-valine deletion in Ralstonia eutropha(R)- and (S)-lactate/2HB dehydrogenases functional in R. eutropha were identifiedThe engineered R. eutropha synthesized block copolymers of 2HB-containing polyhydroxyalkanoates on glucose and 2HBGraphical

Simple and Rapid Access toward AB, BAB and ABAB Block Copolyesters from One-Pot Monomer Mixtures Using an Indium Catalyst.

The synthesis of well-defined block copolymers from one-pot monomer mixtures is particularly challenging when monomers are from the same class and show similar reactivity. Herein, an indium-based catalyst that shows comparable rates in the ring-opening homopolymerization of β-butyrolactone (β-BL) and ε-decalactone (ε-DL), demonstrates monomer-selective behavior in one-pot copolymerizations of β-BL and ε-DL. This provides simple and rapid access to well-defined di-, tri-, or tetra-block copolyesters from monomer mixtures. The sequence-controlled nature of these polymers was confirmed by kinetic analysis, 13C{1H} NMR spectroscopy, DSC, and TGA measurements.

Switchable Copolymerization of Maleic Anhydride/Epoxides/Lactide Mixtures: A Straightforward Approach to Block Copolymers with Unsaturated Polyester Sequences

AbstractSwitchable copolymerization of oxygenated heterocycle mixtures by a single catalytic system has been proved to be a promising approach to sequence‐controlled block copolymers. However, there are still big challenges in one‐step synthesis of multiblock copolymers containing unsaturated polyester blocks from maleic anhydride, epoxides, and lactone mixtures. Herein, a switchable pathway for polylactide‐b‐poly(MAH‐alt‐epoxide)‐b‐polylactide block copolymers is established. The excellent chemoselectivity in multicomponent copolymerization is achieved by bipyridine bisphenolate aluminum complexes that can induce an obvious kinetic differentiation between ring‐opening copolymerization of maleic anhydride/epoxides and ring‐opening polymerization of lactide. The scope of the epoxide for switchable copolymerization is explored and it is found that the steric hindrance of the substituents on epoxide significantly influences the formation of block copolymers. Block copolymers with various sequential and topological structures can be easily prepared by exquisite selection of different initiators. Furthermore, it is demonstrated that the conversion of cis‐maleate units in the block copolyester could be completely converted to trans‐fumarate units by isomerization without chain degradation, cross‐linking, and chain scrambling.

One‐Step Sequence‐Selective Synthesis of Block Copolyester from Mixed Phthalic Anhydride, Cyclohexene Oxide, and δ‐Valerolactone

AbstractOne‐step synthesis of well‐defined block copolymer is of great fundamental and practical values. Here, an aromatic‐aliphatic block copolyester is one‐step synthesized from the mixture of phthalic anhydride (PA), cyclohexene oxide (CHO), and δ‐valerolactone (δ‐VL) at room temperature in the presence of a metal‐free Lewis pair catalyst consisting of triethylborane and excess phosphazene base. Alcohol‐initiated ring‐opening alternating copolymerization of PA and CHO occurs first and selectively because of the overwhelmingly higher activity of PA than CHO and δ‐VL toward the reaction with base‐activated hydroxy species. Only after full conversion of PA is reached can ring‐opening polymerization of δ‐VL occur from the terminus of the aromatic polyester so that a well‐defined (AB)nCm type block copolyester is formed. The two polymerizations are both highly chemoselective without homopolymerization of CHO or extensive transesterification reactions. Owing to the sequence‐selective and living characteristics of the terpolymerization, hepta‐ and undecablock copolyesters with controlled molar mass and low dispersity are obtained through addition of the three‐component monomer mixture in batches. Applicability of the method to propylene oxide and ε‐caprolactone is also examined.

A One-Pot Strategy to Synthesize Block Copolyesters from Monomer Mixtures Using a Hydroxy-Functionized Ionic Liquid.

One-pot transformation of monomer mixtures into block copolymers remains a key challenge. Herein, a metal-free route to prepare block copolymers from monomer mixtures by a hydroxyl functionalized ionic liquid of 3-(2-hydroxyl-ethyl)-1-methylimidazolium bromide (HEMIMB) is described. HEMIMB can bridge two catalytic cycles including ring-opening alternating copolymerization (ROAC) of phthalic anhydride (PA) with epoxides and ring-opening polymerization (ROP) of L-lactide (LA), and enable a selective copolymerization from PA, LA, and epoxides. The selective copolymerization depends on the presence of PA in mixed feedstocks, exhibits the first ROAC of PA with epoxides and then ROP of LA to the formation of block polyesters in one-pot strategy. This work is beneficial to the development of metal-free catalysts for sequence-controlled polymerization that enable block architectures from mixtures of monomers.

Gradient copolymers of ε‐caprolactone and δ‐valerolactone via solvent‐free ring‐opening copolymerization with a pyridyl‐urea/MTBD system

AbstractThe ring‐opening copolymerization of ε‐caprolactone and δ‐valerolactone was carried out under solvent‐free conditions with a pyridyl‐urea (6C‐PU)/7‐methyl‐1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene catalytic system by premixing two monomers, yielding gradient copolyesters with cyclic and linear structures in the absence or presence of an initiator, respectively. The random and block copolyesters of these two monomers were also prepared for comparison. The results of 1H and 13C NMR spectra determined the linear and cyclic structure of copolymers. The kinetic experiment was used to determine the consuming rates of two monomers during the polymerization. The topologies and thermal properties of all the copolymers were characterized and compared by NMR and DSC.

Isothiourea‐based lewis pairs for homopolymerization and copolymerization of 2,2‐dimethyltrimethylene carbonate with ε‐caprolactone and ω‐pentadecalactone

ABSTRACTIn this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with ε‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX2) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(ε‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the 1H and 13C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the 13C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX2, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355

Block Copolyesters Containing 2,5-Furan and trans-1,4-Cyclohexane Subunits with Outstanding Gas Barrier Properties.

Biopolymers are gaining increasing importance as substitutes for plastics derived from fossil fuels, especially for packaging applications. In particular, furanoate-based polyesters appear as the most credible alternative due to their intriguing physic/mechanical and gas barrier properties. In this study, block copolyesters containing 2,5-furan and trans-1,4-cyclohexane moieties were synthesized by reactive blending, starting from the two parent homopolymers: poly(propylene furanoate) (PPF) and poly(propylene cyclohexanedicarboxylate) (PPCE). The whole range of molecular architectures, from long block to random copolymer with a fixed molar composition (1:1 of the two repeating units) was considered. Molecular, thermal, tensile, and gas barrier properties of the prepared materials were investigated and correlated to the copolymer structure. A strict dependence of the functional properties on the copolymers’ block length was found. In particular, short block copolymers, thanks to the introduction of more flexible cyclohexane-containing co-units, displayed high elongation at break and low elastic modulus, thus overcoming PPF’s intrinsic rigidity. Furthermore, the exceptionally low gas permeabilities of PPF were further improved due to the concomitant action of the two rings, both capable of acting as mesogenic groups in the presence of flexible aliphatic units, and thus responsible for the formation of 1D/2D ordered domains, which in turn impart outstanding barrier properties.

Thermo-sensitive micelles based on amphiphilic poly(butylene 2-methylsuccinate)-poly(ethylene glycol) multi-block copolyesters as the pesticide carriers

A novel bio-based and biodegradable aliphatic multi-block copolyester, poly(butylene 2-methylsuccinate)-poly(ethylene glycol) (PBMS-PEG), was synthesized from 1,4-butanediol (BDO), 2-methylsuccinate acid (MSA) and poly(ethylene glycol) (PEG) via direct esterification and polycondensation process with tetrabutyl titanate as catalyst. Thermo-sensitive PBMS-PEG micelles were obtained by self-assembly of amphiphilic block copolyesters in aqueous medium by dialysis method. These micelles with different PEG contents have sizes varying from 74.3 nm to 138.3 nm and are stable in water over 200 days without any precipitation. A hydrophobic pesticide, Avermectin, was encapsulated in micelles by the same dialysis method. Such PBMS-PEG micelles can be used as thermo-responsive drug carrier owing to their controlled lower critical solution temperature (LCST) which can be accurately adjusted by varying the PEG proportion. The LCST increases from 27.0 °C to 40.0 °C while increasing the PEG proportion from 30% to 60%. By using the HPLC measurements, the results show when the drug loading is up to 20%, the loading efficiency is still nearly 100%. The properties of these amphiphilic micelles show that the delivery system has a promising potential to be further explored for developing a highly effective and biodegradable hydrophobic-pesticide-release formulation.

Facile Synthesis of Aliphatic ω-Pentadecalactone Containing Diblock Copolyesters via Sequential ROP with l-Lactide, ε-Caprolactone, and δ-Valerolactone Catalyzed by Cyclic Trimeric Phosphazene Base with Inherent Tribasic Characteristics

Degradable long-chain aliphatic polyesters are promising alternatives to polyolefins. The ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) enables the synthesis of aliphatic polyesters with melting temperature close to low-density polyethylene (LDPE). However, this ROP reaction is of great challenge because of low ring strain of the PDL monomer. The occurrence of intra- and intermolecular transesterification reactions during ROP made it difficult to prepare well-defined block copolyesters for advanced properties. In this context, cyclic trimeric phosphazene base (CTPB) in combination with benzyl alcohol (BnOH) was proved to be an efficient initiator system for ROP of PDL, showing an excellent polymerization rate (TOF up to 600 h–1) at 80 °C. Well-defined diblock copolyesters, i.e., PPDL-b-PLLA, can be easily synthesized by sequential addition of PDL and l-lactide (L-LA). In contrast, sequential addition of PDL and e-caprolactone (CL) or δ-valerolactone (VL) only led to the random copolyesters...

Living/controlled ring-opening (co)polymerization of lactones by Al-based catalysts with different sidearms.

It remains a challenging task to synthesize well-defined multi-block copolymers through the controlled/living ring-opening polymerization (ROP) of lactones without transesterification, the most common side reaction occurring during copolymerization. A series of Al-based complexes with different sidearms were prepared for living ROP of lactones such as ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) in the presence of BnOH at room temperature (RT), affording medium to high molecular weight (MW) linear polyesters with Mw up to 303 kg mol-1 and narrow molecular weight distributions (MWD, Đ as low as 1.12). The coordination-insertion polymerization mechanism was proposed based on the combination of the detailed experimental data and polymerization kinetics. It should be noted that the sidearm plays a significant important role in the reactivity of these Al-based catalyst systems. More specifically, the Al2 system with a butyl substituent on the sidearm exhibited the highest polymerization activity and the Al5 system with the bulkiest sidearm showed the lowest one among the investigated catalysts. Moreover, the Al4 system with a pyridine group on the sidearm could effectively inhibit transesterification and maintain a well-defined block copolymer structure even after heating at 50 °C for 10 h, which could also be confirmed by chain-end analyses of the produced polymers with the MALDI-TOF MS measurement.

Sequence-Selective Terpolymerization from Monomer Mixtures Using a Simple Organocatalyst.

One-step synthesis of block copolymer from mixed monomers is of great interest and challenge. Using a simple non-nucleophilic organobase as the catalyst, we have achieved sequence-selective terpolymerization from a mixture of phthalic anhydride (PA), an epoxide, and rac-lactide (LA). Alcohol-initiated alternating copolymerization of PA and epoxide occurs first and exclusively because PA is substantially more active than LA for reacting with base-activated hydroxyl. When PA is fully consumed, LA polymerizes from the termini of the first block while excess epoxide stays intact because of the mild basicity of the catalyst. The two polymerizations thus occur tandemly, both in chemoselective manners, so that an aromatic-aliphatic block copolyester is generated in this one-step synthesis. The effectiveness and versatility of this approach is demonstrated by the use of ethylene oxide and several monosubstituted epoxides as well as mono-, di-, or tetrahydroxy initiators.

Maintaining the Hydrophilic–Hydrophobic Balance of Polyesters with Adjustable Crystallinity for Tailor-Made Nanoparticles

To explore the relationship between thermal properties of a polymer and the biological performance of the resulting nanoparticle, all other parameters, including the hydrophobicity, should be kept constant. For this purpose, a gradient and a block copolyester were tailor-made via the triazabicyclodecene catalyzed ring-opening copolymerization of δ-valerolactone (δVL) and δ-decalactone (δDL) to match the hydrophobicity of poly(e-caprolactone) (PeCL). The degree of crystallinity of the semicrystalline materials was significantly reduced due to the incorporation of amorphous PδDL segments, as confirmed by dynamic scanning calorimetry. Atomic force microscopy revealed short and randomly oriented crystals in the gradient copolymer but longer and parallel aligned crystals for the block copolymer and PeCL. The stiffness of nanoparticles (Dh ≈ 170 nm) prepared from the polyesters correlated to the bulk crystallinity. The set of nanoparticles with constant hydrophobicity and size will facilitate direct access to t...

Chemo-Enzymatic Synthesis of Poly(4-piperidine lactone- b-ω-pentadecalactone) Block Copolymers as Biomaterials with Antibacterial Properties.

With increasing troubles in bacterial contamination and antibiotic-resistance, new materials possessing both biocompatibility and antimicrobial efficacy are supposed to be developed for future biomedical application. Herein, we demonstrated a chemo-enzymatic ring opening polymerization (ROP) approach for block copolyester, that is, poly(4-benzyl formate piperidine lactone- b-ω-pentadecalactone) (PNPIL- b-PPDL), in a one-pot two-step process. Afterward, cationic poly(4-piperidine lactone- b-ω-pentadecalactone) (PPIL- b-PPDL) with pendent secondary amino groups was obtained via acidic hydrolysis of PNPIL- b-PPDL. The resulting cationic block copolyester exhibited high antibacterial activity against Gram negative E. coli and Gram positive S. aureus, while showed low toxicity toward NIH-3T3 cells. Moreover, the antibacterial property, cytotoxicity and degradation behavior could be tuned simply by variation of PPIL content. Therefore, we anticipate that such cationic block copolymers could potentially be applied as biomaterials for medicine or implants.