Self-Switchable Polymerization: A Smart Approach to Sequence-Controlled Degradable Copolymers

Phase Separation Pathways of Chiral Macromolecules at Liquid-Liquid Interfaces

The phase behavior of chiral macromolecules is one of the key subjects in chemistry, biology, and materials science. Here we take poly(L-lactic acid) (PLLA) and mesomeric poly(D, L-lactic acid) (mPLA) mixtures as a model system and investigate the phase separation behaviors in double emulsion droplets. At high mPLA compositions, phase separation creates transient bicontinuous networks or discrete domains at the liquid-liquid interface and eventually generates eyeball-like microcapsules. At low mPLA compositions, phase separation occurs first but is trapped by the lateral crystallization of PLLA, leading to spindle-like microcapsules. The dynamic pathways of phase separation can be further modulated by PLA-based amphiphilic block copolymers, so that microcapsules are configurable between the eyeball-, spindle-, and Janus-like structures. By comparing with phase separation on a plane substrate, we unveil that the phase separation dynamics at the double emulsion interfaces are significantly affected by interfacial properties and hydrodynamic effects. This work clarifies the phase transition dynamics of PLLA/mPLA mixtures at liquid-liquid interfaces and sheds insight into the phase behaviors of chiral macromolecules for their structural modulation.

Switchable Polymerization from Monomer Mixtures to Synthesize Oxygen-Rich Block Copolymers with Dual Recyclability and Degradability

Switchable catalysis from monomer mixtures has been emerging as a powerful technique to synthesize various useful block copolymers, yet represents a significant challenge in polymer chemistry. Herein, we present the synthesis of well-defined polyacetal/polycarbonate block copolymers through switchable polymerization from mixtures of terminal epoxides, internal epoxides, o-phthalaldehyde (OPA) and CO2. The exclusive chemoselectivity of terminal epoxide or internal epoxide was achieved by controlling the reaction atmosphere. The dynamic equilibrium of acetal anion and alkoxy anion is the key to the successful switch from terminal epoxides/OPA copolymerization to internal epoxides/CO2 copolymerization. Computational studies elucidated the kinetic and thermodynamic preferences underlying this selective polymerization. The acid/base labile nature of the block copolymers enables their sequence-controlled chemical recycling/degradation. These novel polyacetal/polycarbonate block copolymers with facilely sequence-controlled polymerization/depolymerization capabilities will enable their further tailored applications and contribute to the development of a circular plastic economy.

Synthesis of Alternating Copolymers with Substituents Containing Heteroatoms and the Regulation of Nontraditional Intrinsic Luminescence

Compared with other sequence structure polymers, alternating polymers usually have several unique properties, but their properties are more sensitive to changes in structure. By investigating the relationship between the structure and properties of alternating polymer chains, polymers with desired properties can likely be synthesized. In this study, a series of alternating copolymers of 1,1-diphenylethylene (DPE) derivatives and styrene derivatives, which exhibit nontraditional intrinsic luminescence (NTIL), are synthesized using living anionic polymerization. By changing the bridge plane structure of the DPE derivatives and the substituent groups of the styrene derivatives, the rigid chain structure of the alternating copolymers containing styrene derivative with a large steric hindrance is altered, and this change is observed by the altered fluorescence properties. Based on the results from experimental tests and theoretical simulations, copolymers with bridge plane structures have higher fluorescence emission intensities; moreover, a balance is observed between the electronic and steric hindrance effects of substituents on the fluorescence intensities, and polymer chains that are too rigid cause a decrease in the fluorescence intensities. Thus, the influence of the chain structure on the fluorescence properties of NTIL polymers cannot be disregarded.

Modular Access from Acrylate to a Sustainable Polyester Platform with Large-Span Tunability and Chemical Circularity under Mild Conditions

Making polyesters with conventional vinyl monomers is one of the most economical ways to develop sustainable polymeric materials. For polar vinyls, while their transformation into lactones has been studied extensively, there exists no further access to synthesizing polyesters, presumably due to the nonstrained and nonpolymerizable nature of the obtained lactones. Herein, we report the first facile synthesis of polyesters that originated from one of the most critical classes of polar vinyls-acrylates. Specifically, a series of modular six-membered lactones were rationally designed and synthesized from methyl acrylate together with malonic esters containing diverse functional groups and formaldehyde. The monomers underwent ring-opening polymerization (ROP) to yield the first acrylate-derived polyesters, which further constitute a unique polymer platform with a large scope of potential functionalities and performances as well as easy chemical circularity under mild conditions. Notably, the obtained polyesters are a rare example featuring tunable functionalities on the side ester groups whose impact on certain material properties (e.g., glass transition temperature) is similar to that of polyacrylates, implying potential replacement between polyesters and polyacrylates. In addition, by presenting the special geminal disubstitutions originally from the monomers' γ-position for the first time, polyesters also exhibited unprecedentedly enhanced thermal and recycling properties: Variation of the geminal disubstitutions offers a unique access to large-span modulation from completely amorphous to high-level crystalline materials, and the melting temperature of the polymer with high crystallinity was drastically increased by 84 °C compared with the reported monosubstituted counterpart. At the same time, compared with polyesters synthesized from other six-membered lactones whose chemical recycling required harsh conditions (>150 °C and high vacuum), the gem-disubstituted polyesters in this work can undergo complete chemical recycling to monomers under much milder conditions (80 °C and ambient pressure). This study informs the design of future high-performance polyesters derived from polar vinyls.

Precise placement of thioester bonds into sequence-controlled polymers containing ABAC-type units

The precise placement of thioester bonds into sequence-controlled polymers remains a grand challenge. Here, we demonstrate the versatile synthesis of sequence-controlled polymers from the step polymerization of cyclic thioanhydrides (A), diacrylates (B), and diols/diamines (C). In addition to easily accessible diverse monomers, the method is metal-free/catalyst-free, atom-economical, and wide in monomer scope, yielding 107 polymers with >90% yields and weight-average molecular weights of up to 175.4 kDa. The obtained polymers contain ABAC-type repeating units and precisely distributed in-chain thioester and ester (and amide) groups. The chemoselectivity of the polymerization is revealed by density functional theory calculations. The polymer library exhibits considerably tunable performance: glass-transition temperatures of -36-72 °C, melting temperatures of 43-133 °C, degradability, thermoplastics/elastomers, and thioester-based functions. This study furnishes a facile method to precisely incorporate thioester bonds into sequence-controlled polymers.

Binary Catalyst Manipulating the Sequences of Poly(ester-carbonate) Copolymers in Metal-Free Terpolymerization of Epoxide, Anhydride, and CO2

The one-pot terpolymerization of epoxide (EP), anhydride (AH), and CO2 to synthesize polyester-polycarbonate copolymers with precise sequences remains a significant challenge in polymer chemistry. In this study, promising progress was achieved by utilizing a cyclic trimeric phosphazene base (CTPB) and triethylboron (TEB) as a binary catalyst, enabling the synthesis of both well-defined block and truly random poly(ester-carbonate) copolymers through the one-pot terpolymerization of EP/AH/CO2. By adjusting the molar ratio of CTPB/TEB to 1/0.5, remarkable chemoselectivity for ring-opening alternating copolymerization (ROAC) of propylene oxide (PO) and phthalic anhydride (PA) was achieved, followed by the ROAC of PO/CO2. This sequential control allowed for the synthesis of well-defined block poly(ester-carbonate) copolymers, containing three possible sequences, ester-ester sequence (EE)/ester-carbonate sequence (EC)/carbonate-carbonate sequence (CC) = 59/4/37, from a mixture of PO, PA, and CO2. Moreover, the versatility of this CTPB/TEB catalyst in regulating chemoselectivity was demonstrated, with a ratio of 1/3 facilitating the simultaneous ROAC of PO/PA and PO/CO2 with compatible rates, resulting in the production of random poly(ester-carbonate) copolymers, in which three possible sequences (EE/EC/CC = 26/50/24) are very close to theoretical values. This metal-free catalytic system and its flexible chemoselectivity regulation strategy proved to be applicable to a wide range of epoxides (PO, cyclohexene oxide (CHO)) and anhydrides (PA, diglycolic anhydride (DGA), and succinic anhydride (SA)), enabling the successful synthesis of poly(ester-carbonate) copolymers with diverse sequences and compositions.

Bulky Phosphazenium Salt Controlling Chemoselective Terpolymerization of Epoxide, Anhydride and CO2: From Well-Defined Block to Truly Random Copolymers

Copolymers with precise compositions and controlled sequences are great appealing for high-performance polymeric materials, but their synthesis is very challenging. In this study, tetrakis[tris(dimethylamino)phosphoranylidenamino] phosphonium chloride (P5Cl) and triethylboron (TEB) were chosen as the binary catalyst to synthesize both well-defined block and truly random poly(ester-carbonate) copolymers via the one-pot/one-step terpolymerization of epoxide/anhydride/CO2 under metal-free conditions. The bulky nature of phosphazenium cation not only led to loose cation-anion pairs and enhanced the reactivity, but also provided the chain-end an appropriate protection and improved the controllability. In particular, P5Cl/TEB with a molar ratio of 1/0.5 showed an extraordinary chemoselectivity for ring-opening alternating copolymerization (ROAC) of cyclohexene oxide (CHO) and phthalic anhydride (PA) first and then ROAC of CHO/CO2. Thus, well-defined block polyester-polycarbonate copolymers were synthesized by CHO/PA/CO2 terpolymerization. The chemoselectivity was easily tuned and the ROAC of CHO/PA and ROAC of CHO/CO2 occurred simultaneously with P5Cl/TEB=1/2, producing truly random poly(ester-carbonate) copolymers from CHO/PA/CO2. In addition, this P5Cl/TEB catalyst and the strategy to regulate its chemoselectivity are versatile for various anhydrides, epoxides and initiators. Thus, poly(ester-carbonate) copolymers with varying sequences, compositions, and topologies are successfully synthesized, making it possible to compare their properties and to expand their applications.

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.

Evolution of Copolymers of Epoxides and CO2: Catalysts, Monomers, Architectures, and Applications

The copolymerization of CO2 and epoxides presents a transformative approach to converting greenhouse gases into aliphatic polycarbonates (CO2-PCs), thereby reducing the polymer industry's dependence on fossil resources. Over the past 50 years, a wide array of metallic catalysts, both heterogeneous and homogeneous, have been developed to achieve precise control over polymer selectivity, sequence, regio-, and stereoselectivity. This review details the evolution of metal-based catalysts, with a particular focus on the emergence of organoborane catalysts, and explores how these catalysts effectively address kinetic and thermodynamic challenges in CO2/epoxides copoly2merization. Advances in the synthesis of CO2-PCs with varied sequence and chain architectures through diverse polymerization protocols are examined, alongside the applications of functional CO2-PCs produced by incorporating different epoxides. The review also underscores the contributions of computational techniques to our understanding of copolymerization mechanisms and highlights recent advances in the closed-loop chemical recycling of CO2-sourced polycarbonates. Finally, the industrialization efforts of CO2-PCs are discussed, offering readers a comprehensive understanding of the evolution and future potential of epoxide copolymerization with CO2.

Easy access to amphiphilic nitrogenous block copolymers via switchable catalysis

A key challenge in polymer synthesis is to develop new methods that enable block copolymers to be prepared from mixed monomer feedstock. The emerging switchable polymerization catalysis can generate block copolymers with well-defined structures and tunable properties from monomer mixtures. However, constrained by the reactivity of monomers and the incompatibility of different polymerization mechanisms, this method is usually confined to oxygenated monomers. In this work, the switchable polymerization was successfully applied to nitrogenous monomers for the first time, achieving the efficient copolymerization of N-substituted N-carboxyanhydrides (NNCAs) with epoxides and cyclic anhydrides. This leads to easy access towards amphiphilic nitrogenous copolymers, such as polyester-b-polypeptoids. Density functional theory calculations demonstrated that the reaction of cyclic anhydrides with the alkoxide terminal is thermodynamically more favorable than that of NNCAs. Characterization, using nuclear magnetic resonance spectroscopy, size exclusion chromatography and in situ infrared spectroscopy, has confirmed the well-defined block structure of the obtained copolymers. This switchable polymerization strategy is applicable to a range of monomer mixtures with different oxygenated monomers and NNCAs, providing a highly efficient synthetic route towards nitrogenous block copolymers. Most importantly, the easily accessed amphiphilic polyester-b-polypeptoids demonstrated excellent anti-protein adsorption capabilities and barely any cytotoxicity, showing great potential in the field of biomedicine.

Polyester Adhesives via One-Pot, One-Step Copolymerization of Cyclic Anhydride, Epoxide, and Lactide

Polyesters (PEs) are sustainable alternatives for conventional polymers owing to their potential degradability, recyclability, and the wide availability of bio-based monomers for their synthesis. Herein, we used a one-pot, one-step self-switchable polymerization linking the ring-opening alternating copolymerization (ROAC) of epoxides/cyclic anhydrides with the ring-opening polymerization (ROP) of L-lactide (LLA) to synthesize PE-based hot-melt adhesives with a high bio-based content. In the cesium pivalate-catalyzed self-switchable polymerization of glutaric anhydride (GA), butylene oxide (BO), and LLA using a diol initiator, the ROAC of GA and BO proceeded whereas the ROP of LLA simultaneously proceeded very slowly, resulting in a copolyester consisting of poly(GA-alt-BO) and poly(L-lactide) (PLLA) segments with tapered regions, that is, PLLA-tapered block-poly(GA-alt-BO)-tapered block-PLLA (PLLA-tb-poly(GA-alt-BO)-tb-PLLA). Additionally, a series of tapered-block or real-block copolyesters consisting of poly(anhydride-alt-epoxide) (A segment) and PLLA (B segment) with AB-, BAB-, (AB)3-, and (AB)4-type architectures of different compositions and molecular weights were synthesized by varying the monomer combinations, alcohol initiators, and initial feed ratios. The lap shear tests of these copolyesters revealed an excellent relationship between the adhesive strength and polymer structural parameters. The (AB)4-type star-block copolyester (poly(GA-alt-BO)-tb-PLLA)4 exhibited the best adhesive strength (6.74 ± 0.64 MPa), comparable to that of commercial products, such as PE-based and poly(vinyl acetate)-based hot-melt adhesives.

Toward Fully Controllable Monomers Sequence: Binary Organocatalyzed Polymerization from Epoxide/Aziridine/Cyclic Anhydride Monomer Mixture

The sequence of monomers within a polymer chain plays a pivotal role in determining the physicochemical properties of the polymer. In the copolymerization of two or more monomers, the arrangement of monomers within the resulting polymer is primarily dictated by the intrinsic reactivity of the monomers. Precisely controlling the monomer sequence in copolymerization, particularly through the manipulation of catalysts, is a subject of intense interest and poses significant challenges. In this study, we report the catalyst-controlled copolymerization of epoxides, N-tosyl aziridine (TAz), and cyclic anhydrides. To achieve this, a binary catalyst system comprising a Lewis acid, triethylborane, and Brønsted base, t-BuP1, was utilized. This system was utilized to regulate the selectivity between two catalytic reactions: ring-opening alternating copolymerization (ROAC) of epoxides/cyclic anhydrides and ROAC of TAz/cyclic anhydrides. Changing the catalyst ratio made it possible to continuously modulate the resulting poly(ester-amide ester) from ABA-type real block copolymers to gradient, random-like, reversed gradient, and reversed BAB-type block-like copolymers. A range of epoxides and anhydrides was investigated, demonstrating the versatility of this polymerization system. Additionally, density functional theory calculations were conducted to enhance our mechanistic understanding of the process. This synthetic method not only provides a versatile means for producing copolymers with comparable chemical compositions but also facilitates the exploration of the intricate relationship between monomer sequences and the resultant polymer properties, offering valuable insights for advancements in polymer science.

Superior sequence-controlled poly(L-lactide)-based bioplastic with tunable seawater biodegradation

Developing superior-performance marine-biodegradable plastics remains a critical challenge in mitigating marine plastic pollution. Commercially available biodegradable polymers, such as poly(L-lactide) (PLA), undergo slow degradation in complex marine environments. This study introduces an innovative bioplastic design that employs a facile ring-opening and coupling reaction to incorporate hydrophilic polyethylene glycol (PEG) into PLA, yielding PEG-PLA copolymers with either sequence-controlled alternating or random structures. These materials exhibit exceptional toughness in both wet and dry states, with an elongation at break of 1446.8% in the wet state. Specifically, PEG4kPLA2k copolymer biodegraded rapidly in proteinase K enzymatic solutions and had a significant weight loss of 71.5% after 28 d in seawater. The degradation primarily affects the PLA segments within the PEG-PLA copolymer, as evidenced by structural changes confirmed through comprehensive characterization techniques. The seawater biodegradability, in line with the Organization for Economic Cooperation and Development 306 Marine biodegradation test guideline, reached 72.63%, verified by quantitative biochemical oxygen demand analysis, demonstrating rapid chain scission in marine environments. The capacity of PEG-PLA bioplastic to withstand DI water and rapidly biodegrade in seawater makes it a promising candidate for preventing marine plastic pollution.

Sustainable, Recyclable, and Bench-Stable Catalytic System for Synthesis of Poly(ester-b-carbonate)

Transferring abundant, inexpensive, and nontoxic carbon dioxide (CO2) into biodegradable polymers is one of the ideal ways to promote sustainable development. Although a great deal of preeminent researches has been reported in the last decade, including well-designed organometallic complexes, Lewis pairs, etc. The moisture- and air-sensitive nature of these extensively used catalysts preclude their use in industrial applications. Herein, we report a novel stable catalyst system of commercial zinc glutarate (ZnGA) with a supported metal for the synthesis of poly(ester-b-carbonate). The special supported microstructure facilitates efficient polymerizations via a plausible heterometal coordination mechanism. Notably, the resulted biodegradable CO2-based copolymer showed strong tensile strength (>40 MPa), improved elongation (45% versus 7%), excellent transmittance, and low water vapor permeability (WVP) (1.7 × 10-11 g m-1 s-1 Pa-1). Moreover, the supported ZnGA catalyst is recyclable, and its simple and low-cost preparation process is compatible with the manufacturing and processing methods of the existing infrastructure.

Natural polyphenolic antibacterial bio-adhesives for infected wound healing

Bio-adhesives used clinically, commonly have the ability to fill surgical voids and support wound healing, but which are devoid of antibacterial activity, and thus, could not meet the particular needs of the infected wound site. Herein, a series of natural polyphenolic antibacterial bio-adhesives were prepared via simple mixing and heating of polyphenols and acid anhydrides without any solvent or catalyst. Upon the acid anhydride ring opening and acylation reactions, various natural polyphenolic bio-adhesives could adhere to various substrates (i.e., tissue, wood, glass, rubber, paper, plastic, and metal) based on multi-interactions. Moreover, these bio-adhesives showed excellent antibacterial and anti-infection activity, rapid hemostatic performance and appropriate biodegradability, which could be widely used in promoting bacterial infection wound healing and hot burn infection wound repair. This work could provide a new strategy for strong adhesives using naturally occurring molecules, and provide a method for the preparation of novel multifunctional wound dressings for infected wound healing.

A Supported Catalyst that Enables the Synthesis of Colorless CO2 -Polyols with Ultra-Low Molecular Weight

Ultra-low molecular weight (ULMW) CO2 -polyols with well-defined hydroxyl end groups represent useful soft segments for the preparation of high-performance polyurethane foams. However, owing to the poor proton tolerance of catalysts towards CO2 /epoxide telomerization, it remains challenging to synthesize ULMW yet colorless CO2 -polyols. Herein, we propose an immobilization strategy of constructing supported catalysts by chemical anchoring of aluminum porphyrin on Merrifield resin. The resulting supported catalyst displays both extremely high proton tolerance (≈8000 times the equivalents of metal centers) and independence of cocatalyst, affording CO2 -polyols with ULMW (580 g mol-1 ) and high polymer selectivity (>99 %). Moreover, the ULMW CO2 -polyols with various architectures (tri-, quadra-, and hexa-arm) can be obtained, suggesting the wide proton universality of supported catalysts. Notably, benefiting from the heterogeneous nature of the supported catalyst, colorless products can be facilely achieved by simple filtration. The present strategy provides a platform for the synthesis of colorless ULMW polyols derived from not only CO2 /epoxides, but also lactone, anhydrides etc. or their combinations.

Recent Advances in Sequence-Controlled Ring-Opening Copolymerizations of Monomer Mixtures

Transforming renewable resources into functional and degradable polymers is driven by the ever-increasing demand to replace unsustainable polyolefins. However, the utility of many degradable homopolymers remains limited due to their inferior properties compared to commodity polyolefins. Therefore, the synthesis of sequence-defined copolymers from one-pot monomer mixtures is not only conceptually appealing in chemistry, but also economically attractive by maximizing materials usage and improving polymers' performances. Among many polymerization strategies, ring-opening (co)polymerization of cyclic monomers enables efficient access to degradable polymers with high control on molecular weights and molecular weight distributions. Herein, we highlight recent advances in achieving one-pot, sequence-controlled polymerizations of cyclic monomer mixtures using a single catalytic system that combines multiple catalytic cycles. The scopes of cyclic monomers, catalysts, and polymerization mechanisms are presented for this type of sequence-controlled ring-opening copolymerization.

Sequence-Reversible Construction of Oxygen-Rich Block Copolymers from Epoxide Mixtures by Organoboron Catalysts

Switchable catalysis, in combination with epoxide-involved ring-opening (co)polymerization, is a powerful technique that can be used to synthesize various oxygen-rich block copolymers. Despite intense research in this field, the sequence-controlled polymerization from epoxide congeners has never been realized due to their similar ring-strain which exerts a decisive influence on the reaction process. Recently, quaternary ammonium (or phosphonium)-containing bifunctional organoboron catalysts have been developed by our group, showing high efficiency for various epoxide conversions. Herein, we, for the first time, report an operationally simple pathway to access well-defined polyether-block-polycarbonate copolymers from mixtures of epoxides by switchable catalysis, which was enabled through thermodynamically and kinetically preferential ring-opening of terminal epoxides or internal epoxides under different atmospheres (CO₂ or N₂) using one representative bifunctional organoboron catalyst. This strategy shows a broad substrate scope as it is suitable for various combinations of terminal epoxides and internal epoxides, delivering corresponding well-defined block copolymers. NMR, MALDI-TOF, and gel permeation chromatography analyses confirmed the successful construction of polyether-block-polycarbonate copolymers. Kinetic studies and density functional theory calculations elucidate the reversible selectivity between different epoxides in the presence/absence of CO₂. Moreover, by replacing comonomer CO₂ with cyclic anhydride, the well-defined polyether-block-polyester copolymers can also be synthesized. This work provides a rare example of sequence-controlled polymerization from epoxide mixtures, broadening the arsenal of switchable catalysis that can produce oxygen-rich polymers in a controlled manner.

Switchable Polymerization: A Practicable Strategy to Produce Biodegradable Block Copolymers with Diverse Properties

With the global demand for sustainable development, there has been an increasing interest in using natural biomass as raw resources to produce sustainable polymers as an alternative to petroleum-based polymers. Because monocomponent biodegradable polymers are often insufficient in performance, copolymers with well-engineered block structures are synthesized to reach wide tunability. Switchable polymerization is such a practical strategy to produce biodegradable block copolymers with diverse performance. This review focus on the performance of block copolymers bearing biodegradable polymer segments produced by diverse switchable polymerization. We highlight two main segments that are critical for biodegradable block copolymers, i. e., polyester and polycarbonate, summarize the multiple characters of materials from switchable polymerization such as antibacterial, shape memory, adhesives, etc. The state-of-the-art research on biodegradable block copolymers, as well as an outlook on the preparation and application of novel materials, are presented.

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.

Thioanhydride/isothiocyanate/epoxide ring-opening terpolymerisation: sequence selective enchainment of monomer mixtures and switchable catalysis

Lithium mediates sequence selective terpolymerisation of phtalic thioanhydride/PhNCS/butylene oxide yielding poly(ester-alt-ester-alt-dithioimidocarbonates) and enables block- and tetrapolymerisations.