Combining Orthogonal Chain-End Deprotections and Thiol-Maleimide Michael Coupling: Engineering Discrete Oligomers by an Iterative Growth Strategy

Precision Sequence-Defined Polymers: From Sequencing to Biological Functions

Precise sequence-defined polymers (SDPs) with uniform chain-to-chain structure including chain length, unit sequence, and end functionalities represent the pinnacle of sophistication in the realm of polymer science. For example, the absolute control over the unit sequence of SDPs allows for the bottom-up design of polymers with hierarchical microstructures and functions. Accompanied with the development of synthetic techniques towards precision SDPs, the decoding of SDP sequences and construction of advanced functions irreplaceable by other synthetic materials is of central importance. In this Minireview, we focus on recent advances in SDP sequencing techniques including tandem mass spectrometry (MS), chemically assisted primary MS, as well as other non-destructive sequencing methods such as nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), and nanopore sequencing. Additionally, we delve into the promising prospects of SDP functions in the area of cutting-edge biological research. Topics of exploration include gene delivery systems, the development of hybrid materials combining SDPs and nucleic acids, protein recognition and regulation, as well as the interplay between chirality and biological functions. A brief outlook towards the future directions of SDPs is also presented.

Heat Transfer Enhancement in Tree-Structured Polymer Linked Gold Nanoparticle Networks

Human brains use a tree-like neuron network for information processing at high efficiency and low energy consumption. Tree-like structures have also been engineered to enhance mass and heat transfer in various applications. In this work, we reveal the heat transfer mechanism in tree-structured polymer linked gold nanoparticle (AuNP) networks using atomistic simulations. We report both upward and downward heat fluxes between root and leaf nodes in tree-structured polyethylene (PE) and poly(p-phenylene) (PPP) linked AuNP networks at tree levels from 1 to 5. We found that the heat conductance increases with an increasing polymer tree level. The heat transfer enhancement is due to the resulting increase in the low-frequency vibrational modes. This and other thermal properties are affected by the location of the AuNPs in the tree. Moreover, complex tree structures with at least five levels were found to be robust in the sense that disabling half of the leaves did not change the overall heat conductance.

Conception and Evaluation of a Library of Cleavable Mass Tags for Digital Polymers Sequencing

A library of phosphoramidite monomers containing a main-chain cleavable alkoxyamine and a side-chain substituent of variable molar mass (i.e. mass tag) was prepared in this work. These monomers can be used in automated solid-phase phosphoramidite chemistry and therefore incorporated periodically as spacers inside digitally-encoded poly(phosphodiester) chains. Consequently, the formed polymers contain tagged cleavable sites that guide their fragmentation in mass spectrometry sequencing and enhance their digital readability. The spacers were all prepared via a seven steps synthetic procedure. They were afterwards tested for the synthesis and sequencing of model digital polymers. Uniform digitally-encoded polymers were obtained as major species in all cases, even though some minor defects were sometimes detected. Furthermore, the polymers were decoded in pseudo-MS3 conditions, thus confirming the reliability and versatility of the spacers library.

Sequence effect on the self-assembly of discrete amphiphilic co-oligomers with fluorene-azobenzene semirigid backbones

Sequences can have a dramatic impact on the unique properties and self-assembly in natural macromolecules, which has received increasing interest. Herein, we report a series of discrete amphiphilic co-oligomers with the same composition but different building blocks in a semirigid backbone. These sequence-defined oligomers possess two primary amine groups on the side chain of the azobenzene building block, and hence, they become amphipathic due to quaternization of the amine groups when protonated in acidic aqueous solution. These oligomer isomers assembled into different nanoparticles, including nanofibers, hollow vesicles and spherical micellar complexes, in a THF/water/HCl mixture under the same conditions. UV-vis absorption spectra, differential scanning calorimetry (DSC) and X-ray scattering (XRD) experiments combined with theoretical calculations reveal that the sequence-controlled co-oligomers induce different molecular packing conformations and arrangement modes of building blocks in self-assembly. Furthermore, these self-assembled nanoparticles demonstrate photoresponsive morphological transformation and fluorescence emission under UV light irradiation due to trans-to-cis photoisomerization of azobenzene. This work demonstrates that customizing functional nanoparticles can be achieved by controlling the sequence structure in synthetic co-oligomers.

Digital synthetic polymers for information storage

Digital synthetic polymers with uniform chain lengths and defined monomer sequences have recently become intriguing alternatives to traditional silicon-based information devices or natural biomacromolecules for data storage. The structural diversity of information-containing macromolecules endows the digital synthetic polymers with higher stability and storage density but less occupied space. Through subtly designing each unit of coded structure, the information can be readily encoded into digital synthetic polymers in a more economical scheme and more decodable, opening up new avenues for molecular digital data storage with high-level security. This tutorial review summarizes recent advances in salient features of digital synthetic polymers for data storage, including encoding, decoding, editing, erasing, encrypting, and repairing. The current challenges and outlook are finally discussed to offer potential solution guidance and new perspectives for the creation of next-generation digital synthetic polymers and broaden the scope of their applicability.

An Arbitrarily Regulated Monomer Sequence in Multi-Block Copolymer Synthesis by Frustrated Lewis Pairs

Rapid access to sequence-controlled multi-block copolymers (multi-BCPs) remains as a challenging task in the polymer synthesis. Here we employ a Lewis pair (LP) composed of organophosphorus superbase and bulky organoaluminum to effectively copolymerize the mixture of methacrylate, cyclic acrylate, and two acrylates, into well-defined di-, tri-, tetra- and even a hepta-BCP in one-pot one-step manner. The combined livingness, dual-initiation and CSC feature of Lewis pair polymerization enable us to achieve not only a trihexaconta-BCP with the highest record in 8 steps by using four-component monomer mixture as building blocks, but also the arbitrarily-regulated monomer sequence in multi-BCP, simply by changing the composition and adding order of the monomer mixtures, thus demonstrating the powerful capability of our strategy in improving the efficiency and enriching the composition of multi-BCP synthesis.

Dendritic Quaternary-Encoded Oligourethanes for Data Encryption

The use of sequence-defined digital polymers for data storage and encryption has received increasing attention due to their precision structures similar to natural biomacromolecules (e.g., DNA) but increased stability. However, the rapid development of sequencing techniques raises the concern of information leakage. Herein, dendritic quaternary-encoded oligourethanes bearing a photoresponsive trigger, self-immolative backbones, and a mass spectrometry tag of PEG dendron have been developed for data encryption. Although the sequence information in linear analogs can be readily deciphered by mass spectrometry, sequencing of dendritic oligourethanes cannot be achieved by either primary MS or tandem MS/MS owing to the unique spatial conformation. Intriguingly, the fragmentation pathways of a quaternary dendrimer under MS/MS conditions can be converted to 2772-bit 2D matrices with ≈1.98×10⁸⁷ permutations, serving as high-strength encryption keys for highly reliable data encryption.

Molecular data storage with zero synthetic effort and simple read-out

Compound mixtures represent an alternative, additional approach to DNA and synthetic sequence-defined macromolecules in the field of non-conventional molecular data storage, which may be useful depending on the target application. Here, we report a fast and efficient method for information storage in molecular mixtures by the direct use of commercially available chemicals and thus, zero synthetic steps need to be performed. As a proof of principle, a binary coding language is used for encoding words in ASCII or black and white pixels of a bitmap. This way, we stored a 25 × 25-pixel QR code (625 bits) and a picture of the same size. Decoding of the written information is achieved via spectroscopic (¹H NMR) or chromatographic (gas chromatography) analysis. In addition, for a faster and automated read-out of the data, we developed a decoding software, which also orders the data sets according to an internal “ordering” standard. Molecular keys or anticounterfeiting are possible areas of application for information-containing compound mixtures.

Effect of Molecular Architecture and Symmetry on Self-Assembly: A Quantitative Revisit Using Discrete ABA Triblock Copolymers

The inherent statistical heterogeneities associated with chain length, composition, and architecture of synthetic block copolymers compromise the quantitative interpretation of their self-assembly process. This study scrutinizes the contribution of molecular architecture on phase behaviors using discrete ABA triblock copolymers with precise chemical structure and uniform chain length. A group of discrete triblock copolymers with varying composition and symmetry were modularly synthesized through a combination of iterative growth methods and efficient coupling reactions. The symmetric ABA triblock copolymers self-assemble into long-range ordered structures with expanded domain spacings and enhanced phase stability, compared with the diblock counterparts snipped at the middle point. By tuning the relative chain length of two end blocks, the molecular asymmetry reduces the packing frustration, and thus increases the order-to-disorder transition temperature and enlarges the domain sizes. This study would serve as a quantitative model system to correlate the experimental observations with the theoretical assessments and to provide quantitative understandings for the relationship between molecular architecture and self-assembly.

Fabrication and Decryption of a Microarray of Digital Dithiosuccinimide Oligomers

Digital polymer with precisely arranged binary units provides an important option for information storage. This is especially true if the digital polymers are assembled in a device, as it would be of great benefit to data writing and reading in practice. Herein, inspired by DNA microarray technique, the programmable information storing and reading on a mass spectrometry target plate is proposed. First, an array of 4-bit sequence-coded dithiosuccinimide oligomers was efficiently built through sequential thiol-maleimide Michael couplings with good sequence readability by tandem mass spectrometry (MS/MS). Then, toward engineering microarray for information storage, a programmed robotic arm was specifically designed for precisely loading sequence-coded oligomers onto the target plate, and a decoding software was developed for efficient readout of the data from MS/MS sequencing. Notably, short sequence-coded oligomers chains can be used to write long strings of information, and extra error-correction codes are not required as usual due to the inherent concomitant fragmentation signals. Not only text but also bitimages can be automatically stored and decoded with excellent accuracy. This work provides a promising platform of digital polymers for programmable information storing and reading. This article is protected by copyright. All rights reserved.

Iterative Synthesis of Stereo- and Sequence-Defined Polymers via Acid-Orthogonal Deprotection Chemistry

Absolute control over polymer stereo- and sequence structure is highly challenging in polymer chemistry. Here, an acid-orthogonal deprotection strategy is proposed for the iterative synthesis of a family of unimolecular polymers starting with enantiopure serines, featuring precise sequence, stereoconfiguration and side-chain functionalities that cannot be achieved using traditional polymerization techniques. Acid-orthogonal deprotections proceed independently of one another by the selection of protecting groups that feature the respective acid-lability. Under p-toluenesulfonic acid, acidolysis of tert-butyloxycarbonyl can proceed exclusively, while low-dosage trifluoroacetic acid and low temperature only trigger the selective and quantitative cleavage of trityl. The pioneering use of this acid-orthogonal deprotection chemistry increases the compatibility with otherwise sensitive groups and opens up pathways to facilely introduce structural and functional diversity into stereo- and sequence-defined polymers, thus imparting their unique properties beyond natural biopolymers.

Combining Hydroxyl-Yne and Thiol-Ene Click Reactions to Facilely Access Sequence-Defined Macromolecules for High-Density Data Storage

Through mimicking the synthesis of hereditary-information-containing nucleic acids, scientists are committed to synthesizing sequence-defined macromolecules. Herein, a protecting-group-free, metal-free, and atom-economical chemistry combining hydroxyl-yne and thiol-ene click reactions was developed to efficiently synthesize sequence-defined oligo(monothioacetals) (overall yield of 54% for an 11-step synthesis) from readily available starting compounds and monomers under ambient conditions. The sequences of linear oligo(monothioacetals) could be easily decoded via a tandem ESI-MS/MS technique, making them new kinds of digital macromolecules with a high data storage density (0.013 bit/Da). Moreover, star oligo(monothioacetals) could also be facilely generated through divergent and convergent strategies and their combination. An unprecedented sequence-defined miktoarm star oligo(monothioacetal) was obtained, which could serve as a new nonlinear digital macromolecule to achieve 2D information matrix encoding and hold great potential to be applied for information encryption, anticouterfeiting, secret communication, etc. Thus, this work provides a powerful stepwise iterative approach to facilely access sequence-defined linear and topological oligo(monothioacetals) for high-density data storage.

Unraveling Sequence Effect on Glass Transition Temperatures of Discrete Unconjugated Oligomers

Sequence plays a critical role in enabling unique properties and functions of natural biomolecules, which has promoted the rapid advancement of synthetic sequence-defined polymers in recent decades. Particularly, investigation of short chain sequence-defined oligomers (also called discrete oligomers) on their properties has become a hot topic. However, most studies have focused on discrete oligomers with conjugated structures. In contrast, unconjugated oligomers remain relatively underexplored. In this study, three pairs of discrete oligomers with the same composition but different sequence for each pair are employed for investigating their glass transition temperatures (T_g s). The resultant T_g s of sequenced oligomers in each pair are found to be significantly different (up to 11.6 °C), attributable to variations in molecular packing as demonstrated by molecular dynamics and density function theory simulations. Intermolecular interaction is demonstrated to have less impact on T_g s than intramolecular interaction. The mechanistic investigation into two model dimers suggests that monomer sequence caused the difference in intramolecular rotational flexibility of the sequenced oligomers. In addition, despite having different monomer sequence and T_g s, the oligomers have very similar solubility parameters, which supports their potential use as effective oligomeric plasticizers to tune the T_g s of bulk polymer materials.

Precisely Encoding Geometric Features into Discrete Linear Polymer Chains for Robust Structural Engineering

Molecular shape is an essential parameter that regulates the self-organization and recognition process, which has not yet been well appreciated and exploited in block polymers due to the lack of precise and efficient modulation methods. This work (i) develops a robust approach to break the intrinsic symmetry of linear polymers by introducing geometric features into otherwise homogeneous chains and (ii) quantitatively highlights the critical contribution of molecular geometry/architecture to the self-assembly behaviors. Iteratively connecting homologous monomers of different side chains according to pre-designed sequences generates discrete polymers with exact chemical structure, uniform chain length, and programmable side-chain gradient along the backbone, which transcribes into diverse shapes. The precise chemistry eliminates all the defects and heterogeneities, providing a delicate platform for fundamental inquiries into the role of molecular geometry. A rich collection of unconventional complex phases, including Frank-Kasper A15 and σ phases, as well as a dodecagonal quasicrystal phase, were captured in these rigorous single-component systems. The self-assembly behaviors are strikingly sensitive to subtle variations of geometry, such that simply migrating a few methylene units among the side chains would generate substantial differences in lattice size or phase stability, or even trigger a phase transition toward distinct structures. The phenomena can be rationalized with a geometric argument that nonuniform side chain distribution leads to conformational mismatch between two immiscible blocks, resulting in varied interfacial curvatures and distinct lattice symmetries. The profound contribution demonstrates that molecular geometry is an effective and robust parameter for structural engineering.

PET-RAFT single unit monomer insertion of β-methylstyrene derivatives: RAFT degradation and reaction selectivity

Reversible addition-fragmentation chain transfer (RAFT) single unit monomer insertion (SUMI) of β-methylstyrene derivatives into diverse RAFT agents presented fast reaction kinetics, but significant degradation of the SUMI products occurred due to a hydrogen abstraction reaction. Fortunately, such degradation can be suppressed through appropriate design of initial RAFT agents attributed to effective chain transfer and selective photoactivation.

Regio- and sequence-controlled conjugated topological oligomers and polymers via boronate-tag assisted solution-phase strategy

The regulation of polymer topology and the precise control over the monomer sequence is crucial and challenging in polymer science. Herein, we report an efficient solution-phase synthetic strategy to prepare regio- and sequence-controlled conjugated polymers with topological variations via the usage of methyliminodiacetic acid (MIDA) boronates. Based on the solubility of MIDA boronates and their unusual binary affinity for silica gel, the synthesized regio- and sequence-defined conjugated oligomers can be rapidly purified via precipitation or automatic liquid chromatography. These synthesized discrete oligomers can be used for iterative exponential and sequential growth to obtain linear and dendrimer-like star polymers. Moreover, different topological sequence-controlled conjugated polymers are conveniently prepared from these discrete oligomers via condensation polymerization. By investigating the structure-property relationship of these polymers, we find that the optical properties are strongly influenced by the regiochemistry, which may give inspiration to the design of optoelectronic polymeric materials.

Precise Amphiphilic Giant Polymeric Chain Based on Nanosized Monomers with Exact Regio-Configuration

Polymeric chains made of "giant" monomers at a larger length scale provide intriguing insights into the fundamental principles of polymer science. In this study, we modularly prepared a library of discrete amphiphilic polymeric chains using molecular nanoparticles as repeat units, with exact control of composition, chain length, surface property, and regio-configuration. These giant polymeric chains self-assembled into a rich collection of highly ordered phases. The precise chemical structure and uniform chain length eliminate all the inherent molecular "defects", while the nanosized monomer amplifies minute structural differences, providing an ideal platform for a systematic scrutiny of the self-assembly behaviors at a larger length scale. The compositional and regio-configurational contribution was carefully studied. The regio-regularity is found to have a direct and profound impact on the chain conformation, leading to a distinct molecular packing scheme and therefore shifting the phase boundaries. With increasing the length of the linker, the regio-constraint gradually diminishes, and the neighboring particles would eventually be decoupled.

Clip Chemistry: Diverse (Bio)(macro)molecular and Material Function through Breaking Covalent Bonds

In the two decades since the introduction of the "click chemistry" concept, the toolbox of "click reactions" has continually expanded, enabling chemists, materials scientists, and biologists to rapidly and selectively build complexity for their applications of interest. Similarly, selective and efficient covalent bond breaking reactions have provided and will continue to provide transformative advances. Here, we review key examples and applications of efficient, selective covalent bond cleavage reactions, which we refer to herein as "clip reactions." The strategic application of clip reactions offers opportunities to tailor the compositions and structures of complex (bio)(macro)molecular systems with exquisite control. Working in concert, click chemistry and clip chemistry offer scientists and engineers powerful methods to address next-generation challenges across the chemical sciences.

Easily Functionalized and Readable Sequence-Defined Polytriazoles

Developing sequence-defined skeletons that could be conveniently characterized and functionalized with diverse side groups is attractive but challenging. Here we report one novel sequence-defined polytriazole structure bearing side groups at its triazole rings. Its construction was facilely accessed by the iterative employments of azidation and iridium-catalyzed cycloaddition of azide with internal 1-thioalkyne (IrAAC) in solution phase. The easy preparation of 1-thioalkyne monomers and the excellent tolerance of IrAAC enable the introduction of diverse functional side chains to this architecture. The obtained sequence was effectively characterized by tandem mass spectrometry owing to the efficient fractures of both of the Csp³-S and Csp³-N bonds in its backbone, indicating its potential utilization in high-capacity digital polymer developments. Further successful application of this structure in building monodisperse macromolecules exhibiting aggregation-induced emission (AIE) characteristics demonstrates its expected application in functional material fabrications.

Iterative Exponential Growth of Oxygen-Linked Aromatic Polymers Driven by Nucleophilic Aromatic Substitution Reactions

This work presents the first transition metal-free synthesis of oxygen-linked aromatic polymers by integrating iterative exponential polymer growth (IEG) with nucleophilic aromatic substitution (SNAr) reactions. Our approach applies methyl sulfones as the leaving groups, which eliminate the need for a transition metal catalyst, while also providing flexibility in functionality and configuration of the building blocks used. As indicated by 1) 1H-1H NOESY NMR spectroscopy, 2) single-crystal X-ray crystallography, and 3) density functional theory (DFT) calculations, the unimolecular polymers obtained are folded by nonclassical hydrogen bonds formed between the oxygens of the electron-rich aromatic rings and the positively polarized C-H bonds of the electron-poor pyrimidine functions. Our results not only introduce a transition metal-free synthetic methodology to access precision polymers but also demonstrate how interactions between relatively small, neutral aromatic units in the polymers can be utilized as new supramolecular interaction pairs to control the folding of precision macromolecules.

Protecting-Group-Free Iterative Exponential Growth Method for Synthesizing Sequence-Defined Polymers

As a main synthetic strategy for monodisperse sequence-defined polymers, the known iterative exponential growth (IEG) methods were all developed on protecting-group chemistry, where the additional deprotection reactions increased their synthetic steps and decreased their atom economy. In this study, we developed a protecting-group-free IEG method for the formation of sequence-defined polymers by combining three orthogonal click reactions of copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), sulfur-fluoride exchange reaction (SuFEx), and Ugi four-component reaction (Ugi-4CR). In this approach, oligomer synthesis began with three parallel CuAAC, SuFEx, and Ugi-4CR couplings among three monomers each with two orthogonal clickable end groups. By iteratively applying parallel CuAAC, SuFEx, and Ugi-4CR to couple three resultant oligomers, each having two orthogonal clickable terminals, this approach could exponentially grow three different sequence-defined polymers simultaneously with high efficiency, requiring no protecting-group chemistry. Additionally, each Ugi-4CR coupling reaction could introduce two external side groups to provide the molecular variation and side-chain functionalization for the resultant sequence-defined polymers.

Discrete Giant Polymeric Chains Based on Nanosized Monomers

As size-amplified analogues of canonical macromolecules, polymeric chains built up by "giant" monomers represent an experimental realization of the "beads-on-a-string" model at larger length scales, which could provide insights into fundamental principles of polymer science. In this work, we modularly constructed discrete giant polymeric chains using nanosized building blocks (polyhedral oligomeric silsesquioxane, POSS) as basic repeat units through an efficient and robust iterative exponential growth approach, with precise control on molecular parameters, including size, composition, regioconfiguration, and surface functionalities. Their chemical structures were fully characterized by nuclear magnetic resonance spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. With elaborately designed amphiphilic block POSS chains and their analogues made of conventional monomers, the size effects were delicately studied and highlighted. Interesting assembly behaviors emerge as a result of distinct interactions and molecular dynamics. This category of molecules shares general self-assembly characteristics as the conventional counterparts in terms of phase transition and evolution. Meanwhile, it turns out that the monomer size has profound impacts on phase stability, as a trade-off between entropic and enthalpic contributions. It may open up a door for modular and programmable design of interesting materials with complex structures and diverse functions.

Alkylaminomaleimide fluorophores: synthesis via air oxidation and emission modulation by twisted intramolecular charge transfer

A novel strategy to synthesize 3-alkylaminomaleimide fluorophores via air oxidation is developed, and the structural features for the designed TICT fluorophores with bright emission are established.

Sequence-controlled and sequence-defined polypeptoids via the Ugi reaction: synthesis and sequence-driven properties

Ugi reaction offers opportunities to facilely access unprecedented sequence control and sequence-driven properties in polypeptoids.

Progress, challenges and future directions of heterocycles as building blocks in iterative methodologies towards sequence-defined oligomers and polymers

Heterocyclic building blocks for iterative methodologies leading to sequence-defined oligomers and polymers are reviewed. Solid- as well as solution-phase methods, challenges surrounding these systems and potential future directions are presented.

IrAAC-based construction of dual sequence-defined polytriazoles

One novel dual sequence-defined polytriazole structure was facilely achieved through an IrAAC-based iterative sequential growth strategy.

Regulation of tectonic sequences in chain-folding-directed monodisperse isomeric oligomers precisely tailored by Ugi-hydrosilylation orthogonal cycles

Monodisperse discrete oligomers with a tailored sequence of linkages within their backbones, which has been defined as a tectonic sequence, were precisely constructed through Ugi-4CRs coupled to hydrosilylation orthogonal cycles.

Efficient synthesis of discrete oligo(fluorenediacetylene)s toward chain-length-dependent optical and structural properties

A series of discrete oligo(fluorenediacetylene)s with a degree of polymerization up to 10 were obtained by automated flash column chromatography, which indicated the chain-length dependent photophysical properties and crystalline behavior.

Discrete Block Copolymers with Diverse Architectures: Resolving Complex Spherical Phases with One Monomer Resolution

This work describes the first rigorous example of a single-component block copolymer system forming unconventional spherical phases. A library of discrete block polymers with uniform chain length and diverse architectures were modularly prepared through a combination of a step-growth approach and highly efficient coupling reactions. The precise chemical structure eliminates all the molecular defects associated with molar weight, dispersity, and compositional ratio. Complex spherical phases, including the Frank-Kasper phase (A15 and σ) and quasicrystalline phase, were experimentally captured by meticulously tuning the composition and architectures. A phase portrait with unprecedented accuracy was mapped out (up to one monomer resolution), unraveling intriguing details of phase behaviors that have long been compromised by inherent molecular weight distribution. This study serves as a delicate model system to bridge the existing gaps between experimental observations and theoretical assessments and to provide insights into the formation and evolution of the unconventional spherical phases in soft matter systems.

Rapid and Scalable Access to Sequence-Controlled DHDM Multiblock Copolymers by FLP Polymerization

An immortal N-(diphenylphosphanyl)-1,3-diisopropyl-4,5-dimethyl-1,3-dihydro-2H-imidazol-2-imine/diisobutyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum (P(NIⁱ Pr)Ph₂ /(BHT)Alⁱ Bu₂ )-based frustrated Lewis pair (FLP) polymerization strategy is presented for rapid and scalable synthesis of the sequence-controlled multiblock copolymers at room temperature. Without addition of extra initiator or catalyst and complex synthetic procedure, this method enabled a tripentacontablock copolymer (n=53, k=4, dp_n =50) to be achieved with the highest reported block number (n=53) and molecular weight (M_n =310 kg mol^-1 ) within 30 min. More importantly, this FLP polymerization strategy provided access to the multiblock copolymers with tailored properties by precisely adjusting the monomer sequence and block numbers.

High-density information storage in an absolutely defined aperiodic sequence of monodisperse copolyester

Synthesis of a polymer composed of a large discrete number of chemically distinct monomers in an absolutely defined aperiodic sequence remains a challenge in polymer chemistry. The synthesis has largely been limited to oligomers having a limited number of repeating units due to the difficulties associated with the step-by-step addition of individual monomers to achieve high molecular weights. Here we report the copolymers of α-hydroxy acids, poly(phenyllactic-co-lactic acid) (PcL) built via the cross-convergent method from four dyads of monomers as constituent units. Our proposed method allows scalable synthesis of sequence-defined PcL in a minimal number of coupling steps from reagents in stoichiometric amounts. Digital information can be stored in an aperiodic sequence of PcL, which can be fully retrieved as binary code by mass spectrometry sequencing. The information storage density (bit/Da) of PcL is 50% higher than DNA, and the storage capacity of PcL can also be increased by adjusting the molecular weight (~38 kDa).