Copolymer Chains Research Articles

Localized Thermoresponsive Behavior in P(NIPAm‐co‐AAc) Copolymers: Structural Insights From Rheology and Small Angle X‐Ray Scattering

ABSTRACTStimuli‐responsive polymers stand out for their ability to respond to small environmental changes. One of the most representative thermo‐sensitive materials is poly(N‐isopropyl acrylamide) (PNIPAm), which presents reversible phase transitions close to the human body temperature. However, previous studies observed that the copolymerization of NIPAm with small quantities of different monomers like acrylic acid (AAc) results in copolymers with reduced or lost thermo‐responsivity. In this study, thermo‐sensitive PNIPAm, pH‐sensitive poly(acrylic acid) (PAAc), and various proportions of their copolymers P(NIPAm‐co‐AAc) were obtained by free radical polymerization and thoroughly characterized. Rheological and structural studies reveal the remaining thermosensitivity of the copolymers manifested at short molecular ranges. These alterations in short‐range interactions are observed in all samples containing NIPAm, and they are evidenced by changes in the fractality of their structure and flow index behavior of the Viscosity Ostwald–de Waele Model. Particularly, when the copolymer proportion of NIPAm/AAc is about 40/60, the Beaucage model reveals two structural levels, ~200 and ~10 nm. Furthermore, the model exhibits a thermal response of the lower‐size substructures, indicating possible segregation of NIPAm‐rich regions from copolymer chains. The evidence found in this work could contribute to the development of nanosystems, in which local thermoresponsive effects are sought, such as for active drug targeting.

Easy reversible clustering of gold nanoparticles via pH-Induced assembly of PVP-b-PAA copolymer

The growing demand of novel hybrid organic/inorganic systems with exciting properties has contributed to an increasing need for simplifying production strategies. Here, we report a simple method to obtain controlled three-dimensional hybrid architectures, in particular hybrid supracolloids (hSC), formed by gold nanoparticles and a double hydrophilic block copolymer, specifically the poly(acrylic acid)-block-poly(N-vinyl-2-pyrrolidone) (PAA-b-PVP), directly in aqueous medium. The ubiquitous pH-sensitive poly(acrylic acid) (PAA) block initiates the assembly through pH changes, while the poly(N-vinyl-2-pyrrolidone) block assures the close affinity with the AuNPs. We demonstrate that the formation of hybrid supracolloids (hSC) is the result of the synergetic behavior of the two specific polymeric blocks. Additionally, the entire process shows spontaneous and fast switchability. The nanostructured copolymer behaves like a highly swollen hydrogel and displays a disordered internal structure. The driving force for the association of the copolymer chains is induced by the synergetic effects of the decrease in solubility of the poly(acrylic acid) block and the formation of inter and intra chains hydrogen bonds. These were demonstrated by using small angle X-ray scattering (SAXS), quartz crystal microbalance with dissipation monitoring (QCM-D) and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX). In turn, the AuNPs are randomly spread all over the polymeric matrix, as demonstrated by field emission gun – scanning electron microscopy (FEG-SEM). A correlation analysis reveals the hSC density depends mostly on the initial concentration of AuNPs. These results can inspire the fabrication of more complex structures with multicomponent composition.

Effect of ionic liquids on the polymerization behavior of acrylamide‐based copolymers

AbstractTo explore the influence of reaction medium on the copolymerization behavior of acrylamide‐based copolymers, three types of copolymers (P(AM‐St)(ILs), P(AM‐MMA)(ILs), and P(AM‐AMPS)(ILs)) were synthesized by combining insoluble, slightly soluble, and easily soluble monomers with acrylamide in the 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM]BF4) reaction medium. The reactivity ratio, Fourier transform infrared spectroscopy, 1H NMR spectroscopy, elemental analysis, and scanning electron microscopy were employed to characterize the copolymers' properties. The results indicated that in [BMIM]BF4 copolymerization, the reactivity ratio of AM and St in P(AM‐St)(ILs) decreased, the reactivity ratio of AM in P(AM‐MMA)(ILs) will increase. While the reactivity ratio of MMA will decrease. The reactivity ratio of AM in P(AM‐AMPS)(ILs) will increase and the reactivity ratio of AMPS will decrease. The distribution of AM and St segments in P(AM‐St)(ILs) molecular chains is more uniform and compact. When AM polymerizes with hydrophobic monomers (St) in [BMIM]BF4, its copolymer solution exhibits lower viscosity loss rates in temperature, shear, and salt resistance tests. Therefore, ionic liquids are more suitable as reaction media for the synthesis of hydrophobic‐modified polyacrylamides, which facilitate a more uniform distribution of hydrophobic monomers within the copolymer chains and exhibit enhanced resistance to temperature, salt, and shear stresses.

An endothelium membrane mimetic antithrombotic coating enables safer and longer extracorporeal membrane oxygenation application

Thrombosis and plasma leakage are two of the most frequent dysfunctions of polypropylene (PP) hollow fiber membrane (PPM) used in extracorporeal membrane oxygenation (ECMO) therapy. In this study, a superhydrophilic endothelial membrane mimetic coating (SEMMC) was constructed on polydopamine-polyethyleneimine pre-coated surfaces of the PPM oxygenator and its ECMO circuit to explore safer and more sustainable ECMO strategy. The SEMMC is fabricated by multi-point anchoring of a phosphorylcholine and carboxyl side chained copolymer (PMPCC) and grafting of heparin (Hep) to form PMPCC-Hep interface, which endows the membrane superior hemocompatibility and anticoagulation performances. Furthermore, the modified PPM reduces protein adsorption amount to less than 30 ng/cm2. More significantly, the PMPCC-Hep coated ECMO system extends the anti-leakage and non-clotting oxygenation period to more than 15 h in anticoagulant-free animal extracorporeal circulation, much better than the bare and conventional Hep coated ECMO systems with severe clots and plasma leakage in 4 h and 8 h, respectively. This SEMMC strategy of grafting bioactive heparin onto bioinert zwitterionic copolymer interface has great potential in developing safer and longer anticoagulant-free ECMO systems. Statement of significanceA superhydrophilic endothelial membrane mimetic coating was constructed on surfaces of polypropylene hollow fiber membrane (PPM) oxygenator and its ECMO circuit by multi-point anchoring of a phosphorylcholine and carboxyl side chain copolymer (PMPCC) and grafting of heparin (Hep). The strong antifouling nature of the PMPCC-Hep coating resists the adsorption of plasma bio-molecules, resulting in enhanced hemocompatibility and anti-leakage ability. The grafted heparin on the zwitterionic PMPCC interface exhibits superior anticoagulation property. More significantly, the PMPCC-Hep coating achieves an extracorporeal circulation in a pig model for at least 15 h without any systemic anticoagulant. This endothelial membrane mimetic anticoagulation strategy shows great potential for the development of safer and longer anticoagulant-free ECMO systems.

Exploiting the Reversible Dimerization of N-Heterocyclic Carbenes to Access Dynamic Polymer Networks with an Organocatalytic Activity.

The capability of some N-heterocyclic carbenes (NHCs) to reversibly dimerize is exploited to access dynamic polymer networks. Benzimidazolium motifs serving as NHC precursors have thus been supported onto copolymer chains by reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and up to 20 mol % of 4-vinylbenzyl-ethyl-benzimidazolium chloride. Molecular versions of 1,3-dialkyl benzimidazolium salts have been synthesized as models, the deprotonation of which with a strong base yields the NHC dimers in the form of tetraaminoalkenes. The crossover reaction between two distinct NHC homodimers, forming heterodimers, is then evidenced. Applying this deprotonation method to the RAFT-derived copolymers leads to polymer networks with cross-links consisting of labile dimerized NHC motifs. These networks can be subsequently decross-linked using two distinct triggers, namely, a monofunctional NHC precursor as competitor and carbon dioxide (CO2). In the latter case, regeneration of the network occurs by chemically fueling the linear copolymer bearing benzimidazolium motifs with tBuOK in the presence of trace amounts of water. The same networks can also be used as latent precursors of transient polyNHCs to catalyze the benzoin condensation upon heating. The polymer-supported organocatalysts can thus be used in successive catalytic cycles.

Macromolecular architecture effect of dioctyl fumarate‐co‐styrene on the properties of modified asphalts

AbstractIn this study, new statistical copolymers made from dioctyl fumarate (DOF) and styrene (S) with different architectures (linear or branched) were synthesized to assess the impact of this macromolecular characteristic on the modification of Argentine asphalt. Modified asphalts (MA) exhibited good compatibility without evidence of oxidative effect during their manufacturing, as confirmed by fluorescence microscopy and Fourier Transform Infrared spectroscopy assays. The incorporation of copolymers led to an improvement in the basic properties of the MA, and this showed a higher viscosity compared to the base asphalt, with the effect being more pronounced in the MA containing branched copolymer. The last sample exhibits the lowest thermal susceptibility, as determined from the analysis of activation energies.Highlights New linear and branched copolymers were synthesized using fumaric and styrene monomers. Monomers randomly alternate in copolymer chains. No oxidation during asphalt modification and the polymers are stable. Incorporating branched copolymer doubles asphalt's elastic recovery. Asphalt modified with the branched copolymer exhibits reduced thermal susceptibility.

Rheo-Optical Near-Infrared (NIR) Characterization of Styrene-Butadiene Rubber (SBR) Using Two-Trace Two-Dimensional (2T2D) Correlation Analysis.

A rheo-optical characterization technique based on the combination of near-infrared (NIR) spectroscopy and tensile testing was applied for the first time to an actual rubber sample based on styrene-butadiene rubber (SBR) including silica filler. When SBR samples were subjected to mechanical deformation, changes in the NIR spectral features were readily captured. Two-trace two-dimensional (2T2D) correlation analysis was then applied to the sets of NIR spectra to clearly reveal the subtle but pertinent difference between the NIR spectral features of the initial and deformed SBR. The initial deformation of the sample induces greater deformation of the soft butadiene groups than of the hard styrene groups. The inclusion of the silica filler and a coupling agent (CA) essentially develops firm links between the silica and butadiene via the CA to restrict the displacement of the butadiene during the tensile deformation of the system. The development of such linkage requires even more mechanical force to deform the SBR, which, in turn, improves Young's modulus of the rubber system. Asynchronous correlation spectra of SBR with no silica filler revealed that, during the deformation of the SBR, the butadiene groups were initially deformed, and this feature was then replaced by the predominant deformation of the hard styrene groups. On the other hand, this correlation feature became somewhat unclear when a similar analysis was applied to the SBR sample with silica filler, revealing subtle differences in interaction between individual comonomer functional groups distributed randomly along the copolymer chain and CA.

Autohesion Mechanisms at Interfaces Between Random Copolymer Melts: Mesoscopic Simulations with Realistic Coarse-Grained Models.

The increase in welding time during the interdiffusion of a pair of non reacting random copolymer melts favors the strength rate of healing at the interface. Furthermore, the diffusion kinetic during the interpenetration of copolymer chains across the interface is strongly dependent on molecular weight. In this paper we perform mesoscopic simulations with realistic coarse grain models to study the autohesion mechanism across the interface between slightly entangled styrene-butadiene random copolymer melts.

Maleic Anhydride-Derived Copolymers Conjugated with Beta-Lactam Antibiotics: Synthesis, Characterization, In Vitro Activity/Stability Tests with Antibacterial Studies

The synthesis and characterization of biocompatible three different maleic anhydride co-polymer conjugated with two different beta-lactam antibiotics at in vitro conditions were conducted. The polymer–drug conjugates were synthesized by coupling β-lactam antibiotics via amide bonds to the copolymer. In this work, six different drug-functionalized maleic anhydride copolymers (DFMACs) were synthesized by the chemical conjugation method. This method is based on the ring-opening reaction of the anhydride ring of the copolymer to form an amide bond linking the drug. The synthesized DFMACs were characterized by 1H NMR and FTIR/ATR spectroscopies and analyses were carried out by UV/VIS spectroscopy and Zeta-sizer instrument in detail with consecutive antibacterial tests. The existence of a newly formed amide covalent bond between the drug and the copolymer chains was confirmed by 1H NMR and FTIR/ATR studies. This is the first report on the application of the selected branched biodegradable polymeric matrices for the covalent conjugation of ampicillin and cefalexin. Optimum stability and activity conditions for the synthesized DFMACs were determined. Analyses were conducted under in vitro conditions including varying pH values and simulated body fluids as a function of time to obtain new drug delivery system candidates for the two different antibiotics.

Effect of PEG concentration on drug release from PLA-PEG copolymers: A molecular dynamics simulation study

Mercaptopurine (6-MP), a cancer medication limited by its hydrophobic properties, was studied using molecular dynamics simulations with biodegradable copolymers (PLA-PEG, PLA-PEG-PLA, PEG-PLA-PEG) as drug carriers. The influence of PEG concentration in copolymers on drug release was examined. Results revealed that blending PEG with PLA or copolymerizing them affected hydrogen bond numbers and mixing energy in the drug carrier, dependent on copolymer type and PEG concentration. Introducing PEG into PLA chains increased hydrogen bonds and energy, but copolymerizing PLA and PEG did not consistently enhance hydrogen bond energy (PLA-PEG-PLA > PEG-PLA-PEG > PLA-PEG). Mixing energy was consistently elevated by PEG-PLA copolymerization, ranked PEG-PLA-PEG > PLA-PEG > PLA-PEG-PLA. The fastest drug release was observed with the PLA&PEG-10.9 carrier, attributed to weak PLA-PEG chain connections facilitating water access to PEG. Increasing PEG content reduced chain mixing energy, slowed drug release via stronger chain hydrogen bonding. Notably, PEG-PLA-PEG-8.7 exhibited the highest drug release rate due to quicker water penetration. The copolymer type and chain length were found to impact water molecule access to PEG and drug release rate significantly.

Enhancing the foamability of poly(L-lactide-co-ε-caprolactone) through formation of stereocomplex crystal by introducing of poly(D-lactic acid)

The bio-elastomer poly (L-lactide-co-ε-caprolactone) (PLCL) with linear random molecular chain structure exhibits low viscosity and melt strength, resulting in poor foamability, cell merging, or collapse during the foaming process. Consequently, PLCL foams have large cell sizes and low cell densities, limiting their use as biodegradable elastomeric foams. To enhance the foamability of PLCL, poly (D-lactic acid) (PDLA) was incorporated into the PLCL matrix. Stereocomplex crystals (Sc-crystals) formed between the L-LA segments of PLCL and the molecular segments of PDLA. The effects of varying PDLA content on the basic properties and foaming behavior of the blends were investigated. Results indicate that optimal Sc-crystal formation occurs in the PLCL/PDLA-10 blend. The presence of Sc-crystals enhances melt strength and facilitates cell nucleation, reducing cell size from 351.2 to 11.8 μm and increasing cell density from 1.4 × 104 to 1.7 × 108 cells/cm³. Consequently, the mechanical properties of the foam are significantly improved. The Sc-crystal formation between PLCL and PDLA provides an effective method to enhance the processability of linear chain copolymers containing L-lactide.

A Dual-Bond Crosslinking Strategy Enabling Resilient and Recyclable Electrolyte Elastomers for Solid-State Lithium Metal Batteries.

Elastomeric solid polymer electrolytes (SPEs) are highly promising to address the solid-solid-interface issues of solid-state lithium metal batteries (LMBs), but compromises have to be made to balance the intrinsic trade-offs among their conductive, resilient and recyclable properties. Here, we propose a dual-bond crosslinking strategy for SPEs to realize simultaneously high ionic conductivity, elastic resilience and recyclability. An elastomeric SPE is therefore designed with hemiaminal dynamic covalent networks and Li+-dissociation co-polymer chains, where the -C-N- bond maintains the load-bearing covalent network under stress but is chemically reversible through a non-spontaneous reaction, the weaker intramolecular hydrogen bond is mechanically reversible, and the soft chains endow the rapid ion conduction. With this delicate structure, the optimized SPE elastomer achieves high elastic resilience without loading-unloading hysteresis, outstanding ionic conductivity of 0.2 mS cm-1 (25 °C) and chemical recyclability. Then, exceptional room-temperature performances are obtained for repeated Li plating/stripping tests, and stable cycling of LMBs with either LiFePO4 or 4.3 V-class LiFe0.2Mn0.8PO4 cathode. Furthermore, the recycled and reprocessed SPEs can be circularly reused in LMBs without significant performance degradation. Our findings provide an inspiring design principle for SPEs to address the solid-solid-interface and sustainability challenges of solid-state LMBs.

Compressible Hydrogels with Stabilized Chirality from Thermoresponsive Helical Dendronized Poly(phenylacetylene)s

AbstractFabrication of chiral hydrogels from thermoresponsive helical dendronized phenylacetylene copolymers (PPAs) carrying three‐fold dendritic oligoethylene glycols (OEGs) is reported. Three different temperatures, i.e. below or above cloud point temperatures (Tcps) of the copolymers, and under freezing condition, were utilized, affording thermoresponsive hydrogels with different morphologies and mechanical properties. At room temperature, transparent hydrogels were obtained through crosslinking among different copolymer chains. Differently, opaque hydrogels with much improved mechanical properties were formed at elevated temperatures through crosslinking from the thermally dehydrated and collapsed copolymer aggregates, leading to heterogeneity for the hydrogels with highly porous morphology. While crosslinking at freezing temperature synergistically through ice templating, these amphiphilic dendronized copolymers formed hydrogels with highly porous lamellar structures, which exhibited remarkable compressible properties as human articular cartilage with excellent fatigue resistance. Amphiphilicity of the dendronized copolymers played a pivotal role in modulating the network formation during the gelation, as well as morphology and mechanical performance of the resulting hydrogels. Through crosslinking, these dendronized copolymers featured with typical dynamic helical conformations were transformed into hydrogels with unprecedently stabilized helicities due to the restrained chain mobilities in the three‐dimensional networks.

Compressible Hydrogels with Stabilized Chirality from Thermoresponsive Helical Dendronized Poly(phenylacetylene)s.

Fabrication of chiral hydrogels from thermoresponsive helical dendronized phenylacetylene copolymers (PPAs) carrying three-fold dendritic oligoethylene glycols (OEGs) is reported. Three different temperatures, i.e. below or above cloud point temperatures (Tcps) of the copolymers, and under freezing condition, were utilized, affording thermoresponsive hydrogels with different morphologies and mechanical properties. At room temperature, transparent hydrogels were obtained through crosslinking among different copolymer chains. Differently, opaque hydrogels with much improved mechanical properties were formed at elevated temperatures through crosslinking from the thermally dehydrated and collapsed copolymer aggregates, leading to heterogeneity for the hydrogels with highly porous morphology. While crosslinking at freezing temperature synergistically through ice templating, these amphiphilic dendronized copolymers formed hydrogels with highly porous lamellar structures, which exhibited remarkable compressible properties as human articular cartilage with excellent fatigue resistance. Amphiphilicity of the dendronized copolymers played a pivotal role in modulating the network formation during the gelation, as well as morphology and mechanical performance of the resulting hydrogels. Through crosslinking, these dendronized copolymers featured with typical dynamic helical conformations were transformed into hydrogels with unprecedently stabilized helicities due to the restrained chain mobilities in the three-dimensional networks.

Molecular design of antifouling ultrafiltration membranes via copolymerization of bactericidal and hydrophilic polymers

Membrane fouling is still a significant obstacle to applying polyvinylidene fluoride (PVDF) ultrafiltration membranes. We developed bactericidal and hydrophilic comb copolymers to address this issue by introducing quaternary ammonium compounds (QAC) and sulfobetaine methacrylate (SBMA) onto PVDF powder. Utilizing atom transfer radical polymerization, we synthesized a series of polymer brushes by adjusting the QAC and SBMA functional monomers ratio. These polymer brushes were then employed to fabricate modified membranes featuring diverse alkyl chain lengths and hydrophilic layers. All modified membranes exhibited antibacterial and anti-adhesion properties. Increasing the SBMA monomer ratio resulted in reduced membrane pore size, a smoother membrane surface, and enhanced hydrophilicity. This balanced approach synergistically integrates “defensive” and “offensive” strategies, adjusting polymer proportions to confer dual functionality of hydrophilicity and bactericidal action in ultrafiltration membranes. Notably, the functionalized PVDF powder with copolymer chains exhibited a high inhibition efficiency of 100% against E. coli and 52.0% against E. faecalis, and the optimized membranes have an impressive performance of effectively preventing bacteria adhesion and inactivating attached bacteria. Dynamic filtration experiments further revealed the superior anti-biofouling capabilities of the modified membrane. Furthermore, the membrane containing 50% SBMA and 50% QAC exhibited a 69.5% improvement in anti-organic performance compared to those with only QAC. Our study presents a straightforward and efficient approach for designing antifouling PVDF membranes, showing great promise for wastewater treatment applications.

Synthesis of Polymer Brushes on Tannic Acid-Coated Copper Particles and Surface Co-Assembly.

The synthesis of polymer brushes on inorganic particles is an effective approach to surface modification. The polymer brushes on the surface endow the substrates with new surface properties. However, the lack of functional groups and the difficulty of surface modification have made it difficult to develop an effective method for the synthesis of polymer brushes on metal surfaces. Herein, a simple and versatile strategy for synthesizing polymer brushes on copper particles is reported. Tannic acid (TA) molecules are adsorbed onto the surfaces of copper particles, forming TA coatings. Quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (qPDMAEMA-b-PS) block copolymer (BCP) chains are grafted on the TA coatings through hydrogen bonding and electrostatic interaction, and PS brushes are grafted on the copper particles. The effects of TA concentration on the adsorption of TA and PS brush synthesis are discussed. The PS brushes are able to form surface nanostructures on the copper particles through co-assembly with PDMAEMA-b-PS BCP chains. The effect of BCP concentration on the surface nanostructures is investigated. It is reasonable to expect that polymer brushes and surface nanostructures can be synthesized on different metal surfaces by using the TA-coating approach reported in this paper.

Impact of polyglycidol block architecture in polystyrene-b-polyglycidol copolymers on the properties of thin films and protein adsorption

The effect of the architecture of amphiphilic polystyrene-b-polyglycidol and polystyrene-b-(polyglycidol-g-polyglycidol) copolymers on their behavior in thin films and interaction with the protein has been studied. The properties of the copolymer films surface were investigated before and after incubation in water and aqueous solution of PBS buffer. Surface sensitive techniques: time-of-flight secondary ion mass spectrometry, atomic force microscopy, and contact angle measurements show the differences in film surfaces behavior depending on the copolymer architecture. It was found that exposure of the coil-brush copolymer to an aqueous solution reoriented the PGL segments, changing the properties of the surface layer. Greater exposure of antifouling PGL chains at the surface of the copolymer film modified the interaction with bovine serum albumin, significantly reducing its adsorption. In contrast, no changes in the orientation of the PGL chains were observed after incubation of the copolymer films in an aqueous solution of protein in PBS buffer. This suggests that protein adsorption to the thin copolymer film blocks the conformational changes of the copolymer chains and reduces their mobility under the protein molecules.

Preparation and characterization of long carbon chain based polyacrylate latexes and their pressure sensitive adhesive application

Aqueous emulsion homo- and co-polymerization of lauryl methacrylate (LMA), a strong hydrophobic monomer with long carbon chain, is quite challenging. In this study, a long carbon chain emulsifier N-390 was used as the primary emulsifier to facilitate the emulsion copolymerization of LMA with other acrylate monomers through the mutual hydrophobic interaction between N-390 and LMA, and ultimately polyacrylate latex pressure sensitive adhesives modified by LMA via pre-emulsified semi-continuous seeded emulsion polymerization process were synthesized. The effects of LMA on the resulting latex and PSA properties was comprehensively examined. Both FTIR and 1H NMR spectra indicated that LMA has been successfully introduced into copolymer chain with the aid of long carbon chain emulsifier N-390. The results also showed that the introduction of LMA will contribute to decrease in particle size and zeta potential, while increase viscosity and gel content of the acrylate PSA latex. Moreover, as the LMA content increased, the latex PSA films demonstrated gradual improvements in both water resistance and thermal stability. Finally, for the long carbon chains adhesive film, the shear strength was improved greatly while at the sacrifice of loop tack and peel strength, when compared to counterparts without LMA.

Nitroxide mediated controlled radical polymerization of α‐Methylene‐γ‐Butyrolactone

AbstractThe controlled polymerization of α‐methylene‐γ‐butyrolactone (MBL, a naturally occurring sesquiterpene lactone found in tulips) was performed by nitroxide mediated polymerization (NMP) using the alkoxyamine Dispolreg 007 as the initiating system at 80 °C in 50 wt% DMSO. Features of a reversible‐deactivation radical polymerization (RDRP) were observed with a linear growth of the macro‐radical with conversion and a relatively low dispersity (Ð ≤ 1.45). The P(MBL) homopolymer chain ends were mostly re‐activatable as the chain extensions with styrene (S) and glycidyl methacrylate (GMA) in DMSO were successful. Interestingly, the polymerization of MBL initiated by 2‐methyl‐2‐[N‐tert‐butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)‐aminoxy]‐N‐propionyloxysuccinimide (known as NHS‐BlocBuilder) under various experimental conditions did not produce well‐defined P(MBL), possibly due to an excessively high equilibrium constant. However, the bulk copolymerization of MBL with 10–21 mol% of β‐myrcene (Myr, another renewable monomer from the terpene family) initiated by NHS‐BlocBuilder at 100–110 °C led to all the features of a controlled system. The SG1 chain end fidelity of the resulting P(MBL‐co‐Myr) copolymer was confirmed via 31P NMR and by re‐initiating successfully the copolymer chains with a mixture of GMA and Myr monomers at 120 °C in DMSO.

Numerical representations of AB-type copolymer complexes: analysis of 1H NMR chemical shift patterns in terms of a Smith–Cantor set

When considering the possibility of storing information in the sequence of monomer residues within an AB-type copolymer chain, it is constructive to model that sequence as a string of ones and zeros. The intramolecular environment around any given digit (say a “1”) can then be represented by another string of integers—a code—obtained by summing pairs of digits at equivalent positions, in both directions, from that digit. The code can include only integers 0, 1 and 2, and can represent a number in any base b higher than 2. In base b = 3 the resulting set of codes includes all numbers (because only digits 0, 1 and 2 occur in ternary expansions), but in any base b > 3 the codes define a limited set of numbers comprising a fractal we term a Smith–Cantor set. The 1H NMR spectrum of a random, AB-type co(polyester-imide) shows, on complexation with pyrene, a pattern of complexation shifts approximating very closely to the Smith–Cantor set for which b = 4. Other co(polyimide) complexes show a 1H NMR pattern corresponding to a specific sub-set of this fractal. The sub-set arises from a “stop-at-zero” limitation, whereby digits in the initial string are set to zero for code-generating purposes if they occur beyond a zero, as viewed from the central “1”. The limitation arises in copolymers where pyrene binds by intercalation between pairs of adjacent diimide residues. This numerical approach provides a complete, unifying theory to account for the emergence of fractal character in the 1H NMR spectra of AB-type copolymer complexes.