Monomer Polymer Research Articles

Beyond nylon 6: polyamides via ring opening polymerization of designer lactam monomers for biomedical applications.

Ring opening polymerization (ROP) of lactams is a highly efficient and versatile method to synthesize polyamides. Within the last ten years, significant advances in polymerization methodology and monomer diversity are ushering in a new era of polyamide chemistry. We begin with a discussion of polymerization techniques including the most widely used anionic ring opening polymerization (AROP), and less prevalent cationic ROP and enzyme-catalyzed ROP. Next, we describe new monomers being explored for ROP with increased functionality and stereochemistry. We emphasize the relationships between composition, structure, and properties, and how chemists can control composition and structure to dictate a desired property or performance. Finally, we discuss biomedical applications of the synthesized polyamides, specifically as biomaterials and pharmaceuticals, with examples to include as antimicrobial agents, cell adhesion substrates, and drug delivery scaffolds.

Structure formation in suspensions and biocidal properties of copolymer of 2-acrylamido-2-methylpropanesulfonic acid and allylamine

Bentonite is a type of montmorillonite caly that used in many places in the industry. It has been widely used for drilling fluid for many decades. Reducing the friction and lubricating the drilling the bentonite fluid has to be smooth and viscos. In this work, the structure-formation of bentonite clay suspensions in the presence of the 2-acrylamido-2-methylpropanesulfonic acid – allylamine (AMPS-AA) copolymer was studied. The static shear stress (SSS) of the bentonite suspension was investigated at different polymer concentration and monomer molar ratio. The antimicrobial activity of the copolymer AMPS-AA against sulfate-reducing bacteria (SRB) with different molar composition was studied. Based on the research results AMPS-AA copolymer was suggested to be a structuring and antibacterial agent for bentonite clay.

Температурная эволюция взаимодействия релаксационных процессов с локальной динамикой на терагерцевых частотах в полимерах с водородными связями

At terahertz frequencies, the torsional-vibrational motion is associated with dielectric relaxation in disordered solids with hydrogen bonds. The interaction between these processes is still poorly understood, especially at temperatures below the glass transition temperature, which is especially important for molecular mobility in polymers. We have studied polymers with hydrogen bonds (polyamide-6 and polyvinyl chloride) at temperatures from 90 to 400 K in the range 0.25 - 4 THz using far-infrared spectroscopy. Three general features were observed in the spectrum of dielectric losses, ”(a) at temperatures well below the glass transition (Tg), these losses are represented by the low-frequency wing of the absorption peak due to the libration of polymer monomer units. (b) At 0.7Tg <T <Tg, additional temperature-dependent losses are observed, which can be associated with the manifestation of secondary relaxation processes. (c) At temperatures above Tg, primary α-relaxation processes become the dominant contribution to terahertz losses. The results obtained show that the evolution of terahertz losses with temperature is caused by a change in the structure of hydrogen bonds, which, apparently, is universal for systems with similar intermolecular interactions.

Temperature evolution of the interaction of relaxation processes with local dynamics at terahertz frequencies in polimers with hydrogen bonds

At terahertz frequencies, the torsional-vibrational motion is associated with dielectric relaxation in disordered solids with hydrogen bonds. The interaction between these processes is still poorly understood, especially at temperatures below the glass transition temperature, which is especially important for molecular mobility in polymers. We have studied polymers with hydrogen bonds (polyamide-6 and polyvinyl chloride) at temperatures from 90 to 400 K in the range 0.25-4 THz using far-infrared spectroscopy. Three general features were observed in the spectrum of dielectric losses, ε''(ν) (a) at temperatures well below the glass transition (Tg), these losses are represented by the low-frequency wing of the absorption peak due to the libration of polymer monomer units. (b) At 0.7Tg<T<Tg, additional temperature-dependent losses are observed, which can be associated with the manifestation of secondary relaxation processes. (c) At temperatures above Tg, primary α-relaxation processes become the dominant contribution to terahertz losses. The results obtained show that the evolution of terahertz losses with temperature is caused by a change in the structure of hydrogen bonds, which, apparently, is universal for systems with similar intermolecular interactions. Keywords: polymers, terahertz IR-spectra, temperature dependence, α- and β-relaxations, hydrogen bonding.

Effect of UV light polymerization time on the properties of plastic crystal composite polyacrylate polymer electrolyte for all solid‐state lithium‐ion batteries

AbstractTo solve the issues of low ionic conductivity, poor interfacial stability, and weak mechanical strength in the current polymer electrolytes, herein, the UV curing method is proposed to in‐situ polymerize the plastic crystal composite solid polymer electrolyte (S‐PCCE). By using ethoxylated trimethylolpropane triacrylate (ETPTA) as polymerization monomer, in conjunction with the butadiene nitrile and other additives, the S‐PCCE is prepared under ultraviolet light. The S‐PCCE shows improved ionic conductivity than other solid electrolyte materials. The ionic conductivity at room temperature can reach 0.98 × 10−3 S/cm, and it can reach 2.8 × 10−3 S/cm at 55°C, which is beneficial to achieve high battery performance. The LiFePO4/S‐PCCE/Li battery has a high initial discharge specific capacity of 150.4 mAh/g at 0.2C, and the highest discharge specific capacity can reach 162.5 mAh/g. Moreover, after 100 cycles, the battery can still maintain a high discharge specific capacity of 154.2 mAh/g, with a Coulomb efficiency of 98.4%. At the same time, the electrolyte has excellent high‐temperature adaptability, and can still work stably at 55°C with improved ionic conductivity. The superior performance of this material indicates that the plastic crystal composite polyacrylate solid electrolyte based on UV curing method can be used to prepare a high‐performance lithium‐ion battery, and this technology can also be compatible with existing lithium‐ion battery equipment.

Controlled block-polymerization of styrene, divinylbenzene and ethylene oxide. Intermolecular cross-linking towards well-defined miktoarm copolymer stars

• Synthesis of well-defined miktoarm copolymer stars. • Control over the molecular weight and composition for both arm species. • Controlled polymerization of poly(divinylbenzene). • Intermolecular cross-linking of linear triblock terpolymers. A novel approach for the synthesis of miktoarm copolymer stars with divinylbenzene cross-linked core, via anionic polymerization is reported. This synthetic route gives access to polymers, characterized by low dispersity values and improved structural homogeneity for both arm species. Specifically, miktoarm copolymer stars of A n B n type, with cross-linked divinylbenzene (DVB) core and arms of polystyrene (PS) and poly(ethylene oxide) (PEO), are synthesized via anionic polymerization and sequential monomer addition, employing high vacuum techniques. Analytically, the first step involves the synthesis of a triblock terpolymer PS- b -PDVB- b -PEO. Then, in the presence of a free radical initiator the pending vinyl groups of the middle DVB block cross-link intermolecularly, leading to the final miktoarm copolymer star. The novelty of the proposed synthetic route, lies in the potassium alkoxide co -initiator, which is responsible for the controlled polymerization of both DVB and EO in one pot, without the need for end group modification between the two steps. Concerning the final polymer, there are numerous benefits advancing from this synthetic protocol, such as the control of the molecular characteristics of both arms, as well as the easily confirmed structural integrity of the precursor triblock which is inherited to the resulting miktoarm star. For comparison reasons, another batch of (PS)(PEO) miktoarm copolymers was synthesized, following the “in-out” synthetic route. For this reason, styrene was polymerized using s -BuLi, which is used as macroinitiator for the polymerization/cross-linking of DVB, resulting PS star with DVB cross-linked core. With the addition of EO, in the presence of p4 t -Bu phosphazene base, PEO arms are polymerized, initiating from the core’s active cites outwards.

Microscopic Model to Quantify the Difference of Energy-Transfer Rates between Bonded and Nonbonded Monomers in Polymers

Thermal transport properties often dictate the usefulness of materials in a variety of applications. In this context, polymers are an important material class because they provide different pathways of energy transport due to the distinct microscopic interactions, i.e., via stiff, covalently bonded backbone interactions or via soft, nonbonded interactions, such as van der Waals (vdW) forces and/or hydrogen bonds (H-bond). Therefore, the precise control of the delicate balance between bonded and nonbonded energy transfer rates provides a possible strategy to tailor the thermal conductivity of a material. In this work, we devise a simple analytical model that decouples the microscopic bonded, Gb, and nonbonded, Gnb, contributions to the heat transport in polymeric materials. This model considers the diffusion of energy along the macromolecular backbone, involving multiple transfers before it can hop off to a neighboring chain molecule. We show how these individual microscopic components can be combined to obtain a diffusive contribution to the macroscopic thermal transport coefficient, κ. The ability of the model to describe thermal transport is validated by molecular simulations of one universal polymer model and three, chemically specific, all-atom polymer models. These results suggest strategies for tailoring κ of polymeric materials by macromolecular engineering of molecular architecture and conformations.

Odd-even effects in liquid crystals

ABSTRACT In this paper, odd-even effects in liquid crystals are briefly summarised. Based on the position and type of the repeating units, odd-even effects can be caused by methylene (CH2)k units either when terminating the LC molecules or separating monomers in dimers or polymers, or by the parity of the number of rigid mesogenic units separated by odd numbered methylene spacers. These odd-even effects are manifested themselves in the transition temperatures (mainly of the clearing point) and transition entropies, but they can also lead to alteration of phases, such as antiferroelectric or ferroelectric, or the appearance of tilted or orthogonal mesophases. These alternating phase and entropy properties then also lead to alternating secondary properties, such as in birefringence and elastic properties. In each category, we also discuss the theoretical considerations that can explain the observed odd-even effects.

One‐step synthesis of polymer dispersions with large narrow‐size‐distribution particles via heterophase polymerization in the presence of surface‐active water‐insoluble organosilicon macromers

AbstractPolymerizable water‐insoluble surface‐active macromers (SAMs), namely α,ω‐divinylpolydimethylsiloxane (DVPDMS), α,ω‐dipropylmethacrylatepolydimethylsiloxane (DPMPDMS) and α,ω‐pair(vinylbenzyl)polydimethylsiloxane (PVBPDMS), were synthesized and characterized using NMR. The colloidal‐chemical properties of the synthesized compounds were studied in comparison with non‐polymerizable polydimethylsiloxane. Using DVPDMS, DPMPDMS and PVBPDMS as copolymerizable emulsifiers, polystyrene and poly(methyl methacrylate) suspensions with large particles, narrow particle size distribution and with the absence of the residual surfactant in the waste water were obtained. It is shown that in the presence of DPMPDMS it is possible to obtain polymer suspensions with an average particle diameter of 1.6 μm. The proposed mechanism of the effects of the SAMs on the polymerization is based on the copolymerization with the main monomers in the monomer–polymer particle interphases which results in stabilization of the particle protective layers from early stages of the reaction. © 2021 Society of Chemical Industry

Benchmarking Machine Learning Models for Polymer Informatics: An Example of Glass Transition Temperature.

In the field of polymer informatics, utilizing machine learning (ML) techniques to evaluate the glass transition temperature Tg and other properties of polymers has attracted extensive attention. This data-centric approach is much more efficient and practical than the laborious experimental measurements when encountered a daunting number of polymer structures. Various ML models are demonstrated to perform well for Tg prediction. Nevertheless, they are trained on different data sets, using different structure representations, and based on different feature engineering methods. Thus, the critical question arises on selecting a proper ML model to better handle the Tg prediction with generalization ability. To provide a fair comparison of different ML techniques and examine the key factors that affect the model performance, we carry out a systematic benchmark study by compiling 79 different ML models and training them on a large and diverse data set. The three major components in setting up an ML model are structure representations, feature representations, and ML algorithms. In terms of polymer structure representation, we consider the polymer monomer, repeat unit, and oligomer with longer chain structure. Based on that feature, representation is calculated, including Morgan fingerprinting with or without substructure frequency, RDKit descriptors, molecular embedding, molecular graph, etc. Afterward, the obtained feature input is trained using different ML algorithms, such as deep neural networks, convolutional neural networks, random forest, support vector machine, LASSO regression, and Gaussian process regression. We evaluate the performance of these ML models using a holdout test set and an extra unlabeled data set from high-throughput molecular dynamics simulation. The ML model's generalization ability on an unlabeled data set is especially focused, and the model's sensitivity to topology and the molecular weight of polymers is also taken into consideration. This benchmark study provides not only a guideline for the Tg prediction task but also a useful reference for other polymer informatics tasks.

Heterocycle/Heteroallene Ring‐Opening Copolymerization: Selective Catalysis Delivering Alternating Copolymers

AbstractHeteroatom‐containing polymers have strong potential as sustainable replacements for petrochemicals, show controllable monomer–polymer equilibria and properties spanning plastics, elastomers, fibres, resins, foams, coatings, adhesives, and self‐assembled nanostructures. Their current and future applications span packaging, house‐hold goods, clothing, automotive components, electronics, optical materials, sensors, and medical products. An interesting route to these polymers is the catalysed ring‐opening copolymerisation (ROCOP) of heterocycles and heteroallenes. It is a living polymerization, occurs with high atom economy, and creates precise, new polymer structures inaccessible by traditional methods. In the last decade there has been a renaissance in research and increasing examples of commercial products made using ROCOP. It is better known in the production of polycarbonates and polyesters, but is also a powerful route to make N‐, S‐, and other heteroatom‐containing polymers, including polyamides, polycarbamates, and polythioesters. This Review presents an overview of the different catalysts, monomer combinations, and polymer classes that can be accessed by heterocycle/heteroallene ROCOP.

Using 2‐isopropyl‐2‐oxazine to explore the effect of monomer distribution and polymer architecture on the thermoresponsive behavior of copolymers

AbstractPoly(cyclic imino ether)s (PCIE) have emerged as a highly promising class of polymer for use in biomedical applications with their value being derived from their excellent biocompatibility, diverse chemistry, and tunable hydrophilicity. Here, we investigate the properties of poly(2‐isopropyl‐2‐oxazine) (PiPrOz), a relatively unexplored PCIE, determining it to have a cloud point temperature (Tcp) below physiological temperature, not to crystallize from bulk or in solution, and to be highly biocompatible. Furthermore, a series of copolymers consisting of iPrOz and 2‐methyl‐2‐oxazine (MeOz) was investigated with regard to the effect of monomer distribution and polymer architecture on thermoresponsive properties. To this end, linear block and statistical co‐poly(2‐oxazine)s (co‐POz), along with three comb‐shaped POz with block or statistical POz side chains were prepared. Each of the five polymers showed distinct thermoresponsive behavior, with the linear block co‐POz undergoing micelle formation and the other polymers macroscopic phase‐separation at different Tcps. The variety observed in response to heating clearly highlights the importance of monomer sequence and polymer architecture when designing thermoresponsive polymers. We anticipate that our findings will prove useful to polymer chemists seeking to prepare novel thermoresponsive biomaterials.

Polymer stabilized isotropic phase liquid crystals with large Kerr constant

ABSTRACT In this paper, we reported a polymer stabilised isotropic phase liquid crystal (PSILC). The influences of different content of chiral dopant and polymer monomer on PSILC were studied. Adding the proper proportion and total content of polymer monomer TMPTA and C12A into liquid crystal with 1.0 wt.% chiral dopant R5011, and UV photo-polymerisation at the isotropic phase, we obtain the Kerr constant greater than 10 nm/V2, hysteresis less than 2.0% and fast response in PSILC.

P-Type Chemical Doping-Induced High Bipolar Electrical Conductivities in a Thermoelectric Donor–Acceptor Copolymer

P-Type Chemical Doping-Induced High Bipolar Electrical Conductivities in a Thermoelectric Donor–Acceptor Copolymer

Small change, big impact: Simply tailoring the substitution position towards significant improvement of flame retardancy

The use of conventional flame-retardant elements such as Cl, Br, P for carbon-based polymers usually leads to the deterioration of smoke and toxic gas release, and possesses serious environmental and ecological issues. Herein, we proposed a facile strategy to largely improve the flame-retardant efficiency of an eco-friendly flame-retardant method. By simply tailoring the substitution position of the functional polymerization monomer, the corresponding copolymer exhibited extremely high flame retardancy, including a 59% lower peak heat release rate (pHRR), a 48% lower smoke density, a high limiting oxygen index (LOI) of 30%, and passed the UL-94 V-0 rating without dripping. More importantly, the para-substitution copolymer showed a much higher flame-retardant efficiency than the meta-substitution copolymer, for which the monomer content needed for UL-94 V-0 rating, high LOI value, and low smoke and toxic gas release largely decreased by 25%. The detailed mechanism and the different performance between the two copolymers were comprehensively investigated. The results first confirmed the “end-group-capturing” mechanism, then revealed that the different flame-retardant efficiency was owing to the different thermal rearrangement capability of the two functional monomers. The molecular-level mechanism revealed here provided a novel thinking for designing flame-retardant polymers.

Structure design of multi-functional flexible electrocardiogram electrodes based on PEDOT:PSS-coated fabrics

Herein, Polyester woven fabrics as the matrices for the experimental group, while cotton knitted fabrics, cotton woven fabrics, and Polyethylene terephthalate (PET) mesh cloth used as the matrices for the control groups, at 40 °e, using 3,4-ethoxylene dioxy thiophene (EDOT)as the polymer monomer, FeCl3 as the oxidant, and poly(sodium-p-styrenesulfonate) (PSS) as the dopant, are separately coated with PEDOT:PSS polymer to prepare flexible conductive composite fabrics. The influences of the fabric pattern, oxidant concentration, and monomer concentration on the electrical performance of composite fabrics are optimized. The maximal electrical conductivity of PET-based composite fabrics (218 S/m) occurs when monomer concentration is 0.035 mol/L, the molar ratio of oxidant to monomer is 2.5, and the dopant concentration is 2.5 g/L. Moreover, bacteriostasis rate of this composite fabric reaches 71.8%. Furthermore, by electrocardiogram (ECG) simulated human body unit test as well as human body ECG test, the optimal PET-based composite fabric electrode both has a lower impedance which helps form the stabilized ECG signal. The resulting fabric electrodes retain the soft and breathable advantages from fabrics and reduce the discomfort for a long-term use of conventional electrographic gel, thereby validating the empirical evidence for mobile, portable, wearable ECG electrodes.

Electromechanical response of lamellar forming ionic diblock copolymer thin films

Electromechanical responses of lamellar forming neutral-charged diblock copolymers (BCPs) in thin films are investigated using coarse-grained molecular dynamics simulations, where the electric permittivity of polymer monomer is described by explicitly introducing freely rotating dipoles. Effects of an applied electric field on the ion transport, morphological change and stress build-up are studied in detail. In particular, we focus on the responses to strong electric fields in terms of the ion dissociation and stress distribution along the film thickness. The different stages of BCP evolution under the electric field are characterized. This work paves a way towards establishing a modeling scheme that describes the response of ionic polymers in the presence of applied electric field.

Chiral Charge Carriers Chiralions for Polyaniline Examined with Optical Rotation Spectroelectrochemistry

In this study, the optical active polyaniline film was examined with optical rotatory dispersion (ORD) through change in potential with spectroelectrochemical method. Polyaniline is one of the representative conducting polymers. Preparation of polyaniline is convenient because synthesis of polyaniline can perform in water medium. Conducting polymers shows electrochromism via change in the electronic state upon electrochemical redox process. Polyaniline forms various electronic states such as emeraldine base, emeraldine salt, and pernigraniline. This change allows to color tuning through electrochemical method. Further, optically active polyanilines have been synthesized in the presence of (+) or (-)-camphorsulfonic acid (CSA) by electrochemical polymerization or chemical polymerization with ammonium persulfate (oxidizing agent). Both electrochemical method and chemical method produce polyaniline through radical polymerization process. Polyaniline emeraldine salt as prepared form of polyaniline is doped with CSA, showing optical activity in the circular dichroism. In this research, we carried out to synthesis of polyaniline in the presence of optically active CSA, according to previously reported method (by Wallace et al). Here, we have found that the polyaniline thus prepared showed optically active electrochromism via electrochemical redox process in circular dichroism spectroscopy measurements. In our previous study, we calculated the ORD spectra for the polymer by Kramars - Kronich (K-K) conversion from circular dichromism. In the present research, we successfully obtained experimental data of optical rotation-spectroelectrochemical result, as a first example of optical rotation control of natural optical activity for conjugated polymers based on electrochemical method. In the case of low potential for the polymer in the electrochemical redox process, the polymer shows intense optical rotation at visible wavelength range. On the other hands, higher potential at around 1 V affords to give doping process for the polymer, resulting generation of polaron as charge carrier, which shows optical activity at near infrared region. We referred this optical charge carrier as “chiral charge carrier chiralions”. The electrochemical oxidation equivalents to electrochemical doping from the polymer. In other words, electrochemical oxidation gives electrochemical doping which results change in degree of optical rotation for the polymer. The control of optical ration for materials can be driven by magnetic field (Faraday rotation), and electric field (Kerr rotation). We propose a new phenomenon as ‘‘electrochemical optical rotation’’. The electro-conductivity of the polymer is measured with four-probe method. The polymer which is electronic doped state with (+)-CSA as electric dopant for production of radical cation (polarons) or dication (bipolarons) as charge carriers and chiral inducer for twisting main-chain. The polymer film was synthesized as followed. First, electrochemical polymerization of aniline as a monomer was carried out in excessive optically active (+)-CSA with three electrode system consisting of working electrode (indium-tin oxide coated glass), counter electrode (platinum wire), and reference electrode (SCE) in water. The polymerization reaction is rapidly progressed with formation of polymer thin film onto the counter electrode. The polymer was washed with excess amount of water, acetone. The electroactive polymer film was thus deposited on the electrode was used for optical activity measurements. Cyclic voltammetry (CV) measurements were carried out for the resultant polymer (monomer free) deposited on to the ITO coated glass electrode. The CV results with change in scan rate from 10-100 mV/s indicates electroactive. Increase of scan rate increases current density for the polymer due to increase of diffusion of ion in the electrolyte solution. Oxidation signals of the polymer are observed due to change in electronic state of the polymer. Corresponding reduction signals against oxidation process are observed, indicating reversible redox activity for the polymer. ORD measurement reveled that the polymer film thus obtained is optically active. The polyaniline can be formed helical structure due to doping of optically active CSA. We carried out in-situ ORD measurement with potential change, evaluating electrochemical driven change in optical rotation. Chemical structure of the double layer polymer is examined with Fourie transform infrared optical absorption spectroscopy measurements which reveled this polymer is polyaniline, and CSA as a dopant. Ultra-violet optical absorption measurements for the polymer film indicates intense and wide range absorptions from invisible to infrared range as charge carriers the delocalized along the main-chain, indicating the polymers are conductive materials. The advantages of the polymer film are formation of self-standing redox activity, tuning of optical activity and color coordination. This paper reports novel function of control optical rotation with electrochemical method examined with spectroelectrochemistry. This concept can be a first example as optical rotation effect of electro-optically active conducting polymers. This paper reports the charge carries of helical polyaniline as chiralions can tune via electrochemical method.

Rheology of rounded mammalian cells over continuous high-frequencies

Understanding the viscoelastic properties of living cells and their relation to cell state and morphology remains challenging. Low-frequency mechanical perturbations have contributed considerably to the understanding, yet higher frequencies promise to elucidate the link between cellular and molecular properties, such as polymer relaxation and monomer reaction kinetics. Here, we introduce an assay, that uses an actuated microcantilever to confine a single, rounded cell on a second microcantilever, which measures the cell mechanical response across a continuous frequency range ≈ 1–40 kHz. Cell mass measurements and optical microscopy are co-implemented. The fast, high-frequency measurements are applied to rheologically monitor cellular stiffening. We find that the rheology of rounded HeLa cells obeys a cytoskeleton-dependent power-law, similar to spread cells. Cell size and viscoelasticity are uncorrelated, which contrasts an assumption based on the Laplace law. Together with the presented theory of mechanical de-embedding, our assay is generally applicable to other rheological experiments.

Facile Synthesis of CO2 -Responsive Nano-Objects: Batch versus Semi-Batch RAFT Copolymerization.

Precise polymer architecture and self-assembled morphological control are attractive due to their promising applications, such as drug delivery, biosensors, tissue engineering and "smart" optical systems. Herein, starting from the same hydrophilic units poly(ethylene glycol) (PEG), using CO2 -sensitive monomer N, N-diethylaminoethyl methacrylate (DEAEMA) and hydrophobic monomer benzyl methacrylate (BzMA), a series of well-defined statistical, block, and gradient copolymers is designed and synthesized with similar degree of polymerization but different monomer sequences by batch and semi-batch RAFT polymerization process and their CO2 -responsive behaviors of these nano-objects is systematically studied. The gradient copolymers are generated by using semi-batch methods with programmed monomer feed rate controlled by syringe pumps, achieving precise control over desired gradient copolymer composition distribution. In aqueous solution, the copolymers could self-assemble into various aggregates before CO2 stimulus. Upon bubbling CO2 , the gradient copolymers preferred to form nanosheet-like structures, while the block and statistical copolymers with similar molar mass could only form larger vesicles with thinner membrane thickness or disassemble. The semi-batch strategy to precisely control over the desired composition distribution of the gradient segment presents an emerging trend for the fabrication and application of stimuli-responsive polymers.