Similar Molecular Weight Distribution Research Articles

Effects of molecular structure and temperature field on the crystallization behavior of poly(tetrafluoroethylene-co-perfluoroalkylvinyl ether)

Despite the wide industrial application of poly(tetrafluoroethylene-co-perfluoroalkylvinyl ether) (PFA) in semiconductor processing, its crystallization behavior has little been studied. In this work, three PFA resins with similar molecular weight but different comonomer content and distribution were synthetized. Then the non-isothermal crystallization kinetics and crystalline structures were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction systematically. It is found that the incorporation of comonomers destroys the chain regularity and reduces the crystallizability of PFA thermodynamically, while the comonomer insertion improves the chain flexibility to accelerate the crystal growth dynamically. When the comonomer content of PFA is low, both the nucleation and growth rates are quite fast, which is favorable for the formation of spherulite. As the comonomer content increases or distribute uniformly in the chain, the nucleation rate declines notably and the side groups distort the crystal cell to increase the spacing of [100] plane. Moreover, two-dimensional growth mode is dominant to form bundle-like structure when crystallizing at slow cooling, where nucleation is suppressed by growth. But three-dimensional symmetrical spherulite can be activated and perfected at high cooling rate due to the initiation of substantial nucleation sites. This unique crystallization behavior is opposite to that of conventional polymers, providing a guidance for the polymerization and processing of PFA.

An enzyme-pHBH method for specific quantification of porphyran

Porphyran, the major polysaccharide extracted from Porphyra, exhibits tremendous potential for development as functional food or pharmaceutical due to its multiple biological activities. The quantitative analysis of porphyran is important for the quality control in product development. However, the specific quantitative method of porphyran has not been established, and the lack of reference substance makes the quantification more challenging. Here, a common component of porphyran, with high purity, similar molecular weight distribution, sourced from different Porphyra producing areas in China was first prepared by a series of isolation and purification steps, and utilized as the reference substance for porphyran quantification. Subsequently, the porphyran was fully degraded into oligosaccharides by using a β-porphyranase, followed by employing para-hydroxybenzoic acid hydrazide (pHBH) method to detect the content of the generated reducing sugar. The enzyme-pHBH method for porphyran specific quantification was established. Results showed that this method was validated with good linearity, high accuracy and precision, and reliability. Addtionally, NaCl with a concentration below 0.5 %, alcohol under 8 % and other polysaccharide including chitosan, agarose, chondrotin sulfate, alginate, hyaluronic acid and κ-carrageenan did not interfere with this method. This approach is promising for quality control of the porphyran products and offers a feasible strategy for the specific quantification of other polysaccharides.

Changes in composition and structure of nitrogenous bases of resin components of heavy oil from the Nurlatskoe oilfield in the course of thermal decomposition

The relevance. The need to obtain information on heat treatment effect on composition and structure of nitrogenous bases of resin components of heavy oil from the Nurlatskoe field (Republic of Tatarstan) to solve the problems associated with their negative impact on oil refining. The aim. To characterize the composition of nitrogenous organic bases, isolated from the resins of bituminous oil of the Nurlatskoe field, and the products of their thermal cracking. Methods. Complex formation, extraction, liquid adsorption chromatography, potentiometric titration, 1H NMR spectroscopy, structural group analysis, combined gas chromatography-mass spectrometry. Results. Based on a comparative study of the composition and structure of nitrogenous bases of the initial and thermally treated resins of the bituminous oil from the Nurlatskoe field, the authors found out that they both contain high- and low-molecular nitrogenous bases with predominance of high-molecular compounds precipitated by hydrogen chloride. As a result of thermal exposure, the number of such bases increases due to an increase in the proportion of compounds with shorter alkyl substituents in their composition. The method of structural group analysis was used to show that the main directions of thermal transformations of high- and low-molecular bases of resins in Nurlatskoe oil are destruction of alkyl substituents and cyclization of shortened alkyl chains with formation of naphthenic rings. Among the lowest molecular weight bases of the initial resins and thermolysate the authors have identified alkyl-substituted quinolines, benzoquinolines, azapyrenes, thiophenoquinolines, and benzothiophenoquinolines with similar molecular weight distributions. During the thermolysis of resins, the relative content of low molecular weight homologues in the identified nitrogenous bases increases. The share of structures with reduced chromatographic mobility caused by a decrease in the degree of spatial screening of a nitrogen atom increases among similar homologues.

Protein hydrolysis of Camelina sativa meals: A study of molecular weight distribution and emulsifying properties

Camelina is an ancient oilseed known for its healthy oil composition and high crude protein content. Efforts have recently been made to reintroduced camelina in Europe and North America. This study aimed to propose an innovative strategy for valorising the camelina meal, a by-product obtained after oil extraction. Specifically, the investigation focused on the hydrolysis of protein directly applied to camelina meal studying two enzymes (Alcalase® and Protamex®) across three Camelina varieties (Calena, Vera and Sonny). Protein hydrolysates were successfully produced, with a maximum weight yield of 47%, and achieved values above 49 g/100 g in crude protein content and 58% in protein yield. The study revealed that Alcalase® and Protamex® produced similar protein molecular weight distribution but exhibited distinct technological properties. The emulsifying capacities of the protein hydrolysates were enhanced by Alcalase®, with the maximum emulsifying activity index reaching 36 m2/s. Conversely, Protamex® decreased the emulsifying capabilities of protein hydrolysates. To evaluate the applicability of the protein hydrolysates obtained, an oil-in-water emulsion was selected as a food application. The results suggested that camelina protein hydrolysates have the potential to serve as a new emulsifier ingredient. Furthermore, no significant differences were observed among the three camelina varieties in terms of protein yields or technological properties.

Macromolecular Architecture-Dependent Polymorphous Crystallization Behavior of PVDF in the PVDF/γ-BL System via Thermally Induced Phase Separation.

This study investigates the effect of the macromolecular architecture of poly(vinylidene fluoride) (PVDF) on its thermally induced phase separation (TIPS) behavior and polymorphic crystallization in the PVDF/γ-butyrolactone (PVDF/γ-BL) system. Preparative PVDF fractions with specific macromolecular architecture and phase constitution are generated. The results show that PVDF's macromolecular architecture, particularly the degree of branching and regio-defects, plays a significant role in its temperature-dependent crystallization and resulting polymorphic phases. While regio-defects dominate crystallization in the temperature range between 30 and 25 °C, the degree of branching becomes decisive in the 25-20 °C interval. The developed fractions of PVDF are further analyzed in terms of their molecular weight distribution, revealing that the PVDF fractions crystallized out of solution have similar molecular weight distributions with lower dispersity compared with the feed polymer. These findings are crucial for macromolecular separation and adjustment of PVDF polymorphic properties and hence for the development of tailor-made PVDF matrix materials for composites and membranes. The findings suggest the possibility of polymorphous phase tailoring of PVDF based on macromolecular architecture due to temperature-controlled crystallization out of solution and strongly motivate further research to reveal deeper knowledge of regio-defect and branching influence of PVDF solution crystallization.

Material recycling of Acrylonitrile Butadiene Styrene (ABS) from toy waste using density separation and safer solvents

Toy waste is an issue for municipal plastic recycling programs. In particular, toy waste typically is composed of different plastics and some metals. Separation of different parts of toy waste is necessary before recycling. In this study, a dissolution-precipitation process coupled with density separation was developed to extract acrylonitrile butadiene styrene (ABS) from toy waste using safer solvents and antisolvents. The polymer solubility of ABS was measured using Hansen solubility parameters, which were then used to down-select proper safer solvents and antisolvents. The acetone-water with a volumetric ratio of 3:1 was determined to be the most effective safer solvents and antisolvents for extracting 81 wt.% of ABS at room temperature. The recovered ABS has comparable mechanical behavior to the feedstock material with a similar glass transition temperature and molecular weight distribution. Compared to producing virgin ABS material, the dissolution-precipitation process reduces embodied energy by 58%.

Metal-chelating activity of soy and pea protein hydrolysates obtained after different enzymatic treatments from protein isolates

Soy and pea proteins are two rich sources of essential amino acids. The hydrolysis of these proteins reveals functional and bioactive properties of the produced small peptide mixtures. In our study, we employed the hydrolysis of soy and pea protein isolates with the endopeptidases Alcalase® and Protamex®, used alone or followed by the exopeptidase Flavourzyme®. The sequential enzyme treatments were the most efficient regarding the degree of hydrolysis. Then, soy and pea protein hydrolysates (SPHs and PPHs, respectively) were ultrafiltrated in order to select peptides of molecular weight ≤ 1 kDa. Whatever the protein source or the hydrolysis treatment, the hydrolysates showed similar molecular weight distributions and amino acid compositions. In addition, all the ultrafiltrated hydrolysates possess metal-chelating activities, as determined by UV-spectrophotometry and Surface Plasmon Resonance (SPR). However, the SPR data revealed better chelating affinities in SPHs and PPHs when produced by sequential enzymatic treatment.

Lactic Acid-Derived Copolymeric Surfactants with Monomer Distribution Profile-Dependent Solution and Thermoresponsive Properties

We report the synthesis and solution properties of novel biobased thermoresponsive amphiphilic copolymers prepared using N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA) as hydrophilic and hydrophobic monomers, respectively. Copolymers with similar overall molecular weight but different monomer distribution profiles, such as random, diblock, triblock, and random–blocks, were prepared using photoinduced electron/energy transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization activated by a Zn-based photoredox catalyst. The synthesized polymers show interesting self-assembly and thermoresponsive behavior in water, depending on the monomers distribution along the chain. Different critical solution temperatures, in the range of 13–70 °C, were observed by tuning the monomers molar ratio and distribution. The formation of aggregates of various types was proven by transmission electron microscopy (TEM). The prepared polymers also display different surface activity with the fully random copolymer being significantly more surface active than block systems. A study of emulsion stabilization was performed with oils of various polarity, showing promising results for applications of these novel polymers as biobased surfactants and water/oil (w/o) emulsion stabilizers.

Fractionation and purification of antioxidant peptides from abalone viscera by a combination of Sephadex G‐15 and Toyopearl HW‐40F chromatography

SummaryAbalone viscera, a protein‐rich by‐products from the abalone processing industry, are normally discarded as wastes. In the present study, four different proteases were used to hydrolyse abalone viscera to prepare high‐activity antioxidant peptides, and their hydrolysis effects were compared. Although the hydrolytic abilities of papain and trypsin were inferior to the alcalase and neutrase, their use resulted in significantly (P < 0.05) higher scavenging activities for DPPH. The hydrolysates mainly consisted of peptides with a molecular weight <3 kDa, and the fractionation was achieved using a combination of Sephadex G‐15 and Toyopearl HW‐40F gel filtration chromatography, which overcomes the disadvantages of traditional membrane separation technology in fractionating peptides with relatively similar molecular weight distribution. The DPPH scavenging activities of the components containing peptides <1 kDa (fractions E) were significantly (P < 0.01) higher than those containing peptides >1 kDa. The different fractions E were further purified by reversed‐phase high‐performance liquid chromatography, and a total of 16 target peptides, containing 4‐8 amino acids, enriched in hydrophobic amino acids and C‐terminal Arg, with molecular weights ranging from 500 to 850 Da, were identified.

Correlation Analysis between Properties and Calcium-holding Capacity of Different Casein Phosphopeptide Products

In order to investigate the influence of the properties of casein phosphopeptide(CPP) on its calcium-holding capacity, the content of CPP, nitrogen and phosphorus content, molecular weight distribution, amino acid composition and content were determined using 7 kinds of commercial CPP products. The correlation between physical and chemical properties and calcium holding capacity was analyzed. The results showed that the CPP content and N/P of 7 kinds of CPP products were 1.30%~18.50% and 12.70~46.80, respectively. The content of total amino acid of 7 kinds of CPP products were 70.50~901.00 mg/g, and proline was the most abundant amino acid among those CPP products. The molecular weight of those CPP products were 10 kDa showed a highly significant negative correlation with the calcium-holding capacity of CPP samples(correlation coefficient −0.985~−0.975, P<0.01), while CPP samples with similar molecular weight distribution and higher content of isoleucine(correlation coefficient 0.766~0.768, P<0.05) and phenylalanine(correlation coefficient 0.758~0.759, P<0.05) showed a stronger calcium-holding capacity. This study provided a theoretical basis for evaluating and improving the quality of CPP products.

Mechano‐Optical Characterization of Extrusion Flow Instabilities in Styrene‐Butadiene Rubbers: Investigating the Influence of Molecular Properties and Die Geometry

AbstractThe extrusion flow instabilities of two commercial styrene‐butadiene rubbers are investigated as they vary in isomer content (1,4‐cis, 1,4‐trans, and 1,2 conformation) of the butadiene monomer and the molecular architecture (linear, branched). The investigated samples have similar multimodal molecular weight distribution. Two geometries of extrusion dies, slit and round capillary, are compared in terms of the type and the spatial characteristics of the flow instabilities. The latter are quantified using three methods: a highly pressure sensitive slit die, online and offline optical analysis. The highly pressure‐sensitive slit die has three piezoelectric pressure transducers (Δt ≈ 10−3 s and Δp ≈ 10−5 bar) placed along the die length. The characteristic frequency (fChar.) of the flow instabilities follows a power law behavior as a function of shear rate to a 0.5 power for both materials, . A qualitative model is used to predict the spatial characteristic wavelength (λ) of the flow instabilities from round capillary to slit dies and vice versa. Slip velocities (Vs) are used to quantify the slippage at slit and round capillary dies as well.

Sustainable indigo dyeing and improvement of rubbing fastness of dyed cotton fiber using different fixing agents for obtaining eco-friendly cowboy products

Abstract Indigo dyeing for cotton fibers can achieve ideal color depth in silicone non-aqueous medium dyeing system and solve some environmental pollution problems which were caused by the traditional water bath dyeing. However, the rubbing fastness of indigo-dyed cotton fiber is poor, which will influence the spinning process. In this investigation, three fixing agents commonly used in the market were screened to treat the indigo-dyed cotton fibers and their working mechanism was also studied. The results of GPC and FTIR showed that all the three fixing agents were polyurethanes which have a similar narrow molecular weight distribution and they could combine with indigo-dyed cotton fiber with intermolecular forces (hydrogen bonds) and ionic bonds with indigo-dyed cotton fiber. Compared with these fixing agents, fixing agent J has a better effect on reducing the friction coefficient of fiber because cotton fiber was the smoothest after fixing. After adding some cationic surfactant during fixing, the effect of fixation was influenced because there was a competition relation between the fixing agent and surfactant. From the spinning process, the rubbing fastness of fiber treated with fixing agent can meet the spinning requirements. 100 kg/d industrial application provides compelling proof of indigo dyeing in non-aqueous medium dyeing system, because this dyeing technology can change the complex process of traditional indigo dyeing, the monotonous style, and the serious waste water pollution for cowboy wear production.

Understanding the Roles of Triethylaluminum in Phosphinimide-Supported Titanium Catalyst Systems for Ethylene Polymerization

Treatment of [(Ind)(tBu3P═N)TiCl2] (1; Ind = indenyl) with AlEt3 in a range of solvents affords the emerald green heterobimetallic complex [(Ind)(tBu3P═N)Ti(μ2-Cl)2AlEt2] (2). Single-crystal X-ray diffraction studies, as well as nuclear magnetic and X-band electron paramagnetic resonance spectra, support formulation of 2 as a paramagnetic, formally [TiIIIAlIII] complex. Both 1 and 2 are active precatalysts for ethylene polymerization in the presence of AlEt3 and a solid superacid; the product polyethylene materials are found to have similar molecular weight distributions in each case (3.29 with 1 and 3.05 with 2), implicating involvement of similar active catalysts in both. Electrochemical studies reveal that 1 can undergo one-electron reduction to TiIII near −2.0 V versus ferrocenium/ferrocene in tetrahydrofuran electrolyte, whereas 2 undergoes one-electron oxidation at a significantly more positive potential (ca. −1.30 V). Spectroelectrochemical studies show that reduction of 1 in the presence of AlEt3 ...

Effect of short chain branches distribution on fracture behavior of polyethylene pipe resins

In this paper, a series of unimodal and bimodal high density polyethylene (HDPE) pipe resins with the similar molecular weight distribution and low short chain branches (SCB) contents were investigated to discover the relationship between short chain branches distribution (SCBD) and fracture behaviors. Three characterization methods, namely temperature rising elution fractionation (TREF), high temperature gel permeation chromatography (HT-GPC) and self-annealing fraction (SSA), have been effectively combined to qualitatively analyze investigate the SCBD of HDPE pipe resins. The results showed the preference of incorporation of SCB into long chains caused the enhancement of yielding stress and strain hardening (SH) modulus, and thus the extension of rupture time. On one hand, this kind of SCB distribution is conductive to induce the nucleation of long chains and form more void volume in the neighborhood of long chains indicating faster migration speed of polymer chains. On the other hand, short chains with less SCBs are easy to rapidly occupy nearby sites on the crystal growth front of long chains to co-crystallize. Whereas, these HDPE resins with the more SCBs incorporated into short chains spent much longer time occupying the growth front, so that parts of these types of short chains form very thinner lamella differentiated from the main crystallizing region. During the initiation and propagation of craze, these parts were firstly broken and their resistance to slow crack growth was based on the incorporating degree of SCBs into short chains. Therefore, besides molecular weight distribution, SCBD is another main cause for long-term properties of HDPE pipe resins.

Rheological and structural properties of complex arabinoxylans from Plantago ovata seed mucilage under non-gelled conditions

Two gel-forming arabinoxylan (AX) fractions with very similar linkage composition and molecular weight distributions have been isolated from Plantago ovata seed mucilage. Both isolated fractions have distinct gel properties attributed to differences in intermolecular hydrogen bonding. This study probes the effect of hydrogen bonding on molecular interactions of P. ovata AX fractions under non-gelled conditions achieved using a mild hydrogen bonding inhibitor, 0.2 M KOH. Chain conformation, relaxation dynamics and interactions between AX molecules are investigated using a combination of rheological techniques and small angle X-ray and neutron scattering. The scattering data confirm similar molecular dimensions and chain rigidity for both fractions, while showing distinct patterns of molecular interactions which result in the formation of a self-associated polymer network. The relationship between molecular associations, chain relaxation time and entanglement behaviour of P. ovata AX solutions are corroborated though the analysis of flow profiles and small amplitude oscillatory shear rheology.

Thermoplastic development of coking and non-coking maceral concentrates and molecular weight distribution of their pyrolysis products

A suit of nitrogen-dried maceral concentrates derived from a coking coal and a non-coking coal was investigated to reveal the impact of varying coal main organic constituent, the vitrinite, on their thermoplasticity and pyrolysis products. The thermoplastic development of maceral concentrates during pyrolysis was evaluated via their thermo-swelling and dynamic volatile release. These measurements were then linked to molecular weight distributions of vaporised tars and tetrahydrofuran (THF) extracts obtained from heat-treated samples. Regardless of the vitrinite content, only coking macerals agglomerated during pyrolysis while non-coking macerals retained their powdered structure. This result indicated that although concentrating the vitrinite could alter the extent of coal thermoplasticity, such process could not grant or remove thermoplasticity from a maceral concentrate. This was reflected in the similar molecular weight distribution of solvent extracts produced between the parent coals and their concentrates. In specific, coking concentrates generated extractable materials with a relatively more complex structure, consisting of a bimodal molecular weight distribution with 12–14Da repeating structures at <600Da and 24Da reoccurring units between 600 and ∼1500Da. Solvent extracts isolated from non-coking concentrates, on the other hand, possessed a unimodal molecular weight distribution with only 12–14Da repeating structures extending to ∼800Da. The absence of high-range molecular weight materials (the 24Da repeating units) in non-coking coal and its concentrates was speculated to play a vital role to their inability to exhibit thermoplastic behaviour during pyrolysis.

Exploring the roles of molecular structure on the β-crystallization of polypropylene random copolymer

To investigate effects of molecular structures on β-crystallization of polypropylene random copolymer (PPR), PPR-A and PPR-B with similar molecular weight and distribution but significantly different polymorphic behavior were used. Wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FT-IR), solvent fractionation combined with successive self-nucleation and annealing (SSA) and Gel Permeation Chromatography (GPC) were applied. Results revealed that after addition of same amount of β-nucleating agent (β-NA), large amount of β-phase is obtained in PPR-A (K β = 0.603), while no β-phase can be seen from PPR-B; Structure characterizations revealed that they have similar molecular weight but different total amount and distribution of ethylene comonomer: the total content of ethylene comonomer of PPR-A is higher compared with PPR-B, but its ethylene comonomer distribution is less uniform. In this way, PPR-A possesses high molecular weight high isotactic fraction, which cannot be seen from PPR-B due to its more uniform comonomer distribution. Therefore, the presence of highly isotactic PP (HPP) is the key factor in β-crystallization of PPR. For verification, HPP with low or high molecular weights are respectively added into β-nucleated PPR-B. Results revealed that HPP was effective in enhancing β-crystallization of PPR-B; higher molecular weight of HPP was more favorable and more effective.

Quasi‐living copolymerization of ethylene with 1‐hexene by heteroligated (salicylaldiminato β‐enaminoketonato) titanium complexes

ABSTRACTA series of heteroligated (salicylaldiminato)(β‐enaminoketonato)titanium complexes [3‐But‐2‐OC6H3CH = N(C6F5)] [PhN = C(R1)CHC(R2)O]TiCl2 [3a: R1 = CF3, R2 = tBu; 3b: R1 = Me, R2 = CF3; 3c: R1 = CF3, R2 = Ph; 3d: R1 = CF3, R2 = C6H4Ph(p); 3e: R1 = CF3, R2 = C6H4Ph(o); 3f: R = CF3, R2 = C6H4Cl(p); 3g: R1 = CF3; R2 = C6H3Cl2(2,5); 3h: R1 = CF3, R2 = C6H4Me(p)] were investigated as catalysts for ethylene (co)polymerization. In the presence of modified methylaluminoxane as a cocatalyst, these complexes showed activities about 50%–1000% and 10%–100% higher than their corresponding bis(β‐enaminoketonato) titanium complexes for ethylene homo‐ and ethylene/1‐hexene copolymerization, respectively. They produced high or moderate molecular weight copolymers with 1‐hexene incorporations about 10%–200% higher than their homoligated counterpart pentafluorinated FI‐Ti complex. Among them, complex 3b displayed the highest activity [2.06 × 106 g/molTi•h], affording copolymers with the highest 1‐hexene incorporations of 34.8 mol% under mild conditions. Moreover, catalyst 3h with electron‐donating group not only exhibited much higher 1‐hexene incorporations (9.0 mol% vs. 3.2 mol%) than pentafluorinated FI‐Ti complex but also generated copolymers with similar narrow molecular weight distributions (Mw/Mn = 1.20–1.26). When the 1‐hexene concentration in the feed was about 2.0 mol/L and the hexene incorporation of resultant polymer was about 9.0 mol%, a quasi‐living copolymerization behavior could be achieved. 1H and 13C NMR spectroscopic analysis of their resulting copolymers demonstrated the possible copolymerization mechanism, which was related with the chain initiation, monomer insertion style, chain transfer and termination during the polymerization process. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2787–2797

Immunomodulatory activities of non-prolamin proteins in wheat germ and gluten

Albumin (Alb), globulin (Glo), glutelin (Gll) and glutenin (Gln) were separately extracted from wheat germ and wheat gluten. Amino acisd composition, molecular weight distribution, solubility, in vitro digestibility, and immunomodulatory activities were all analyzed. Gll and Gln have similar molecular weight distributions, which differed from those of Alb and Glo. Alb showed the highest solubility at various pH values (except pH 4.0), whereas Glo showed the highest in vitro digestibility. Glo and Gll have the highest proportion of essential to total amino acids, while Alb and Gll have the highest protein digestibility-corrected amino acid scores. Gll had the strongest immunomodulatory effects in terms of stimulation of RAW 264.7 cells to produce IL-6, TNF-α, and IL-10, and good stimulatory effects on splenocyte proliferation, production of IL-2, phagocytosis, and secretion of nitric oxide in RAW 264.7 cells. Gll can be considered a good protein source for use in health foods.

Comparative analyses of structural features and scaffold diversity for purchasable compound libraries

Large purchasable screening libraries of small molecules afforded by commercial vendors are indispensable sources for virtual screening (VS). Selecting an optimal screening library for a specific VS campaign is quite important to improve the success rates and avoid wasting resources in later experimental phases. Analysis of the structural features and molecular diversity for different screening libraries can provide valuable information to the decision making process when selecting screening libraries for VS. In this study, the structural features and scaffold diversity of eleven purchasable screening libraries and Traditional Chinese Medicine Compound Database (TCMCD) were analyzed and compared. Their scaffold diversity represented by the Murcko frameworks and Level 1 scaffolds was characterized by the scaffold counts and cumulative scaffold frequency plots, and visualized by Tree Maps and SAR Maps. The analysis demonstrates that, based on the standardized subsets with similar molecular weight distributions, Chembridge, ChemicalBlock, Mucle, TCMCD and VitasM are more structurally diverse than the others. Compared with all purchasable screening libraries, TCMCD has the highest structural complexity indeed but more conservative molecular scaffolds. Moreover, we found that some representative scaffolds were important components of drug candidates against different drug targets, such as kinases and guanosine-binding protein coupled receptors, and therefore the molecules containing pharmacologically important scaffolds found in screening libraries might be potential inhibitors against the relevant targets. This study may provide valuable perspective on which purchasable compound libraries are better for you to screen.Graphical abstractSelecting diverse compound libraries with scaffold analyses.