Hypercrosslinking Reaction Research Articles

Carbon fiber‐reinforced thermoplastic synthesized by the hypercrosslinking reaction of polyether ether ketone

AbstractRecently, thermoplastic resins were used as matrix to synthesize carbon fiber‐reinforced thermoplastic (CFRTP) for recycling it easily. In this study, a CFRTP with excellent mechanical properties and heat resistance was synthesized using a polyether ether ketone (PEEK) as a matrix resin. The PEEK resin was modified to form cross‐linked structures through Friedel–Crafts reaction alkylation. The synthesis temperature of CFRTP was optimized considering the mechanical properties of PEEK, and its heat resistance was enhanced because of the cross‐linked structures. Further, the cross‐linked PEEK resin was partially used as a matrix resin, and the mechanical properties of the CFRTP were enhanced. We plan to develop a method for recycling CFRTP using PEEK and crosslinked PEEK for synthesizing C/C composites by focusing on the high heat resistance of the crosslinked PEEK containing a large amount of carbon and reducing mass loss after heat treatment.Highlights CC bonds were introduced into the polyether ether ketone (PEEK) resin by Friedel–Crafts reaction alkylation. Thermal properties of PEEK were enhanced by hypercrosslinking reaction. Optimization of synthesized temperature was investigated to fabricate carbon fiber‐reinforced thermoplastic (CFRTP). Mechanical properties were enhanced CFRTP modified with hypercrosslinking reaction.

Hierarchically porous boronic acid functioned copolymers fabricated from HIPEs microreactor for ultrafast transport and specific recognition of flavonoids

In this work, two new kinds of boronic acid functioned sorbents (HCLPH-N3@PCAPBA and HCLPH@N3-PBA) based on emulsion reactors coupled with click chemistry and boronate affinity were developed for the separation of naringin (NRG). The new clickable boronate ligands 3-(prop-2-ynyloxycarbonylamino) phenylboronic acid (PCAPBA) and azide phenylboronic acid (N3-PBA) were utilized as functional monomers for the specific separation and purification of NRG molecules, respectively. The pore structure of macroporous polymers were adjusted via the hypercrosslinking reactions, which can effectively increase their specific surface area and provide abundant recognition sites. The resulting HCLPH-N3@PCAPBA and HCLPH@N3-PBA exhibited fast equilibrium adsorption at 120 min, and their maximum absorption amounts were 29.85 μmol g−1 and 41.27 μmol g−1 at 303 K, respectively. The HCLPH-N3@PCAPBA and HCLPH@N3-PBA demonstrated remarkable stability in six cycles of adsorption–desorption experiments (88.48% and 92.02%, respectively). Furthermore, the HCLPH@N3-PBA achieved an efficient extraction 93.4% for the commercially available NRG. Our findings provided an idea for constructing hierarchically porous high-surface-area polymers with fast penetrability and various abundant binding sites have great potential for separation and purification of industrial samples.

Mechanical Properties, Radiation Resistance Performances, and Mechanism Insights of Nitrile Butadiene Rubber Irradiated with High-Dose Gamma Rays.

The radiation effect of materials is very important and directly related to the safety and reliability of nuclear reactors. Polymer materials, one of the indispensable materials in nuclear power equipment, must withstand the ordeal of high-energy ionizing rays. In this work, through screening different γ-ray dose irradiation conditions, we systematically and comprehensively study the changes in the structure and properties of nitrile butadiene rubber (NBR) before and after γ-ray static irradiation at a high dose rate, and master the rule and mechanism of the γ-ray static irradiation effect of these polymer materials. The mapping relationship between the macroscopic properties, microstructure, and irradiation dose of NBR is accurately characterized. With an increase in total irradiation dose, the C=C double bond reaction occurs, and the C≡N bond, C=C, and C=O participate in the hyper crosslinking reaction. The glass transition temperature (Tg) increases with the cumulative irradiation amount. With the increased total irradiation amount, the degree of rubber cross-linking increases, causing an increased crystallinity and decomposition temperature. A growing amount of gamma irradiation causes the mechanical properties of the rubber to degrade simultaneously, increasing the shore hardness while decreasing the tensile strength and ultimate elongation at break. When the cumulative amount reaches 1 MGy, the ultimate elongation at break decreases significantly. A cumulative dose of radiation resistance of 4 MGy can be achieved by the samples. This work can provide theoretical and experimental support for the long-term stability of nitrile butadiene rubber and its derivatives in nuclear radiation fields and space radiation conditions.

Comprehensive use of fossil derivative: High value-added conversion of waste plastics to thermal energy storage materials

As one of the most common fossil derivatives, plastic is indispensable in daily life because of its promising mechanical properties, chemical stability, and easy accessibility. However, plastics still present a huge burden on the global environment due to their high production volume, difficulty with degradation and low recycling rate. At the same time, global primary energy reserves are decreasing, thus achieving highly efficient use of energy has become a hot topic of research. Herein, the waste plastics can be utilized as a supporting material and encapsulation the phase change materials through intermolecular hyper-crosslinking reaction with the assistance of Lewis acids. To illustrate the effect of porous structure on the thermophysical properties and energy storage characteristics of the obtained materials, three aromatic crosslinkers, triphenylphosphine, triphenylbenzene, and benzene were examined regarding their performance on the Fridel-Crafts reactions. It is found that the obtained materials bearing a thermal conductivity and latent heat of 0.22 W/mK and 145.7 J/g, respectively, without liquid leakage.

RAFT Polymerisation and Hypercrosslinking Improve Crosslink Homogeneity and Surface Area of Styrene Based PolyHIPEs.

The influence of a polymerisation mechanism (reversible addition-fragmentation chain transfer; RAFT vs. free radical polymerisation; FRP) on the porous structure of highly porous poly(styrene-co-divinylbenzene) polymers was investigated. The highly porous polymers were synthesised via high internal phase emulsion templating (polymerizing the continuous phase of a high internal phase emulsion), utilising either FRP or RAFT processes. Furthermore, residual vinyl groups in the polymer chains were used for the subsequent crosslinking (hypercrosslinking) applying di-tert-butyl peroxide as the source of radicals. A significant difference in the specific surface area of polymers prepared by FRP (between 20 and 35 m2/g) and samples prepared by RAFT polymerisation (between 60 and 150 m2/g) was found. Based on the results from gas adsorption and solid state NMR, it could be concluded that the RAFT polymerisation affects the homogeneous distribution of the crosslinks in the highly crosslinked styrene-co-divinylbenzene polymer network. During the initial crosslinking, RAFT polymerisation leads to the increase in mesopores with diameters between 2 and 20 nm, resulting in good accessibility of polymer chains during the hypercrosslinking reaction, which is reflected in increased microporosity. The fraction of micropores created during the hypercrosslinking of polymers prepared via RAFT is around 10% of the total pore volume, which is up to 10 times more than for polymers prepared by FRP. Specific surface area, mesopore surface area, and total pore volume after hypercrosslinking reach almost the same values, regardless of the initial crosslinking. The degree of hypercrosslinking was confirmed by determination of the remaining double bonds by solid-state NMR analysis.

Fabrication of fire-retardant building materials via a hyper-crosslinking chemical conversion process from waste polystyrenes

• Waste PS was used for the preparation of fire-retardant building materials. • Hypercross-linking reaction induced high value-added use of waste PS. • The preparation process can be facilely scaled up. Polystyrene (PS) is rich in plastic materials, but it produces a large amount of waste every year, causing a huge burden on the environment. Although PS plastic is the source of a common "white pollution" in daily life, it still has a high utilization value. At the same time, the flammability of PS material determines that it cannot be applicated in places where fire accidents occur frequently. As a result, its application has been greatly limited. In order to realize the efficient utilization of waste PS and broaden its scope of application, PS was modified by hyper-crosslinking in order to improve its fire-retardant performance. In this method, the PS solution with high purity was obtained by dissolving waste PS foam with 1,2-dichloroethane (DCE), and then the hyper-crosslinked polymer with high specific surface area was prepared by adding cross-linking agent formaldehyde dimethyl acetal (FDA) and a Lewis-acid catalyst ferric chloride (FeCl 3 ). Further studies showed that the effects of the amount of cross-linking agent FDA, catalyst FeCl 3 and PS on the reaction products were different. In addition, compared the as-prepared fire-retardant materials with PS foam from the aspects of flame retardancy and thermal insulation, it can be concluded that the fire-retardant performance of the materials prepared by this method has been significantly enhanced. And it is proved that this method is feasible towards the preparation of a large number of fire-retardant composite materials by using a scale-up experiment.

Novel porous carbon electrode derived from hypercross-linked polymer of poly(divinylbenzene-co-vinyl benzyl chloride) for supercapacitor applications

In the present study, pores enriched high surface area of carbon electrode obtained from hypercross-linked polymer of poly(divinylbenzene-co-vinylbenzyl chloride) [P(DVB:VBC)] for supercapacitor application. First, hypercross-linking reaction was carried out in [P(DVB:VBC)] via. simple Friedel-Crafts alkylation method (HCP) followed by pyrolysis at 800 °C (HCP-800). The surface morphology of the synthesized HCP and HCP-800 materials was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) technique. HCP-800 showed a remarkable surface area of 1027 m2 g−1 with the abundance of micropores. In addition, the oxidation state of the porous carbon was assessed by x-ray photo electron spectroscopy (XPS). In a three-electrode and symmetric two-electrode configurations, electrodes exhibited a supreme specific capacitance of 272 and 145 F g−1 in aqueous electrolyte, respectively. Specific energy of 39.47 Wh kg−1 at specific power of 699.96 W kg−1 is yielded from the symmetric supercapacitor device (SSCD). Furthermore, SSCD retains more than 94% of its residual capacitance after 5000 GCD cycles at a current density of 5 A g−1 suggests a good cyclic stability.

Highly Efficient Thermal Energy Storage Using a Hybrid Hypercrosslinked Polymer**

AbstractIn this work, an organic/inorganic hybrid polymer containing siloxyl functional groups was synthesized and applied to encapsulate phase change materials (PCMs). Owing to the mild conditions of the hypercrosslinking reaction, which only requires the addition of a catalytic amount of aqueous alkaline solution, both organic and inorganic PCMs are tolerated. It is noteworthy that the initial homogeneous state of the reaction mixture allowed the ultimate encapsulation rate of the PCMs and the uniform blending of the third nano‐additives with the aim of thermal conductivity enhancement. Further study reveals that the presence of this hybrid hydrophobic polymer in a phase change composite endows the latter with a unique self‐cleaning property. This novel PCM encapsulation protocol is suitable for nanoparticles including carbon‐based nanomaterials, metal oxide nanoparticles, and inorganic oxide nanoparticles. A thermal conductivity enhancement of 600 % was achieved along with 93.7 % light‐to‐thermal conversion efficiency with a latent heat of 180 J g−1 without leakage.

Plasticization- and aging-resistant membranes with venation-like architecture for efficient carbon capture

Plasticization and physical aging due to the undesirable deformation of chain microstructure under high pressure or long-term operation hamper the practical application of polymer membranes. Fixing the polymer chain architecture without sacrificing the internal free volume and thereby the membrane permeability remains a grand challenge. The venation architecture in plant leaf, featured by its stable vein structure with abundant interveinal spaces, offers us an inspiration for designing a highly permeable and stable chain architecture. Here, we construct a venation-like chain architecture in polyphenylene oxide (PPO) membrane by introducing numerous interchain crosslinking bridges using Friedel-Crafts-based hypercrosslinking reaction. These crosslinking bridges rigidify the chains and prevent them from dense packing, inhibiting the microstructural deformation, while simultaneously generating abundant free volume. The resulting membranes display ultrahigh CO2 permeability of 5130 Barrer (73-fold higher than pristine PPO membrane), along with superior structural stability. Particularly, the plasticization is fully suppressed under high pressure even up to 70 bar and the physical aging-induced loss of CO2 permeability is reduced remarkably down to as low as 19% after 360 days, transcending most of the state-of-the-art membranes. This venation-like chain architecture opens a new avenue to solving the current permeability-stability dilemma for the implementation of polymer membrane technology.

Effects of chemical modification on the performance evaluation of photoinitiated, dispersion-polymerized poly(methyl methacrylate-co-ethylene glycol dimethacrylate-co-vinylbenzyl chloride) microsphere

Poly(methyl methacrylate- co-ethylene glycol dimethacrylate- co-vinylbenzyl chloride) microsphere was prepared by dispersion polymerization, initiated by light using water/ethanol mixture. The sulfonated hypercrosslinked (HXL) polymer resin was synthesized via three stages, namely, precursor synthesis (photoinitiated dispersion polymerization), post-polymerization after hypercrosslinking reaction, and post-polymerization before hypercrosslinking reaction. The optimized precursor was functionalized before the hypercrosslinking reaction to investigate its ion-exchange capacity, specific surface area (SSA), morphology, and thermal stability. Post-polymerization after hypercrosslinking reaction showed that the chlorine content and SSA are higher than post-polymerization before hypercrosslinking reaction. HXL reaction took place using Friedel–Crafts alkylation with the aid of FeCl3 catalyst. Lewis acid (FeCl3) also played a significant role which contributed to high SSA of the HXL polymer. The particles produced from photoinitiated dispersion polymerization have advantages and could be used in solid-phase extraction, drug delivery, and high-performance liquid chromatography.

PRE-EVALUATION OF CROSSLINKED ANION EXCHANGE (CAX) RESIN ON NITRATES REMOVAL

This study is present the result of synthesizing crosslinked anion exchange (CAX) resin bearing quaternary ammonium functionalities. Crosslinked anion exchange of poly(HEMA-co-EGDMA-co-VBC) were synthesized via the modified suspension polymerization technique, then treated in hyper-crosslinking reaction to increase specific surface area (SSA) of CAX beads resin from ~5 to 124 m2/g and followed by amination treatment with N,N-dimethylbutylaminee (DMBA) to obtain CAX resin. After functionalized process, the amount of nitrogen content increased and intensity at 1265 cm-1 that assigned for chloromethyl group has decreased, showing that DMBA successfully being attached to the backbone. CAX resin was fully characterized by using Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FT-IR) respectively. A pre-evaluation study was carried to investigate the performance of CAX beads resin to remove nitrate by using ion exchange method. Three parameters were used to study the sorption process; contact time, influent concentration and amount of resin used. For overall sorption, the sorption managed to obtain 88 % nitrate removal by using 0.5 g of CAX resin at 50 ppm influent concentration within 1-hour contact time and the highest adsorption of CAX achieved was 93 % removal of nitrate ions within 4-hours contact time.

Preparation of Ethylene Glycol Dimethacrylate (EGDMA)-Based Terpolymer as Potential Sorbents for Pharmaceuticals Adsorption.

Ethylene glycol dimethacrylate (EGDMA) is used as a crosslinker in poly(acrylonitrile (AN)-co-vinylbenzyl chloride (VBC)) to investigate the effect of long-chain crosslinker to the porosity of the terpolymer system. Poly(AN-co-EGDMA-co-VBC) is synthesized by using precipitation polymerization method and further hypercrosslinked by Friedel-Crafts reaction. FT-IR spectra of poly(AN-co-EGDMA-co-VBC) show that the absorption bands at ~1290 cm−1 that are assigned to the C–Cl vibrations are almost disappeared in hypercrosslinked (HXL) poly(AN-co-EGDMA-co-VBC) polymers, confirming that the hypercrosslinking reaction is successful. SEM images show that the morphologies of the polymers are retained through the hypercrosslinking reactions. Brunauer–Emmett–Teller (BET) analysis shows that hypercrosslinked polymers had a specific surface area up to 59 m2·g−1. The preliminary performance of the terpolymer adsorbent to capture polar analyte is evaluated by adsorbing salicylic acid and mefenamic acid from aqueous solution in a batch system. The maximum adsorption capacity of salicylic acid and mefenamic acid were up to 416.7 mg·g−1 and 625 mg·g−1, respectively, and the adsorption kinetic data obeyed pseudo-second-order rate equation.

Preparation of Chloromethylated Pitch–Based Hyper–Crosslinked Polymers and An Immobilized Acidic Ionic Liquid as A Catalyst for the Synthesis of Biodiesel

Hyper-crosslinking polymers and its immobilized acid ionic liquid catalyst were prepared using cheap pitch, as a monomer, through hyper-crosslinking reactions and allyl chloride, as a chlorine source, for chloromethylation and further grafting with imidazole and functionalizing with sulfonic acid. The polymers were characterized by FE-SEM, FTIR, TG, and nitrogen sorption. The grafting ratios of the chloromethylated pitch-based hyper-crosslinked polymer (HCPpitch–CH2–Cl) and immobilized acid ionic liquid [HCPpitch–Im–Pros][Tos] were 3.5 mmol/g and 3.0 mmol/g, and the BET specific surface areas were 520 m2/g and 380 m2/g, respectively. This strategy provides an easy approach to preparing highly stable and acid functionalized mesoporous catalysts. The immobilized acidic ionic liquid was used as a catalyst for the esterification of oleic acid and methanol to synthesize biodiesel. The results demonstrated that under the optimal conditions of an alcohol to acid molar ratio of 7:1, ionic liquid to oleic acid molar ratio of 0.12, and a reaction time of 3 h at atmospheric pressure, the yield of methyl oleate can reach up to 93%. Moreover, the catalyst was reused five times without the yield decreasing significantly. This study shows that [HCPpitch–Im–Pros][Tos] is a robust catalyst for the synthesis of biodiesel.

Design and preparation of self-driven BSA surface imprinted tubular carbon nanofibers and their specific adsorption performance

Increasing mass transfer rate and adsorption amount are always challenges in the field of surface protein imprinting. In order to promote the development of protein purification, surface imprinted tubular carbon nanofibers (SIPTCFs) with self-driven property are first developed in this paper. The carrier is tubular carbon nanofiber obtained by hypercrosslinking reaction, carbonization and carboxyl functionalization. Bovine serum albumin (BSA) and polydopamine (PDA) are used as template and imprinted polymer layer, respectively. The resulted materials contain cavity and porous tube wall, which make the osmotic pressure difference between inside and outside of SIPTCFs during the adsorption process. Thereby it endows the SIPTCFs self-driven specific adsorption performance. The SIPTCFs have high specific surface area, reasonable pore structure and self-driven properties. They are the main reasons for accelerating the adsorption process and increasing the adsorption amount. The adsorption amount of SIPTCFs to BSA can reach 541.99 mg/g within 60 min. In addition, SIPTCFs can recognize the target protein BSA with high selectivity from the mixed proteins of HSA, Lyz, Cyt C and Bhb as well as fetal bovine serum (FBS). Because of the excellent reusability and separation ability for actual samples, SIPTCFs will be intensely promising materials for protein separation and purification.

Hypercrosslinked strong anion-exchange polymers for selective extraction of fluoroquinolones in milk samples

In this work, hypercrosslinked strong anion-exchange polymer resins (HXLPP-SAX) were synthesized and evaluated as solid-phase extraction (SPE) sorbents for extracting fluoroquinolones (FQs) in milk samples. These particles were prepared using a protocol that was facile and cost-effective by combining hypercrosslinking reactions and quaternisation reactions in one step. After the synthesis, the morphological properties and anion-exchange, adsorption, and selectivity performances of the HXLPP-SAX resins were characterized and evaluated. It was shown that the polymers were monodisperse microspheres, with the mean diameters of 2–4 μm, ion-exchange capacity (IEC) of 0.311 meq/g, and specific surface area more than 1000 m2/g. The resins applied as SPE sorbents possessed high selectivity in the extraction of amphoteric compounds (enoxacin and enrofloxacin as the representatives) followed by HPLC-UV analysis, as compared to commercially available strong anion-exchange sorbents (Oasis MAX). The SPE-HPLC-UV method was fully validated and exhibited good linearity (10–2000 ng/g, R2 ≥ 0.997), low limits of detection (2.8–5.1 ng/g), good recoveries (85.8%–117.9%, RSDs ≤ 7.1%) and precisions (intra-day RSDs ≤ 7.7% and inter-day RSDs ≤ 9.4%). Then the method was performed the selective enrichment of six FQs (enoxacin, norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, and sparfloxacin) in milk samples. The present results demonstrated that the proposed resins exhibited a promising potential for the enrichment and determination of FQ residues in milk samples as well as in other samples with complex matrices.

Carboxyl group functionalized hollow microporous organic nanospheres for efficient catalysis and adsorption

Abstract Carboxyl group functionalized hollow microporous organic nanospheres (HMONs-COOH) were successfully synthesized by hyper-crosslinking reaction between polylactide-b-polystyrene (PLA-b-PS) diblock copolymers and 2,4,6-tris(bromomethyl)mesitylene as well as subsequent alkaline KMnO4 oxidation. The synthesized HMONs-COOH possess the high special surface area, robust organic framework and hierarchically porous structure, which shows highly catalytic activity in the Friedel-Crafts alkylation of indole with aldehydes and outstanding adsorption efficiency toward cationic dyes.

Fabrication of powdery polymer aerogel as the stationary phase for high-resolution gas chromatographic separation

Novel powdery polymer aerogel (PPA) prepared via the (micro)emulsion polymerization and the following hyper crosslinking reaction was fabricated as stationary phase of capillary column for the first time. Due to its powdery morphology, unique 3D nano-network structure, high surface area and good thermostability, the PPA-coated capillary column demonstrated high-resolution chromatographic separation towards nonpolar and weakly polar organic compounds, including benzene series, n-alkanes, ketone mixtures and trichlorobenzenes. Moreover, the reproducibility, quantitative analysis ability and thermostability of PPA-coated capillary column were also evaluated. The relative standard deviations for three replicate determinations of selected analytes were 0.02–0.11%, 0.12–0.26% and 1.2–3.6% for run-to-run, day-to-day and column-to-column analyses, respectively. The PPA demonstrated good thermostability, and the PPA-coated capillary column was proved to be heat-resistant (270 °C). The results of this study show PPA is an excellent candidate to be employed as stationary phase for gas chromatography capillary.

Capillary electrochromatography using knitted aromatic polymer as the stationary phase for the separation of small biomolecules and drugs

Hypercrosslinked polymers (HCPs) are currently receiving great attention due to their unique characteristics and potential uses in diverse areas. However, the field of HCPs for open-tubular capillary electrochromatography (OT-CEC) separations has not been explored. Here, a knitted aromatic polymer (KAP) was in-situ grown on the inner wall of the capillary column for OT-CEC for the first time. The silylating reagent containing phenyl was served as monomer, immobilized on the inner wall of the capillary column, and then KAPs-modified capillary column was prepared through in-situ hypercrosslinking reaction. The surface structure and morphology of KAPs-modified capillary column was characterized by Fourier transform infrared spectra (FT-IR) and scanning electron microscopy (SEM). The prepared capillary columns showed good separation performance for neutral compounds, small biomolecules, such as nucleosides, amino acids, small peptides, and non-steroidal anti-inflammatory drugs, sulfa drugs. In addition, the KAPs-modified capillaries showed good reproducibility, with relative standard deviations for intra-day, inter-day and column-to-column runs less than 1.59%, 2.55%, and 5.19% respectively. The strategy of in-situ immobilization of KAPs provides a new approach for the application of the material in the analytical fields.

Organic ligands incorporated hypercrosslinked microporous organic nanotube frameworks for accelerating mass transfer in efficient heterogeneous catalysis

Microporous organic polymers (MOP) usually have dominated micropores smaller than 2nm, which may restrict their performance in the mass transfer processes. Adding mesopores into microporous materials to form hierarchical structure has been recognized as a promising route to eliminate their transport limitations and further improve their value in applications. Here we report a straightforward method for the synthesis of organic ligands incorporated hypercrosslinked microporous organic nanotube frameworks (O-HMONFs) via Friedel-Crafts hyper-crosslinking reaction of small aromatic organic ligands with core-shell bottlebrush copolymers as platforms for heterogeneous catalysts. In particular, because of the mesopores produced by the core degradation, O-HMONFs-based catalysts showed more comparable activities than the corresponding disordered MOP-based catalyst and homogeneous molecular catalyst under similar conditions. More importantly, this method might be suitable for various aromatic organic ligands and could be used as a general approach to produce a variety of functional microporous organic nanotube frameworks.

Monolithic stationary phases with a longitudinal gradient of porosity.

The duration of the hypercrosslinking reaction has been used to control the extent of small pores formation in polymer-based monolithic stationary phases. Segments of five columns hypercrosslinked for 30-360min were coupled via zero-volume unions to prepare columns with segmented porosity gradients. The steepness of the porosity gradient affected column efficiency, mass transfer resistance, and separation of both small-molecule alkylbenzenes and high-molar-mass polystyrene standards. In addition, the segmented column with the steepest porosity gradient was prepared as a single column with a continuous porosity gradient. The steepness of porosity gradient in this type column was tuned. Compared to a completely hypercrosslinked column, the column with the shallower gradient produced comparable size-exclusion separation of polystyrene standards but allowed higher column permeability. The completely hypercrosslinked column and the column with porosity gradient were successfully coupled in online two-dimensional liquid chromatography of polymers.