A series of homo and copolymers of styrene (ST) and 2-hydroxyethyl methacrylate (HEMA) in three different media (bulk, tetrahydrofuran, and benzene) have been investigated by free radical polymerization method. The sa...A series of homo and copolymers of styrene (ST) and 2-hydroxyethyl methacrylate (HEMA) in three different media (bulk, tetrahydrofuran, and benzene) have been investigated by free radical polymerization method. The samples obtained from the synthesis were characterized by Fourier Transform-Infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (<sup>1</sup>H NMR), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The results show that the synthesis of the polymers is more feasible under neat conditions rather than solvent directed reaction. Moreover, the DSC data shows that the polystyrene obtained is amorphous in nature and therefore displayed only a glass transition signal rather than crystallization and melting peaks. In addition, this study indicates that homolopolymerization of styrene via free radical polymerization tends to be preferable in less polar solvents like THF than in non-polar solvents like benzene. Benzene might destabilize the formation of the reactive radicals leading to the formation of the products. In summary, the homolpolymerization of styrene is more feasible than the homopolymerization 2-hydroxyethyl methacrylate under the experimental setup used. Styrene is more reactive than 2-hydroxyethyl methacrylate than free radical polymerization reaction due in part of the generation of the benzylic radical intermediate which is more stable leading to the formation of products than alkyl radical which are less stable. Furthermore, polymerization of styrene under neat conditions is preferable in solvent-assisted environments. The choice of solvent for the synthesis of these polymers is crucial and therefore the selection of solvent that leads to the formation of a more stable reaction intermediate is more favorable. It is worth noting that the structure of the proposed copolymer consists of a highly polar and hydrophilic monomer, 2-hydroxyethyl methacrylate and a highly non-polar and hydrophobic monomer, styrene. These functionalities constitute an amphiphilic copolymer with diverse characteristics. A plausible explanation underlying our observations is that the reaction conditions employed in the synthesis of these copolymers might not be the right route required under free radical polymerization.展开更多
Preparing polymeric coatings with well corrosion resistance and high thermal conductivity(TC)to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive...Preparing polymeric coatings with well corrosion resistance and high thermal conductivity(TC)to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive and urgent need while a difficult task.Here we report a multifunctional epoxy composite coating(F-CB/CEP)by synthesizing cerium methacrylate and ingeniously using it as a novel curing agent with corrosion inhibit for epoxy resin and modifier for boron nitride through"cation-π"interaction.The prepared F-CB/CEP coating presents a high TC of 4.29 W m^(−1)K^(−1),which is much higher than other reported anti-corrosion polymer coatings and thereby endowing metal materials coated by this coating with outstanding thermal management performance compared with those coated by pure epoxy coating.Meanwhile,the low-frequency impedance remains at 5.1×10^(11)Ωcm^(2)even after 181 days of immersion in 3.5 wt%NaCl solution.Besides,the coating also exhibits well hydrophobicity,self-cleaning properties,temperature resistance and adhesion.This work provides valuable insights for the preparation of high-performance composite coatings with potential to be used as advanced multifunctional thermal management materials,especially for heat conduction metals protection.展开更多
Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylen...Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylene glycol methacrylate(P(EO2-co-EG4/5))are synthesized via atom transfer radical polymerization(ATRP).The successful synthesis and the narrow polydispersity index(PDI)of two copolymers are indicated by 1H nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)analyses.The transition behaviors of polymers in the aqueous solution are demonstrated by changes in turbidity and particle sizes.The transition behavior of P(EO2-co-EG4/5)is found to be milder than that of P(EO2-co-EO4/5).Moreover,the presence of hydrogen bonds without thermo-responsive properties established by hydroxyl groups in the end-side chain of P(EO_(2)-co-EG_(4/5))hinders the dehydration at the transition temperature(TT).Attenuated total reflection Fourier transform infrared spectrometry(ATR-FTIR)analysis along with contact angle measurements reveals that both P(EO_(2)-co-EO_(4/5))and P(EO_(2)-co-EG_(4/5))films undergo phase transitions from hydrophilicity to hydrophobicity above TT.By examining the swelling and collapse behaviors of the polymer films during phase transitions,it can be concluded that the end hydroxyl groups may establish hydrogen bonds with neighboring ether groups within the films,which remain intact throughout the phase transition process due to their strong bonding interactions.This leads to an increase in steric hindrance within swollen films thereby impeding dehydration processes and inducing hysteresis during phase transitions.展开更多
文摘A series of homo and copolymers of styrene (ST) and 2-hydroxyethyl methacrylate (HEMA) in three different media (bulk, tetrahydrofuran, and benzene) have been investigated by free radical polymerization method. The samples obtained from the synthesis were characterized by Fourier Transform-Infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (<sup>1</sup>H NMR), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The results show that the synthesis of the polymers is more feasible under neat conditions rather than solvent directed reaction. Moreover, the DSC data shows that the polystyrene obtained is amorphous in nature and therefore displayed only a glass transition signal rather than crystallization and melting peaks. In addition, this study indicates that homolopolymerization of styrene via free radical polymerization tends to be preferable in less polar solvents like THF than in non-polar solvents like benzene. Benzene might destabilize the formation of the reactive radicals leading to the formation of the products. In summary, the homolpolymerization of styrene is more feasible than the homopolymerization 2-hydroxyethyl methacrylate under the experimental setup used. Styrene is more reactive than 2-hydroxyethyl methacrylate than free radical polymerization reaction due in part of the generation of the benzylic radical intermediate which is more stable leading to the formation of products than alkyl radical which are less stable. Furthermore, polymerization of styrene under neat conditions is preferable in solvent-assisted environments. The choice of solvent for the synthesis of these polymers is crucial and therefore the selection of solvent that leads to the formation of a more stable reaction intermediate is more favorable. It is worth noting that the structure of the proposed copolymer consists of a highly polar and hydrophilic monomer, 2-hydroxyethyl methacrylate and a highly non-polar and hydrophobic monomer, styrene. These functionalities constitute an amphiphilic copolymer with diverse characteristics. A plausible explanation underlying our observations is that the reaction conditions employed in the synthesis of these copolymers might not be the right route required under free radical polymerization.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.51925403)Major Research plan of the National Natural Science Foundation of China(Grant No.91934302)+2 种基金the National Science Foundation of China(21676052,21606042)Independent Innovation Fund of Tianjin University(2023XJD0050)Funding for National Key R&D Program of China(2022YFB3808800).
文摘Preparing polymeric coatings with well corrosion resistance and high thermal conductivity(TC)to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive and urgent need while a difficult task.Here we report a multifunctional epoxy composite coating(F-CB/CEP)by synthesizing cerium methacrylate and ingeniously using it as a novel curing agent with corrosion inhibit for epoxy resin and modifier for boron nitride through"cation-π"interaction.The prepared F-CB/CEP coating presents a high TC of 4.29 W m^(−1)K^(−1),which is much higher than other reported anti-corrosion polymer coatings and thereby endowing metal materials coated by this coating with outstanding thermal management performance compared with those coated by pure epoxy coating.Meanwhile,the low-frequency impedance remains at 5.1×10^(11)Ωcm^(2)even after 181 days of immersion in 3.5 wt%NaCl solution.Besides,the coating also exhibits well hydrophobicity,self-cleaning properties,temperature resistance and adhesion.This work provides valuable insights for the preparation of high-performance composite coatings with potential to be used as advanced multifunctional thermal management materials,especially for heat conduction metals protection.
基金Fujian External Cooperation project of Natural Science Foundation,China(No.2022I0042)。
文摘Thermo-responsive random copolymers,poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-(ethylene glycol)methyl ether methacrylate)(P(EO_(2)-co-EO_(4/5)))and poly(2-(2-methoxyethoxy)ethoxyethyl methacrylate-co-ethylene glycol methacrylate(P(EO2-co-EG4/5))are synthesized via atom transfer radical polymerization(ATRP).The successful synthesis and the narrow polydispersity index(PDI)of two copolymers are indicated by 1H nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)analyses.The transition behaviors of polymers in the aqueous solution are demonstrated by changes in turbidity and particle sizes.The transition behavior of P(EO2-co-EG4/5)is found to be milder than that of P(EO2-co-EO4/5).Moreover,the presence of hydrogen bonds without thermo-responsive properties established by hydroxyl groups in the end-side chain of P(EO_(2)-co-EG_(4/5))hinders the dehydration at the transition temperature(TT).Attenuated total reflection Fourier transform infrared spectrometry(ATR-FTIR)analysis along with contact angle measurements reveals that both P(EO_(2)-co-EO_(4/5))and P(EO_(2)-co-EG_(4/5))films undergo phase transitions from hydrophilicity to hydrophobicity above TT.By examining the swelling and collapse behaviors of the polymer films during phase transitions,it can be concluded that the end hydroxyl groups may establish hydrogen bonds with neighboring ether groups within the films,which remain intact throughout the phase transition process due to their strong bonding interactions.This leads to an increase in steric hindrance within swollen films thereby impeding dehydration processes and inducing hysteresis during phase transitions.
