Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ ...Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ AlR_3-H_2O (R=ethyl, iso-butyl) catalysts gavehigher molecular weight (M_w～10~4), while Al(OR)_3 catalysts gave the higher alternatingcopolymer structure with slightly lower molecular weight. The in-situ AlR_3-H_2O systemshave been evaluated in more detail for the reaction which showed the optimum H_2O/Almolar ratio to be 0.5. The copolymers with different composition (F_(SA)/F_(EO)= 36/64to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melt-ing point (T_m), glass transition temperature (T_g) and enthalpy of fusion (ΔH_f) of thesecopolymers are depended on the copolymer composition and in the range of 87～102℃,-12～-18℃, and 37～66J/g, respectively. The second heating scan of DSC also in-dicated that the higher alternating copolymer was more easily recrystallized. The onsetdecomposition temperature was more than 300℃ under nitrogen and influenced by thecopolymer composition.展开更多
The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly（propylene adipate） could be synthesized by controlling the copolymerization condi...The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly（propylene adipate） could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by ^1H NMR analyses.展开更多
Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of...Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of ABRP and AIRP in various feed ratios were carried out with SbCl_5 and BF_3OEt_2 as catalyst at low temperatures.The copolymer structure was characterized by means of ^(1)H,^(13)C NMR spectroscopy and specific rotation.When SbCl_(5)was used as catalyst,the copolymer obtained had completely 1,4-β-pyranosidic structure,i.e.,cellulosetype structure.However,when BF_(3)OEt_2 was used as catalyst,the copolymer had a mixed structure of furanosidic and pyranosidic units.展开更多
Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization usin...Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,^(13)CNMR and optical rotation.展开更多
Aiming at the difficult problem of solving the conformation statistics of complex polymers, this study presents a novel and concise conformation statistics theoretical approach based on Monte Carlo and Neural Network ...Aiming at the difficult problem of solving the conformation statistics of complex polymers, this study presents a novel and concise conformation statistics theoretical approach based on Monte Carlo and Neural Network method. This method offers a new research idea for investigating the conformation statistics of complex polymers, characterized by its simplicity and practicality. It can be applied to more complex topological structure, more higher degree of freedom polymer systems with higher dimensions, theory research on dynamic self-consistent field theory and polymer field theory, as well as the analysis of scattering experimental data. The conformation statistics of complex polymers determine the structure and response properties of the system. Using the new method proposed in this study, taking the semiflexible ring diblock copolymer as an example, Monte Carlo simulation is used to sample this ring conformation to construct the dataset of polymer. The structure factor describing conformation statistics are expressed as continuous functions of structure parameters by neural network supervised learning. This is the innovation of this work. As an application, the structure factors represented by neural networks were introduced into the random phase approximation theory to study the microphase separation of semiflexible ring diblock copolymers. The influence of the ring's topological properties on the phase transition behavior was pointed out.展开更多
Novel biodegradable copolymer poly（CC-co-EEP） was synthesized by ring-opening copolymerization of cyclic carbonate 9-phenyl-2, 4, 8, 10-tetraoxaspiro-[5, 5]undcane-3-one （CC） and ethylene ethyl phosphate （EEP）. ...Novel biodegradable copolymer poly（CC-co-EEP） was synthesized by ring-opening copolymerization of cyclic carbonate 9-phenyl-2, 4, 8, 10-tetraoxaspiro-[5, 5]undcane-3-one （CC） and ethylene ethyl phosphate （EEP）. The obtained poly （CC-co-EEP）s were characterized by FTIR, ^1H NMR, ^13C NMR and gel permeation chromatography （GPC）. In vitro hydrolytic degradation of the copolymers were investigated in phosphate buffer solution （pH=7.4）. Hydrophilic phosphate units apparently improved the degradability of poly（carbonate-phosphate）.展开更多
文摘Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ AlR_3-H_2O (R=ethyl, iso-butyl) catalysts gavehigher molecular weight (M_w～10~4), while Al(OR)_3 catalysts gave the higher alternatingcopolymer structure with slightly lower molecular weight. The in-situ AlR_3-H_2O systemshave been evaluated in more detail for the reaction which showed the optimum H_2O/Almolar ratio to be 0.5. The copolymers with different composition (F_(SA)/F_(EO)= 36/64to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melt-ing point (T_m), glass transition temperature (T_g) and enthalpy of fusion (ΔH_f) of thesecopolymers are depended on the copolymer composition and in the range of 87～102℃,-12～-18℃, and 37～66J/g, respectively. The second heating scan of DSC also in-dicated that the higher alternating copolymer was more easily recrystallized. The onsetdecomposition temperature was more than 300℃ under nitrogen and influenced by thecopolymer composition.
基金Supported by the National Natural Science Foundation of China(Nos.20704036, Key Program 20434020)the State Basic Research Projects of China(No.2005CB623802)
文摘The ring-opening copolymerization of adipic anhydride with propylene oxide was carried out with yttrium triflates as a catalyst. Poly（propylene adipate） could be synthesized by controlling the copolymerization conditions. The copolymerization procedure was tracked by ^1H NMR analyses.
文摘Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of ABRP and AIRP in various feed ratios were carried out with SbCl_5 and BF_3OEt_2 as catalyst at low temperatures.The copolymer structure was characterized by means of ^(1)H,^(13)C NMR spectroscopy and specific rotation.When SbCl_(5)was used as catalyst,the copolymer obtained had completely 1,4-β-pyranosidic structure,i.e.,cellulosetype structure.However,when BF_(3)OEt_2 was used as catalyst,the copolymer had a mixed structure of furanosidic and pyranosidic units.
文摘Cationic ring-opening copolymerization of 1, 4-anhydro-2, 3-O-isopropylidene-α-D-ribo-pyranose (AIRP) with 1,4-anhydro-2,3-di-O-benzyl-α-D-ribopyranose (ADBR) preparedfrom D-ribose was studied. Copolymerization using SbCl_5 or BF_3 OEt_2 as catalyst atlow temperature gave stereoregular (1→4)β-D-ribofuranan (C-1 and C-4 ring cleavagesee Scheme 1) or (1→5) α-D-ribofuranan (C-1 and C-5 ring cleavage) respectively. Theeffects of catalysts, reaction time and temperatures on yield and stereoregularity of the ob-tained polymers were studied. Polymers were characterized by molecular weight, ~1HNMR,^(13)CNMR and optical rotation.
基金financially supported by the National Natural Science Foundation of China (No. 22173004)。
文摘Aiming at the difficult problem of solving the conformation statistics of complex polymers, this study presents a novel and concise conformation statistics theoretical approach based on Monte Carlo and Neural Network method. This method offers a new research idea for investigating the conformation statistics of complex polymers, characterized by its simplicity and practicality. It can be applied to more complex topological structure, more higher degree of freedom polymer systems with higher dimensions, theory research on dynamic self-consistent field theory and polymer field theory, as well as the analysis of scattering experimental data. The conformation statistics of complex polymers determine the structure and response properties of the system. Using the new method proposed in this study, taking the semiflexible ring diblock copolymer as an example, Monte Carlo simulation is used to sample this ring conformation to construct the dataset of polymer. The structure factor describing conformation statistics are expressed as continuous functions of structure parameters by neural network supervised learning. This is the innovation of this work. As an application, the structure factors represented by neural networks were introduced into the random phase approximation theory to study the microphase separation of semiflexible ring diblock copolymers. The influence of the ring's topological properties on the phase transition behavior was pointed out.
基金The authors are grateful for the financial support of National Key Basic Research and Development Program （2005CB623903） National Natural Science Foundation of China （Grant No. 20174029）.
文摘Novel biodegradable copolymer poly（CC-co-EEP） was synthesized by ring-opening copolymerization of cyclic carbonate 9-phenyl-2, 4, 8, 10-tetraoxaspiro-[5, 5]undcane-3-one （CC） and ethylene ethyl phosphate （EEP）. The obtained poly （CC-co-EEP）s were characterized by FTIR, ^1H NMR, ^13C NMR and gel permeation chromatography （GPC）. In vitro hydrolytic degradation of the copolymers were investigated in phosphate buffer solution （pH=7.4）. Hydrophilic phosphate units apparently improved the degradability of poly（carbonate-phosphate）.
