This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCh and ethylaluminum dichloride (EtAlCh) as coinitiators a...This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCh and ethylaluminum dichloride (EtAlCh) as coinitiators and adventitious moisture as the initiator. Both AlCh and EtAlCb produced high molecular weight (Mn > 1.0 x 10^5 g/mol) thermoplastic elastomers (TPEs) with good mechanical properties in short reaction time (< 10 min). These unique TPEs have unsaturations in the end blocks, leading to easy functionalization and/or crosslinking.展开更多
The low-activity cationic monomer tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane was synthesized by Grignard reaction and hydroxyl-protection reaction. Living polyisobutylene chains were initially synthesized by...The low-activity cationic monomer tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane was synthesized by Grignard reaction and hydroxyl-protection reaction. Living polyisobutylene chains were initially synthesized by controlled cationic polymerization and then capped with tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane. The hydrolysis of these polyisobutylenes end capped with tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane gave rise to hydroxytelechelic polyisobutylene. NMR analysis confirmed that the hydrolysis was complete. Results also showed that a low polymerization temperature favored the participation of tert-butyl-dimethyl-(4- methyl-pent-4?enyloxy)-silane in the end-capping reaction. Moreover, polyisobutylene-based polyurethane exhibited greater acid resistance than commercial polyurethane.展开更多
篢he carbocationic reaction between 2, 4, 4-trimethy1-2-chloropentane, which is a model compound of polyisobutylene’s end group, and 1, ldsdiphenyl ethylene was investigated by high pressure liquid chromatography, it...篢he carbocationic reaction between 2, 4, 4-trimethy1-2-chloropentane, which is a model compound of polyisobutylene’s end group, and 1, ldsdiphenyl ethylene was investigated by high pressure liquid chromatography, it was found that the reaction presents a strong reverse reaction even if at low temperature. The ceiling temperature is about -18℃. The reaction with tirne and effect of concentration of TiCl4, temperature, polarity of solvent on the reaction show that the main features of this reaction are very close to that of carbocationic polymerization of isobutylene. So the reaction would be ideal model reaction for the carbocationic polymerization.展开更多
The carbocationic polymerization of styrene（St） initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane（CH2Cl2）/hexane（n-Hex）（50/50 V/V） in the presence of pyridine（Py）,2-methyl pyridine（MPy...The carbocationic polymerization of styrene（St） initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane（CH2Cl2）/hexane（n-Hex）（50/50 V/V） in the presence of pyridine（Py）,2-methyl pyridine（MPy） and 2,6-dimethyl pyridine（DMPy）.A desirable polymerization process with a relative slow polymerization rate and PS products with relatively narrow molecular weight distribution（MWD,Mw/Mn ca.1.8） were obtained.Py and its derivants and/or their complexes with Lewis acid TiCl4 interact with the growing chain end to reduced its 'cationicity' and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narrow MWD.The experimental results also show that the monomer conversion as well as the molecular weight of polymer products increased but MWD almost kept unchanged with polymerization time.The number-average molecular weight of polymer increased linearly with monomer conversion but the line did not pass through the origin.展开更多
The living cationic polymerization of 4-[2-(tert-butyldimethylsiloxy)ethyl]styrene (TBDMES) was studied in methylcyclohexane (MeChx)/methylchloride (MeCl) (50/50 V/V) solvent mixture at -80 degrees C. The initiator 1,...The living cationic polymerization of 4-[2-(tert-butyldimethylsiloxy)ethyl]styrene (TBDMES) was studied in methylcyclohexane (MeChx)/methylchloride (MeCl) (50/50 V/V) solvent mixture at -80 degrees C. The initiator 1,1-diphenylethylene (DPE) capped 2-chloro-2,4,4-trimethylpentane (TMPCl) was formed in situ in conjunction with titanium tetrachloride (TiCl(4)). The Lewis acidity of TiCl(4) was decreased by the addition of titanium(IV) isopropoxide (Ti(OiPr)(4)) to accomplish living polymerization of TBDMES. Hydrolysis of poly(TBDMES) in the presence of tetra-butylammonium fluoride yielded poly[4-(2-hydroxyethyl)styrene] (poly(HOES)). FT-IR, NMR and DSC demonstrated the hydrolysis was complete.展开更多
基金financially supported by the National Science Foundation (No. IIP-1434014) (Accelerating Innovation Research)Support by the Breast Cancer Innovation Foundation was also acknowledged
文摘This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCh and ethylaluminum dichloride (EtAlCh) as coinitiators and adventitious moisture as the initiator. Both AlCh and EtAlCb produced high molecular weight (Mn > 1.0 x 10^5 g/mol) thermoplastic elastomers (TPEs) with good mechanical properties in short reaction time (< 10 min). These unique TPEs have unsaturations in the end blocks, leading to easy functionalization and/or crosslinking.
基金financially supported by the National Natural Science Foundation of China (No. 51573020)Beijing Natural Science Foundation (No. 2172022)+2 种基金Scientific Research Project of Beijing Educational Committee (No. KM201810017008)Project of Petrochina (No. kywx-18-002)URT program (No. 2018J00074)
文摘The low-activity cationic monomer tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane was synthesized by Grignard reaction and hydroxyl-protection reaction. Living polyisobutylene chains were initially synthesized by controlled cationic polymerization and then capped with tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane. The hydrolysis of these polyisobutylenes end capped with tert-butyl-dimethyl-(4-methyl-pent-4-enyloxy)-silane gave rise to hydroxytelechelic polyisobutylene. NMR analysis confirmed that the hydrolysis was complete. Results also showed that a low polymerization temperature favored the participation of tert-butyl-dimethyl-(4- methyl-pent-4?enyloxy)-silane in the end-capping reaction. Moreover, polyisobutylene-based polyurethane exhibited greater acid resistance than commercial polyurethane.
文摘篢he carbocationic reaction between 2, 4, 4-trimethy1-2-chloropentane, which is a model compound of polyisobutylene’s end group, and 1, ldsdiphenyl ethylene was investigated by high pressure liquid chromatography, it was found that the reaction presents a strong reverse reaction even if at low temperature. The ceiling temperature is about -18℃. The reaction with tirne and effect of concentration of TiCl4, temperature, polarity of solvent on the reaction show that the main features of this reaction are very close to that of carbocationic polymerization of isobutylene. So the reaction would be ideal model reaction for the carbocationic polymerization.
文摘The carbocationic polymerization of styrene（St） initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane（CH2Cl2）/hexane（n-Hex）（50/50 V/V） in the presence of pyridine（Py）,2-methyl pyridine（MPy） and 2,6-dimethyl pyridine（DMPy）.A desirable polymerization process with a relative slow polymerization rate and PS products with relatively narrow molecular weight distribution（MWD,Mw/Mn ca.1.8） were obtained.Py and its derivants and/or their complexes with Lewis acid TiCl4 interact with the growing chain end to reduced its 'cationicity' and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narrow MWD.The experimental results also show that the monomer conversion as well as the molecular weight of polymer products increased but MWD almost kept unchanged with polymerization time.The number-average molecular weight of polymer increased linearly with monomer conversion but the line did not pass through the origin.
基金supported by the Beijing Municipal Project for Developing Advanced Human Resources for Higher Education(Elastomers and Biomaterials).
文摘The living cationic polymerization of 4-[2-(tert-butyldimethylsiloxy)ethyl]styrene (TBDMES) was studied in methylcyclohexane (MeChx)/methylchloride (MeCl) (50/50 V/V) solvent mixture at -80 degrees C. The initiator 1,1-diphenylethylene (DPE) capped 2-chloro-2,4,4-trimethylpentane (TMPCl) was formed in situ in conjunction with titanium tetrachloride (TiCl(4)). The Lewis acidity of TiCl(4) was decreased by the addition of titanium(IV) isopropoxide (Ti(OiPr)(4)) to accomplish living polymerization of TBDMES. Hydrolysis of poly(TBDMES) in the presence of tetra-butylammonium fluoride yielded poly[4-(2-hydroxyethyl)styrene] (poly(HOES)). FT-IR, NMR and DSC demonstrated the hydrolysis was complete.
