POLYMER
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2023
·
IF 4.6
Lunliang Chen,Lianwei Li,Jinxian Yang
For the first time, this work has explored the cyclization kinetics of multi -mers during step-growth polymerization by using alkyne-PS-azide ( l -PS-N 3 ) as model macromonomer, where PS represents polystyrene. First, three AB-type PS macromonomers with different chain lengths have been prepared by atom transfer radical polymerization (ATRP), namely, l -PS 77 -N 3 , l -PS 240 -N 3 and l -PS 380 -N 3 . Second, the polymerization and cyclization kinetics has been monitored in dimethylformamide (DMF), tetrahydrofuran (THF) and cyclopentane (CyP). Third, by size exclusion chromatography (SEC) and liquid chromatography at the critical condition (LCCC) methods, we have quantified how the macromonomer chain length, solvent type and reaction concentration affect the intra-chain cyclization process. The analysis results have demonstrated that, for macromonomer l -PS 77 -N 3 with shorter chain length, the reaction rate of macromonomer cyclization, multi -mer cyclization and inter-chain coupling, is significantly faster than that for l -PS 240 -N 3 and l -PS 380 -N 3 with longer chain lengths. The total percentage of final cyclic product ( wt cyclic ) slightly decreases with the increase of macromonomer chain length, namely, 33%, 25% and 23% for l -PS 77 -N 3 , l -PS 240 -N 3 and l -PS 380 -N 3 , respectively. At the same time, we found that, solvent with lower solvent viscosity and relatively poor solvent quality is more conducive to the cyclization reaction of PS chains. In addition, we also found that the inter-chain and intra-chain reaction rate are both faster than that at other reaction concentrations when the reaction concentration is near the critical overlapping concentration.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
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2016
·Vol. 23
·期 6
·1-8
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IF 1.969
Li Hui,Zhang Qiuyu
In this paper, P n BA- g -PMMA brush-like and centipede multigraft copolymers were synthesized via DPE seeded emulsion polymerization and miniemulsion polymerization. PMMA macromonomers with single tail and double tails were prepared by DPE-technique in emulsion and Steglich esterification. Then P n BA- g -PMMA multigraft copolymers were obtained by miniemulsion copolymerization. The molecular weight and polydispersity indices of PMMA macromonomers and graft copolymers were characterized by GPC. The structural characteristics, weight content of PMMA and the number of grafting sites in brush-like and centipede multigraft copolymers were determined by 1 H NMR. The thermal performance of graft copolymers were analyzed by DSC and TGA. AFM confirmed microphase separation between P n BA block and PMMA block.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2022
·
IF 6.057
Jinxian Yang,Lunliang Chen,Mo Zhu,Muhammad Waqas Ishaq,Shengqi Chen,Lianwei Li
In this work, by combining size exclusion chromatography (SEC) and liquid chromatography at the critical condition (LCCC) techniques, we have studied the multimer cyclization effect during click step-growth polymerization of AB-type macromonomers. First, by atom transfer radical polymerization (ATRP), we have synthesized a series of alkynyl and azide functional AB-type polystyrene macromonomers with different molar masses, i.e., PSn. Second, via the click step-growth polymerization of a PSn macromonomer in dimethylformamide (DMF) at varied reaction concentrations (Cs), we have prepared polyaddition products [(PSn)m] with large polydispersity indices, where m represents the average degree of polymerization of the macromonomer. Further, narrowly distributed fractions have been obtained by SEC fractionation. Third, we have quantitatively analyzed how the macromonomer molar mass, reaction concentration, and multimer molar mass influence the percentage of a cyclic topoisomer (wtcyclic) for (PSn)m samples. In particular, we have established the relation between wtcyclic and C for unfractionated (PSn)m, i.e., wtcyclic = 0.86–0.32 log C, and the relation between wtcyclic and m for fractionated (PSn)m prepared at a constant C = 100 g/L, i.e., log wtcyclic = −0.46m + 0.16. For the first time, our result has unambiguously pointed out that neither a cyclic topoisomer nor a linear topoisomer can be ignored when considering the structure–property quantitative relationship for polyaddition products.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Macromolecular Science Part B-Physics
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2015
·
IF 0.74
Jian Zhang,Bo Jing,Guorong Tan,Shenwen Fang,Hu Wang
Several surfactant macromonomers (SMMxyz) were prepared by using triblock polymers of ethylene oxide (EO) and propylene oxide (PO) (POx–EOy–POz triblock polymer, x: y: z represent the weight ratio of the different blocks). Then graft copolymers of acrylamide and SMMxyz (PAM-g-SMMxyz) were synthesized. The effects of EO/PO mole ratio, length of grafted SMMxyz and the three relative block sizes on the surface activity and thermo-associativity of PAM-g-SMMxyz dilute solutions were studied. The results showed that the surface tension decreased with increasing PO in the graft at 30°C and decreased with the length of the graft when the temperature was higher than the cloud points of the grafted POx–EOy–POz chains, regardless of EO/PO ratio. When the EO/PO ratio was the same in the SMMxyz, the PAM-g-SMMxyz with higher PO content at the graft end had higher surface activity. With increasing temperature, the hydrodynamic radius (Rh) of PAM-g-SMMxyz in dilute aqueous solution increased. The polymer with shorter grafts may have much more intermolecular interaction points and there were more polymer chains in the polymeric aggregates, which led to Rh increasing with decreasing length of graft. In addition, when the EO/PO was not more than 1:1.74, the three relative block sizes had no great influence on the temperature-associativity of PAM-g-SMMxyz. However, for PAM-g-SMM217 and PAM-g-SMM712, the Rh of PAM-g-SMM217 was smaller than PAM-g- SMM712.
研究领域:
高分子科学
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材料化学
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物理化学
·
胶体与界面科学
✓ 已验证
DOI
高影响因子
Journal of Macromolecular Science Part B-Physics
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2014
·
IF 0.619
Weihong Long,Ming Duan,Shenwen Fang,Liehui Zhang,Linyu Li,Ya
Hui Tian
Three new surfactant macromonomers (SMM) with different ethylene oxide (EO)/propylene oxide (PO) ratios (for SMM1, SMM2, and SMM3, the EO/PO ratios were 1:0.5, 1:0.9, and 1:1.25, respectively) were synthesized by the reaction between PEO-PPO di-block polymers having terminal tertiary amine groups and chloropropene. Graft copolymers of acrylamide and SMM (PAM-g-SMM) were prepared with different SMMs and grafting densities in water, and the products were confirmed by FTIR and elemental analysis. Owing to the strong hydrophobicity of the graft, the PAM-g-SMM3 was not water soluble. However, PAM-g-SMM1 and PAM-g-SMM2 aqueous solutions had good surface activity and their surface tensions were 44.26 and 37.63 mN/m at a concentration of 1000 mg/L, respectively. In general, in diluted graft PAM solutions, the copolymer predominantly formed intrapolymeric associates. The PAM-g-SMM2 was both thermo-associative and salt-associative in dilute solution. For PAM-g-SMM2, when the temperature and salt concentration increased, interpolymeric aggregations were formed.
研究领域:
高分子化学
·
材料科学
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物理化学
·
化学工程
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2016
·
IF 5.267
Chengguo Liu,Yan Dai,Yun Hu,Qianqian Shang,Guodong Feng,Jing Zhou,Yonghong Zhou
A highly functional unsaturated ester macromonomer was synthesized from soybean oil (SBO), and its chemical structure was confirmed by FT-IR, 1H NMR, 13C NMR, and gel permeation chromatography. The monomer was prepared through modifying epoxidized soybean oil (ESO) first with a synthesized precursor, hydroxyethyl acrylated maleate (HEAMA), and then employing maleic anhydride (MA) to modify the produced ESO-HEAMA. The obtained SBO-based monomer (ESO-HEAMA-MA) possessed a C═C bond functionality of 6.75–8.15 per ESO. Effects of styrene concentration, feed ratio, and initiator concentration on the dynamic mechanical properties of the cured bioresins were investigated carefully. When the monomer with the highest C═C bond functionality was used, the cured resins with 20–60 wt % styrene demonstrated cross-link densities of 5.07–9.52 (103 mol)/m3, storage moduli at 25 °C of 1.32–2.16 GPa, glass transition temperatures of 69.9–114.1 °C, and tensile strengths and moduli of 19.7–33.1 MPa and 1.17–2.11 GPa, respectively. Microstructural morphologies of tensile-fractured surfaces of the cured resins were studied by scanning electron microscopy. Finally, curing behaviors of the resultant resin was studied by differential scanning calorimetry. The developed eco-friendly biomaterials have potential applications in the industry of unsaturated polyester resins.
研究领域:
材料科学
·
高分子化学
·
生物技术
✓ 已验证
DOI
高影响因子
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