Coatings
·
2017
·Vol. 7
·期 10
·159
·
IF 2.175
Shaolong Li,Changlian Xu,Wenfeng Yang,Qingru Tang
We report an efficient and green approach to synthesize a linear castor oil-based polyurethane (CPU) without using any solvent or catalyst. Diol monomers were first synthesized by the aminolysis reaction between castor oil and diamines; this was accomplished within 6 h at 130 °C. Polymerization of the diols and isocyanate was further confirmed by Fourier transform infrared (FTIR),1H-nuclear magnetic resonance (1H-NMR), and gel permeation chromatography analyses. The resultant CPUs showed a good thermal stability with an initial degradation temperature higher than 300 °C, and their mechanical and wood bonding property can be modulated by the structures of diamine. In addition, the CPUs possessed a satisfying water resistance property with the water absorption amount lower than 2%. The green conversion of castor oil to thermoplastic polyurethane affords new opportunities in bio-based industries.Keywords:castor oil;linear polyurethane;catalyst-free;solvent-free
研究领域:
材料科学
·
绿色化学
✓ 已验证
DOI
高影响因子
MACROMOLECULAR RESEARCH
·
2018
·Vol. 26
·期 4
·365-373
·
IF 1.767
Ling Lei,Li Jinhui,Zhang Guoping,Sun Rong,Wong Ching-Ping
Self-healing polymeric materials have attracted extensively interests due to the ability to heal the damage autonomously. The self-healing systems based on dynamic disulfide bonds have been the most promising due to the efficient healing capacity at a mild condition. However, it is still of great challenge for designing the polymer with excellent mechanical and self-healing property by a simple synthetic route. Herein, a novel series of self-healing linear polyurethanes with the disulfide linkage as the grafting point were developed. The synthetic polymers all exhibited excellent mechanical properties (breaking strength and elongation at break were as much as 31.91 MPa and 1156% for PU-A). Meanwhile, the effects of different ratios of soft/hard segments on the mechanical properties and healing efficiencies have been investigated by stress-strain tests. The results showed that with the increase of soft segments contents, the breaking strength and elongation at break of the polymer improved significantly, while the healing efficiency and Young’s modulus showed a declining trend. The self-healing polyurethane can quickly restore its over 90% of mechanical property after healing at moderate temperature for 10 min. The cyclic tensile tests also showed the dissipated efficiencies and self-recovery abilities of the polymers. Finally, the recovery capability tests verified the shape memory effect in the polymers, which can replace an external force to accelerate the healing process.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2023
·
IF 5
Fansen Meng,Donglin Tang
Vitrimers are generally constructed via crosslinking polymerization in which a crosslinker is reacted along with monomer(s). Herein, we report another strategy named group revival-induced crosslinking (GRIC) to prepare polyurethane vitrimer (PUV) directly from liner polyurethane (LPU) without using any crosslinker. Under the catalysis of K2CO3, the NH function in the urethane group is activated and it is able to attack another urethane group to form an allophanate crosslinker and, in the meantime, to release a free OH group. The allophanate is a dynamic covalent crosslinker in which reversible transesterification between free OH and allophanate groups allows the reprocessibilty for the obtained networks. The stress relaxation of the obtained networks prove the formation of the vitrimer. Both catalyst loading and vitrimerization temperature affect the gel fraction and further the mechanical properties of the obtained PUVs. Compared with LPU, the elongation at break of PUVs could be increased from 180 to 370%, while the tensile strength remains at the same level. Furthermore, the chemical structures and thermal and mechanical properties of the reprocessed PUVs remain the same as the pristine ones. This GRIC strategy is an efficient tool for enhancing the performance of thermoplastic polyurethanes (PUs) and, especially, for the value-added modification of recycled thermoplastic PUs as well as recycled polyamides.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
SOLAR ENERGY MATERIALS AND SOLAR CELLS
·
2014
·
IF 5.03
Kai Chen,Ruowang Liu,Chao Zou,Qinyi Shao,Yunjun Lan,Xiaoqing Cai,Lanlan Zhai
Linear polyurethane (PU) ionomers were synthesized as solid–solid phase changing materials (PCMs) for thermal energy storage . Poly(ethylene glycol)s (PEGs) with 6000 and 10,000 g/mol number average molecular weight were used as latent heat storage materials, and 4,4-diphenylmethane diisocyanate (MDI), N-methyldiethanolamine (MDEA) and 1,3-Propanesulfonate (PS) were used as supporting materials. The phase change enthalpies of PU ionomers were 142.5 J/g and 152.3 J/g respectively, which were much close to the highest reported value of the branched PUPCM or the cross-linking PUPCM. The results of Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM) suggested a high degree of phase separation existed in PU ionomers . And the thermal resistance of PU ionomers was improved by the introduction of ionic groups.
研究领域:
材料科学
·
能源工程
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2013
·
IF 2.206
Lei Xu,Guorong Shan
Simultaneous interpenetrating polymer networks (SIPNs) of linear polyurethane (PU) and linear poly(methyl methacrylate) (PMMA) were synthesized. Kinetic studies were carried out by means of titration of −NCO functional groups for PU and gas chromatography for methyl methacrylate (MMA). Factors that influence the kinetics of SIPN formation, such as the composition ratio, temperature, initiator concentration, catalyst concentration, time of initiator addition, and presence of the chain extender 1,4-butanediol, were investigated. It was found that all of the factors that influenced the system viscosity also affected the kinetics of SIPN formation and that the step-growth polymerization process was related to the radical polymerization process. If too much of the catalyst was added to the system, SIPNs would not completely form. The kinetics of polyurethane formation obeyed a second-order function during the early period of the reaction and a third-order function at high −NCO functional group conversions.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULAR MATERIALS AND ENGINEERING
·
2020
·Vol. 305
·期 7
·2000042
·
IF 3.853
Yimei Chen,Yanli Meng,Yanfeng Luo,Yuanliang Wang
Linear shape memory polyurethanes based on poly( dl -lactic acid) (PDLLA) macrodiol (PDLLA-SMPUs) have various advantages such as good processability, biodegradability, shape memory effect, and biocompatibility, yet the insufficient mechanical properties prevent their effective applications in bone repair. 2-Ureido-4[1 H ]-pyrimidone (UPy) can form strong quadruple hydrogen bonding. Here, a new linear PDLLA-SMPU containing pendant UPy units (UPy- p -PDLLA-SMPU) is designed and synthesized. The pendant UPy units may dimerize to form physical crosslinking among UPy- p -PDLLA-SMPU chains. As a result, UPy- p -PDLLA-SMPU demonstrates both good processability and significantly higher mechanical properties than the corresponding linear PDLLA-SMPU without pendant UPys. In addition, UPy- p -PDLLA-SMPU shows excellent shape memory effect near body temperature, with a shape fixity ratio of up to 98.6% and a recovery ratio of up to 92.9%. This work provides a new strategy to design SMPUs integrating the merits of linear and crosslinked polyurethanes, and the obtained UPy- p -PDLLA-SMPU is a promising material for bone tissue repair in view of the mechanical, thermal, and shape memory properties.
研究领域:
材料科学
·
生物医学工程
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）