程镕时
长期从事高分子物理和物理化学的研究工作。
个性化签名
- 姓名:程镕时
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学术头衔:
博士生导师, 中国科学院院士
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学科领域:
高分子化学
- 研究兴趣:长期从事高分子物理和物理化学的研究工作。
程镕时,男,1927年10月出生,江苏宜兴人,著名高分子物理及物理化学家。 1949年毕业于金陵大学化学系,1951年毕业于北京大学化学研究部,1991年当选为中国科学院院士(学部委员)。现任南京大学、华南理工大学教授、博士生导师。程镕时院士长期从事高分子物理和物理化学的研究工作。自1952年起参与了天然和各种合成橡胶的分子表征工作,建立了高分子分子量和分子量分布测定的多种实验方法,其结果为顺丁橡胶的工业化选型和优化提供了科学依据;在高分子溶液粘度性质的研究工作中提出一系列新概念和应用广泛的理论公式;在凝胶色谱的研究工作中,阐明了多孔填料的成孔机理并给出控制孔度的理论关系,建立了简易凝胶色谱方法、凝胶色谱扩展和分离效应的统一理论、凝胶色谱的绝对定量化原则和一种研究分子水平上的吸附作用以及分子间配合作用的有效而直接的定量方法,拓展了凝胶色谱的应用范围。近年来在对高分子溶液凝聚过程的研究中又取得新的进展,提出了高分子溶液粘度的团蔟理论。获国家自然科学二等奖等国家级奖励4项,部委级奖励3项。在国内外学术刊物上发表论文190多篇。中国化学会高分子学科委员会委员,江苏化工化学会高分子专业委员会主任委员,中国科学院高分子物理联合开放实验室学术委员,国家自然科学基金委员会高分子化学学科评审组成员,《高分子学报》编委,《色谱》编委。
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程镕时, Hu Yang, , Weisi Yin, Xueqin Zhang, Zhengchun Cai, Zhiliu Wang, Rongshi Cheng
Journal of Applied Polymer Science, Vol. 96, 2454-2458 (2005),-0001,():
-1年11月30日
The growth of poly (ethylene oxide) (PEO) spherulites was observed synchronously with a polarized optical microscope, which was equipped with a video detector, and so the whole growing process of the PEO spherulites was dynamically recorded as a movie. There was a series of concentric diffractive bands on the surface of the PEO spherulites; furthermore, the diffractive banding did not exist until at least two independent PEO spherulites came into contact with each other. However, the formation of the diffractive banding on the PEO spherulites was also related to the crystallization conditions. It was concluded qualitatively that the diffractive banding formed more easily at the crystallization temperature with a high degree of supercooling, and this was explained in kinetic terms.
spherulites, structure, water-soluble polymers
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【期刊论文】States of water in partially swollen poly(vinyl alcohol) hydrogels
程镕时, Wenbo Li a, Feng Xue a, Rongshi Cheng a, b, *
Polymer 46 (2005) 12026-12031,-0001,():
-1年11月30日
A poly(vinyl alcohol) hydrogel was prepared by coupling poly(vinyl alcohol) with epichlorohydrin as cross-linking agent. Various amounts of water were added into the dry hydrogel to swell it and the quantity of water in various states in the partially swollen hydrogel were determined by DSC ice-melting technique. A parameter S denoted the degree of the saturation of swelling was introduced for describing the various stages of water absorption. The analytical results indicate that there exists two critical threshold degree of saturation. At the first threshold S*, the freezable bound water starts to appear and at the second threshold S**, the free water begins to appear. In the region of S!S*, the adsorbed water exists only in the non-freezable form and increases linearly with S until reaching S*. The sum of non-freezable and freezable bound water consists of the hydration layer around the chain segments of the network. The hydration number HN of the repeating unit of PVA hydrogel increases from zero to a limiting value about 2.5 as the degree of saturation varies from zero to one.
DSC, States of water, Saturation of swelling
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程镕时, XUEQIN ZHANG, , HU YANG, QUANWEI LIU, YUN ZHENG, HONGFENG XIE, ZHILIU WANG, RONGSHI CHENG
,-0001,():
-1年11月30日
Biodegradable poly(tert-butyl acrylate)–poly[(R)-3-hydroxybutyrate]–poly (tert-butyl acrylate) triblock copolymers based on bacterial poly[(R)-3-hydroxybutyrate] (PHB) were synthesized by atom transfer radical polymerization. The chain architectures of the triblock copolymers were confirmed by 1H NMR and 13C NMR spectra. Gel permeation chromatography analysis was used to estimate the molecular weight characteristics and lengths of the PHB and poly(tert-butyl acrylate) blocks of the copolymers. The thermal properties of the copolymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA showed that the triblock copolymers underwent stepwise thermal degradation and had better thermal stability than their respective homopolymers, whereas DSC analyses showed that a microphase-separation structure was formed only in the triblock copolymers with the longer PHB block. As a similar result, from wide-angle X-ray diffraction experimentation, the crystalline phase of PHB could not be seen evidently in the triblock copolymers with the shorter PHB block. The enzymatic hydrolysis of the copolymer films was carried at 378C and pH7.4 in a potassium phosphate buffer with an extracellular PHB depolymerase from Penicillum sp. The biodegradability of the triblock copolymers increased with an increase in the PHB block content.
atom transfer radical polymerization (, ATRP), , biodegradable, characterization, poly (, tert-butyl acrylate), -poly[(, R), -3-hydroxybutyrate]-poly(, tert-butyl acrylate), (, PtBA–PHB- PtBA), triblock copolymers, synthesis
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程镕时, Hu Yang a, *, Rongshi Cheng a, b, Hongfeng Xie a, Zhiliu Wang a
H. Yang et al./Polymer 46 (2005) 7557-7562,-0001,():
-1年11月30日
The effect of solvation-desolvation process on the conformational change of poly(vinyl alcohol) in an extremely dilute aqueous solution during the repeated freezing–thawing treatment was investigated by a differential refractometer. It was found that the hydrodynamic volume of PVA decreased regularly and smoothly with the number of freezing-thawing cycles treatment increasing, as the intra-molecular entanglement points made the polymer chain contract, and even in a full compacted globule state, there were still some solvent molecules in the chain. The extraordinary phenomenon was successfully explained and treated by a quantitative theory in terms of accompanying solvation-desolvation process during the macromolecular chain having contracted.
Poly(, vinyl alcohol), , Solvation-desolvation effect, Cryogenic cycles treatment
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程镕时, LIU Quanwei, LI Yi, WANG Zhiliu, XIE Hongfeng, YANG Hu, CHENG Rongshi
高分子学报,2005,(4):484~485,-0001,():
-1年11月30日
In order to investigate the property and concentration dependence of dissociation and hydrolysis of polyelectrolytes, acrylic acid-sodium acrylate copolymers with various degree of neutralization were prepared by adding calculated amounts of sodium hydroxide into the aqueous solutions of a poly(acrylic acid) sample, and the pH values of the solutions covering a wide concentration range were measured for each copolymer at 25℃. It was found that the pH values of the solutions of a copolymer with degree of neutralization of 0.96 kept constant and equaled to 9.80 as c>0.001mol/L. For another copolymer with degree of neutralization of 0.30, the pH values of its solutions remained constant and equaled to 6.25 as c<0.001mol/L. These two copolymers may serve as polymeric buffer reagents which couldn't penetrate through semi-permeable membranes in the corresponding concentration regions.
聚电解质,, 离解,, 高分子缓冲溶液
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程镕时, Xue Feng, Fu Wei-wen, Cheng Rong-shi,
,-0001,():
-1年11月30日
将聚甲基丙烯酸甲酯(PMMA)丙酮溶液分别在自然以及超声振动下成膜,所得薄膜分别作差示扫描量热(DSC)和裂解气相色谱-质谱(PyGC-MS)表征。分析结果表明:不同成膜条件下,高分子的凝聚态结构有所不同,试样中残留的溶剂量也有差别;自然挥发所得的初生态薄膜中残留的溶剂是超声作用下所得薄膜的12倍。
溶液凝聚, 聚甲基丙烯酸甲酯, 超声, 凝聚态结构, 表征
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【期刊论文】Cure Kinetic Study of Carbon Nanofibers/Epoxy Composites by Isothermal DSC
程镕时, Hongfeng Xie, , Binghua Liu, Qing Sun, Zuanru Yuan, Jianyi Shen, Rongshi Cheng
Journal of Applied Polymer Science, Vol. 96, 329-335 (2005),-0001,():
-1年11月30日
An investigation was carried out into the cure kinetics of carbon nanofibers (CNF)/epoxy composites, composed of tetraglycidyl-4,4 -diaminodiphenylmethane (TGDDM) resin and 4,4 -diaminodiphenylsulfone (DDS) as a curing agent. The experimental data for both neat system and CNF/epoxy composites revealed an autocatalytic behavior. Analysis of DSC data indicated that the presence of carbon nanofibers had only a negligible effect on the cure kinetics of the epoxy. Kinetic analysis was performed using the phenomenological model of Kamal and two diffusion factors were introduced to describe the cure reaction in thelatter stage. Activation energies and kinetic parameters were determined by fitting experimental data. Comparison between the two diffusion factors was performed, showing that the modified factor was successfully applied to the experimental data over the whole curing temperature range.
curing of polymers, carbon nanofibers, vaporgrown carbon fibers, differential scanning calorimetry (, DSC), , resins
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程镕时, Jiali Cai a, b, Rongshi Cheng b, d, *, Shuqin Bo c
Polymer 46 (2005) 10457-10465,-0001,():
-1年11月30日
The phenomena of reduced viscosity bending up and sometimes appearing a maximum in extremely dilute concentration regime of polymer solution are resulted from the concentration reduction due to adsorption of polymer onto the glass capillary wall. A quantitative theoretical description of this effect based on Langmuir adsorption isotherm is given. Applying the deduced formula to fit Ohrn’s precisely measured reduced viscosity data of polystyrene, linear and branched polyvinyl acetate solutions for three viscometers with different capillary radius gave satisfactory results. The radius dependence of the effective adsorption layer thickness of these polymers indicates it consists of two parts, that is a true adsorption layer and a repulsion layer between anchored chains on the capillary surface and flowing chains in solution. The reduced viscosities of an ultrahigh molar mass polyethylene oxide sample in aqueous solution were measured both by an ordinary glass viscometer and by a viscometer constructed with a polytetrafluoroethylene capillary. The former exhibits a maximum due to adsorption and the later possesses the typical behavior of slipping flow. After correction for solute adsorption and slippage, respectively, the two sets of data coincide well and gave a common linear reduced viscosity plot down to extremely dilute concentration regime.
Concentration reduction, Polymer adsorption, Adsorption layer thickness
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程镕时, Weisi Yin, , Hu Yang, Xueqin Zhang, Zhiliu Wang, Yanwei Ding, Guangzhao Zhang, Rongshi Cheng
,-0001,():
-1年11月30日
The special thermosensitive copolymer with lower critical solubility temperature near human heat of 37℃ in aqueous solution has been prepared successfully by copolymerizing N-isopropylacrylamide (NIPAM) and N-isopropylmethacrylamide (NIPMAM) randomly at an appropriate monomer ratio. The self-association behavior of the poly[NIPAM-ran-NIPMAM] copolymer has been studied by dynamic laser light scattering (DLLS) at a concentration higher than the critical concentration of the self-association calculated from viscosity data according to cluster theory. The effect of the concentration and temperature on the self-association behavior in water has been discussed respectively.
copolymerization, thermosenstitive copolymer, self-association, cluster theory, viscosity, dynamic laser light scattering
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【期刊论文】Glass transition of the two distinct single-chain particles of poly(N-isopropylacrylamide)
程镕时, Weisi Yin, Hu Yang a, and Rongshi Cheng
,-0001,():
-1年11月30日
Two distinct single-chain particles of poly(N-isopropylacrylamide) (PNIPAM) in the state of loose coil and compact globule, have been prepared successfully below and above the lower critical solution temperature (LCST) in extreme dilute aqueous solution by the freeze-drying method, respectively. During the preparation of the compact globular single-chain sample, the surfactant of sodium n-dodecyl sulfate (SDS) was added into the system to prevent aggregation of globular single chains formed at a temperature above the LCST. After all the coil has been transformed into the compact globular particle, the SDS molecules were removed by dialysis. The glass transition temperature (T g) of the two single-chain samples has been measured by di
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