Synthesis of an amphiphilic styrenic block copolymer: Polycondensation of dichloromethane and low molecular weight poly(ethylene glycol) in the presence of hydroxypropylated polystyrene‐block‐polybutadiene

An amphiphilic styrenic block copolymer, polystyrene‐block‐polybutadiene‐block‐poly[oxymethylene‐alt‐oligo(oxyethylene)] (PS‐b‐PB‐b‐POME), was synthesized through a polycondensation reaction of low molecular weight poly(ethylene glycol) and dichloromethane in the presence of hydroxypropylated polystyrene‐block‐polybutadiene (PS‐b‐PB‐OH) used as a monofunctional chain‐capping reagent. PS‐b‐PB‐OH was in turn prepared via an anionic synthesis of PS‐b‐PB followed by oxetane capping and methanol quenching. Although PS‐b‐PB‐OH has insignificant hydrophilicity, PS‐b‐PB‐b‐POME containing both the hydrophobic PS‐b‐PB segment and the hydrophilic POME segment had an improved emulsifying capability and effectively decreased the interfacial tension between water and toluene. The hydrophile–lipophile balance value of this amphiphilic PS‐b‐PB‐b‐POME copolymer, consisting of 86 wt % of the POME segment and 14 wt % of the PS‐b‐PB segment, was 17.2. The molecular weight of the copolymer molecule was determined by gel permeation chromatography–multi‐angle laser light scattering, and the microstructure was analyzed using ¹H NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2625–2632, 2001     

Preparation of a Polyethylene Latex by Catalytic Hydrogenation of a Polybuta‐1,4‐diene‐Based Dispersion

Summary: Fully linear polyethylene‐based latexes have been prepared by the hydrogenation of polybuta‐1,4‐diene dispersions. The latter were synthesized via dispersion ring‐opening metathesis polymerization of cycloocta‐1,5‐diene, and hydrogenated using RuCl₂(PPh₃)₃ as catalyst, without any further treatment. A high hydrogenation efficiency was achieved as demonstrated by different techniques including DSC, and ¹H NMR and FT‐IR spectroscopy. The hydrogenation process could be carried out without detrimental effect on particle size and colloidal stability as evidenced by optical microscopy and light scattering analysis.

Optical microscopy photograph of a polybutadiene‐based dispersion after hydrogenation. No change in size is observed.     

Triallylstannyllithium-allyllithium as an initiator for the anionic reversible chain transfer polymerization of 1,3-butadiene

The anionic polymerization of 1,3-butadiene using a novel metalloidal anion initiator, triallylstannyllithium (TALi)-allyllithium (ALi), was studied. The TALi-ALi initiated anionic polymerization of 1,3-butadiene gave the star polymer along with the linear polybutadiene (PBD). The star polymer consisted of three PBD branches and a central tin atom. What is striking is a fact that the number-average molecular weights (M_n) and molecular weight distribution of three PBD branches and linear PBD were almost identical. A reversible chain transfer polymerization mechanism, which includes the equilibrium between tri(macroallyl)-stannyllithium and macroallylic anion, is proposed. © 1996 John Wiley & Sons, Inc.     

Grafting of dodecyl methacrylate onto hydroxylated polybutadiene by miniemulsion polymerization

Homogeneous copolymer latex particles of dodecyl methacrylate (DMA) and low‐molecular‐weight hydroxy‐terminated polybutadiene (HTPB) oligomers were prepared by free‐radical polymerization using miniemulsion methods. Rate data and latex characteristics were consistent with the classical miniemulsion mechanism where nucleation of monomer droplets is the predominant pathway of particle formation. There is essentially no particle formation by secondary nucleation in the water phase. Characterization of the copolymer latex particles using transmission electron microscopy and modulated differential scanning calorimetry suggested that there is a significant amount of grafted poly(DMA)/HTPB polymer contributing to the miscibility of the HTPB and poly(DMA) phases. Particles were more homogeneous at increased HTPB composition, of relatively narrow polydispersity, and could be prepared reproducibly using a number of different initiation systems. The observed trends can all be rationalized in terms of conventional understanding of miniemulsion polymerization systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3404–3416, 2004     

含液晶二醇聚氨酯研究

合成了具有液晶性质的二元醇一对苯二甲酰二羟苯甲酸丁二醇酯（ＴＯＢＢ），这种二元醇单独或与端羟基聚了二烯（ＨＴＰＢ）混合后与二异氰酸酯反应生成几种聚氨酯，用ＩＲ，ＤＳＣ，偏光显微镜和ＷＡＸＤ对它们进行了表征，证明这种二元醇和聚氨酯都具有液晶性质。     

Miniemulsion polymerization of styrene with liquid polybutadiene as the sole co-stabilizer

A low-molecular-weight liquid polybutadiene (LPB) is employed as the sole co-stabilizer in miniemulsion polymerization of styrene in present work. Results indicate that the LPB can be used as an effective co-stabilizer to retard the diffusional degradation of monomer droplets in miniemulsion system and get stable miniemulsions. When the miniemulsions were initiated, particle formation occurred predominantly by monomer droplet nucleation. Moreover, the effects of various reaction parameters on the polymerization kinetics and the nucleation mechanisms were also investigated. These parameters include the level of LPB ([LPB]) and the concentrations of SDS ([SDS]) and potassium persulfate ([KPS]). It is shown that the polymerization rate indicates little dependence on [LPB], while increases with increasing [SDS] and [KPS]. Competition between droplet nucleation and homogeneous nucleation occur in the course of polymerization, but droplet nucleation becomes more important by increasing [LPB] or decreasing [SDS]. Furthermore, the result that the particle size is rather insensitive to changes in [KPS] provides the most compelling evidence for the dominant droplet nucleation.     

Relationship between the α‐ and β‐relaxation processes in amorphous polymers: Insight from atomistic molecular dynamics simulations of 1,4‐polybutadiene melts and blends

Amorphous polymers exhibit a primary (glass, or α‐) relaxation process and a low‐temperature relaxation process associated with polymer backbone motion usually referred to as the β‐relaxation process. The latter process can be observed below the glass transition temperature of the polymer and usually merges with the α‐relaxation process at temperatures somewhat above the glass transition temperature. While it is widely held that both the α‐relaxation and β‐relaxation processes are engendered by localized (segmental) motions of the polymer backbone, and that there is a strong mechanistic connection between them, the molecular mechanisms of the α‐relaxation and β‐relaxation processes in amorphous polymers are not well understood. Recently, atomistic molecular dynamics simulations of melts and blends of 1,4‐polybutadiene have provided insight into the relationship between the α‐ and β‐relaxation processes in glass‐forming polymers and an improved understanding of their molecular origins. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 627–643, 2007     

A highly stretchable and self-healing hydroxy-terminated polybutadiene elastomer

The damage such as microcracks limits the application of hydroxy-terminated polybutadiene (HTPB) elastomer. Here, hydroxy-carboxy-terminated polybutadiene (HCTPB) and Fe³⁺ selected to facilitate ionic bonds (COO⁻⋯Fe³⁺) formation is proposed as a strategy to alleviate the intrinsic self-healing problem for HTPB elastomer. In typical HTPB polyurethane elastomer, the elongation at break is 997.3% while the tensile strength is 1.83 MPa, the damage cannot repair by intrinsic covalent or non-covalent, resulting in permanent damage. In contrast, HCTPB is able to offer COO⁻, entailing a COO⁻⋯Fe³⁺ ionic bonds. Incorporated 6 wt% HCTPB and Fe³⁺ into the HTPB elastomer elevates the tensile strength to 5.2 MPa, reducing the elongation at break in 877.8%. HCTPB and Fe³⁺ enhance the self-repair rate reaches up to 92% after repairing at 80 °C for 10 h after cutting for HTPB elastomer. This strategy has immediate implications for using COO⁻⋯Fe³⁺ ionic bonds to improve the performance of HTPB polyurethane elastomer devices.     

Synthesis and properties of fluorinated telechelic macromolecular diols prepared by radical grafting of fluorinated thiols onto hydroxyl-terminated polybutadienes

The radical grafting of C_nF_{2n +1} CH₂CH₂SH (n = 6,8) onto the double bonds of hydroxyl-terminated liquid polybutadienes (HTPBD) was studied. Various methods for investigating the amount of grafting (titration of residual thiol and fluorine analysis) were used and compared. The nature and the amount of the initiator, the quantity of thiol, the temperature and the time of the reaction. the solvent, and the microstructure of HTPBD were optimized. The kinetic aspect showed that the thiol disappeared according to a first-norder law. A method using up to 100% of grafting fluorinated mercaptan was described and standards were set up with fluorine contents of 5–59% to evaluate the physicochemical properties of these thioether group-containing polymers: solubility, refractive index, intrinsic and dynamic viscosities, and thermal characteristics (glass transition and decomposition temperatures). Finally, the surface properties of these standards showed improvements of surface energy as low as 9 mN m^?1 for a totally saturated fluorinated HTPBD. © 1993 John Wiley & Sons, Inc.     

水溶性聚合物和两亲聚合物19．磺化液体聚丁二烯──种新型液膜用表面活性剂

一种新的聚工二烯型表面活性剂ＬＹＦ经液体聚了二烯磺化方法制备而得，并应用于液膜分离研究之中。发现无论内水相是酸性还是碱性，由该表面活性剂制得的Ｗ／Ｏ型乳状液在稳定性、溶胀率和破乳诸方面均具有令人满意的综合性能。为深入了解液膜的稳定性，我们测定了处于两种水相间的双分子膜的强度。发现由ＬＹＦ所形成的双分子膜具有最大的膜强值，优于聚异丁烯型的表面活性剂ＥＣＡ４３６０和ＥＭ３０１．