Mechanical Properties of Films from Hybrid Acrylic‐Polyurethane Polymer Colloids

A variety of polyurethane based on the polyaddition of isophoronediisocyanate and polypropyleneglycol has been used to prepare acrylic‐polyurethane hybrid polymer colloids, through either mini‐emulsion polymerization of their solutions in a mixture of monomers or seeded emulsion polymerization of this mixture from seeds of modified polyurethane containing dimethylolpropionic acid neutralized with triethylamine. The mixture of monomer is composed of 30% styrene, 30% methylmethacrylate, and 40% butylacrylate. The mechanical properies of films prepared through coalescence of these latexes where studied. The effect of various parameters such as the composition and the amount of polyurethane as well as the synthesis process are discussed.     

The delayed crosslinking amphiphilic polymer gel system based on multiple emulsion for in-depth profile control

Delayed crosslinking polymer gel systems are widely used in-depth profile control technology for water production control. In this paper, an amphiphilic polymer P(AM-NaA-DDAM) was synthesized by a free radical micellar polymerization method and a delayed crosslinking amphiphilic polymer gel system was prepared based on multiple emulsion of W₁/O/W₂ emulsion which was prepared by a two-step emulsification method. The optimized formulation of amphiphilic polymer gel systems is: 0.15% P(AM-NaA-DDAM), 0.3% methenamine, 0.02% resorcinol, and 0.3% citric acid. The delayed gelation time of the delayed crosslinking amphiphilic polymer gel system is closely related to the stability of the W₁/O emulsion. By using multiple emulsion delayed crosslinking method, the delayed crosslinking amphiphilic polymer gel system with diesel as the oil phase can delay the gelation time up to 168 hours.     

Synthesis strategies and properties of smart amphiphilic networks

This paper briefly surveys recent developments in the field of amphiphilic networks (APN) which are a new class of crosslinked polymer systems consisting of covalently bonded hydrophobic and hydrophilic chain segments. The covalent bonds between immiscible hydrophobic and hydrophilic polymer chains prevent demixing and yield polymer networks with unique structure and properties. Telechelic macromonomers provide the basis for the first generation of APNs obtained by copolymerization of the macromonomer with selected low molecular weight monomers. Synthesis of a variety of APNs using methacrylate-telechelic polyisobutylene (PIB) macromonomers prepared by living carbocationic polymerization (LCCP) and quantitative chain end derivatization is reviewed. The second generation of PIB-based amphiphilic networks is prepared by crosslinking of well-defined hydroxy-telechelic PIB and partially deprotected silylated poly(2-hydroxyethyl methacrylate) (PHEMA) precursor chains. Other opportunities providing better structural control of APNs by crosslinking of functional amphiphilic block copolymers (or precursors) obtained by combining living carbocationic and anionic polymerizations are outlined as well. Properties of APNs, such as control of swellability by composition, pH-response of swelling, fast surface structure reorganization by contacting with solvent, morphology, sustained release of drugs and bio- and blood compatibility, are also summarized.     

Synthesis and characterization of block copolymers containing poly(di(ethylene glycol) 2‐ethylhexyl ether acrylate) by reversible addition–fragmentation chain transfer polymerization

Reversible addition–fragmentation chain transfer (RAFT) polymerization has emerged as one of the important living radical polymerization techniques. Herein, we report the polymerization of di(ethylene glycol) 2‐ethylhexyl ether acrylate (DEHEA), a commercially‐available monomer consisting of an amphiphilic side chain, via RAFT by using bis(2‐propionic acid) trithiocarbonate as the chain transfer agent (CTA) and AIBN as the radical initiator, at 70 °C. The kinetics of DEHEA polymerization was also evaluated. Synthesis of well‐defined ABA triblock copolymers consisting of poly(tert‐butyl acrylate) (PtBA) or poly(octadecyl acrylate) (PODA) middle blocks were prepared from a PDEHEA macroCTA. By starting from a PtBA macroCTA, a BAB triblock copolymer with PDEHEA as the middle block was also readily prepared. These amphiphilic block copolymers with PDEHEA segments bearing unique amphiphilic side chains could potentially be used as the precursor components for construction of self‐assembled nanostructures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5420–5430, 2007     

Effect of spatial constraints on phase separation during polymerization in sequential semi-interpenetrating polymer networks

The viscoelastic properties of sequential semi-interpenetrating polymer networks prepared via the swelling of network polyurethane in different monomers (butyl methacrylate, styrene) followed by their polymerization in the polyurethane matrix have been studied by means of dynamic mechanical analysis. It is found that the relaxation behavior of the test systems and the degree of segregation of the components depends on M _c of the polyurethane matrix because of a change in the molecular mass of the polymer block. The compatibility of the components in sequential semi-interpenetrating polymer networks substantially increases when the network inner space in the polyurethane matrix decreases.     

聚氨酯乳液的合成及流变性能

The polyurethane emulsion was prepared by introducing carboxylic groups into urethane chains, and its rheology was investigated with rotation viscosimeter. The results of rheology showed that the polyether-urethanc emulsion exhibited the character of Newtonian liquid. The viscosity and stability of the polyurethane emulsion depended on the temperature and carboxylic group content.     

Photochemically prepared polysulfone/poly(ethylene glycol) amphiphilic networks and their biomolecule adsorption properties

Polysulfone/poly(ethylene glycol) amphiphilic networks were prepared via in situ photo-induced free radical crosslinking polymerization. First, the hydrophobic polysulfone diacrylate (PSU-DA) oligomer was synthesized by condensation polymerization and subsequent esterification processes. Then, the obtained oligomer was co-crosslinked with the hydrophilic poly(ethylene glycol) diacrylate (PEG-DA) or poly(ethylene glycol) methyl ether acrylate (PEG-MA) at different feed ratios. In the case of PEG-MA, the resulting network possessed dangling pendant hydrophilic chains on the crosslinked surface. The structure and the morphology of the membranes were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM). The enhancement of surface hydrophilicity was investigated by water contact angle measurements. The biomolecule adsorption properties of these networks were also studied. The biomolecules easily adsorbed on the surface of the hydrophobic polysulfone networks whereas dangling hydrophilic chains on the surface prevented the adsorption of the biomolecules.     

两亲性杂侧链聚合物刷的合成及其乳化功能

报道了一种随机高密度接枝亲水、疏水聚合物侧链的刷形两亲性聚合物.首先,结合可逆加成-断裂链转移(RAFT)聚合和后修饰方法,得到含叠氮侧基的聚甲基丙烯酸缩水甘油酯(PGMA-N3)作为主链;再分别合成端炔基聚苯乙烯(PS)和端炔基聚环氧乙烷(PEO),然后通过铜催化的叠氮-炔环加成反应,将疏水性PS和亲水性PEO同时高效的接到PGMA主链上,制得两亲性杂侧链的聚合物刷.由凝胶渗透色谱(SEC)分析得知,在主链叠氮基团与两侧链总炔基的摩尔投料比为1∶1的条件下,PS和PEO的接枝效率很高,都大于90%.通过调节主链长度和2种侧链的投料比,获得不同组成的聚合物刷.通过等质量的甲苯/水混合体系,考察两亲性聚合物刷的乳化能力,发现主链聚合度为100,PS∶PEO比例为70∶30的聚合物刷表现出最佳的乳化性能.     

Synthesis of hematite/silica/polymer composite colloids with a tunable morphology

Hematite/SiO₂/polystyrene colloidal particles were synthesized through emulsion polymerization, in the presence of seeds coated with 3-methacryloxypropyltrimethoxysilane (MPS). Scanning and transmission electron microscopy studies indicate that flying saucer-like particles can be prepared by taking advantage of the coalescence phenomenon which occurs between growing polymer nodules when the MPS surface density of the coupling agent is high. By decreasing this density, multipod-like and raspberry-like composite particles were obtained, depending on the concentration of monomer.     

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The T_g of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388     

两亲性RAFT试剂存在下丙烯酸六氟丁醋和苯乙烯的无皂乳液聚合

合成了具有两亲性结构的可逆加成断裂链转移(RAFT)试剂,在RAFT试剂的作用下,通过无皂乳液聚合方法合成了丙烯酸六氟丁酯与苯乙烯的共聚物.研究了RAFT试剂浓度和聚合温度对聚合动力学、聚合反应可控性及乳胶粒粒径的影响.通过红外光谱(FTIR)、核磁共振谱(1H NMR)、示差扫描量热仪(DSC)、凝胶渗透色谱仪(GPC)及表面张力仪表征了共聚物的结构、玻璃化转变温度(Tg)、分子量和分子量分布及乳胶膜表面性能.结果表明,得到的苯乙烯和丙烯酸六氟丁酯共聚物无皂乳液的乳胶粒粒径在100 nm左右且呈单分散分布.当RAFT试剂浓度高于0.016 mol/L时聚合体系有较好的可控性.共聚物乳液的乳胶膜对水和二碘甲烷的接触角都很高.     

New polymer structures based on vinyl ether polymerization

Sequential living cationic polymerization of octadecyl vinyl ether (ODVE) and methyl vinyl ether (MVE) was used for the preparation of amphiphilic ABA‐type block copolymers. The polymerization of ODVE was initiated with the trimethyl silyl iodide/1,1,3,3‐tetramethoxy propane/ZnI₂ system at 0°C in toluene. The living bifunctional polyODVE thus obtained was used as initiator for the polymerization of MVE. Below the LCST of polyMVE (37°C), the copolymers are amphiphiles. Above the LCST of polyMVE, the polyMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymer is lost. This was demonstrated by using the block copolymers as emulsifiers for water/decane mixtures. The emulsions were stable for several hours at room temperature, while the emulsion stability decreased to about 30 seconds at 40°C. PolyMVE‐α,ω‐bis‐methacrylates were obtained by end‐capping of living bifunctional polyMVE with 2‐hydroxyethyl methacrylate (HEMA). Copolymerization of these bis‐macromers with HEMA leads to segmented networks. The networks showed a reversible swelling/deswelling behavior in water as a function of temperature. This is caused by a change of the hydrophilicity of the polyMVE segments in the networks. Hexa(chloromethyl)melamine, combined with zinc chloride was found to be an efficient hexafunctional initiator for the living cationic polymerization of vinyl ethers. This simple initiating system opens new ways for the synthesis of endgroup‐functionalized star‐shaped poly(vinyl ethers).     

聚氨酯/聚丙烯酸酯复合乳液粒子热力学平衡形态预测

以水性聚氨酯分散液为种子采用无皂乳液聚合新技术合成出了具有核壳结构的聚氨酯/聚丙烯酸酯（PU/PA）复合聚合物乳液。采用界面张力简化计算方法计算了聚合物与聚合物之间以及聚合物和水之间的界面张力,通过界面自由能变化最小的热力学判据对合成的复合乳液粒子的热力学平衡形态进行了预测。并利用透射电子显微镜观察和用接触角法测定的膜的表面极性对其进行了证实。结果表明：界面自由能变化的最小判据可以推广到PU/PA 体系,本文给出的界面张力的简化计算方法是可行的。     

Complex macromolecular structures from stable radical containing block copolymers

A novel synthetic strategy for the synthesis of graft copolymers is reported. Block copolymers containing segments with stable nitroxyl radicals side groups were first prepared by anionic polymerization, which were then used as a precursor for the subsequent nitroxide-mediated radical polymerization (NMRP) of styrene. This way, block–graft copolymers with polystyrene side chains grafted from one of the blocks were successfully synthesized in a controlled manner. In addition, block–graft copolymers with grafted polystyrene chains and a poly(tert-butyl methacrylate) block were subjected to hydrolysis to yield the corresponding amphiphilic polymers. The structures and the molecular weight characteristics of the polymers were characterized by spectral and chromatographic analyses. The surface morphology of thus obtained polymers was also investigated by microscopic techniques. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 62–69     

Characterization of polyurethane network chains by gel permeation chromatography

Starting materials, prepolymers, chain-extended oligomers, and polyurethane network chains were characterized by gel permeation chromatography in order to make clear the change of molecular distribution in the formation of polyurethane networks. The polyurethane networks were prepared from poly(oxypropylene)glycol (PPG 1000, M _n = 997, M _w/M _n = 1.04), 2,4-tolylene diisocyanate, and 1,4-butanediol by the prepolymer method. Polyurethane networks were degraded by the amine degradation method, by which allophanate groups as crosslinking sites were decomposed selectively. The prepolymer had four species. The polydispersity index of the prepolymer (M _w/M _n) was about 2, that is, the most probable distribution. The product of the chain-extending reaction of prepolymer with BD had five species. The molecular-weight distribution of this product was narrower than that of the prepolymer. The polydispersity of the interstitial chains between crosslinking sites was also narrower than that of the chain-extended product. The polyaddition mechanism in the formation of PPG–TDI–BD polyurethane networks was discussed.     

Covalent amphiphilic polymer networks

The recent literature on chemically cross-linked amphiphilic polymer networks is reviewed. The main subjects covered are network synthesis, characterization, modeling and applications. Special mention is made to more modern methods for amphiphilic network synthesis and in particular to those involving controlled polymerization techniques. A key question regarding synthesis is which method gives the most perfect networks. On the characterization side is the issue of microphase separation of amphiphilic networks in water and the morphologies obtained in these systems, in comparison with the morphologies of amphiphilic linear block copolymers in water. Major recent advances: The most important developments of the past year in the field of amphiphilic polymer networks involved mainly new syntheses: cross-linked stars of various star architectures, cross-linked linear chains of various architectures and compositions, poly(tetrahydrofuran)- and poly(propylene fumarate)-based networks, tricomponent networks containing silicon, and cross-linked poly(acrylic acid)-grafted Pluronics. A first crude model was also developed which shows that amphiphilic networks prefer to be mostly in the microphase separated state. Extensive and systematic experimental studies on network microphase separation are yet to be performed.     

两亲性RAFT试剂存在下丙烯酸六氟丁醋和苯乙烯的无皂乳液聚合

合成了具有两亲性结构的可逆加成断裂链转移(RAFT)试剂,在RAFT试剂的作用下,通过无皂乳液聚合方法合成了丙烯酸六氟丁酯与苯乙烯的共聚物.研究了RAFT试剂浓度和聚合温度对聚合动力学、聚合反应可控性及乳胶粒粒径的影响.通过红外光谱(FTIR)、核磁共振谱(1H NMR)、示差扫描量热仪(DSC)、凝胶渗透色谱仪(GP...     

Synthetic approaches towards new polymer systems by the combination of living carbocationic and anionic polymerizations

This study summarizes recent efforts to obtain by combination of living carbocationic and anionic polymerizations block copolymers which are potential precursors for building new well-defined polymeric architectures with microphase separated morphology. Living carbocationic polymerization (LCCP) yields telechelic polyisobutylene (PIB) chains with a variety of useful endgroups, such as tert-chlorine, isopropenyl, primary hydroxyl, tolyl etc. When tolyl-ended PIB was used as precursor for macroinitiator of living anionic polymerization of 2-(tert-butyldimethylsilyloxy)ethyl methacrylate (tBuMe₂SiOEMA), mixtures of homopolymers and block copolymers were formed due to incomplete lithiation of this chain end. In another approach a new functionalization method was developed by end-quenching living PIB chains with 1,1-diphenylethylene (DPE). In the presence of BCl₃ a new telechelic PIB with 2,2-diphenylvinyl (DPV) endgroups was formed. A corresponding DPV model compound was synthesized from 2-chloro-2,4,4-trimethylpentane (TMPCl). Because of steric hindrance less than quantitative lithiation of this material occurred. Controlled deprotection of PtBuMe₂SiOEMA obtained by living anionic polymerization (LAP) was utilized to prepare a precursor network composed of partially deprotected PtBuM₂SiOEMA and hydroxyl-telechelic PIB by using a diisocyanate crosslinker. After network formation deprotection with HCl was completed and a new amphiphilic network (APN) containing PIB and poly(2-hydroxyethyl) methacrylate) (PHEMA) segments crosslinked by urethane linkages was obtained.     

具有疏水核/亲水壳的双亲胶体粒子的制备

制备了具有疏水性聚苯乙烯核/亲水性聚丙烯酰胺壳的双亲粒子.疏水核通过超浓乳液聚合制备,亲水壳层通过过氧化羟基异丙苯和硫酸亚铁的界面引发制备.控制条件可得到网孔(半包覆)、褶皱(全包覆)两种形态的壳层.壳层孔的存在使得核层聚合物能够与外界接触.粒子的双亲性通过吸水吸油率进行表征.     

Semibatch emulsion polymerization of methyl methacrylate using different polyurethane particles

Aqueous acrylic‐polyurethane (AC–PU) hybrid emulsions were prepared by semibatch emulsion polymerization of methyl methacrylate (MMA) in the presence of four polyurethane (PU) dispersions. The PU dispersions were synthesized with isophorone diisocyanate (IPDI), 1000 and 2000 molecular weight (MW) poly(neopentyl) adipate, 1000 MW polytetramethyleneetherglycol, butanediol (BD), and dimethylol propionic acid (DMPA). MMA was added in the monomer emulsion feed. We studied the effect of the use of different PU seed particles on the rate of polymerization, the particle size and distribution, the number of particles, and the average number of radicals per particle. The PU rigidity was controlled by varying the polyol chemical structure, the polyol MW (M_n), and by adding BD. The monomer feed rate was varied to study its influence on the process. It was observed that the PU particles that had been prepared with a higher MW polyol swelled better with MMA before the monomer‐starved conditions occurred. There seemed to be no significant discrepancies between the series with different PU seeds in the monomer‐starved conditions. The overall conversion depended on the monomer addition rate, and the polymerization rate acquired a constant value that was comparable to the value of the monomer addition rate. The instantaneous conversion increased slightly. The average particle size increased, and the total particle number in the reactor was constant and similar to the number of PU particles in the initial charge. The average number of radicals per particle increased. The differences between the system with a constant particle number and average number of radicals per particle and the system with a fixed radical concentration are discussed. The semibatch emulsion polymerization of MMA in the presence of PU particles studied was better compared to the system with a fixed radical concentration. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 844–858, 2005