Synthesis of Fluorinated Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization

Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in T_g and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.

Synthesis of fluorinated hyperbranched polyester.     

Phenolic Hyperbranched Polymers as Additives in Cationic Photopolymerization of Epoxy Systems

Summary: A phenolic group containing hyperbranched polyester (HBP) was synthesized and employed as chain transfer agent in cationic photopolymerization of a biscycloaliphatic epoxy monomer ( CE ). The epoxy group conversion increases by increasing the amount of HBP in the photocurable resin, due to a chain transfer reaction involving the phenolic‐OH groups. HBP acts as a plasticizer inducing decrease of the T_g values together with an increase of the toughness properties. Meanwhile gel content increases together with the E′ values. By increasing the amount of HBP in the photocurable resin an increase of the density is evident indicating a decrease of free volume. Therefore an improvement of the gas barrier properties might be expected; at the same time an increase of the thermal stability is evident.

     

Synthesis of Alkyl‐Functionalized Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization of Epoxy Resins

Summary: An alkyl‐functionalized hyperbranched polymer, HBP(OH)–C16, was synthesized by partial modification with fatty acid of an aromatic‐aliphatic OH‐terminated hyperbranched polyester HBP? OH. This product was used as additive in the cationic photopolymerization of an epoxy resin. The alkyl‐modified polyester takes part in the photopolymerization process thanks to the residual OH groups by means of chain‐transfer reactions. An increase of the epoxy conversion is observed by increasing the amount of the HBP additive in the photocurable resin with a modification of the bulk properties of the final ultraviolet‐cured films. The presence of HBP(OH)–C16 induces an increase in glass transition temperature, thermal stability, and solvent resistance. Moreover the surface properties of the films are modified achieving highly hydrophobic surfaces in the presence of even very low amounts of HBP(OH)–C16.

Structure of HBP–C16.     

The Effect of the Degree of Branching in Hyperbranched Polyesters Used as Reactive Modifiers in Epoxy Thermosets

The effect of the degree of branching (DB) of a hyperbranched polyester (GBPEX) added as a modifier of new thermosets obtained from diglycidylether of bisphenol A has been studied. The use of ytterbium triflate as cationic initiator allows the hydroxyl chain‐ends in the GBPEX to become covalently linked to the matrix through the monomer activated propagation mechanism. The curing process has been studied by DSC and rheology. The DB of the modifier does not affect appreciably the thermal stability and the chemical reworkability but shrinkage exhibits a significant reduction on increasing the DB. Thermomechanical characteristics are also improved with increasing the DB of the modifier.

     

Cationic photopolymerization of oxetane‐functionalized hyperbranched polymers

An aliphatic–aromatic pehenolic hyperbranched starting material (HBP‐OH) with phenolic end groups was 85% functionalized by a Mitsunobu reaction with oxetane groups (OXT‐HBP). This new hyperbranched polyester was used, at a concentration of 5–20 wt %, as an additive for the cationic photopolymerization of a commercial oxetane‐based resin, 4,4′‐bis[(3‐ethyl‐3‐ethyl‐3‐oxetanyl) methoxymethyl]biphenyl (OXBP). HBP‐OXT acted as a multifunctional crosslinker, copolymerizing with the oxetane ring of the OXBP resin, reacting through chain transfer with the remaining phenolic OH groups, or doing both. The result was an increase in the glass‐transition temperature due to the increase in the crosslinking density. An increase in the weight residue at a high temperature was found in the presence of HBP‐OXT and was attributed to the presence of phenolic groups, which are commonly used as antioxidant additives. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 293–299, 2005     

超支化聚合物在功能材料中的应用

超支化聚合物由于具有高度支化的三维结构以及众多的端基,显示出与相应线型分子截然不同的性质。对超支化聚合物及其在纳米材料、发光材料、特种涂料等功能材料方面的应用做了介绍,显示出其所具有的广阔应用前景。     

Hyperbranched Polymers Containing Cyclopentadienyliron Complexes

A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A₂+B₃ method. The A₂ compounds used were common diols, dithiols or dichloroarenecomplexes. B₃ compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the properties of the products was probed. Analysis of the prepared polymers was conducted using ¹H and ¹³C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C, corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures ranged from 155 to 190°C.     

Investigation on the effect of the presence of hyperbranched polymers on thermal and mechanical properties of an epoxy UV‐cured system

The use of hydroxyl‐functionalized hyperbranched polymers (HBPs) (Boltorn^® H20, H30 and H40) was investigated with respect to a UV‐cured epoxy system. Their presence induced an increase of the final epoxy conversion, which was interpreted on the basis of a chain‐transfer reaction. A decrease of the T_g values in the photocured films was observed when the amount of HBP additive in the photocurable formulation was increased. When the amount of HBP in the photocurable resin was increased, the density of photocured films increased, indicating a decrease on the free volume. Moreover, a clear increase in toughness was observed and attributed to the plasticization effect induced by the presence of HBP. This effect is particularly interesting for epoxy thermosets, which are characterized by good mechanical properties, although they are brittle and fragile. By increasing the toughness properties of these photocured resins it may be possible to broad their applications. Copyright © 2005 Society of Chemical Industry     

阳离子聚合物的研究

对于阳离子聚合物的制备，分成两部分进行了简单综述。第一部分主要介绍了合成法制备阳离子聚合物，第二部分主要介绍了通过大分子改性的途径制备阳离子聚合物。并简要论述了阳离子聚合物的特性及应用。     

Hyperbranched Rigid Aromatic Phosphorus-Containing Flame Retardants for Epoxy Resins

A rigid aromatic phosphorus-containing hyperbranched flame retardant structure is synthesized from 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ), tris(4-hydroxyphenyl)phosphine oxide (THPPO), and 1,4-terephthaloyl chloride (TPC). The resulting poly-(DOPO-HQ/THPPO-terephthalate) (PDTT) is implemented as a flame retardant into an epoxy resin (EP) at a 10 wt% loading. The effects on EP are compared with those of the monomer DOPO-HQ and triphenylphosphine oxide (OPPh₃) as low molar mass flame retardants. The glass transition temperature, thermal decomposition, flammability (reaction to small flame), and burning behavior of the thermosets are investigated using differential scanning calorimetry, thermogravimetric analysis, pyrolysis combustion flow calorimetry, UL 94-burning chamber testing, and cone calorimeter measurements. Although P-contents are low at only 0.6 wt%, the study aims not at attaining V-0, but at presenting a proof of principle: Epoxy resinswith PDTT show promising fire performance, exhibiting a 25% reduction in total heat evolved (THE), a 30% reduction in peak heat release rate (PHRR) due to flame inhibition (21% reduction in effective heat of combustion (EHC)), and an increase in T_g at the same time. This study indicates that rigid aromatic hyperbranched polymeric structures offer a promising route toward multifunctional flame retardancy.     

Interpenetrating Polymer Networks of Hydrocarbon and Fluorocarbon Polymers: Epoxy/Fluorinated Acrylic Macromonomers

A fluorinated acrylic resin was synthesized for use as a co‐monomer with a commercially available epoxy resin for UV‐cured interpenetrating polymer network preparation. Hybrid IPN networks were achieved with morphology ranging from a co‐continuous IPN to complete phase separation simply by changing monomer ratios. Highly hydrophobic coatings with good adhesion properties on glass substrates were obtained.

     

季戊四醇-偏苯三酸酐-环氧氯丙烷合成超支化聚合物

以季戊四醇为“中心核”，与1，2，4-偏苯三甲酸酐和环氧氯丙烷反应合成超支化碱溶性聚酯，利用合成聚合物分子外围的羧基与甲基丙烯酸缩水甘油酯反应，在超支化聚合物分子外围引入反应性甲基丙烯酰氧基．研究了树脂组成对感光性和碱溶性的影响．结果表明：通过调整分子外围的羧基及反应性甲基丙烯酰氧基含量，可以获得较好的碱溶性和光固化性能。     

含氟超支化聚合物的UV耐指纹涂层研究

研究了含氟超支化聚合物光固化涂层的抗指纹效果及其影响因素。在光固化涂料中添加含氟超支化聚合物,大大提高了涂层表面的抗指纹效果。同时研究了含氟超支化聚合物的添加量、含氟超支化聚合物末端氟改性比例以及双键的引入对涂层表面抗指纹性能及其耐久性的影响。研究发现,较低含量的含氟超支化聚合物(1%)就能明显提高涂层的抗指纹效果,且双键的引入增加了涂层抗指纹效果的耐久性。     

阳离子型超支化聚丙烯酰胺的合成与反应中影响产物黏度因素的探讨

以季戊四醇为支化剂,按一定的比例加入丙烯酰胺(AM)并加入阳离子单体甲基丙烯酰氧乙基三甲基氯化铵(DMC)增加其阳离子性,合成了具有阳离子性的超支化聚丙烯酰胺。对产物进行了红外光谱(FTIR)分析,并使用旋转粘度计和一定计算测得了聚合物的增比黏度。而后探讨了反应温度、反应时间和引发剂用量对产物粘度的影响。     

稠环化合物敏化硫鎓盐引发阳离子光聚合的研究

合成了三芳基硫六氟磷酸盐光引发剂。研究了不同稠环化合物对硫盐引发阳离子光聚合速度的影响,用光致电子转移(光氧化还原)理论解释了这些稠环化合物的光敏机理。     

可聚合阳离子含氟表面活性剂在含氟丙烯酸酯乳液聚合中的应用

以可聚合阳离子含氟表面活性剂N-(乙酸全氟辛基乙基酯)-N-(乙醇丙烯酸酯)二甲基溴化铵(PF8DM)为乳化剂,进行含氟丙烯酸酯的细乳液聚合研究,考察了PF8DM用量对单体转化率和凝胶率的影响,PF8DM用量对乳液的稳定性和表面性能的影响;分别采用PF8DM和十六烷基三甲基溴化铵作为乳化剂考察其对乳胶膜性能的影响。结果表明,当PF8DM含量为单体总质量的4%时,单体转化率达95%,凝胶率为0.6%;所得乳液具有优异的贮存、稀释、离心稳定性;当PF8DM用量为单体总质量的6%时得到的乳胶膜接触角达118.6°。在总含氟量相同的条件下,采用PF8DM为乳化剂制备的含氟丙烯酸酯乳液,其乳胶膜的吸水率大大降低,拒水性也明显增强。     

氟代聚丙烯酸酯改性阳离子型聚氨酯乳液的制备

以丙烯酸十二氟庚酯(FA)、丙烯酸羟丙酯(HpAA)为单体,通过偶氮二异丁腈(AIBN)引发聚丙烯酸酯自由基在交联的聚氨酯预聚体中进行聚合,并用N-甲基二乙醇胺(MDEA)进行亲水基扩链,溶液聚合相转化法制得新型氟代聚丙烯酸酯改性阳离子型聚氨酯复合乳液(FPUA)。对聚合物结构、乳胶粒形态进行表征。结果表明,以丙酮为溶剂,n_(NCO)/n_(OH)=1.3,MDEA质量分数6.5%、FA质量分数为8%时能得到半透明蓝光、稳定性良好的核-壳结构乳液,FPUA胶膜拉伸强度为19 MPa,吸水率为6.9%,接触角为101°,产品的耐水性优良。     

阳离子型含氟聚丙烯酸酯无皂乳液的合成 及其性能研究

以可逆加成-断裂链转移(RAFT)聚合合成的聚甲基丙烯酸N,N-二甲氨基乙酯-b-丙烯酸六氟丁酯（PDMAEMA-b-PHFBA）为稳定剂,通过无皂乳液聚合技术合成了阳离子型含氟聚丙烯酸酯无皂乳液。采用红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、透射电子显微镜(TEM)、动态光散射(DLS)对乳胶粒子和聚合物的结构进行了表征。结果表明,当PDMAEMA-b-PHFBA用量为2.4%时,乳液的稳定性好,转化率高,乳胶粒具有明显的核壳结构,且粒径分布窄。将阳离子型含氟聚丙烯酸酯无皂乳液用于皮革涂饰后,皮革表面的防水防油性得到明显提高,随着丙烯酸六氟丁酯用量的增加,涂饰后的皮革对水和二碘甲烷的接触角逐渐增加,当丙烯酸六氟丁酯用量为10%时,涂饰后的皮革对水的接触角为125?,对二碘甲烷的接触角为81.5?。