New concept of positive photosensitive polyimide: Reaction development patterning (RDP)

A soluble multiblock copolyimide without specific functional groups such as OH and COOH was prepared by a direct one‐pot polycondensation of two types of dianhydrides and diamines in the presence of γ‐valerolactone/pyridine catalyst using N‐methylpyrrolidone (NMP)/toluene mixture as a solvent. The polyimide film containing the photosensitive agent diazonaphthoquinone (DNQ) compound gave positive‐tone behavior by UV irradiation, followed by development in a mixture of ethanolamine/NMP/H₂O (1/1/1 by weight). The scanning electron microscopic photograph of the resultant image showed fine patterns with about 20 μm film thickness. Its pattern forming was based on the photorearrangement of diazonaphthoquinone, a process in which the ring‐opening reaction of imide units of the polyimide with the amine used as a developer and the following degradation of the polymer are induced. Such a new imaging technique combines principles of photolithography and etching of a polyimide to give, what we call, reaction development patterning in which the main chemical reactions directly related to the pattern formation occur during development. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3451–3463, 2001     

Photosensitive fluorinated polyimides with a low dielectric constant based on reaction development patterning

The fluorinated polyimide PI(6FDA/HFBAPP) was prepared by the reaction of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,2‐bis[4‐(4‐aminophenoxy)phenyl]hexafluoropropane (HFBAPP) in 1‐methyl‐2‐pyrrolidone/toluene. A multiblock copolyimide with both fluorinated and rigid‐rod segments, PI(6FDA/HFBAPP)(BPDA/2‐DMB), was prepared by the addition of a second dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and a second diamine, 2,2′‐dimethylbenzidine (2‐DMB), to the polyimide main chain. The potential lithographic performance of photosensitive polyimides composed of nonphotosensitive fluorine‐containing polyimides and photosensitive diazonaphthoquinone (DNQ) was studied on the basis of a new imaging principle recently proposed by our laboratory, that is, reaction development patterning. Neat PI(6FDA/HFBAPP) showed a low dielectric constant (?) of 2.41 and a low dissipation factor (tan δ) of 0.0027 at 20 GHz, and a 10‐μm resolution of the fluorinated polyimide/DNQ system was demonstrated with reactive development with a solution including ethanolamine after ultraviolet exposure. Although slight changes in the dielectric properties were observed in the presence of DNQ residues, these values (? = 2.63 and tan δ = 0.0033 at 20 GHz) were low enough for use in microelectronic applications. However, PI(6FDA/HFBAPP)(BPDA/2‐DMB), having a lower coefficient of thermal expansion (CTE; 33 ppm/°C) than PI(6FDA/HFBAPP) (49 ppm/°C), exhibited good positive photosensitivity, whereas the relatively low‐CTE multiblock copolyimide displayed a much higher ? value (3.48 at 1 MHz) than the highly fluorinated polyimide (2.88 at 1 MHz). A film consisting of PI(6FDA/HFBAPP)(BPDA/2‐DMB) and the remaining DNQ derivatives showed a CTE value comparable to that of the neat polyimide film. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 861–871, 2003     

Photosensitive Polyarylates Based on Reaction Development Patterning

Films of a commercially available polyarylate (U polymer®) containing a photosensitive agent were prepared by means of spin‐coating onto copper foil, which showed positive‐tone behavior after UV irradiation and development with an ethanolamine/N‐methylpyrrolidone/H₂O mixture. Scanning electron microscope photographs of the images exhibited fine patterns (≈10 μm line/space resolution) with 9–14 μm film thickness. The pattern‐forming mechanism is based on the reaction development patterning (RDP) process, where the main pattern‐forming reaction occurs during development.     

Syntheses of pyrimidine‐based polymers containing electron‐withdrawing substituent with high open circuit voltage and applications for polymer solar cells

Polymers using new electron‐deficient units, 2‐pyriminecarbonitrile and 2‐fluoropyrimidine, were synthesized and utilized for the photovoltaics. Donor‐acceptor (D‐A) types of conjugated polymers ( PBDTCN, PBDTTCN, PBDTF, and PBDTTF ) containing 4,8‐bis(2‐octyldodecyloxy)benzo[1,2‐b;3,4‐b′]dithiophene (BDT) or 4,8‐bis(5‐(2‐octyldodecyloxy)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene (BDTT) as electron rich unit and 2‐pyriminecarbonitrile or 2‐fluoropyrimidine as electron deficient unit were synthesized. We designed pyrimidine derivatives in which strong electron‐withdrawing group (C?N or fluorine) was introduced to the C2 position for the generation of strong electron‐deficient property. By the combination with the electron‐rich unit, the pyrimidines will provide low band gap polymers with low highest occupied molecular orbital (HOMO) energy levels for higher open‐circuit voltages (V_OC). For the syntheses of the polymers, the electron‐rich and the electron‐deficient units were combined by Stille coupling reaction with Pd(0)‐catalyst. Absorption spectra of the thin films of PBDTTCN and PBDTTF with BDTT unit show shift to a longer wavelength region than PBDTCN and PBDTF with BDT unit. Four synthesized polymers provided low electrochemical bandgaps of 1.56 to 1.96 eV and deep HOMO energy levels between ?5.67 and ?5.14 eV. © 2015 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 771–784     

Effect of substituent polarity,bulk, and substitution site toward enhancing gas permeation in dibromohexafluorobisphenol‐a based polyarylates

The gas permeation properties of polyarylates were tuned by varying nature and site of substituents present on both of its monomers, viz., bisphenol and dicarboxylic acid. The phenyl rings of hexafluorobisphenol‐A were substituted in asymmetric manner by polar bromine to obtain dibromohexafluorobisphenol‐A. This bisphenol was polymerized with equimolar mixture of iso‐ and terephthalic acid (base case), bromo‐ and nitroterephthalic acid (polar group substituted acids), 4,4′‐hexafluoroisopropylidene bis(benzoic acid), and t‐butyl isophthalic acid (bulky group containing acids). Physical properties and gas permeation properties of these polyarylates were investigated to assess combined effects of asymmetric nature of bisphenol substitution, polar nature of substituent bromine, hexafluoroisopropylidene group present at the bridge position of bisphenol, and substituent present on the acid moiety. The combination of these substituent types led these polyarylates to lie near Robeson upper bound. The gas sorption analysis and estimation of diffusivity in these polyarylates shed a light on observed variations in gas permeation properties by attempted structural variations. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3156–3168, 2007     

Synthesis of soluble poly(para‐phenylene) with a long polymer chain: Characteristics of regioregular poly(1,4‐phenylene)

Soluble poly(para‐phenylene) having a long polymer chain (more than six repeat units) was synthesized with a tert‐butyl end‐group (t‐PPP) and was found to have improved solubility and excellent optical properties. Poly(1,3‐cyclohexadiene) (PCHD) consisting of only 1,4‐cyclohexadiene (1,4‐CHD) units was synthesized with a tert‐butyl end‐group (t‐PCHD), and completely dehydrogenated to obtain t‐PPP. This end‐group effectively prevented the crystallization of t‐PPP, and polymers containing up to 16 repeat units were soluble in tetrahydrofuran. Soluble t‐PPP obtained had an ability to form a tough thin film prepared by spin‐coating method. Optical analyses of t‐PPP provided strong evidence for a linear polymer chain structure. A block copolymer of t‐PPP and a soluble polyphenylene (PPH) was then synthesized, and the excellent optical properties were retained by this block copolymer along with its solubility. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5223–5231, 2008     

Diketopyrrolopyrrole‐based acceptor–acceptor conjugated polymers: The importance of comonomer on their charge transportation nature

Besides the donor–acceptor (D–A) type, acceptor–acceptor (A–A) polymers are another class of important alternative conjugated copolymers, but have been less studied in the past. In this study, two kinds of A–A polymers, P1 and P2 , have been designed and synthesized based on diketopyrrolopyrrole in combination with the second electron‐deficient unit, perylenediimide or thieno[3,4‐c]pyrrole‐4,6‐dione. UV–vis absorption spectroscopy revealed that these two kinds of polymers have a band gap of 1.28–1.33 eV. Their highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels are around ?5.6 and ?4.0 eV for P1 polymers, whereas ?5.4 and ?3.7 eV for P2 polymers, respectively. Density functional theory study disclosed that P1 backbone is in a vastly twisting state, whereas that of P2 is completely planar. Furthermore, organic field‐effect transistor devices were fabricated using these two kinds of polymers as the active material. Of interest, the devices based on P1 polymers displayed n‐channel behaviors with an electron mobility in the order of 10^?4 cm² V^?1 s^?1. In contrast, the P2 ‐based devices exhibited only p‐channel charge transportation characteristics with a hole mobility in the order of 10^?3 cm² V^?1 s^?1. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2356–2366     

Classification of homogeneous copolymers of propylene and 1‐octene based on comonomer content

The solid‐state structure and properties of homogeneous copolymers of propylene and 1‐octene were examined. Based on the combined observations from melting behavior, dynamic mechanical response, morphology with primarily atomic force microscopy, X‐ray diffraction, and tensile deformation, a classification scheme with four distinct categories is proposed. The homopolymer constitutes Type IV. It is characterized by large α‐positive spherulites with thick lamellae, good lamellar organization, and considerable secondary crystallization. Copolymers with up to 5 mol % octene, with at least 28 wt % crystallinity, are classified as Type III. Like the homopolymer, these copolymers crystallize as α‐positive spherulites, however, they have smaller spherulites and thinner lamellae. Both Type IV and Type III materials exhibit thermoplastic behavior characterized by yielding with formation of a sharp neck, cold drawing, strong strain hardening, and small recovery. Copolymers classified as Type II have between 5 and 10 mol % octene with crystallinity in the range of 15–28%. Type II materials have smaller impinging spherulites and thinner lamellae than Type III copolymers. Moreover, the spherulites are α‐negative, meaning that they exhibit very little crystallographic branching. These copolymers also contain predominately α‐phase crystallinity. The materials in this category have plastomeric behavior. They form a diffuse neck upon yielding and exhibit some recovery. Type I copolymers have more than 10 mol % octene and less than 15% crystallinity. They exhibit a granular texture with the granules often assembled into beaded strings that resemble poorly developed lamellae. Type I copolymers crystallize predominantly in the mesophase. Materials belonging to this class deform with a very diffuse neck and also exhibit some recovery. They are identified as elastoplastomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4357–4370, 2004     

基于荷移反应的高效液相色谱法测定氨基丁醇

建立了一种基于荷移反应的高效液相色谱测定氨基丁醇含量的分析方法。在pH 8.4的硼砂-硼酸缓冲溶液中,氨基丁醇与四氯苯醌于60℃反应60 min,利用高效液相色谱法-紫外检测器进行分析。荷移络合物采用Agilent Extend C18色谱柱（250 mm×4.6 mm,5 μm）分离,以0.001%（体积分数）三乙胺甲醇溶液为流动相进行梯度洗脱,流速为1 mL/min,检测波长为350 nm。该方法对氨基丁醇的定量限为0.01 g/L,线性范围为0.1~0.6 g/L,相关系数（R²）为0.9994;方法的加标回收率为98.3%~103.6%,相对标准偏差（RSD）为0.9%~1.6%。该法简便快捷,适用于氨基丁醇含量的快速检测。     

Response of a biphasic poly(n‐hexyl isocyanate)/p‐xylene solution to applied high electric fields

The effect of a high electric field on a solution of a lyotropic liquid‐crystalline polymer, poly(n‐hexyl isocyanate) in p‐xylene, was studied. The application of a high‐voltage alternating‐current electric field to the biphasic solution resulted in an elongation of the nematic domains in the field direction, the degree of elongation varying approximately with the square of the electric field. At a constant field, the extent of elongation decreased, varying inversely with the frequency in an exponential fashion. The domain structure and thus the molecular orientation were examined to explain these electric field effects. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1124–1133, 2005     

Synthesis and FET characterization of novel ambipolar and low‐bandgap naphthalene‐diimide‐based semiconducting polymers

A novel series of naphthalene‐diimide‐based semiconducting polymers ( P1–P4 ) containing benzodithiophene or dithienopyrrole were successfully synthesized for ambipolar semiconducting materials showing near infrared absorptions. The incorporation of a 3‐hexylthiophene (3HT) spacer extended the intramolecular charge‐transfer (ICT) peak from λ_onset = 739 nm ( P1 ) to 785 nm ( P3 ). Moreover, about 250 nm red‐shift of the ICT peaks was observed in P2 and P4 compared to P1 and P3 due to the increased high‐lying HOMO energy levels. The grazing incidence X‐ray scattering of the P3 and P4 films proved the slightly improved crystalline order in the π?π stacking direction, indicating that the planar backbone is probably due to the introduced 3HT. The P1–P4 ‐based field‐effect transistor showed n‐type dominant ambipolar characteristics. The P2 and P4 showed higher electron mobilities up to 1.5 × 10^?2 cm² V^?1 s^?1 than P1 and P3 , which might be influenced by the orientation of the polymer backbone and the intermolecular orbital overlap. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 359–367     

The effect of structural variations on aromatic polyethers for high‐temperature PEM fuel cells

Three series of new aromatic polyether sulfones bearing phenyl, p‐tolyl or carboxyl side groups, respectively, and polar pyridine main chain groups were developed. Most of the polymeric materials presented high molecular weights and excellent solubility in common organic solvents. More importantly, they formed stable, self‐standing membranes that were thoroughly characterized in respect to their thermal, mechanical and oxidative stability, their phosphoric acid doping ability and ionic conductivity. Particularly, the copolymers bearing side p‐tolyl or carboxyl groups fulfill all necessary requirements for application as proton electrolyte membranes in high temperature fuel cells, which are glass transition temperatures higher than 220 °C, thermal stability up to 400 °C, oxidative stability, high doping levels (DLs) and proton conductivities of about 0.02 S/cm. Initial single fuel cell results at high temperatures, 160 °C or 180 °C, using a copolymer bearing p‐tolyl side groups with a relatively low DLs around 200 wt % and dry H₂/Air feed gases, revealed efficient power generation with a current density of 0.5 A/cm² at 500 mV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of comb‐type polycarbosilanes via nucleophilic substitution reactions on the main‐chain silicon atoms

A series of comb‐type polycarbosilanes of the type [Si(CH₃)(OR)CH₂]_n {where R = (CH₂)_mR′, R′ = ? O‐p‐biphenyl? X [X = H (m = 3, 6, 8, or 11) or CN (m = 11)], and R′ = (CF₂)₇CF₃ (m = 4)} were prepared from poly(chloromethylsilylenemethylene) by reactions with the respective hydroxy‐terminated side chains in the presence of triethylamine. The product side‐chain polymers were typically greater than 90% substituted and, for R′ = ? O‐p‐biphenyl? X derivatives, they exhibited phase transitions between 27 and 150 °C involving both crystalline and liquid‐crystalline phases. The introduction of the polar p‐CN substituent to the biphenyl mesogen resulted in a substantial increase in both the isotropization temperature and the liquid‐crystalline phase range with respect to the corresponding unsubstituted biphenyl derivative. For R = (CH₂)₁₁? O‐biphenyl side chains, an analogous side‐chain liquid‐crystalline (SCLC) polysiloxane derivative of the type [Si(CH₃)(O(CH₂)₁₁? O‐biphenyl)O]_n was prepared by means of a catalytic dehydrogenation reaction. In contrast to the polycarbosilane bearing the same side chain, this polymer did not exhibit any liquid‐crystalline phases but melted directly from a crystalline phase to an isotropic liquid at 94 °C. Similar behavior was observed for the polycarbosilane with a fluorocarbon chain, for which a single transition from a crystalline phase to an isotropic liquid was observed at ?0.7 °C. The molecular structures of these polymers were characterized by means of gel permeation chromatography and high‐resolution NMR studies, and the crystalline and liquid‐crystalline phases of the SCLC polymers were identified by differential scanning calorimetry, polarized optical microscopy, and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 984–997, 2003     

Poly(vinylpyrrolidone)‐based films grown on copper surfaces

The influence of molecular weight and the amount of the poly(vinylpyrrolidone) (PVP) on the growth of poly(vinylpyrrolidone)–based films on copper surfaces was studied by electrochemical, infrared and electronic spectroscopy, and thermogravimetric methods. Complex polymer/metal ions were deposited onto a copper surface, as the result of the electrochemically generated reaction of copper cations with PVP and SCN^?, in sulfuric acid media. Spontaneous film growth on copper surfaces was generated and characterized as a Cu(II)/PVP/SCN^? complex. Infrared spectra and thermal gravimetric curves of the films generated at + 0.7 V were compared with the chemically synthesized complex, and show the same patterns. The oxidation process can be described as: Cu(0)→Cu(I) and Cu(I)→Cu(II), and the copper complex formed at more positive potentials was characterized as Cu(II)/PVP/SCN^?, with copper bonded to the oxygen atom of PVP and thiocyanate ligand N‐linked. This study focuses on the complex formation on a copper surface in acid media and its characterization through electrochemical and spontaneously generated reactions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2206–2214, 2009     

Synthesis and characterization of negative‐type photosensitive hyperbranched polyimides with excellent organosolubility from an A2 + B3 monomer system

A series of photosensitive hyperbranched polyimides (HB‐PIs) were prepared through facile end‐group modifications of the fully imidized polymer. A triamine, 1,3,5‐tris(4‐aminophenoxy)benzene, and a dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, were condensed with a dropwise addition method in a molar ratio of 1/2 to afford an anhydride‐terminated poly(amic acid) precursor, which was then end‐capped by 4‐aminophenol and chemically imidized to yield a phenol‐terminated HB‐PI. The modifications of the terminal phenol groups of the polyimide by acyl chloride compounds (acryloyl chloride, methylacryloyl chloride, and cinnamoyl chloride) gave the target polymers. The photosensitive HB‐PIs showed good thermal properties and excellent solubility even in low‐boiling‐point solvents at room temperature, such as acetone, 1,1,2‐trichloroethane, tetrahydrofuran, and chloroform. Photosensitive property studies revealed good photolithographic properties with a resolution greater than 3 μm and a sensitivity of 650–680 mJ/cm². © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1735–1744, 2004     

Syntheses and properties of novel fluorinated polyamides based on a bis(ether‐carboxylic acid) or a bis(ether amine) extended from bis(4‐hydroxyphenyl)phenyl‐2,2,2‐trifluoroethane

Two series of novel fluorinated aromatic polyamides were prepared from 1,1‐bis[4‐(4‐carboxyphenoxy)phenyl]‐1‐phenyl‐2,2,2‐trifluoroethane with various aromatic diamines or from 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐phenyl‐2,2,2‐trifluoroethane with various aromatic dicarboxylic acids with the phosphorylation polyamidation technique. These polyamides had inherent viscosities ranging from 0.51 to 1.54 dL/g that corresponded to weight‐average and number‐average molecular weights (by gel permeation chromatography) of 36,200–80,000 and 17,200–64,300, respectively. All polymers were highly soluble in aprotic polar solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide, and some could even be dissolved in less‐polar solvents like tetrahydrofuran. The flexible and tough films cast from the polymer solutions possessed tensile strengths of 76–94 MPa and initial moduli of 1.70–2.22 GPa. Glass‐transition temperatures (T_g's) and softening temperatures of these polyamides were observed in the range of 185–268 °C by differential scanning calorimetry or thermomechanical analysis. Decomposition temperatures (T_d's) for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. Almost all the fluorinated polyamides displayed relatively higher T_g and T_d values than the corresponding nonfluorinated analogues. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 420–431, 2003     

Synthesis of medium‐bandgap π‐Conjugated polymers based on isomers of 5‐Alkylphenanthridin‐6(5H)‐one and 6‐Alkoxylphenanthridine

Two novel dibromo monomers consisting of the isomers of 5‐alkylphenanthridin‐6(5H)‐one (PN) and 6‐alkoxylphenanthridine (PO) were synthesized through alkylation of the precursor 3,8‐dibromophenanthrindi‐6(5H)‐one, where the molecular structures were confirmed by NMR spectroscopy. The medium bandgap conjugated polymers PDBTPN and PDBTPO were constructed by utilizing such two isomers PN and PO as the electron‐donating units and dithiophenebenzo[2,1,3]diathiazole as the electron‐accepting unit. The resulting polymers exhibited analogous absorption profiles with optical bandgap of 1.90 eV, while PDBTPO showed slightly higher absorption coefficiency. Cyclic voltammetry measurements revealed that these polymers had relatively deep highest occupied molecular orbital levels of about ?5.70 eV. Polymer solar cells based on such two polymers showed relatively high open‐circuit voltage of about 0.90 V. All devices exhibited moderate performances with the best power conversion efficiency of 3.77% achieved based on PDBTPO. Devices based on PDBTPO showed slightly higher power conversion efficiency than those based on PDBTPN, which can be ascribed to higher hole mobility and more favorable film morphology of the former. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2119–2127     

Low‐CTE photosensitive polyimide based on semialicyclic poly(amic acid) and photobase generator

A negative‐type photosensitive polyimide (PSPI) based on semialicyclic poly(amic acid) (PAA), poly(trans‐1,4‐cyclohexylenediphenylene amic acid), and {[(4,5‐dimethoxy‐2‐nitrobenzyl)oxy]carbonyl} 2,6‐dimethylpiperidine (DNCDP) as a photobase generator has been developed as a next‐generation buffer coat material. The semialicyclic PAA was synthesized from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and trans‐1,4‐cyclohexyldiamine in the presence of acetic acid, and the PAA polymerization solution was directly used for PSPI formulation. This PSPI, consisting of PAA (80 wt %) and DNCDP (20 wt %), showed high sensitivity of 70 mJ/cm² and high contrast of 10.3, when it was exposed to a 365‐nm line (i‐line), postexposure baked at 190 °C for 5 min, and developed with 2.38 wt % tetramethylammonium hydroxide aqueous solution containing 20 wt % isopropanol at 25 °C. A clear negative image of 6‐μm line and space pattern was printed on a film, which was exposed to 500 mJ/cm² of i‐line by a contact printing mode and fully converted to poly(trans‐1,4‐cyclohexylenebiphenylene imide) pattern upon heating at 250 °C for 1 h. The PSPI film had a low coefficient of thermal expansion of 16 ppm/K compared to typical PIs, such as prepared from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and 4,4′‐oxydianiline. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1317–1323, 2010     

Polypropylene modified with elastomeric metallocene‐catalyzed polyolefin blends: Fracture behavior and development of damage mechanisms

The fracture behavior and deformation mechanisms of polypropylene modified by elastomeric metallocene‐catalyzed polyolefin blends were investigated under both static and dynamic loading conditions. The fracture toughness was evaluated with the J integral approach. The development of damage mechanisms was studied by the examination of fracture surfaces with scanning electron microscopy and by the examination of single‐edge, double‐notch, four‐point‐bending or low‐impact‐energy fractured samples with optical microscopy. In addition, tensile dilatometry measurements were carried out to determine the nature of the deformation micromechanisms. The fracture behavior and the size and shape of the damage zones were drastically influenced by the elastomeric particles and the imposed constraint. The role of the elastomeric particles was different, depending on the strain rate. Under impact loading, particle pullout and crazing were responsible for the increased fracture toughness of polypropylene. Under quasistatic loading, stable fracture growth was caused by particle cavitation, which promoted ductile tearing of polypropylene before failure continued in an unstable fashion via crazing. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1075–1089, 2004