Influence of the synthesis conditions on the curing behavior of phenol–urea–formaldehyde resol resins

The curing behavior of synthesized phenol–urea–formaldehyde (PUF) resol resins with various formaldehyde/urea/phenol ratios was studied with differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The results indicated that the synthesis parameters, including the urea content, formaldehyde/phenol ratio, and pH value, had a combined effect on the curing behavior. The pH value played an important role in affecting the shape of the DSC curing curves, the activation energy, and the reaction rate constant. Depending on the pH value, one or two peaks could appear in the DSC curve. The activation energy was lower when pH was below 11. The reaction rate constant increased with an increase in the pH value at both low and high temperatures. The urea content and formaldehyde/phenol ratio had no significant influence on the activation energy and rate constant. DMA showed that both the gel point and tan δ peak temperature (T_tanδ) had the lowest values in the mid‐pH range for the PUF resins. A different trend was observed for the phenol–formaldehyde resin without the urea component. Instead, the gel point and T_tanδ decreased monotonically with an increase in the pH value. For the PUF resins, a high urea content or a low formaldehyde/phenol ratio resulted in a high gel point. The effect of the urea content on T_tanδ was bigger than that on the gel point because of the reversible reaction associated with the urea component. Too much formaldehyde could lead to more reversible reactions and a higher T_tanδ value. The effects of the synthesis conditions on the rigidity of the cured network were complex for the PUF resins. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1368–1375, 2005     

EVALUATION OF LIQUID-LIQUID PARTITION COEFFICIENTS OF MULTTDENTATE AMINES BY SCALED PARTICLE THEORY

ABSTRACT

For some aliphatic and aromatic bidentate amines, e.g., ethylenedi-amine derivatives, which were used in the synergistic extraction system, the liquid-liquid partition coefficients (P) were measured between benzene and water phases and discussed together with other aliphatic and aromatic multidentate amines by using the scaled particle theory (SPT). The contributions of three kinds of Gibbs energies, i.e, the cavity formation energy (G¯_h), the dispersion energy (G¯_dis) and hydrogen-bonding energy (G¯_h), to the P values were successfully evaluated. The main factor to determine the P value was G¯_h (10–55 kJ/mol) in the aqueous phase, but the contributions of G¯_c (6–15 kJ/mol) and G¯_dis (6–28 kJ/mol) were not negligibly small.     

The perception of static colored noise: Detection and masking described by CIE94

We present psychophysical data on the perception of static colored noise. In our experiments, we use the CIE94 color difference formula to quantify the noise strength and for describing our threshold data. In Experiment 1 we measure the visual detection thresholds for fixed pattern noise on a uniform background color. The noise was present in one of three perceptual color dimensions lightness (L*), chroma (C*), or hue (h). Results show that the average detection threshold for noise in L* is independent of hue angle and significantly lower than that for noise in C* or h. Thresholds for noise in C* and h depend on hue angle in an opponent fashion. The measured detection thresholds, expressed in terms of the components ΔL*/k_LS_L, ΔC*/k_CS_C, and ΔH*/k_HS_H that build up the CIE94 color difference formula are used to tune CIE94 to our experimental conditions by adjusting the parametric scaling factors k_L, k_C, and k_H. In Experiment 2, we measure thresholds for recognizing the orientation (left, right, up, down) of a test symbol that was incremental in L*, C*, or h, masked by supra‐threshold background noise levels in L*, C*, or h. On the basis of the CIE94 color difference formula we hypothesized (a) a constant ratio between recognition threshold and noise level when the test symbol and background noise are in the same perceptual dimension, and (b) a constant recognition threshold when in different dimensions. The first hypothesis was confirmed for each color dimension, the second however, was only confirmed for background noise in L*. The L*, C*, h recognition thresholds increase with increasing background noise in C* or h. On the basis of some 16,200 visual observations we conclude that the three perceptual dimensions L*, C*, and h require different scaling factors (hue dependent for C* and h) in the CIE94 color difference formula, to predict detection threshold data for color noise. In addition these dimensions are not independent for symbol recognition in color noise. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 178–191, 2008     

Thermal,mechanical, and fracture properties of copolyureas formed by reaction injection molding: Effects of hard segment structure

A series of copolyureas containing 50% by weight hard segment have been formed by RIM. The hard segment structure was systematically varied to investigate the effects of urea group density, hard segment crosslinking, relative reaction rates, and to compare the properties of aromatic and aliphatic hard segment materials. In each case the soft segment was based on a 2000 molecular weight polyether diamine. The RIM materials formed ranged from flexible elastomers to brittle plastics depending on composition and were characterized by SAXS, DSC, DMA, tensile stress–strain and fracture mechanics studies. SAXS, DSC, and DMA showed that microphase separation had occurred to give materials with a non-equilibrium morphology. DMA and tensile stress–strain studies showed the small strain properties to be very sensitive to the volume fraction of glassy material whereas the ultimate properties were dependent on chemical structure of the hard segment. Fracture properties were determined using the single-edge notch technique. In most cases ductile failure occurred with G_c > 2.5 kJ m^?2 and the fracture surfaces showed gross yielding and tearing. In the case of the copolyurea with the highest urea group content, brittle fracture occurred with G_c = 0.06 kJ m^?2.     

Curing characteristics of urea–formaldehyde resin in the presence of various amounts of wood extracts and catalysts

The characteristics of urea–formaldehyde (UF) resin curing in the presence of wood extracts and a catalyst [ammonium chloride (NH₄Cl)] were investigated by differential scanning calorimetry (DSC). The effects of extracts from 16 wood species on resin curing behaviors were evaluated. A model developed in this study, T_p = 53.296 exp(?9.72C) + 93.104, could be used to predict the resin curing rate in terms of the DSC peak temperature (T_p) as influenced by the NH₄Cl content (C). The results indicated that the curing rate of UF resin increased as the catalyst content increased and reached a maximum when the catalyst content ranged from 0.5 to 1.0% (solid basis over liquid UF resin weight). Further increases in the catalyst content had no effect on the resin curing rate. The curing rates of UF resin in the presence of wood extracts increased with decreased pH values or increased base buffer capacities. It was also discovered that the activation energy could not fully explain the resin curing behavior when some species of wood extracts were present, and therefore, the pre‐exponential factor had to be taken into account. The concept of the equivalent catalyst content (ECC) of wood extracts to the NH₄Cl content was introduced in this study; ECCs ranged from 0.0022 to 0.0331% among the 16 wood species. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of linear low‐density polyethylene by in situ copolymerization of ethylene with Zr supported on montmorillonite/Fe/methylaluminoxane catalyst system

Linear low‐density polyethylene (LLDPE) was prepared by in situ copolymerization of ethylene with dual‐functional catalysts that were composed of rac‐Et(Ind)₂ZrCl₂ supported on montmorillonite (MMT) and {[(2‐ArN?C(Me))₂C₅H₃N]FeCl₂} [Ar = 2,4‐C₆H₄(Me)₂] oligomerization catalyst. A series of polyethylenes with different degrees of branching were obtained by adjusting the ratio of Fe and Zr (Fe/Zr). DSC, NMR, GPC, SEM, and density‐gradient method were used to characterize the polymers. With increasing Fe/Zr ratio, the densities and melting points of polymers decreased, whereas the branching degrees and molecular weights increased. When the Fe/Zr ratio was increased, the activities of the catalysts decreased at atmospheric pressure and increased at 0.7 MPa ethylene pressure. SEM micrographs revealed that the morphology of branched polyethylene, produced with the catalyst supported on MMT, is better than that produced by the catalyst in a homogeneous system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1690–1696, 2004     

Cocrystallization behavior of poly(n‐docosyl acrylate) with n‐docosanoic acid by X‐ray and differential scanning calorimetry studies

Cocrystallization behavior of comb‐like poly(n‐docosyl acrylate) (PDA) with n‐docosanoic acid (C₂₂) has been studied by means of differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) methods. The DSC curves of blended samples of neat PDA with C₂₂ show the characteristic melting endotherms that correspond to the melting of the crystallites. DSC measurements of PDA/C₂₂ blends also suggest the existence of another crystalline form induced by the addition of the C₂₂. From the XRD measurements, the existence of hexagonally‐packed crystalline lattice and the phase behavior of PDA/C₂₂ blends at different mole percent are confirmed. Thermal degradation behavior of PDA and its corresponding blends with C₂₂ is studied by thermogravimetric analysis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2140–2146, 2005     

Structural and Mechanical Properties Changes of Ethylene‐α‐olefin Copolymer Blends Induced by Thermal Treatments and Composition

Summary: Blends of single‐site catalysed ethylene‐α‐butene (C₄VLDPE) and ethylene‐α‐octene (C₈VLDPE) copolymers were prepared by melt extrusion. The phase morphology, thermal and mechanical properties of the blends have been investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile test and dynamic mechanical analysis (DMA). Depending on the composition and thermal history, significant differences in structure and behaviour were found. It was also found that some degree of co‐crystallization occurred for quenched blends; whereas most of the oven slowly cooled blends showed two well‐defined melting peaks, indicating that the slow cooling favoured partial segregation of the fractions with different degrees of branching to form two morphologies. Moreover, SEM revealed morphology of the thinner crystals distributed in‐between the thicker sheaf‐like crystals for the slowly cooled blends with 20–50% C₈VLDPE. Therefore, the synergism in mechanical properties for the blends with 20–50% C₈VLDPE is due to a combination of larger crystal size, more complete phase separation and interfacial interaction produced by the segregation effect of the slow cooling treatment. DMA studies showed that the storage modulus increased as the addition of C₈VLDPE and modulus for the slowly cooled blends are about twice those measured for the quenched ones, indicating higher stiffness of the blends. The smooth shift of β relaxation temperature with addition of C₈VLDPE for both sets of blends confirmed the miscibility in the amorphous phase.

SEM image of the C₄VLDPE‐C₈VLDPE (50/50) blend after oven slow cooling treatment.     

Chemical Structure and Curing Behavior of Phenol–Urea–Formaldehyde Cocondensed Resins of High Urea Content

Phenol–urea–formaldehyde cocondensed (PUF) resins of high urea content were prepared by adding different forms of urea to the reaction system. The structure, curing behavior, and water resistance of the PUF resins were investigated, and their relations were also discussed by liquid ¹³C nuclear magnetic resonance (NMR) and different scanning calorimetry (DSC). The liquid ¹³C-NMR analysis showed that urea added in the form of methylolureas was well incorporated into the cocondensed resins by reacting with phenolic methylols to form cocondensed methylene bridges, and that the PUF resins had no free formaldehyde with any form. Unreacted urea and low molecule monosubstituted urea of PUF resins play a dominant role in the curing behavior and water resistance of resins. The peak temperature, curing time, and curing enthalpy (ΔH) value correspondingly increased, however, the water resistance of PUF resins decreased when urea content in PUF resins increased. The PUF cocondensed resin with up to 89.4 % (W _U/W _P) urea has relatively low cost, and moreover can pass the requirements of China Industry Standard for the exterior grade of structural plywood after 4-h cyclic boiling test.     

Probing effects of alternately‐embedded phenoxy phenyl lateral groups on properties of novel aromatic poly(ether‐urea)s

A new class of alternate aromatic poly(ether‐urea)s having bulky phenoxy phenyl lateral groups was prepared by the reaction of 2,2′‐bis[(p‐phenoxy phenyl)]‐4,4′‐diaminodiphenyl ether (PPAPE) with two diisocyanates, isophorone diisocyanate and 2,4‐tolylene diisocyanate. The limited viscosity values as well as M _n and M _w values of the resulting polymers were determined. The resulting poly(ether‐urea)s could be easily cast into optically‐transparent, flexible, and light color films. The cut‐off wavelength values and the percentage of transmittance at 800 nm were found to be at about 415 nm and 85%, respectively. PPAPE‐derived poly(ether‐urea)s showed a low‐crystallinity and had excellent solubility in polar organic solvents. T_onset, T_g, T_d5%, and T_d10% values of the PPAPE‐derived polymers measured from their DSC and TGA thermograms were up to 270, 280, 315, and 340°C, respectively. Surface morphology of the resulted poly(ether‐urea)s were also evaluated by their scanning electron microscopy images. Excellent organo‐solubility, satisfactory film quality, moderate T_g values, and good thermal stability make this class of poly (ether‐urea)s promising high‐performance polymeric materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of paraffin microcapsules for energy-saving applications

A series of microencapsulated phase-change materials (PCMs) with styrene–divinyl benzene shells composed of an n-octadecane (OD or C₁₈)–n-hexadecane (HD or C₁₆) mixture as the core were synthesized by an emulsion polymerization method. The effects of the core/shell ratio (C/S) and surfactant concentration (C_surf) on the thermal properties and encapsulation ratios of the PCMs were investigated. The chemical structures and morphological properties of the microcapsules were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy analysis, respectively. The characteristic peaks of the paraffin mixtures and shell material located in the FTIR spectrum of the microencapsulated PCMs proved that the encapsulation of the PCM mixture was performed successfully. The thermal properties of the paraffin microcapsules were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis. DSC analysis demonstrated that the microcapsules containing the maximum amount of paraffin mixture (C/S = 2:1) and the minimum C_surf (45 mmol/L) had the highest latent heat value of 88 kJ/kg and a latent heat of temperature of 21.06°C. Moreover, the maximum encapsulation ratio of the paraffin mixture was found to be 56.77%. With respect to the analysis results, the encapsulated binary mixture, which consisted of OD–HD with a poly(styrene-co-divinyl benzene) shell, is a promising material for thermal energy storage applications operating at low temperatures, such as in the thermal control of indoor temperatures and air-conditioning applications in buildings for desirable thermal comfort and energy conservation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47874.     

Coagel Prepared from Aqueous Octyl β‐d‐Galactoside Solution

Structuring of semi‐crystalline networks in water systems is significant for a variety of industrial applications. In the present work, we investigated the coagel formation from aqueous octyl β‐d ‐galactoside (C₈‐β‐Gal) solutions and characterized the crystal structure and crystallite network in the prepared coagel. Differential scanning calorimetry (DSC) confirmed that the Krafft boundary temperature (T_K) is 32–35 °C for C₈‐β‐Gal concentrations below 30 wt% and a knee of the Krafft boundary exists around 2.5 wt% C₈‐β‐Gal concentrations. The addition of NaCl increased T_K slightly because of the salting‐out effect. Powder X‐ray diffraction (PXRD) analysis, field‐emission scanning electron microscopy (FE‐SEM) and atomic force microscopy (AFM) observations revealed that the coagel is comprised of the three dimensional bundled semi‐crystalline network consisting of a “ribbon crystal phase” of hemihydrate crystals. Moreover, the excellent ability of C₈‐β‐Gal to form a macroscopically homogeneous coagel was demonstrated by the comparison with other representative mono‐alkylated glycoside’ systems containing octyl a‐d ‐glucoside or dodecyl β‐d ‐glucoside. Persistence of the liquid phase without liquid–liquid phase separation prior to and during the coagel formation was a key factor for the preparation. A novel coagel was obtained from a principal synthetic galactoside.     

Effect of phase modifiers TBP and iso-decanol on the extraction and complexation of Eu3+ with CMPO

The effect of tri-n-butyl phosphate (TBP) and iso-decanol as phase modifiers on the complexation of Eu³⁺ with octyl-phenyl N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) was studied. On an increase of iso-decanol the extraction efficiency of Eu³⁺ decreases. The metal–ligand stoichiometry was found to be 1:3. The Eu complex of CMPO–TBP was more symmetric compared to CMPO–iso-decanol. The Eu³⁺ complex exhibited D_3h and C_3h symmetry for 30% and 5% iso-decanol, while that for TBP was C_6v. The radiative, non-radiative life time, electric and magnetic dipole transition probabilities, branching ratio, quantum efficiency etc. were evaluated. The covalency between Eu³⁺ and CMPO is as follows: CMPO–TBP < CMPO-5% iso-decanol < CMPO-30% iso-decanol.     

Conversion of canola oil to various hydrocarbons over Pt/HZSM-5 bifunctional catalyst

Canola oil conversion was studied at atmospheric pressure over Pt/HZSM-5 catalyst (0.5 mass% Pt) in a fixed bed micro-reactor. The operating conditions were: temperature range of 400?500°C, weight hourly space velocity (WHSV) of 1.8 and 3.6 h^?1 and steam/oil ratio of 4. The objective was to optimize the amount of gasoline range hydrocarbons in the organic liquid product (OLP) and the selectivity towards olefins and isohydrocarbons in the gas product. The gas yields varied between 22–65 mass% and were higher in the presence of steam compared to the operation without steam. The olefin/paraffin mass ratio of C₂-C₄ hydrocarbon gases varied between 0.31–0.79. The isohydrocarbons/n-hydrocarbons ratio was higher with Pt/HZSM-5 (1.6–4.8) compared with pure HZSM-5 catalyst (0.2–1.0). The OLP yields with Pt/HZSM-5 (20–55 mass% of canola oil) were slightly lower compared to HZSM-5 (40–63 mass% of canola oil) under similar conditions. The major components of OLP were aliphatic and aromatic hydrocarbons. A scheme postulating the reaction pathways for the conversion of canola oil over Pt/HZSM-5 catalyst is also presented.     

One-pot Synthesis of 5-Unsubstituted 3,4-Dihydropyrimidin-2(1H)-ones from Aldehydes,Ketones, and Urea under Solvent-free Conditions

Various 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones were synthesized efficiently by a one-pot three-component condensation of aromatic aldehydes, aromatic ketones, and urea using SnCl₂·2H₂O as a catalyst under solvent-free conditions. All products were identified by IR, NMR, MS, and elemental analysis. The novel method offers several advantages such as excellent yields (81–95%), short reaction time (5–16 min), broader substrate scope, and environmentally friendly conditions.     

Phase relationships of rigid rod polymer/flexible coil polymer/solvent ternary systems

Phase diagrams of two types of rigid rod polymer/flexible coil polymer/methanesulfonic acid (MSA) ternary systems were determined by polarized optical microscopy at ambient conditions. The rigid rod polymer is a wholly aromatic high temperature resistant (no measurable T_g) poly (p-phenylenebenzobisthiazole) (PPBT). One of the flexible coil polymers is a wholly aromatic high temperature resistant poly (2,5′(6′) benzimidazole) (ABPBI), the other is a thermoplastic poly[2,2′ -(1–4-phenylene)-6,6′ -bis (3-phenyl-quinoxaline)] (PPQ) with T_g of 359°C. The solvent is methane-sulfonic acid (MSA). The experimentally determined critical concentration points, C_cr, are in excellent agreement with Flory's recent theory. Total phase segregation between the polymer pair in ternary solution was predicted and observed at C > C_cr. Different decomposition mechanisms of phase separation were observed as a function of concentration.     

Experimental assessment of the thermodynamic theory of the compositional variation of Tg: PVC systems

The glass-transition temperatures (T_g's) and specific heats (C_p) of poly(vinyl chloride) (PVC) and PVC plasticized with 5–120 phr di(2-ethylhexyl) adipate (DOA) and tri(2-ethylhexyl) trimellitate (TOTM) have been determined by differential scanning calorimetry (DSC). Measured T_g's were compared to predictions by the Couchman and Karasz (C–K) thermodynamic theory, three related empirical equations, and a new equation obtained from the C–K relation by assuming the product T_gΔC_p to be constant. It was found that the T_g's of the PVC/TOTM mixtures are adequately predicted only by the C–K and the derivative relation. The T_g's of the PVC/DOA mixtures follow a sigmoidal or cusp-like dependence on plasticizer composition as has been observed for some other PVC/plasticizer mixtures. In this case, the approximation afforded by the C–K or derivative equations is still superior to the empirical models over a wide composition range. Dynamic mechanical analysis of the PVC/DOA mixtures suggests that the DSC transitions may consist of two overlapping phase transitions. The reported sigmoidal composition dependence of the DSC T_g's may therefore result from the measured T_g's being weighted towards the temperature corresponding to the predominant dynamic mechanical transition (i.e., the high T_g phase at low plasticizer concentrations and the low T_g phase at high plasticizer concentrations). In such cases of partial phase separation, the C–K or the derivative equation may be used to estimate the composition of the two phases at each overall plasticizer concentration.     

Hybrid 2D nanofibers based on poly(ethylene oxide)/polystyrene matrix and poly(ferrocenylphosphinoboranes) as functional agents

Template smart inorganic polymers within an organic polymeric matrix to form hybrid nanostructured materials are a unique approach to induce novel multifunctionality. In particular, the fabrication of one-dimensional materials via electrospinning is an advanced tool, which has gained success in fulfilling the purpose to fabricate two-dimensional nanostructured materials. We have explored the formation of novel hybrid nanofibers by co-spinning of poly(ferrocenylphosphinoboranes) Fe A [{Fe(C₅H₅)(C₅H₄CH₂PHBH₂)} _n] and Fe B [{Fe(C₅H₅)(C₅H₄PHBH₂)} _n] with poly(ethylene oxide) (PEO) and polystyrene (PS). Fe A and Fe B contain main-group elements and a ferrocene moiety as pendent group and have different properties compared to their only carbon-containing counterparts. The use of PEO and polystyrene provided a matrix to spin those inorganic polymers as hybrid nanofibers which were collected in the form of a nonwoven mat. They were characterized by multinuclear NMR spectroscopy, scanning electron microscopy (SEM), and IR spectroscopy. Thermal properties of the polymers have been checked by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ¹H, ³¹P, and ¹¹B NMR and IR spectroscopy revealed the nature and types of interactions of the components after co-spinning. The SEM micrographs identify the underlying unidirectional morphology of the generated hybrid nanofibers. Nonetheless, the DSC and TGA confirmed the significant boost toward the thermal stability of the resultant multifunctional fibers. It is believed that these unique types of multifunctional electrospun nanofibers will open new avenues toward the next generation of miniaturized devices.     

Remendable polymers via reversible Diels–Alder cycloaddition of anthracene‐containing copolymers with fullerenes

Poly(lauryl methacrylate)s with anthracene moieties in the side chain were converted with C₆₀‐fullerene and phenyl‐C₆₁‐butyric acid methyl ester (PCBM), resulting in new remendable (self‐healing) polymeric materials. The utilization of differently substituted anthracene monomers enabled the tuning of the reactivity and the resulting mechanical properties. Copolymers with different contents of the anthracene moieties were synthesized and characterized using size exclusion chromatography, ¹H nuclear magnetic resonance (NMR) spectroscopy as well as differential scanning calorimetry (DSC). ¹H NMR spectroscopic studies were utilized in order to investigate the reversibility of the Diels–Alder reaction between copolymers with C₆₀‐fullerene and PCBM, respectively, in solution. In order to investigate the conversion of the polymers with C₆₀‐fullerene and PCBM in bulk, additionally, DSC, nanoindentation, rheology, atomic force microscopy (AFM), 3D microscopy, simultaneous thermal analysis (STA) and FT‐Raman investigations were performed. The fullerene‐containing copolymers could be healed in a temperature range of 40–80 °C. Consequently, a new generation of low temperature remendable polymers could be established. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45916.     

Direct synthesis of poly(D,L‐lactic acid) by melt polycondensation and its application in drug delivery

Starting from D,L ‐acid and SnCl₂ as catalyst, poly(D,L ‐lactic acid) (PDLLA) was directly synthesized by melt polycondensation. Under the appropriate conditions such as 0.5 wt % SnCl₂, 170–180°C, 70 Pa, and 10 h, the viscosity‐average molecular weight (M_η) of PDLLA was 4100 Da. PDLLA produced by the most practical method was used as the drug‐delivery material for erythromycin and ciprofloxacin. The optimal conditions for the preparation of erythromycin–poly(D,L ‐lactic acid)–microsphere (ERY–PDLLA–MS) for lung targeting was investigated, and further confirmed by good reappearance tests. DSC and SEM demonstrated that ERY–PDLLA–MS had good spherical shape. The release in vitro of ERY–PDLLA–MS was effective and the half‐time (T_1/2) was 51.0 h. After 175 h, the accumulated release percentage was 80.0%. The test in vivo showed that ERY–PDLLA–MS was more easily distributed in rabbit lung tissue. When PDLLA was applied in an antibacterial ciprofloxacin drug‐delivery microsphere (CIP–PDLLA–MS), CIP–PDLLA–MS was also characterized with DSC and SEM, and the release T_1/2 in vitro was 24.9 h. After 53.2 h, the accumulated release percentage reached 84.0%, which indicated that CIP–PDLLA–MS was advantageous to long‐term release. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2143–2150, 2004