Miscibility and hydrogen‐bonding interactions in blends of carbon dioxide/epoxy propane copolymer with poly(p‐vinylphenol)

The miscibility and hydrogen‐bonding interactions of carbon dioxide and epoxy propane copolymer to poly(propylene carbonate) (PPC)/poly(p‐vinylphenol) (PVPh) blends were investigated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). The single glass‐transition temperature for each composition showed miscibility over the entire composition range. FTIR indicates the presence of strong hydrogen‐bonding interassociation between the hydroxyl groups of PVPh and the oxygen functional groups of PPC as a function of composition and temperature. XPS results testify to intermolecular hydrogen‐bonding interactions between the oxygen atoms of carbon–oxygen single bonds and carbon–oxygen double bonds in carbonate groups of PPC and the hydroxyl groups of PVPh by the shift of C_1s peaks and the evolution of three novel O_1s peaks in the blends, which supports the suggestion from FTIR analyses. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1957–1964, 2002     

Effect of inert diluent segment on the miscibility behavior of poly(vinylphenol) with poly(acetoxystyrene) blends

Polymer blends of poly(vinylphenol) (PVPh) and poly(styrene‐co‐vinylphenol) with poly(p‐acetoxystyrene) (PAS) were prepared by solution casting from tetrahydrofuran solution. The thermal properties and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. Although hydrogen bonding existed between the PVPh and PAS segments, the experimental results indicated that PVPh is immiscible with PAS as shown by the existence of two glass‐transition temperatures over the entire composition range by DSC. This phenomenon is attributed to the strong self‐association of PVPh, intramolecular screening, and functional group accessibility effects of the PVPh/PAS blend system. However, the incorporation of an inert diluent moiety such as styrene into the PVPh chain renders the modified polymer to be miscible with PAS. Copolymers containing between 16 and 51 mol % vinylphenol were fully miscible with PAS according to DSC studies. These observed results were caused by the reduction of the strong self‐association of PVPh and the increase of the interassociation between PVPh and PAS segments with the incorporation of styrene on the PVPh chain. According to the Painter‐Coleman association model, the interassociation equilibrium constant of PVPh/PAS blends was determined by a model compound and polymer blend. Good correlation between these two methods was obtained after considering the intramolecular screening and functional group accessibility effect in the polymer blend. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1661–1672, 2002     

Spontaneous thinning/thickening deformation observed for plastic blend films and some factors affecting film deformation

The fully amorphous films of highly syndiotactic poly[(R,S)‐3‐hydroxybutyrate] (s‐PHB)/atactic poly(4‐vinylphenol) (PVPh) blends show reversible thinning/thickening phenomena at 37 °C in aqueous medium. On the other hand, isotactic poly[(R)‐3‐hydroxybutyrate] (i‐PHB)/PVPh blend film, in which i‐PHB blend component was partially crystalline, did not show any thinning/thickening phenomena under the same conditions. To elucidate the factors influencing these phenomena, the structure and molecular interaction in these blends were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and wide‐angle X‐ray diffraction. The FTIR spectra indicated that the ester carbonyl of PHB and the phenolic hydroxyl of PVPh formed hydrogen bonds in both the thinned and thickened s‐PHB/PVPh blend films. The blend composition, intermolecular hydrogen‐bonding interaction, crystallization behavior, miscibility, and the glass‐transition temperature of the blends affected the thinning/thickening phenomena. Some other polyesters such as poly(?‐caprolactone), poly (L‐lactic acid), atactic poly(D,L‐lactic acid), and poly(ethylene terephthalate) had no ability to exhibit thinning/thickening phenomena in water at 37 °C when they were blended with PVPh. This result implies that s‐PHB/PVPh is the rare example with the ability to show reversible thinning/thickening phenomena. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2736–2743, 2002     

Hydrogen‐bonding interaction and miscibility between poly(ε‐caprolactone) and enzymatically polymerized novel polyphenols

The intermolecular hydrogen‐bonding interaction and miscibility between enzymatically prepared novel polyphenols [poly(bisphenol A) and poly(p‐tert‐butyl phenol)] and poly(ε‐caprolactone) (PCL) were investigated as a function of composition by Fourier transform infrared spectroscopy (FTIR) and DSC. The blend films of PCL and polyphenols were prepared by casting polymer solution. The FTIR spectra clearly indicated that PCL and polyphenols interact through strong intermolecular hydrogen bonds formed between the PCL carbonyls and the polyphenol hydroxyl groups. The melting point and degree of crystallinity of the PCL component decreased with an increased polyphenol content. A single glass‐transition temperature was observed for the blend, and its value increased with the content of polyphenol, indicating that PCL and polyphenols are miscible in the amorphous state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2898–2905, 2001     

Epoxy resin/poly(ϵ‐caprolactone) blends cured with 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane. II. Studies by Fourier transform infrared and carbon‐13 cross‐polarization/magic‐angle spinning nuclear magnetic resonance spectroscopy

Crystalline thermosetting blends composed of 2,2′‐bis[4‐(4‐aminophenoxy)phenyl]propane‐crosslinked epoxy resin (ER) and poly(?‐caprolactone) (PCL) were investigated by means of Fourier transform infrared (FTIR) spectroscopy and high‐resolution solid‐state NMR spectroscopy. FTIR investigations indicated that there were specific intermolecular interactions between ER and PCL and that the intermolecular hydrogen‐bonding interactions were weaker than the self‐association in pure epoxy. The intermolecular hydrogen bonding was considered to be the driving force for the miscibility of the thermosetting blends. For the examination of the miscibility of the thermosetting blends at the molecular level, high‐resolution solid‐state ¹³C cross‐polarity/magic‐angle spinning (CP‐MAS) NMR spectroscopy was employed. The line width of ¹³C CP‐MAS spectra decreased with increasing PCL contents, and the chemical shift of the carbonyl carbon resonance of PCL shifted to a low field with an increasing epoxy content in the blends. The proton spin–lattice relaxation experiments in the laboratory frame showed that all the blends possessed identical, composition‐dependent relaxation times (i.e., the proton spin–lattice relaxation times in the laboratory frame), suggesting that the thermosetting blends were homogeneous on the scale of 20–30 nm in terms of the spin‐diffusion mechanism, and this was in a good agreement with the results of differential scanning calorimetry and dynamic mechanical analysis. For the examination of the miscibility of the blends at the molecular level, the behavior of the proton lattice relaxation in the rotating frame was investigated. The homogeneity of the thermosetting blends at the molecular level was quite dependent on the blend composition. The PCL‐lean ER/PCL blends (e.g., 70/30) displayed a single homogeneous amorphous phase, and the molecular chains were intimately mixed on the segmental scale. The PCL‐rich blends displayed biexponential decay in experiments concerning the proton spin–lattice relaxation times in the rotating frame, which was ascribed to amorphous and crystalline phases. In the amorphous region, the molecular chains of epoxy and PCL were intimately mixed at the molecular level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1099–1111, 2003     

Studies on poly(ε‐caprolactone)/thiodiphenol blends: The specific interaction and the thermal and dynamic mechanical properties

The effects of several low molecular weight compounds with hydroxyl groups on the physical properties of poly(ε‐caprolactone) (PCL) were investigated by Fourier transform infrared (FTIR) spectroscopy and high‐resolution solid‐state ¹³C NMR. PCL and 4,4′‐thiodiphenol (TDP) interact through strong intermolecular hydrogen bonds and form hydrogen‐bonded networks in the blends at an appropriate TDP content. The thermal and dynamic mechanical properties of PCL/TDP blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis, respectively. The melting point of PCL decreased, whereas both the glass‐transition temperature and the loss tangent tan δ of the blend increased with an increase in TDP content. The addition of 40 wt % TDP changed PCL from a semicrystalline polymer in the pure state to a fully amorphous elastomer. The molecules of TDP lost their crystallizability in the blends with TDP contents not greater than 40 wt %. In addition to TDP, three other PCL blend systems with low molecular weight additives containing two hydroxyl groups, 1,4‐dihydroxybenzene, 1,4‐di‐(2‐hydroxyethoxy) benzene, and 1,6‐hexanediol, were also investigated with FTIR and DSC, and the effects of the chemical structure of the additives on the morphology and thermal properties are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1848–1859, 2000     

Competitive hydrogen bonding and self‐assembly in poly(2‐vinyl pyridine)‐block‐poly(methyl methacrylate)/poly(hydroxyether of bisphenol A) blends

Blends of poly(2‐vinyl pyridine)‐block‐poly(methyl methacrylate) (P2VP‐b‐PMMA) and poly(hydroxyether of bisphenol A) (phenoxy) were prepared by solvent casting from chloroform solution. The specific interactions, phase behavior and nanostructure morphologies of these blends were investigated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In this block copolymer/homopolymer blend system, it is established that competitive hydrogen bonding exists as both blocks of the P2VP‐b‐PMMA are capable of forming intermolecular hydrogen bonds with phenoxy. It was observed that the interaction between phenoxy and P2VP is stronger than that between phenoxy and PMMA. This imbalance in the intermolecular interactions and the repulsions between the two blocks of the diblock copolymer lead to a variety of phase morphologies. At low phenoxy concentration, spherical micelles are observed. As the concentration increases, PMMA begins to interact with phenoxy, leading to the changes of morphology from spherical to wormlike micelles and finally forms a homogenous system. A model is proposed to describe the self‐assembled nanostructures of the P2VP‐b‐PMMA/phenoxy blends, and the competitive hydrogen bonding is responsible for the morphological changes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1894–1905, 2009     

Miscible blends of poly(vinyl phenyl ketone) and poly(4‐vinyl phenol)

An analysis by differential scanning calorimetry, modulated differential scanning calorimetry, and Fourier transform infrared spectroscopy (FTIR) indicates that blends of poly(vinyl phenyl ketone) (PVPhK) and poly(4‐vinyl phenol) (P4VPh) are miscible at ambient temperature. Miscibility, ascertained, is supported by the existence of a single glass transition for each composition of the PVPhK/P4VPh blends. The FTIR spectroscopy analysis demonstrates the formation of hydrogen bonds between carbonyl groups of PVPhK and hydroxyl groups of P4VPh. This specific interaction has a crucial role on the miscibility behavior of PVPhK/P4VPh blends. The evolution of the glass transition of the PVPhK, P4VPh, and its blends as a function of mixture composition shows negative deviations with to respect to the ideal mixing rule, and both Fox and Gordon–Taylor equations predict this behavior successfully. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2404–2411, 2006     

Supramolecular inclusion complexes of star‐shaped poly(ε‐caprolactone) with α‐cyclodextrin

Both star‐shaped poly(ε‐caprolactone) (PCL) having 4 arms (4sPCL) and 6 arms (6sPCL) and linear PCL having 1 arm (LPCL) and 2 arms (2LPCL) were synthesized and then investigated for inclusion complexation with α‐cyclodextrin (α‐CD). The supramolecular inclusion complexes (ICs) were in detail characterized by ¹H NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X‐ray diffraction, solid‐state carbon nuclear magnetic resonance spectroscopy using cross‐polarization and magic‐angle spinning, and Fourier transform infrared, respectively. The stoichiometry (CL:CD, mol:mol) of all ICs increased with the increasing branch arm of PCL polymers, and it was in the order of α‐CD‐6sPCL1 ICs > α‐CD‐4sPCL ICs > α‐CD‐2LPCL ICs > α‐CD‐LPCL ICs. All analyses indicated that the branch arms of star‐shaped PCL polymers were included into the hydrophobic α‐CD cavities and their original crystalline properties were completely suppressed. Moreover, the ICs of star‐shaped PCL with α‐CD had a channel‐type crystalline structure similar to that formed between the linear PCL and α‐CD. Furthermore, the thermal stability of the free PCL polymers probably controlled that of the guest polymers included in the ICs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4721–4730, 2005     

Competitive specific interactions in miscible blends of poly(hydroxyether terephthalate ester) and poly(4‐vinyl pyridine)

The miscibility of poly(hydroxyether terephthalate ester) (PHETE) with poly(4‐vinyl pyridine) (P4VP) was established on the basis of thermal analysis. Differential scanning calorimetry showed that each blend displayed a single glass‐transition temperature (T_g), which is intermediate between those of the pure polymers and varies with the composition of blend. The T_g‐composition relationship can be well described with Kwei equation with k = 1 and q = ?30.8 (K), suggesting the presence of the intermolecular specific interactions in the blend system. To investigate the intermolecular specific interactions in the blends, the model compounds such as 1,3‐diphenoxy‐2‐propanol, 4‐methyl pyridine, and ethyl benzoate were used to determine the equilibrium constants, according to Coleman and Painter model, to account for the association equilibriums of several structural moieties, using liquid Fourier transform infrared difference spectroscopy. In terms of the difference in the association equilibrium constant, it is proposed that there are the competitive specific interactions in the blends, which were confirmed by means of Fourier transform infrared spectroscopy of the blends. It is observed that upon adding P4VP to the system, the ester carbonyls of PHETE that were H‐bonded with the hydroxyl groups were released because of the formation of the stronger interchain association via the hydrogen bonding between the hydroxyls of PHETE and tertiary nitrogen atoms of P4VP. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1618–1626, 2006     

Crystallizability of Poly(ε-caprolactone) Blends with Poly(vinylphenol) under Different Conditions

The intermolecular interaction between poly（vinylphenol） （PVPh） and polycaprolactone （PCL） and the crystallization behavior of PCL in PCL/PVPh blends with different compositions and under different conditions were investigated by Fourier transform infrared spectra （FTIR） and differential scanning calorimetry （DSC）. It has been shown that the PCL in the blends with different blend ratios all exists in crystalline state after solution casting, even though the crystallinity decreases with increasing PVPh content. For the melt crystallized samples, PCL in its 80/20 PCL/PVPh sample can still crystallize. The crystallinity is, however, lower than that of the solution cast sample. For blends containing 50% or 20% PCL, the as-cast samples are semicrystalline and can change to compatible amorphous state after heat treatment process. FTIR analysis shows the existence of hydrogen bonding between PCL and PVPh and the fraction of hydrogen bonds increases remarkably after heat treatment process.     

Inorganic–organic hybrids involving poly(ε‐caprolactone) and silica network: Hydrogen‐bonding interactions and isothermal crystallization kinetics

Inorganic–organic hybrids mediated by hydrogen‐bonding interactions involving silicon oxide network and poly(ε‐caprolactone) (PCL) were prepared via an in situ sol–gel process of tetraethoxysilane in the presence of PCL. Fourier transform infrared spectroscopy indicated that there were hydrogen‐bonding interactions between carbonyls of PCL and silanol hydroxyls that were formed by incomplete polycondensation in the sol–gel process. In terms of the frequency shift of the hydroxyl stretching vibration bands, it is concluded that the strength of the interassociation between PCL and silicon oxide networks is weaker than that of the self‐association in the control silica network. The phenomenon of equilibrium melting point depression was observed for the PCL/silica system. The hybridization of PCL with silica network causes a considerable increase in the overall crystallization rate and dramatically influences the mechanism of nucleation and growth of the PCL crystallization. The analysis of isothermal crystallization kinetic data according to the Hoffman‐Lauritzen theory shows that with increasing silica content in the hybrids, the surface energy of extremity surfaces increases dramatically for the hybrids. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2594–2603, 2005     

Blends of poly(3‐hydroxybutyrate)/4,4′‐thiodiphenol and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ 4,4′‐thiodiphenol: Specific interaction and properties

The specific interaction between poly(3‐hydroxybutyrate) [P(3HB)] and 4,4′‐thiodiphenol (TDP) and between poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and TDP was investigated by Fourier transform infrared (FTIR) spectroscopy. Interassociated hydrogen bonds were found between the polyester chains and the TDP molecules in the binary blends. The fractions of associated carbonyl groups, F_b 's, in the blends first increased and then decreased as the TDP content increased. The thermal and dynamic mechanical properties of P(3HB)–TDP and PHBV–TDP blends were investigated by differential scanning calorimetry and dynamic mechanical thermal analysis, respectively. Thermal analysis revealed that the P(3HB)–TDP blends possessed eutectic phase behavior. Furthermore, it was found that the thermal and dynamic mechanical properties of P(3HB) and PHBV were greatly modified through blending with TDP. Environmental degradability in river water was evaluated by a biochemical oxygen demand tester, and it was clarified that TDP lowered the degradation rate of P(3HB). The results suggest that TDP is effective in modifying the physical properties as well as the biodegradability of polyesters. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2891–2900, 2000     

Synthesis and characterization of hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators

Three UV‐sensitive, hyperbranched‐poly(siloxysilane)‐based polymeric photoinitiators, bearing an alkyl phenone moiety linked to the surface of the hyperbranched polymer, were synthesized via the hydrosilylation of hyperbranched poly(siloxysilane) and modified UV‐sensitive compounds. Hyperbranched poly(siloxysilane) was prepared via the polyhydrosilylation of the AB₂‐type monomer methylvinyldichlorosilane. The chemical structures of the polymeric photoinitiators were characterized with ¹H, ¹³C, and ²⁹Si NMR, elemental analysis, Fourier transform infrared, differential scanning calorimetry, UV spectrophotometry, and thermogravimetric analysis. The UV‐curing behaviors of the blends of the hyperbranched polymeric photoinitiators with UV‐curable epoxy acrylate (EA) resin were determined by Fourier transform infrared, and the results showed that the initiation efficiency of the polymeric photoinitiators was excellent and that the thermostability of the EA/polymeric photoinitiator curing systems was higher than that of the EA/photoinitiators. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3261–3270, 2006     

Synthesis and characterization of poly(β‐hydroxybutyrate) and poly(ϵ‐caprolactone) copolyester by transesterification

To synthesize the copolyester of poly(β‐hydroxybutyrate) (PHB) and poly(?‐caprolactone) (PCL), the transesterification of PHB and PCL was carried out in the liquid phase with stannous octoate as the catalyzer. The effects of reaction conditions on the transesterification, including catalyzer concentration, reaction temperature, and reaction time, were investigated. The results showed that both rising reaction temperature and increasing reaction time were advantageous to the transesterification. The sequence distribution, thermal behavior, and thermal stability of the copolyesters were investigated by ¹³C NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction, optical microscopy, and thermogravimetric analysis. The transesterification of PHB and PCL was confirmed to produce the block copolymers. With an increasing PCL content in the copolyesters, the thermal behavior of the copolyesters changed evidently. However, the introduction of PCL segments into PHB chains did not affect its crystalline structure. Moreover, thermal stability of the copolyesters was little improved in air as compared with that of pure PHB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1893–1903, 2002     

Library synthesis and characterization of 3‐aminopropyl‐terminated poly(dimethylsiloxane)s and poly(ϵ‐caprolactone)‐b‐poly(dimethylsiloxane)s

Libraries of 3‐aminopropyl‐terminated poly(dimethylsiloxane) (APT–PDMS) and poly(?‐caprolactone)–poly(dimethylsiloxane)–poly(?‐caprolactone) (PCL—PDMS–PCL) triblock copolymers were synthesized. Preliminary experiments were carried out to select an appropriate catalyst and route for the poly(dimethylsiloxane) synthesis, and trial experiments were conducted to verify the successful synthesis of the intended polymer compositions. Then, a series of APT–PDMS oligomers were synthesized with an automated combinatorial high‐throughput synthesis system to cover a molecular weight range of 2500–50,000 g/mol. Trial PCL—PDMS–PCL triblock copolymers were synthesized with the automated reactor system and characterized in detail with rapid gel permeation chromatography, high‐throughput Fourier transform infrared, nuclear magnetic resonance, and differential scanning calorimetry. Finally, two library synthesis experiments were carried out in which the lengths of both the poly(dimethylsiloxane) and poly(?‐caprolactone) blocks in the PCL—PDMS–PCL triblock copolymers were varied. The results obtained from these experiments demonstrated that it was possible to synthesize libraries of well‐defined APT–PDMS oligomers and PCL—PDMS–PCL triblock copolymers with an automated high‐throughput system. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4880–4894, 2006     

Hydrogen‐Bonding Interaction and Crystalline Morphology in the Binary Blends of Poly(ε‐caprolactone) and Polyphenol Catechin

The specific intermolecular hydrogen‐bonding interaction between the ester carbonyl groups of poly(ε‐caprolactone) (PCL) and the phenolic hydroxyl groups of catechin has been studied by Fourier‐transform infrared spectroscopy (FT‐IR) and differential scanning calorimetry (DSC). According to quantitative curve‐fitting analysis of the FT‐IR spectra of PCL/catechin blends, it was found that the fraction of hydrogen‐bonded carbonyl groups of PCL increased with catechin content, while that of hydrogen‐bonded hydroxyl groups of catechin decreased. The calculated crystallinity of PCL in the binary blends, based on the curve‐fitting results, suggested that the crystallization of PCL was restrained in the blends with catechin. Only single glass transition temperature, T_g, was observed over the whole range of blend compositions, which was between those of the pure components. The melting point, T_m, depressed and T_g increased, indicating also the existence of strong intermolecular association. The blend composition dependence of T_g could be predicted very well by the Kwei equation with a positive ‘q’ value of 124. With the aid of small angle X‐ray scattering measurement, the segregation of catechin was investigated. It was found that the extent of extra‐lamellar segregation increased with catechin content. It was suggested that the crystal growth rate played the dominant role in the formation of morphology. With decreasing crystal growth rate of PCL component in the blends, enough time has been given to catechin molecules to diffuse into extra‐lamellar region.

     

Thermal behavior and intermolecular interactions in blends of poly(3‐hydroxybutyrate) and maleated poly(3‐hydroxybutyrate) with chitosan

The thermal behavior and intermolecular interactions of blends of poly(3‐hydroxybutyrate) (PHB) and maleated PHB with chitosan were studied with differential scanning calorimetry, Fourier transform infrared (FTIR), wide‐angle X‐ray diffraction (WAXD), and X‐ray photoelectron spectroscopy (XPS). The differences in the two blend systems with respect to their thermal behavior and intermolecular interactions were investigated. The melting temperatures, melting enthalpies, and crystallinities of the two blend systems gradually decreased as the chitosan content in the blends increased. Compared with that of the PHB component with the same composition, the crystallization of the maleated PHB component was more intensively suppressed by the chitosan component in the blends because of the rigid chitosan molecular chains and the intermolecular hydrogen bonds between the components. FTIR, WAXD, and XPS showed that the intermolecular hydrogen bonds in the blends were caused by the carbonyls of PHB or maleated PHB and chitosan aminos, and their existence depended on the compositions of the blends. The introduction of maleic anhydride groups onto PHB chains promoted intermolecular interactions between the maleated PHB and chitosan components. In addition, the intermolecular interactions disturbed the original crystal structures of the PHB, maleated PHB, and chitosan components; this was further proven by WAXD results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 35–47, 2005     

Phase behavior,crystallization, and morphology in thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin and poly(ϵ‐caprolactone)

Thermosetting blends of a biodegradable poly(ethylene glycol)‐type epoxy resin (PEG‐ER) and poly(?‐caprolactone) (PCL) were prepared via an in situ curing reaction of poly(ethylene glycol) diglycidyl ether (PEGDGE) and maleic anhydride (MAH) in the presence of PCL. The miscibility, phase behavior, crystallization, and morphology of these blends were investigated. The uncured PCL/PEGDGE blends were miscible, mainly because of the entropic contribution, as the molecular weight of PEGDGE was very low. The crystallization and melting behavior of both PCL and the poly(ethylene glycol) (PEG) segment of PEGDGE were less affected in the uncured PCL/PEGDGE blends because of the very close glass‐transition temperatures of PCL and PEGDGE. However, the cured PCL/PEG‐ER blends were immiscible and exhibited two separate glass transitions, as revealed by differential scanning calorimetry and dynamic mechanical analysis. There existed two phases in the cured PCL/PEG‐ER blends, that is, a PCL‐rich phase and a PEG‐ER crosslinked phase composed of an MAH‐cured PEGDGE network. The crystallization of PCL was slightly enhanced in the cured blends because of the phase‐separated nature; meanwhile, the PEG segment was highly restricted in the crosslinked network and was noncrystallizable in the cured blends. The phase structure and morphology of the cured PCL/PEG‐ER blends were examined with scanning electron microscopy; a variety of phase morphologies were observed that depended on the blend composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2833–2843, 2004     

Synthesis and properties of photocurable biodegradable multiblock copolymers based on poly(ε‐caprolactone) and poly(L‐lactide) segments

Photocurable biodegradable multiblock copolymers were synthesized from poly(ε‐caprolactone) (PCL) diol and poly(L ‐lactide) (PLLA) diol with 4,4′‐(adipoyldioxy)dicinnamic acid (CAC) dichloride as a chain extender derived from adipoyl chloride and 4‐hydroxycinnamic acid, and they were characterized with Fourier transform infrared and ¹H NMR spectroscopy, gel permeation chromatography, wide‐angle X‐ray diffraction, differential scanning calorimetry, and tensile tests. The copolymers were irradiated with a 400‐W high‐pressure mercury lamp from 30 min to 3 h to form a network structure in the absence of photoinitiators. The gel concentration increased with time, and a concentration of approximately 90% was obtained in 90–180 min for all the films. The photocuring hardly affected the crystallinity and melting temperature of the PCL segments but reduced the crystallinity of the PLLA segments. The mechanical properties, such as the tensile strength, modulus, and elongation, were significantly affected by the copolymer compositions and gel concentrations. Shape‐memory properties were determined with cyclic thermomechanical experiments. The CAC/PCL and CAC/PCL/PLLA (75/25) films photocured for 30–120 min showed good shape‐memory properties with strain fixity rates and recovery rates of approximately 100%. The formation of the network structure and the crystallization and melting of the PCL segments played very important roles for the typical shape‐memory properties. Finally, the degradation characteristics of these copolymers were investigated in a phosphate buffer solution at 37 °C with proteinase‐k and Pseudomonas cepacia lipase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2426–2439, 2005