Confined crystallization behaviors in polyethylene/silica nanocomposites: Synergetic effects of interfacial interactions and filler network

The confinement effects introduced by nanoparticles have been reported to influence the phase behaviors thus the properties of polymer nanocomposites. In this study, molecular dynamics and crystallization behaviors of polyethylene (PE) composited with three types of silica (SiO₂) nanoparticles, namely unmodified SiO₂, hydrophobically modified SiO₂, SiO₂‐APTES (3‐aminopropyltriethoxysilane) and SiO₂‐PTES (n‐propyltriethoxysilane), were systematically investigated via a combination of DSC, XRD and ¹H solid‐state NMR measurements. The suppressions in crystallization and chain mobilities of PE rank in the order of unmodified SiO₂ < SiO₂‐APTES < SiO₂‐PTES due to the increasing interfacial interactions between PE and SiO₂ nanoparticles. Additionally, independent of polymer–nanoparticle interactions, a silica network forms for all three kinds of nanocomposites when SiO₂ content reaches 83 wt %. The mobilities of polymer chains are severely restricted by such a percolated network structure, leading to a turning point in the crystallization ability of nanocomposites and a new crystallization peak at 45 °C lower than that of pure PE. The synergetic effects of interfacial interactions and filler network on polymer crystallization have been thoroughly studied in this work, which will provide guidance on modifying and designing nanocomposites with controlled properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 498–505     

Synthesis and optical properties of organic–inorganic hybrid semi‐interpenetrating polymer network gels containing polyfluorenes

Organic–inorganic hybrid semi‐interpenetrating polymer network (semi‐IPN) gels containing polyfluorenes (PFs) are synthesized by hydrosilylation reaction of joint and rod molecules in toluene, where PFs are poly(9,9‐dihexylfluorene‐2,7‐diyl) (PF6) or, poly(9,9‐dioctylfluorene‐2,7‐diyl) (PF8), joint molecules are 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS), or 1,3,5,7,9,11,13,15‐octakis(dimethylsilyloxy)pentacyclo‐[9,5,1,1,1,1]octasilsesquioxane (POSS), and rod molecules are 1,5‐hexadiene (HD) or 1,9‐decadiene (DD). The semi‐IPN gels containing low molecular weight PF6 show higher photoluminescence efficiency (?_g) than the toluene solution of PF6L (?_s). The semi‐IPN gels composed of long rod molecule of DD and cubic joint molecule of POSS show the most effective increase in the emission intensity. The emission intensity of PF6L increases as formation of the network in the POSS‐DD semi‐IPN gel. The POSS‐DD semi‐IPN gels containing high molecular weight PF6 and PF8 also show the increase of emission intensity than those of the toluene solutions. The semi‐IPN synthesized in cyclohexane show syneresis and phase separation between network structure and PF chains. The semi‐IPN gels containing PF8 show emission peaks at 450 and 470 nm derived from β‐sheet structure of PF8. A systematic study clears correlation between emission property and network structure and/or composition of semi‐IPN gels. The semi‐IPN gels provide emissive self‐standing soft materials with high efficiency and in a narrow wavelength range emission. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 973–984     

Glass transition and relaxation behavior of epoxy nanocomposites

With advances in nanoscience and nanotechnology, there is increasing interest in polymer nanocomposites, both in scientific research and for engineering applications. Because of the small size of nanoparticles, the polymer–filler interface property becomes a dominant factor in determining the macroscopic material properties of the nanocomposites. The glass‐transition behaviors of several epoxy nanocomposites have been investigated with modulated differential scanning calorimetry. The effect of the filler size, filler loading, and dispersion conditions of the nanofillers on the glass‐transition temperature (T_g) have been studied. In comparison with their counterparts with micrometer‐sized fillers, the nanocomposites show a T_g depression. For the determination of the reason for the T_g depression, the thermomechanical and dielectric relaxation processes of the silica nanocomposites have been investigated with dynamic mechanical analysis and dielectric analysis. The T_g depression is related to the enhanced polymer dynamics due to the extra free volume at the resin–filler interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3849–3858, 2004     

3D diamond‐containing nanocomposites based on hybrid polyurethane–poly(2‐hydroxyethyl methacrylate) semi‐IPNs: Composition‐nanostructure‐segmental dynamics‐elastic properties relationships

Nanostructure, glass transition dynamics and elastic properties were studied in the 3D nanodiamond‐containing composites based on polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks (PU‐PHEMA semi‐IPNs), neat PU or PHEMA matrices. Nanodiamond (ND) content in the nanocomposites varied from 0.25 to 3 wt %. Combined differential scanning calorimetry/ laser‐interferometric creep rate spectroscopy/atomic force microscopy approach was utilized. A large impact of small 3D ND additives on PU‐PHEMA networks' dynamics and properties was revealed under conditions when an average inter‐particle distance L exceeds by far gyration radius R_g. The pronounced heterogeneity of glass transitions' dynamics and two opposite effects were observed. The main effect was a strong suppression of PHEMA glass transition dynamics at 90–180 °C, with the enhancement of creep resistance and threefold to sixfold increasing modulus of elasticity. The peculiarly crosslinked structure of nanocomposites, due to double covalent hybridization, resulted in low rheological percolation threshold, and a synergistic effect in dynamics was observed. Less pronounced effect of accelerating dynamics in the temperature region between β‐ and α‐transitions in PHEMA was associated with dynamics in domains with loosened molecular packing. The distinct physical limit for “anomalous” decreasing T_g is predicted in terms of the notion of the common segmental nature of α‐ and β‐relaxations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1696–1712, 2008     

Decoupling the effects of screw speed and particle surface functionality on the filler suspension state in PBS/fumed silica nanocomposites

This work assessed the relative effects of processing conditions and interfacial interactions on the structure and properties of PBS/fumed silica nanocomposites. Rheology and scattering were used to investigate the dispersion state of silica particles with different surface treatments in nanocomposites produced by ultra‐high speed twin‐screw extrusion. Structural parameters of the silica, such as fractal dimension and Fisher exponent, were estimated by low‐frequency rheology responses and lower q scattering data. This study demonstrates that both decreased bulk polymer properties and improved filler suspension caused by high shear compounding determine the final properties of these PBS based nanocomposites. While the molecular weight of bulk polymer matrix was significantly reduced, the extreme shear increased the probability of forming percolated clusters, leading to remarkable reinforcement (up to 4000%) as evidenced by the low‐frequency rheological response. Further, the improvement in dispersion was enhanced when the filler was functionalized with a compatibilizing surface treatment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1820–1828     

Miscibility and properties of polyurethane/benzyl starch semi‐interpenetrating polymer networks

We successfully prepared a series of transparent materials with semi‐interpenetrating polymer networks (semi‐IPNs) from castor‐oil‐based polyurethane (PU) and benzyl starch (BS). The miscibility, morphology, and properties of the semi‐IPN films were investigated with attenuated total reflection/Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy, wide‐angle X‐ray diffraction, electron spin resonance (ESR), ultraviolet–visible spectroscopy, and tensile testing. The results revealed that the semi‐IPN films had good or certain miscibility with BS concentrations of 5–70 wt % because of the strong intermolecular interactions between PU and BS. With an increase in the concentration of BS, the tensile strength and Young's modulus of the semi‐IPN materials increased. The ESR data confirmed that the segment volume of PU in the semi‐IPNs increased with the addition of BS; that is, the chain stiffness increased as a result of strong interactions between PU and BS macromolecules. It was concluded that starch derivatives containing benzyl groups in the side chains more easily penetrated the PU networks to form semi‐IPNs than those containing aliphatic groups, and this led to improved properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 603–615, 2005     

Characterization of the interactions in polymer/silica systems by inverse gas chromatography

Authors propose to express the magnitude of modified filler/polymer interactions by Flory ‐ Huggins χ₂₃ parameter. We investigated polyether‐urethane/modified silica systems containing different amounts of filler (5, 10,20%wt). Moreover, information on the physicochemical properties of oligomer and modified silicas were presented with the use of the following parameters: • solubility parameter δ₂, describing properties of the polymer layer; • Flory‐Huggins parameter χ₁₂^∞ which describes polymer‐solute or mixture polymer/silica‐solute interactions. These parameters δ₂ and χ₁₂^∞ are obtained from Inverse Gas Chromatography experiments. The influence of the IGC experiment temperature, the content of modified silica, the nature of test solute on the evaluated parameters are presented and discussed.     

Stable second‐order NLO semi‐IPN system based on bipyridine‐containing polyimide and alkoxysilane dye

An organosoluble polyimide based on bipyridyl moiety and an alkoxysilane dye have been developed for second‐order non‐linear optics (NLOs). This bipyridine‐containing polyimide exhibits a glass transition temperature of 254°C and a degradation temperature of 400°C. An NLO‐active semi‐interpenetrating network (IPN) system was prepared by blending the polyimide with the alkoxysilane dye via in situ sol‐gel process of alkoxysilane. The selection of this bipyridine‐containing polyimide as the polymeric matrices provides improved solubility and thermal stability, and most importantly enhanced intermolecular interactions. No aggregation of the NLO chromophores in the polyimide matrices was observed through morphology and NLO studies. Under the limitation of chromophore degradation at elevated temperatures, the pristine poled/cured alkoxysilane dye exhibits poorer long‐term stability. By introducing the polyimide upon a silica network by the semi‐IPN system, randomization of the oriented chromophores can be effectively suppressed. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V were obtained for the optically clear semi‐IPN NLO materials. Excellent temporal stability (100°C) was also achieved for these semi‐IPN materials. Copyright © 2005 John Wiley & Sons, Ltd.     

A novel pH‐ and thermo‐sensitive PVP/CMC semi‐IPN hydrogel: Swelling,phase behavior,and drug release study

Poly(N‐vinyl‐pyrrolidone) (PVP) hydrogel has been considered as a very interesting and promising thermosensitive material. The most vital shortcoming of PVP hydrogel as thermosensitive material is that it does not exhibit thermosensitivity under usual conditions. In this work, semi‐interpenetrating polymer network (semi‐IPN) hydrogels based on PVP and carboxymethylcellulose (CMC) were prepared. The volume phase transition temperature (VPTT) of the hydrogels was determined by swelling behavior and differential scanning calorimetry (DSC). The results showed that the VPTT was significantly dependent on CMC content and the pH of the swelling medium. The amount of CMC in the semi‐IPN hydrogels was 0.050, 0.075, and 0.100 g, the VPTT in buffer solution of pH 1.2 was 29.9 °C, 27.5 °C and 24.5 °C, respectively. In addition, the VPTT occurred in buffer solution of pH 1.2, but did not appear in alkaline medium. Bovine serum albumin (BSA) as a model drug was loaded and the in vitro release studies were carried out in different buffer solutions and at different temperatures. The results of this study suggest that PVP/CMC semi‐IPN hydrogels could serve as potential candidates for protein drug delivery in the intestine. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1749–1756, 2010     

Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 10² times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003     

Heterogeneity of glass transition dynamics in polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks

The peculiarities of segmental dynamics over the temperature range of ?140 to 180 °C were studied in polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks (PU‐PHEMA semi‐IPNs) with two‐phase, nanoheterogeneous structure. The networks were synthesized by the sequential method when the PU network was obtained from poly(oxypropylene glycol) (PPG) and adduct of trimethylolpropane (TMP) and toluylene diisocyanate (TDI), and then swollen with 2‐hydroxyethyl methacrylate monomer with its subsequent photopolymerization. PHEMA content in the semi‐IPNs varied from 10 to 57 wt %. Laser‐interferometric creep rate spectroscopy (CRS), supplemented with differential scanning calorimetry (DSC), was used for discrete dynamic analysis of these IPNs. The effects of anomalous, large broadening of the PHEMA glass transition to higher temperatures in comparison with that of neat PHEMA, despite much lower T_g of the PU constituent, and the pronounced heterogeneity of glass transition dynamics were found in these networks. Up to 3 or 4 overlapping creep rate peaks, characterizing different segmental dynamics modes, have been registered within both PU and PHEMA glass transitions in these semi‐IPNs. On the whole, the united semi‐IPN glass transition ranged virtually from ?60 to 160 °C. As proved by IR spectra, some hybridization of the semi‐IPN constituents took place, and therefore the effects observed could be properly interpreted in the framework of the notion of “constrained dynamics.” The peculiar segmental dynamics in the semi‐IPNs studied may help in developing advanced biomedical, damping, and membrane materials based thereon. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 963–975, 2007     

Filler–polymer interactions in both silica and carbon black‐filled styrene–butadiene rubber compounds

Bound rubber in a filled rubber compound is formed by physical adsorption and chemisorption between the rubber and the filler. Styrene–butadiene rubber (SBR) is composed of four components of styrene, cis‐1,4‐, trans‐1,4‐, and 1,2‐units. Filler–polymer interactions in both silica and carbon black‐filled SBR compounds were studied by analyzing microstructures of the bound rubbers with pyrolysis‐gas chromatography. Differences in the filler–polymer interactions of the styrene, cis‐1,4‐, trans‐1,4‐, and 1,2‐units were investigated. The filler–polymer interactions of the butadiene units were found to be stronger than that of the styrene unit. The interactions of the cis‐1,4‐ and trans‐1,4‐units were stronger with carbon black than with silica, whereas the 1,2‐unit interacted more strongly with silica than with carbon black. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 439–445, 2001     

Computational synthesis,structure, and glass transition of (1,4) Cis‐polyisoprene‐based nanocomposite by multiscale modeling

The main goal of the present study was to produce insights from the atomistic modeling into the structural changes in elastomer‐based polymer nanocomposites caused by the surface modifications of the filler particles, and by the crosslinking of the participating polymer matrix. The fully atomistic molecular‐dynamics computer simulations of crosslinked (1,4) cis‐polyisoprene (PI) films capped by amorphous silica substrates was set‐up, in the presence of realistic coupling and covering agents. The PI film stratified structure has been studied in the proximity of the corresponding glass transition, by varying the degree of crosslinking and the PI film thickness. Some monomer ordering induced by the pristine (bare) silica disappeared almost completely in films with modified surfaces. The average monomer density increased with degree of crosslinking. As compared with PI bulk, the glass‐transition temperature was slightly larger for highly crosslinked PI films with bare silica and surfaces with coupling agents, and increased with increasing confinement. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 473–485     

Polymer–filler interactions in sol–gel derived polymer/silica hybrid nanocomposites

The effect of polymer–filler interaction on solvent swelling and dynamic mechanical properties of the sol–gel derived acrylic rubber (ACM)/silica, epoxidized natural rubber (ENR)/silica, and poly (vinyl alcohol) (PVA)/silica hybrid nanocomposites has been described for the first time. Tetraethoxysilane (TEOS) at three different concentrations (10, 30, and 50 wt %) was used as the precursor for in situ silica generation. Equilibrium swelling of the hybrid nanocomposites in respective solvents at ambient condition showed highest volume fraction of the polymer in the swollen gel in PVA/silica system and least in ACM/silica, with ENR/silica recording an intermediate value. The Kraus constant (C) also followed a similar trend. In dynamic mechanical analysis, the storage modulus dropped at higher strain (>1%), which indicated disengagement of polymer segments from the filler surfaces. This drop was maximum in ACM/silica, intermediate in ENR/silica, and minimum in PVA/silica, both at 50 and 70 °C. The drop in modulus with theoretical volume fraction of silica (ϕ) was interpreted with the help of a Power law model ΔE′ = a₁ϕ, where a₁ was a constant and b₁ was primarily a filler attachment parameter. Strain dependence of loss modulus was observed in ACM/silica hybrid nanocomposites, while ENR/silica and PVA/silica nanocomposites showed almost strain‐independent behavior. The storage modulus showed sharp increase with increasing frequency in ACM/silica system, while that was lower in both ENR/silica (at higher frequency) and PVA/silica systems (in the entire frequency spectrum). The increase in modulus with ϕ also followed similar model ΔE′ = a₂ϕ proposed in the strain sweep mode. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2399–2412, 2005     

Effect of a post‐annealing process on microstructure and mechanical properties of high‐density polyethylene/silica nanocomposites

High‐density polyethylene (HDPE) and nanosilica nanocomposites were prepared for SiO₂ content up to 15 wt%. Microstructural characterization evidenced a homogenous distribution of silica aggregates with a mean size increasing with the filler content finally resulting in a rheological percolation between 7.5 and 10 wt%. Nanoparticles did not induce any significant impact on the matrix crystallinity but led to a real improvement on elastic properties accompanied with a large embrittlement above the percolation threshold. The effect of annealing near HDPE melting temperature was studied. Differential scanning calorimetry, X‐ray diffraction, and small‐angle X‐ray scattering analyses showed a significant change in the HDPE microstructure after annealing at 125°C. A large increase in the crystallinity (from 68 to 76%) and a clear improvement of Young's modulus (by 55%) were observed prior to polymer degradation. A valuable impact of silica particles on thermal stability was also obvious regarding the evolution of elastic properties for extended exposure times (850–1,200 h). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 535–546     

Semi‐interpenetrating polymer networks composed of diisocyanate‐bridged 4‐arm star‐shaped l‐lactide oligomers and poly(ε‐caprolactone)

Semi‐interpenetrating polymer networks (semi‐IPNs) were prepared by reactions of 2,4‐tolylene diisocyanate (TDI) and hydroxy‐terminated 4‐arm star‐shaped l ‐lactide oligomers (H4LAO_n's) with the degrees of polymerization of lactate unit per one arm, n = 3, 5, and 10 in the presence of poly(ε‐caprolactone) (PCL). Morphologies, thermal, and mechanical properties of the TDI‐bridged H4LAO_n (TH4LAO_n)/PCL semi‐IPNs were evaluated by comparing with those of poly(l ‐lactide) (PLA)/PCL blends. Compatibility between the two components of the TH4LAO_n/PCL semi‐IPN with a PCL content not more than 50 wt % was much better than those of the PLA/PCL blends with the same PCL content. All the TH4LAO_n networks were substantially amorphous and their tan δ peak or glass transition temperatures increased with decreasing n value. Most of the semi‐IPNs did not show clear glass transition temperature related to both the components. Tensile toughness and elongation at break for all the TH4LAO_n/PCL semi‐IPNs were much higher than those for the PLA/PCL blends with the same PCL content. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1420–1428     

Polymer/clay nanocomposites through multiple hydrogen‐bonding interactions

An 2‐ureido‐4[1H]pyrimidinone (UPy) motif with self‐association capability (through quadruple hydrogen bonds) was successfully anchored onto montmorillonite clay layers. Polymer/clay nanocomposites were prepared by specific hydrogen bonding interactions between surface functionalized silica nanoclays and UPy‐bonded supramolecular poly(ethylene glycol) or poly(?‐caprolactone). The mixed morphologies including intercalated layers with a non‐uniform separation and exfoliated single layers isolated from any stack were determined by combined X‐ray diffraction and transmission electron microscopic measurements. Thermal analyses showed that all nanocomposites had higher decomposition temperatures and thermal stabilities compared with neat polymer. The differential scanning calorimetric data implied that the crystallinity of polymers did not show essential changes upon introduction of organomodified UPy clays. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 650–658     

Effect of nano‐modified SiO2/Al2O3 mixed‐matrix micro‐composite fillers on thermal,mechanical, and tribological properties of epoxy polymers

Thermo‐mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano‐modified of micronic SiO₂/Al₂O₃ particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano‐modified micro‐composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano‐modified SiO₂/Al₂O₃ micro‐composite fillers enhanced inter‐particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano‐modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano‐modified mixed‐matrix micro‐composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of κ‐carrageenan/poly(N,N‐diethylacrylamide) semi‐interpenetrating polymer network hydrogels with rapid response to temperature

In this study, a novel classical thermo‐ and salt‐sensitive semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of poly(N,N‐diethylacrylamide) (PDEAm) and κ‐carrageenan (KC) was synthesized by free radical polymerization. The structure of the hydrogels was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR and SEM revealed that the semi‐IPN hydrogels possessed the structure of H‐bonds and larger number of pores in the network. Compared to the PDEAm hydrogel, the prepared semi‐IPN hydrogels exhibited a much faster response rate to temperature changes and had larger equilibrium swelling ratios at temperatures below the lower critical solution temperature (LCST). The salt‐sensitive behavior of the semi‐IPN hydrogels was dependent on the content of KC. In addition, during the reswelling process, semi‐IPN hydrogels showed a non‐sigmoidal swelling pattern. Copyright © 2008 John Wiley & Sons, Ltd.     

Novel Shape‐Memory Polymer with Two Transition Temperatures

Summary: This communication describes a novel kind of PMMA‐PEG semi‐interpenetrating network (semi‐IPN) which shows excellent shape‐memory behavior at two transition temperatures, the T_m of the PEG crystal and the T_g of the semi‐IPN. Based on a reversible order‐disorder transition of the crystals below and above the T_m of PEG, and the large difference in storage modulus below and above the T_g of the semi‐IPN, the polymer has a recovery ratio of 91 and 99%, respectively.

Shape‐memory phenomena of PMMA‐PEG2000 semi‐IPN.