Fe2+–Thioureadioxide–H2O2-induced polymerization of glycidyl methacrylate and its mixtures with acrylamide,acrylonitrile, butylmethacrylate,or styrene with cotton fabric

Fe²⁺–thioureadioxide-H₂O₂-induced polymerization of glycidyl methacrylate (GMA) and its mixtures with acrylamide (Aam), acrylonitrile (AN), butylmethacrylate (BMA), or styrene was investigated at different temperatures (50–95°C), for different periods of time (5–130 min) using different concentrations of Fe²⁺-thioureadioxide and H₂O₂. The add-on increased by increasing the thioureadioxide concentration up to 0.05% then decreased. H₂O₂ concentration of 0.005% constituted the optimal for GMA and GMA/Aam mixtures, and 0.02% H₂O₂ for GMA/AN, GMA/BMA and GMA/styrene mixtures. Increasing the concentration of GMA either alone or in admixtures resulted in improved add-ons; the magnitude of this improvement relied on the nature of the monomer used along with GMA. The polymerization reaction was characterized by an initial fast rate followed by a slower one irrespective of monomer or monomer mixtures used. Presence of Aam along with GMA offset the fast termination observed with the latter at higher temperatures (above 60°C). GMA/Aam mixtures produced higher add-ons than Aam alone irrespective of their rations in the mixtures, indicating activation of Aam with GMA. On the other hand, Aam deactivated GMA. Similar situation was encountered when styrene or acrylonitrile was used instead of Aam except that the percent add-ons obtained with GMA/AN mixtures decreased upon raising the polymerization temperature above 80°C. Contribution of GMA in the add-ons obtained with the different mixtures was also examined. For instance, the add-on was composed mainly of poly(GMA) when GMA/Aam at a ratio of 8:2 was used. On the other hand, using GMA/Aam at a ratio of 2:8 brought about add-ons of poly(GMA/Aam) in which the concentration of GMA and Aam were roughly equal.     

Graft copolymerization of perfluoroheptyl methacrylate/glycidyl methacrylate mixtures with cotton fabric using Fe2+-thioureadioxide-H2O2 redox system

The ability of Fe²⁺-thioureadioxide-H₂O₂ redox system to induce polymerization of perfluoroheptyl methacrylate (PFHMA) and glycidyl methacrylate (GMA) individually as well as in binary mixtures was investigated under different conditions. Results obtained indicated that (a) PFHMA monomer could substantially be polymerized with cotton cellulose only in presence of GMA, (b) maximum contribution of PFHMA in the polymer add-on occurred upon using PFHMA mixture at a ratio of 50:50 at 80°C, (c) presence of PFHMA along with GMA offsets the fast termination rate of the latter as temperature increased from 60° to 90°C, (d) GMA activated PFHMA while the latter adversely affected GMA, (e) none of the PFHMA/GMA mixtures at ratios 2:8, 5:5, 8:2 showed synergetic effects, (f) H₂O₂ concentration of 0.01% and thioureadioxide concentration of 0.04% constituted the optimal concentrations for polymerization of PFHMA/GMA at a ratio of 5:5, and (g) the polymerization reaction proceeded initially very fast, then levelled off. (h) The water/oil repellency of the copolymerized cotton samples relied on the percent of PFHMA in total percent polymer add-on; these properties attained maximum at 4.25% PFHMA in a total polymer add-on of 22.5%.     

Synthesis and characterization of cellulose ion exchangers. I. Polymerization of glycidyl methacrylate,dimethylaminoethyl methacrylate,and acrylic acid with cotton cellulose using thiocarbonate-H2O2 redox system

Polymerization of glycidyl methacrylate (GMA), dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AA) with cotton fabric using a cellulose thiocarbonate-hydrogen peroxide redox system as an initiator was investigated under different conditions. This includes the nature and concentration of the initiator and monomer, polymerization time and temperature, and liquor ratio. The percent of polymer add-on is generally favored by increasing monomer and H₂O₂ concentration, as well as duration and temperature of the polymerization, but with the certainty that the percent of polymer add-on follows the following order: GMA > DMAEMA > AA. On the other hand, the percent of polymer add-on increases by decreasing the liquor ratio. Incorporation of Fe²⁺ or Cu²⁺ ion in the polymerization system enhances the percent of polymer add-on significantly. Replacing the H₂O₂ by other oxidants such as Cr⁶⁺ or Mn⁴⁺ is made, and the capability of such cations to expedite polymerization of the said monomers with cotton cellulose is studied. Also studied is the synthesis of cation exchanger via reaction of poly(GMA)-cellulose copolymer with hexamethylene tetramine. Furthermore, the ion exchange characteristics of the cellulosic copolymers obtained with this as well as with other monomers are reported. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1029–1037, 1997     

Polymerization of glycidyl methacrylate with poly(ethylene terephthalate) fibers using Fe+2–H2O2 redox system

Fe⁺²–H₂O₂ redox system initiated polymerization reactions of glycidyl methacrylate (GMA) from aqueous solution with poly(ethylene terephthalate) fibers (PET) were investigated. The polymer add-on is greatly influenced by H₂O₂ concentration, GMA concentration, as well as reaction time and temperature. Polymer add-on was directly related to H₂O₂ concentration up to 30 meq/L and GMA concentration up to 4%. Further increase in concentrations of H₂O₂ and GMA resulted in lower polymer add-on. Raising the reaction temperature from 65°C to 95°C caused a significant enhancement in the rate of polymerization, the latter follows the order 95 > 85 > 75 > 65°C. However, at 65°C, the polymerization reaction showed an induction period of about 120 min, in contrast with reactions at 75°C, 85°C, and 95°C, where no induction period was observed though the polymer add-on was quite low at 75°C during the initial stages of the reaction. Using dimethylformamide (DMF) alone or mixed with water as polymerization medium offset the polymerization reaction. Incorporation of thioureadioxide in the polymerization system decreased the polymer add-on significantly.     

Grafting of Methacrylic Acid and Other Vinyl Monomers Onto Cotton Fabric Using Ce (IV) Ion–Cellulose Thiocarbonate Redox System

Graft copolymerization of methacrylic acid (MAA) onto cotton fabric using tetravalent ceric ion (Ce^IV)–cellulose thiocarbonate redox system was investigated under different conditions including pH of the polymerization medium (1–4), ceric sulphate (CS) concentration (4–20 m mole/l), MAA concentration (1%–6%), polymerization time (1/4–2 h) and polymerization temperature (0–70°C). Results obtained indicated that the optimal conditions for MAA grafting onto cotton fabric using the said redox system consisted of: [CS], 20 m mole/l; [MAA], 4%; pH of the medium, 2; time, 2 h; temperature, 60 °C keeping a material-to-liquor ratio at 1:0. Applying optimized conditions to different monomers, namely, acrylic acid (AA), methacrylic acid (MAA), acrylamide (Aam), acrylonitrile (AN), butyl acrylate (BuA), methyl methacrylate (MMA), ethyl methacrylate (EMA) and glycidyl methacrylate (GMA) onto the same substrate, the rates of grafting followed the order:

Environmentally benign precipitation copolymerization of methacrylate ester and styrene to make polymeric microspheres in supercritical carbon dioxide

The polymeric microspheres were synthesized by the precipitation copolymerization of glycidyl methacrylate (GMA) with methacrylic acid(MAA) or 2‐hydoxyethyl methacrylate (2‐HEMA) containing styrene (ST) in SC‐CO₂. Scanning electron microscopy (SEM) showed that the products were spherical microparticles, with the addition of MAA and/or 2‐HEMA as the monomer, with diameter of 0.2–2 μm. The effects of copolymerization pressure, temperature, and ratios of GMA/MAA, ST, and/or GMA/2‐HEMA, on the particle size and morphology were investigated in detail. A new experiment setup is proposed for the large amount of production, based on the rule of lower monomer concentration, more stable system, and better use of the present polymerization apparatus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2425–2431, 2007     

Synthesis and Photopolymerizations of New Crosslinkers for Dental Applications

Summary: Five new crosslinkers for use in dental composites were synthesized. Four are based on TBHMA: 1 via reaction of TBBr and Bisphenol A; 2 by hydrolysis of t‐butyl groups of the first monomer to give a diacid derivative; 3 by conversion of the first monomer to an amide derivative using benzyl amine; 4 by conversion of the first monomer to amide derivative using APTES. The AHM‐based monomer 5 was synthesized from the Michael addition of APTES to AHM. The photopolymerization behaviors of the synthesized monomers with Bis‐GMA, TEGDMA and HEMA were investigated using photodifferential scanning calorimetry at 40 °C using DMPA as photoinitiator. The polymerization rates and degrees of conversion for mixtures of any of the monomers 1 – 4 with Bis‐GMA:TEGDMA were found to be similar to Bis‐GMA:TEGDMA, higher than Bis‐GMA:HEMA, and also higher than mixtures with Bis‐GMA:HEMA. The incorporation of TBHMA‐based monomers into the conventional resin mixture (Bis‐GMA and TEGDMA) reduced the polymerization shrinkages. Monomer 5 and its mixtures polymerized much faster and to higher degrees of conversion than the other investigated systems, however, this system exhibited the largest volume shrinkage.

Structures of some of the new crosslinkers synthesized.     

Synthesis,characterization, and rheological studies of methacrylic acid–ethyl acrylate–diallyl phthalate copolymers

Copolymerization of methacrylic acid (MAA) and ethyl acrylate (EA) was performed by the emulsion polymerization technique in the presence of a mixture of ionic and nonionic emulsifiers, at 85°C, using potassium persulfate as initiator (0.16 wt % of monomer). The molar ratio of MAA : EA varied between 44 : 56 and 54 : 46 in the monomer feed. Copolymers of MAA and EA were synthesized by incorporating diallyl phthalate (DAP) with varying concentrations (0–1.7 mol % of total monomer) in the feed. A copolymer latex of MAA, EA, and DAP was also prepared by the variable feed process. The intrinsic viscosity and gel content were determined. Copolymers were characterized by IR and NMR spectroscopic techniques. The composition of copolymers was determined by ¹H‐NMR spectra and sequential distribution from ¹³C{¹H}‐NMR spectra. The pH of the copolymer emulsion varied between 3 and 10 by addition of aqueous ammonia (23% w/w) and its effect on Brookfield viscosity was studied. The effects of copolymer composition, crosslinking agent concentration in the feed, monomer feed process, polymer solid contents, and shear rate on Brookfield viscosity were studied at pH ～ 8. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1430–1441, 2003     

First RAFT polymerization of captodative 2-acetamidoacrylic acid (AAA) monomer: An experimental and theoretical study

A capto-dative monomer, 2-acetamidoacrylic acid (AAA), was homopolymerized through RAFT polymerization method using 2-(2-cyanopropanyl dithiobenzoate) (CPDB) as a chain transfer agent and AIBN free radical initiator in DMF at 70 °C. DFT calculations were performed in the selection of the CTA for this unique monomer as well as to elucidate the influence of cd-stabilized growing radical on the kinetic parameters in comparison to methacrylic acid (MAA) and N-(prop-1-en-2-yl)acetamide (NPAA), which represent the captive and dative groups of AAA, respectively. K_eq for these three monomers is in the order of AAA < MAA < NPAA. While k_β > k_−add for NPAA and MAA, for AAA k_−add is about four orders of magnitude larger than k_β. This is the major disadvantage in the RAFT process of AAA using CPDB. Yet, poly(AAA) could be achieved with PDI as low as 1.49. Molecular weight of the polymer can be tuned by the monomer/AIBN ratio. First block copolymers of AAA with MAA and MMA using poly(AAA) as a macro-CTA were also synthesized, indicating the presence of active chain ends.     

Grafting of methacrylic acid to loomastate viscose fabric using KMnO4/NaClO2 system

Graft polymerization of methacrylic acid (MAA) to loomstate viscose fabric (greige fabric) using KMnO₄/NaClO₂ system was studied. Residual thiocarbonate and/or sizing materials on the fabric as well as presence of NaClO₂ act in favor of primary radical formation which, in turn, accelerate formation of cellulose macroradicals capable of initiating grafting. The polymerization reaction was studied with respect to polymer yield, graft yield, homopolymer, total conversion, and graft efficiency. The magnitude of each of these characteristics was found to depend upon parameters such as concentrations of KMnO₄, NaClO₂, and MAA as well as liquor ratio, reaction time, and temperature of polymerization. By and large all these parameters enhance the polymerization process with the exception of the liquor ratio. A reaction mechanism for the polymerization reaction is also reported. © 1995 John Wiley & Sons, Inc.     

Preparation of high PMMA grafted particle SiO2 using surface initiated free radical polymerization

In this work, a convenient surface-initiated free radical graft-polymerization method, by which polymethacrylic acid (PMAA) with a high grafting density was grafted on silica gel particles, was put forward, and it was feasible and effective. The coupling agent γ-aminopropyltrimethoxysilane (AMPS) was first bound onto the surfaces of silica gel particles, obtaining the modified particles AMPS-SiO₂. So a redox initiation system was constituted with the amino groups on the surfaces of AMPS-SiO₂ particles and ammonium persulphate in the solution. A great deal of primary free radicals on the surfaces of AMPS-SiO₂ particles is produced via the redox initiating reaction, so that the surface-initiated free radical graft- polymerization of methacrylic acid (MAA) on the silica gel particles was realized, giving the grafted particles PMAA/SiO₂ with a high grafting degree (about 30 g/100 g) of PMAA. The effects of the main factors on the surface initiated graft polymerization were examined and the corresponding mechanism was investigated in depth. The experimental results show that for this surface-initiated free radical graft-polymerization of MAA, the suitable temperature is 40 °C. If the temperature is over 40 °C, the graft polymerization will be affected negatively, and the grafting degree of PMAA will decline because of the intense heat decomposition of ammonium persulphate. During the graft polymerization, the grafted polymer layer that has formed is a hindrance to the subsequent graft polymerization. The used amount of initiator and the monomer concentration affect the graft polymerization greatly. The appropriate reaction conditions are as follows: reaction time of 10 h, initiator persulphate amount of 1.1% (it implies the mass percent of the monomer), and monomer MAA concentration of about 5% (it drives at the mass percent of the solution).     

Porous properties of poly(glycidyl methacrylate‐co‐trimethylolpropane trimethacrylate) resins synthesized by suspension polymerization

Porous copolymer beads of 2,3‐epoxypropyl methacrylate (glycidyl methacrylate, GMA) crosslinked with 2‐ethyl‐2‐(hydroxymethyl)‐propan‐1,3‐diol trimethacrylate (trimethylolpropane trimethacrylate, TRIM) were prepared with toluene and octan‐2‐one as porogens by suspension polymerization. With an increase in the ratio of porogen to monomer, the total pore volume of poly(GMA‐co‐TRIM) increases significantly, whereas the surface area hardly changes. The total pore volume also depends on the nature of the porogen, exhibiting a maximum at the larger GMA contents in the monomer mixture of 50% v/v with octan‐2‐one and of 60% v/v with toluene, compared to that at the GMA content of 25% v/v with a 9/1 v/v mixture of cyclohexanol and dodecan‐1‐ol [Verweij, P. D.; Sherrington, D. C. J Mater Chem 1991, 1 (3), 371]. The surface area decreases significantly with an increase in the ratio of GMA to TRIM, almost regardless of the nature of the porogen. The porous properties of poly(GMA‐co‐TRIM) was well explained on the basis of phase separation, particularly taking into account not only the solubility parameters of the resulting polymer network and porogen but also the rigidity of TRIM. The porous poly(GMA‐co‐TRIM) may be a promising polymer matrix of novel materials for separation of boron isotopes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2374–2381, 2002     

High performance biocompatible cellulose‐based microcapsules encapsulating gallic acid prepared by inverse microsuspension polymerization

In this study, the preparation of biocompatible cellulose‐based microcapsules encapsulating gallic acid (GA), an important antioxidant of Bambara groundnut extracts, by water‐in‐oil inverse microsuspension polymerization was studied. GA and carboxymethyl cellulose (CMC) were selected as core and shell materials, respectively. For high encapsulation efficiency, CMC was firstly modified (modified‐CMC (m‐CMC)) with 3‐(trimethoxysilyl)propyl methacrylate (MPS) as a silane coupling agent. It was subsequently polymerized with methacrylic acid (MAA) monomer through a radical route, forming a PMAA grafted m‐CMC (m‐CMC‐g‐PMAA) biocompatible polymer shell. Using CMC:MPS in a ratio of 75:25 (w/w %), highly water‐soluble m‐CMC containing a C=C bond for further radical polymerization was obtained. After inverse microsuspension polymerization at various ratios of m‐CMC:MAA, highly stable spherical m‐CMC‐g‐PMAA microcapsules encapsulating GA were formed in all ratios. It was observed that the encapsulation efficiency increased with increase in MAA content. m‐CMC:MAA in a ratio of 33:67 (w/w%) presented the highest encapsulation efficiency which may due to the increase of hydrophilicity of the aqueous phase. It also presented rapid release and non‐cytotoxic characteristics, suited for use in cosmetic products. © 2018 Society of Chemical Industry     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Preparation of composite reverse osmosis membranes by plasma polymerization of organic compounds. IV. Influence of plasma–polymer (substrate) interaction

Preparation of composite membranes by plasma polymerization is affected not only by the type of monomer and the mode of discharge but also by the interaction of plasma–polymer substrate. Consequently, the reverse osmosis characteristics of composite membranes are dependent on the combination of substrate and monomer(s). The interactions of plasma and polymer are investigated using porous polysulfone film and cellulose nitrate–cellulose acetate (CNCA) porous film as the substrates, and acetylene/H₂O/N₂ and acetylene/H₂O/CO as the monomer systems. The effects of plasma pretreatment of the substrates on the chlorine resistance of the membranes are also investigated.     

The research of preparation of polyvinyl acetate with lower polydispersity index

In this study, the way of preparing polyvinyl acetate (PVAc) with lower polydispersity index (PDI) was studied. By adding small amount of monomer with polar group, such as acrylic acid (AA), α-methacrylic acid (MAA), or acrylamide (AM), as modulation monomer, the polymerization was carried out at 65°C with a mechanical agitator using AIBN as initiator under N₂ atmosphere. Effects of the mol ratio of modulation monomer/VAc and structure of the modulation monomer on the polymerization conversion, the molecular weight and molecular weight distribution of the obtained polymers were investigated through ¹H NMR, gravity method, and gel permeation chromatography. The results show that by adding modulation monomer into the reactive system the PVAc with lower PDI could be got. With the increase of the modulation monomer amount, the conversion and the molecular weight decrease, and the PDI of the obtained polymer is lower. When the mol ratio of AA/VAc is 3 : 100, the PDI of the obtained polymer is 1.84. When the mol ratio of AM/VAc is 1 : 100, the PDI of the obtained polymer is 1.68, which is narrower than that without AM. All researches we have done laid a foundation for further study. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Copolymerization kinetics of acrylonitrile with amino ethyl‐2‐methyl propenoate in H2O/DMSO mixture

Amino ethyl‐2‐methyl propenoate (AEMP) was used successfully to copolymerize with acrylonitrile (AN). This was achieved by using azobisisobutyronitrile as the initiator. Kinetics of copolymerization of AN with AEMP was investigated in H₂O/dimethylsulfoxide (DMSO) mixture between 50 and 70 °C under N₂ atmosphere. The rate of copolymerization was measured. The kinetic equation of copolymerization system was obtained and the overall activation energy for the copolymerization system was determined. Values of monomer apparent reactivity ratios were calculated using Kelen–Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system are similar to those in solution polymerization system at polymerization conversion less than 25%. At conversion beyond 45%, the changes of monomer apparent reactivity ratios become less prominent. In water‐rich reaction medium (H₂O/DMSO > 70/30), monomer apparent reactivity ratios are approximately equivalent to those in aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H₂O > 70/30), apparent reactivity ratios are similar to those in solution polymerization system. With an increase of polarity of solvent, values of apparent reaction ratios both decrease. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2095–2100, 2006     

A new strategy for plasticizing and stabilization of PVC mixtures

This study was undertaken to examine possible use of classic tetravalent tin‐based heat stabilizers for the preparation of a polymer plasticizer: poly(ε‐caprolactone) (PCL) and simultaneous stabilization of PVC in PVC/PCL mixtures. PCL was prepared from ε‐caprolactone (CL) by polymerization initiated by tin‐containing organic compounds and successfully used to simultaneously plasticize and stabilize PVC. Moreover, conditions under which the polymerization of CL took place directly in situ during PVC/CL mixture processing were found. The procedure yielded homogeneous plasticized PVC/PCL mixtures, which were stable and contained >90% of the original monomer content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41066.     

Preparation of composite reverse osmosis membranes by plasma polymerization of organic compounds. III. Plasma polymers of acetylene/CO/H2O

Reverse osmosis characteristics of composite membranes prepared by the plasma polymerization of acetylene/CO/H₂O mixtures with various ratios of components are investigated; porous film of cellulose nitrate-cellulose acetate is used as the substrate. This monomer system seems to have the following advantages: (1) A relatively short deposition time (1–2 min) is enough to produce reasonably good reverse osmosis membranes; and (2) good chemical stability of membranes can be obtained, especially in the case of chlorine resistance.     

Effects of water on the long‐term properties of Bis‐GMA and silylated‐(Bis‐GMA) polymers

Bis‐GMA (2,2‐bis‐[4‐(2‐hydroxy‐3‐methacryloxypropoxy)phenyl]propane) is a viscous hygroscopic monomer which is used with triethyleneglycol‐dimethacrylate (TEGDMA) for dental restorations. Bis‐GMA was silylated with dimethyl‐isopropyl‐siloxane and further polymerized in order to increase water resistance and viscosity. The viscosity of the silylated monomer, Sil·Bis‐GMA, was 50 times lower than that of the parent monomer. After 1 month in water, poly(Bis‐GMA/TEGDMA) absorbed 2.6% water and the silylated polymer, poly(Sil·Bis‐GMA), only 0.56%. During this process water extracted residual monomer from each polymer. The behavior of water sorption and desorption as a function of time in poly(Sil·Bis‐GMA) was completely different from that shown by poly(Bis‐GMA/TEGDMA). The difference is discussed in terms of diffusion coefficients. Initially, water advancing contact angles (θ_ADV) were 75° and 95°, respectively. After 1 month in water both polymers showed a reduction of about 20° in θ_ADV. In poly(Bis‐GMA/TEGDMA), the reduction in θ_ADV obey to water absorption and bulk plasticization; it showed a reduction of 15°C in glass transition temperature, T_g. In contrast, the reduction in θ_ADV in poly (Sil·Bis‐GMA) obeyed to water adsorption and reorientation of the molecules at the surface in contact with the water phase; it only showed a change of 2°C in T_g. Contact angle hysteresis provided further evidence about plasticization. According to our results poly(Sil·Bis‐GMA) is more stable in water than poly(Bis‐GMA/TEGDMA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008