Casting Polymer Solution Research Articles

Electroless Plating of Honeycomb and Pincushion Polymer Films Prepared by Self-Organization

This report describes the fabrication and electroless plating of regular porous and pincushion-like polymer structures prepared by self-organization. Honeycomb-patterned films were prepared by simple casting of polymer solution under applied humid air and pincushion structures by peeling off the top layer of the former films. Silver-deposited honeycomb-patterned films and pincushion films were obtained by simple electroless plating of the respective original structures. XPS revealed Ag deposition on the honeycomb-patterned film. After thermal decomposition or solvent elution of the template polymer, unique metal mesoscopic structures were obtained.

Synthesis, photoluminescent and electrochromic properties of new aromatic poly(amine-hydrazide)s and poly(amine-1,3,4-oxadiazole)s derived from 4,4′-dicarboxy-4″-methyltriphenylamine

A series of new poly(amine-hydrazide)s I were prepared from the dicarboxylic acid 4,4′-dicarboxy-4″-methyltriphenylamine with terephthalic dihydrazide (TPH) and isophthalic dihydrazide (IPH), respectively, via the Yamazaki phosphorylation reaction. Polymers I were readily soluble in many common organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. Differential scanning calorimetry (DSC) indicated that the hydrazide polymers had T g’s in the range of 222–223 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(amine-1,3,4-oxadiazole)s II exhibited T g’s in the range of 269–283 °C, 10% weight-loss temperatures in excess of 511 °C, and char yield at 800 °C in nitrogen higher than 63%. These poly(amine-hydrazide)s I exhibited strong UV–Vis absorption bands at 351–355 nm in NMP solution. Their photoluminescence spectra in NMP solution and film showed maximum bands around 459–461 nm in the blue region for I series. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-hydrazide)s I prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited one reversible oxidation redox couples at 1.32–1.33 V vs. Ag/AgCl in acetonitrile solution. All obtained poly(amine-hydrazide)s I revealed excellent stability of electrochromic characteristics, changing color from original pale yellowish to blue.

Electrochemical behavior of N, N, N′, N′-tetraphenyl-1,4-phenylenediamine moiety on novel aromatic polyamides and their electrochromic properties

A series of novel aromatic polyamides with N, N, N′, N′-tetraphenyl-1,4-phenylenediamine units were prepared from the diamine, N, N′-bis(4-aminophenyl)- N, N′-diphenyl-1,4-phenylenediamine, and various aromatic dicarboxylic acids via the direct phosphorylation polycondensation. All the polyamides were amorphous, readily soluble in many organic solvents and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (257–287 °C). These polymers exhibited strong UV–vis absorption bands with a maximum at 320–336 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms (CV) of these films prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at potentials 0.61–0.64 and 0.99–1.07 V, respectively, vs Ag/AgCl in acetonitrile solution. All obtained polyamides revealed excellent stability of electrochromic characteristics, changing color from original pale yellowish to green, and then to blue at electrode potentials 0.65 and 1.10 V, respectively.

Poly(ethylene- co-vinyl acetate) copolymer matrix for delivery of chlorhexidine and acyclovir drugs for use in the oral environment: Effect of drug combination, copolymer composition and coating on the drug release rate

Objectives This study utilizes a bio-compatible ethylene vinyl acetate (EVA) copolymer to deliver drugs at therapeutic levels over extended periods of time. The release rate of an anti-fungal and an anti-microbial drug namely acyclovir (ACY) and chlorhexidine diacetate (CDA) from EVA was investigated individually and as a mixture. The effect of drug combination, the composition of the copolymer and the coating of the matrix with a different polymer on the rate of drug release are presented. Method Polymer casting solutions were prepared by homogeneously dissolving EVA copolymer and the drugs in the ratio (40:1) in dichloromethane. The drugs ACY and CDA were used individually as well as in three different weight ratios maintaining the total drug concentration in the polymer at 2.5%. Different concentrations of vinyl acetate (VA) 28, 32 and 40% in the EVA matrix were used to study the release of either ACY or CDA alone while 40% VA was used for the release study of the individual drug as well as their mixtures. Thin square films of 3 cm × 3 cm with a thickness of 0.7 mm were cut from the dry sheet obtained by solvent evaporation. Coated films were prepared by dipping ACY and CDA drug-loaded EVA films (VA 40%) into EVA copolymer of VA 32% and then dried. All of the drug-loaded samples were extracted at 37 °C in 10 ml distilled water that was replaced daily. The rate of individual drug release was measured by UV-spectrophotometer while the mixtures of drugs were measured by high performance liquid chromatography (HPLC). Results The release rate of ACY is higher than that of CDA both individually and in the ACY/CDA 50/50 mixture. In the other mixtures, the release of the drug is proportional to its concentration in the mixture. Total release of ACY is higher than CDA in most compositions. The effect of increasing the vinyl acetate content of the EVA matrix increased the drug release rate ( p = 0.02) while coating of films resulted in a decrease of the release rate of the drugs. Significance Measurements of the in vitro rate of drug release showed that there was a sustained release of drug at an almost constant concentration over extended period of time, thus providing a basis for oral treatment modality. We show that it is possible to alter the rate of drug release in the EVA matrix to a desired value by: (1) changing the composition of the EVA copolymer, (2) altering the mixtures of drugs and (3) coating the matrix with additional polymer. The use of mixtures of drugs that can enhance or decrease the rate of drug release may prove more effective in treating persistent oral infections in immunocompromised patients.

Electrochromic properties of novel strictly alternating poly(amine–amide–imide)s with electroactive triphenylamine moieties

A series of novel triphenylamine-containing aromatic poly(amine–amide–imide)s (PAAIs) were prepared by the phosphorylation polyamidation reactions from the diamine, N, N′-bis(4-aminophenyl)- N, N′-diphenyl-1,4-phenylenediamine, and various imide ring-preformed dicarboxylic acids. All the PAAIs were amorphous, had good solubility in many polar aprotic solvents, and exhibited excellent thin film forming capability with good mechanical properties. They displayed relatively high glass-transition temperatures (220–306 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 522 °C in air or nitrogen and char yields at 800 °C in nitrogen higher than 66%. The solutions of polymers in NMP exhibited strong UV–vis absorption bands with a maximum around 315 nm. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the PAAIs prepared by casting polymer solution onto an indium–tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at 0.63 and 1.01 V vs. Ag/AgCl in acetonitrile solution. All the PAAIs revealed very stable electrochromic characteristics, changing color from original pale brownish to green, and then to blue at 0.67 and 1.08 V, respectively.

Synthesis of polyblends from polypropylene and poly(R,S)‐β‐hydroxybutyrate, and their characterization

AbstractBlends of modified polypropylene (PP) with poly(R,S)‐β‐hydroxybutyrate (PHB) were prepared by casting polymer solutions, followed by compression molding into thin films. The modified polypropylene was obtained by oxidation with hydrogen peroxide. Oxidation of polypropylene produced new functional groups such as carbonyl and hydroxyl groups on the polymer chain, and a decrease in molecular weight and crystallinity of the polymers. Maximum crystallinity and mechanical properties of the polyblends were found with a PP/PHB ratio of 90/10 (w/w), and then decreased with increasing PHB content in the polyblends. Biodegradability of the polyblends was lower than that of bacterial and synthetic PHBs. Furthermore, an increase of PHB proportion in the polyblends resulted in highly non‐compatible polyblends. Hence only PHB and small parts of the polyblends were decomposed by microorganisms. Copyright © 2006 Society of Chemical Industry

Surface Properties of Self-Organized Honeycomb-Patterned Films

ABSTRACT This paper describes the preparation of honeycomb-patterned films from hydrophobic fluorinated copolymers. Micro-porous polymer films from fluorinated copolymers with hexagonally arranged micro-pores were prepared by casting polymer solution under humid condition. The pore size of the honeycomb-patterned film was controlled by changing casting volume. The water contact angles on the honeycomb-patterned films were measured with changing their pore sizes. The water contact angle increased up to 145°, when the pore size decreased. These values fitted the theoretical calculations.

Electrochemical and electrochromic properties of novel aromatic poly(amine–amide)s derived from N, N′-bis(4-carboxyphenyl)- N, N′-diphenyl-1,4-phenylenediamine

A series of novel triphenylamine-containing aromatic poly(amine–amide)s were prepared from the dicarboxylic acid, N, N′-bis(4-carboxyphenyl)- N, N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine–amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195–280 °C). These polymers exhibited strong UV–Vis absorption bands at 330–346 nm and their photoluminescence showed maximum bands around 516–535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine–amide)s prepared by casting polymer solution onto an indium–tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73–0.78 V and 1.12–1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine–amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms.

Biomedical Application of Patterned Polymer Films Prepared by Self-organization

We have found that micro porous polymer films were prepared by simple casting of polymer solution under humid atmospheric condition when water-immiscible organic solvent was used as evaporating solvent. Mono-dispersed water droplets are formed on the surface of the casting polymer solution by water condensation due to evaporation cooling. A surface monolayer of the self-packed water droplets formed on the polymer solution surface acts as a temporary template of micropores. Honeycomb-like hexagonally packed regular-sized micro-pores were formed in the polymer film after evaporation of solvent and water. Biomedical application is an emerging requirement for the honeycomb-patterned polymer flms, especially of biodegradable polymers. Hepatocytes cultured on the honeycomb-patterned film formed spheroid expressing liver functionality, e.g. albumin secretion. The shapes and function of the liver cells can be regulated by the pore size of the honeycomb film. Spheroid aggregates were also formed from neural stem cells on the honeycomb-patterned film.

Drug release from cast films of ethylene vinyl acetate (EVA) copolymer: Stability of drugs by 1H NMR and solid state 13C CP/MAS NMR

The study utilizes an oral biocompatible material based on ethylene vinyl acetate copolymer (EVA) designed to release drugs in vitro at therapeutic levels over several days. We examined the drug stability during film casting process using proton and solid state NMR techniques. The drug-loaded EVA films were prepared from the dry sheet obtained by solvent (dichloromethane) evaporation of polymer casting solutions. Drugs tested include chlorhexidine diacetate (CDA), doxycycline hydrochloride (DOH), tetracycline hydrochloride (TTH) and nystatin (NST). Drug release from the films was examined for at least 14 days in 10 ml ddH2O (NST in water/ethanol (4:1)) which was replaced daily. Changes in optical density were followed spectraphotometrically. Effect of temperature on rate measurements was studied and the energies of activation (E*) were calculated using Arrhenius plots. Effect of EVA copolymer composition on CDA release rate was also investigated. The enhanced rates with temperature increase may be attributed to the formation of channels with increased geometry in the polymer. The highest E* observed for CDA compared to DOH and TTH may be related to their average molecular weights. Spectral analyses for CDA and NST revealed that the chemical and physical structures of the drugs remained unaffected during the film casting process.

Novel electrochromic aromatic poly(amine–amide–imide)s with pendent triphenylamine structures

Three new aromatic poly(amine–amide–imide)s (PAAIs) having pendent triphenylamine units were prepared from the phosphorylation polyamidation reactions of a newly synthesized diamine, N, N-bis(4-aminophenyl)- N′, N′-diphenyl-1,4-phenylenediamine, with three imide ring-preformed dicarboxylic acids. These PAAIs had inherent viscosities of 0.54–0.86 dL/g, and they were amorphous and readily soluble in many organic solvents and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They displayed relatively high glass-transition temperatures (279–287 °C) and good thermal stability, with 10% weight-loss temperatures in excess of 522 °C in nitrogen and char yields at 800 °C in nitrogen higher than 67%. The solutions of polymers in NMP exhibited strong UV–vis absorption bands with a maximum around 315 nm. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the PAAIs prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidation redox couples at 0.67 and 1.08 V vs. Ag/AgCl in acetonitrile solution. All the PAAIs revealed very stable electrochromic characteristics, changing color from original pale brownish to green, and then to blue at 0.67 and 1.08 V, respectively.

Novel family of triphenylamine‐containing, hole‐transporting, amorphous, aromatic polyamides with stable electrochromic properties

AbstractWe report the preparation and characterization of a series of novel electrochromic, aromatic poly(amine amide)s with pendent triphenylamine units. The synthesis proceeded via direct phosphorylation polycondensation between a novel diamine, N,N‐bis(4‐aminophenyl)‐N′,N′‐diphenyl‐1,4‐phenylenediamine, and various aromatic dicarboxylic acids. All the poly(amine amide)s were amorphous and readily soluble in many common organic solvents and could be solution‐cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability and 10% weight‐loss temperatures above 540 °C. Their glass‐transition temperatures were 263–290 °C. These polymers in N‐methyl‐2‐pyrrolidinone solutions exhibited strong ultraviolet–visible absorption peaks at 307–358 nm and photoluminescence peaks around 532–590 nm in the green region. The hole‐transporting and electrochromic properties were studied with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of poly(amine amide) films prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidation redox couples at 0.65 and 1.03 V versus Ag/AgCl in an acetonitrile solution. All the poly(amine amide)s showed excellent stability with respect to their electrochromic characteristics; the color of the films changed from pale yellow to green and then blue at 0.85 and 1.25 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2085–2098, 2005

Morphology and transport properties of protons and methanol through partially sulfonated block copolymers

The morphological changes with different compositions of casting solvents in the membranes of sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) were investigated with small-angle X-ray scattering (SAXS) and transmission electron microscope (TEM). Using the single solvent of tetrahydrofuran (THF) and the solvent mixtures of methanol/THF with different compositions, the casting polymer solutions were prepared for the membrane fabrication. The proton conductivity and the methanol permeability of membranes were measured, and the effect of morphological changes on the casting solvents was discussed through Flory–Huggins theory. It was found that the sulfonated SEBS membranes were transformed from well ordered lamellar to disordered co-continuous structure and the morphological difference caused abrupt enhancement in the proton conductivity and the methanol permeability as the concentration of methanol in the mixed solvents (MeOH/THF) increased.

Phase separation of polymer casting solution by nonsolvent vapor

Kinetics of phase separation of polymer solution layers induced by nonsolvent vapor was investigated. Polymer solutions were prepared with polysulfone (PSF) and N-methyl-2-pyrrolidinone (NMP) as a solvent. The phase separation was induced by exposing the solution layers to controlled water vapor. Using time-resolved small angle light scattering and phase contrast optical microscope, the kinetics of the phase separation was studied for several concentrations of polymer solution films. The phase separation took place as the solution layers absorbed nonsolvent (water) vapor. As the phase separation proceeds, the scattering halo was observed, which implies that the phase separation occurs via spinodal decomposition. Bicontinuous network structure, which is a characteristic morphology of the spinodal decomposition, was confirmed by optical microscopy. The analysis of the early stage of phase separation was based on Cahn–Hilliard theory and mutual diffusion coefficients were evaluated. The late stage of phase separation was analyzed by means of power law ( q m ∼ t −α). In the late stage of the phase separation, spontaneous pinning of phase domain was observed. Finally, when the phase-separated solution layers were coagulated in the water bath, it was found that the correlation length at pinning regime is proportional to the pore size of the resulting material.

Anion-exchange membranes containing diamines: preparation and stability in alkaline solution

Anion-exchange membranes (AEM) are prepared from chloromethylated polysulfone and a number of diamine compounds. The properties of the new AEM including the water content, ion-exchange capacity, permselectivity and area resistance are thoroughly studied. By varying the amount of diamine into the casting polymer solution, the properties of the membranes can be optimized. Generally for diamines with small aliphatic length of the alkanoic chain, excess of diamine is required to produce AEM with low electrical resistance and high permselectivity. The properties of the new AEM are also tested after exposure for several days into 2 M NaOH, at 40 °C. Generally, this exposure causes reduction of the membrane's ion-exchange capacity resulting in an increase of its electrical resistance and decrease of its water content and permselectivity. The degradation of the membranes depends on the length of the alkanoic chain in the diamine units, i.e. slower degradation rate is observed for membranes with longer alkanoic residues. Therefore, the membranes containing the N, N, N′, N′-tetramethylhexanediammonium (TMHDA) groups are the most stable under the studied alkaline environment. The AEM, however, containing N, N, N′, N′-tetramethylethylenediammonium (TMEDA) and bis- N, N, N′, N′-tetramethylbutanediammonium (TMBDA) groups decompose significantly.

Helical Shape Memory of Screw-Sense Switchable Polysilanes in Cast Films

The optically active poly[{(R)-3,7-dimethyloctyl-(S)-3-methylpentylsilane}-co-{decylisobutyl- silane}](PS-1) underwent a thermodriven helix−helix transition at 13 °C in isooctane. The casting of polymer solution from the pre- and post-transition temperatures led to P (right-handed) or M (left-handed) helical films, which gave positive and negative Cotton circular dichroism (CD) signals, respectively. This result suggests that the helical sense of PS-1 below and above transition temperature in the homogeneous solution was memorized in the cast films. Furthermore, the CD spectra of P- and M-helical films were mirror images to each other at 319 nm, indicating the 73 helical pitch of the polymers with opposite helical sense.

Spray Coatable Electrochromic Dioxythiophene Polymers with High Coloration Efficiencies

Four new disubstituted propylenedioxythiophene polymers have been synthesized by Grignard metathesis on the 1−5 g scale. All polymers were found to be soluble in chloroform, methylene chloride, toluene, and tetrahydrofuran and were fully structurally characterized having GPC determined number-average molecular weights ranging from 33000 to 47000 g mol-1. Dilute polymer solutions in toluene exhibited strong red fluorescence with moderate quantum efficiencies from 0.38 to 0.50. Homogeneous thin films were formed by electropolymerization and spray casting polymer solutions onto ITO coated glass slides at thicknesses of ca. 150 nm. The films were electroactive, switching from a dark blue-purple to a transmissive sky blue upon p-doping, often with subsecond switching times, and high electrochromic contrast luminance changes (% ΔY) of 40−70%. These studies revealed that the branched derivatives, [poly(3,3-bis(2-ethylhexyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)] and [poly(6,8-dibromo-3,3-bis(2-ethylhexyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)], gave an electrochemical response and associated color change over a much smaller voltage range in comparison to the linear chain substituted derivatives, [poly(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)] and [poly(3,3-bis(octadecyloxymethyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)]. Composite coloration efficiency values were found up to 1365 cm2/C; this was considerably larger than values obtained from previously studied alkylenedioxythiophene based polymers (∼375 cm2/C).

Membrane surface modification and characterization by X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements

Surface modifying macromolecules (SMMs) were used to modify the top surface of polymeric membranes. SMMs are oligomeric fluoropolymers synthesized by polyurethane chemistry and tailored with fluorinated end groups. In this study, the surface of polyetherimide (PEI) flat-sheet membranes prepared by the phase inversion method was modified using 2wt.% of SMM and 15wt.% PEI concentration in the polymer casting solution. The effect of solvent evaporation time on membrane surface modification was investigated. X-ray photoelectron spectroscopy analysis shows enrichment of fluorine on the modified PEI membrane surfaces and their contact angles were higher than those of the unmodified PEI membrane. Both the surface fluorine content and contact angles of the SMM/PEI blended membrane increased when the solvent evaporation time was increased up to 5min. The SMM modified and unmodified PEI membranes were characterized by means of tapping mode atomic force microscopy (TM-AFM). The mean pore size, nodule size, pore density, surface porosity and mean roughness of the modified membranes were determined and compared with those of the unmodified membrane.

Synthesis and characterization of fluorinated poly(amide imide)s derived from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and aromatic diamines

AbstractA series of fluorinated poly(amide imide)s were prepared from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and various aromatic diamines [3,3′,5,5′‐tetramethyl‐4,4′‐diaminediphenylmethane, α,α‐bis(4‐amino‐3,5‐dimethyl phenyl)‐3′‐trifluoromethylphenylmethane, 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene, 4‐(3′‐trifluoromethylphenyl)‐2,6‐bis(3′‐aminophenyl)pyridine, and 1,1‐bis(4′‐aminophenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane]. The fluorinated poly(amide imide)s, prepared by a one‐step polycondensation procedure, had good solubility both in strong aprotic solvents, such as N‐methyl‐2‐pyrrolidinone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and cyclopentanone, and in common organic solvents, such as tetrahydrofuran and m‐cresol. Strong and flexible polymer films with tensile strengths of 84–99 MPa and ultimate elongation values of 6–9% were prepared by the casting of polymer solutions onto glass substrates, followed by thermal baking. The poly(amide imide) films exhibited high thermal stability, with glass‐transition temperatures of 257–266 °C and initial thermal decomposition temperatures of greater than 540 °C. The polymer films also had good dielectric properties, with dielectric constants of 3.26–3.52 and dissipation factors of 3.0–7.7 × 10−3, and acceptable electrical insulating properties. The balance of excellent solubility and thermal stability associated with good mechanical and electrical properties made the poly(amide imide)s potential candidates for practical applications in the microelectronics industry and other related fields. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1831–1840, 2003

A polymeric device for delivery of anti-microbial and anti-fungal drugs in the oral environment: effect of temperature and medium on the rate of drug release

Objectives. The use of drug delivery systems in dentistry is a relatively new area of research with the exception of fluoride ion release from polyalkenoate cements and their predecessor silicate cements. The present study is based on the use of a bio-compatible material ethylene vinyl acetate copolymer (EVA) that enables constant release of drugs of therapeutic levels over extended periods of time at doses suitable for the treatment of oral conditions. Method. Polymer casting solutions were made by dissolving EVA and the drug in the ratio of 40:1 in 70 ml of dichloromethane at 38 °C for 6 h. Thin square films of 3×3 cm 2 with a thickness of 1 mm were cut from the dry sheet obtained by solvent evaporation technique. Drug loaded samples were extracted for a minimum of 14 days in 10 ml medium (double distilled water or water/ethanol (4:1)) which was replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Effect of temperature (24 and 37 °C) on the rate of drug release was studied and the energies of activation (Δ E ≠) were calculated using Arrehenius equation for the diffusion (translocation) of molecules of tetracycline hydrochloride (TTH), doxycycline hydrochloride (DOH), and chlorhexidine diacetate (CDA) in water as extracting medium. Effect of extracting medium (water and water/ethanol (4:1)) was also investigated on the rate of drug release measurements at 24 °C. Results. Analysis of variance of the data revealed that significantly enhanced rates were observed at the higher temperature (37 °C) and when extracting medium was changed to water/ethanol (4:1) for TTH, DOH and CDA ( p<0.0015). The enhanced rate values seem to be due to the formation of channels in the polymer. The largest activation energy (21.83 kcal mol −1) observed for CDA was interpreted as due to the highest average molecular weight (626) compared to TTH (481) and DOH (481). Significance. These in vitro rate of drug release measurements will provide a basis for establishing a novel approach (treatment modality) for sustained intra-oral drug delivery over extended time periods using laboratory methods and materials that are readily available to dentists.