To improve the efficiency of topical ocular drug administration, we focused on development of a nanoparticles loaded contact lens to deliver the hydrophobic drug over a prolonged period of time. The cross-linked nanoparticles based on PCL (poly ε-caprolactone), 2-hydroxy ethyl methacrylate (HEMA), and poly ethylene glycol diacrylate (PEG-DA) were prepared by surfactant-free miniemulsion polymerization. The lens material was prepared through photopolymerization of HEMA and N-vinylpyrrolidone (NVP) using PEG-DA as the cross-linker. Effects of nanoparticles loading on critical contact lens properties such as transparency, water content, modulus and ion and oxygen permeabilities were studied. Nanoparticles and hydrogel showed high viability, indicating the absence of cytotoxicity and stimulatory effect. Drug release studies revealed that the hydrogel embedded with nanoparticles released the drug for a period of 12 days. The results of this study provide evidence that nanoparticles loaded hydrogels could be used for extended delivery of loteprednol etabonate and perhaps other drugs.

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4,4'-(Hexa¯uoroisopropylidene)-bis-(phthalic anhydride) (1) was reacted with L-leucine (2) in toluene solution at re¯uxing temperature in the presence of triethylamine and the resulting imideacid (4) was obtained in quantitative yield. The compound (4) was converted to the diacid chloride (5) by reaction with thionyl chloride. The polymerization reaction of the imide-acid chloride (5) with 1,6hexamethylenediamine (6a), benzidine (6b), 4,4'-diaminodiphenylmethane (6c), 1,5-diaminoanthraquinone (6d), 4,4'-sulfonyldianiline (6e), 3,3'-diaminobenzophenone (6f), p-phenylenediamine (6g) and 2,6-diaminopyridine (6h) was carried out in chloroform/DMAc solution. The resulting poly(amide-imide)s were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by IR, elemental analyses and speci®c rotation. Some structural characterization and physical properties of those optically active poly(amide-imide)s are reported.

The aim of this study is to investigate the in situ encapsulation of n-hexadecane as a phase change material (PCM) with a polymethyl methacrylate (PMMA) shell through miniemulsion polymerization. n-Hexadecane (HD) and methyl methacrylate (MMA) form dispersed minidroplets in the aqueous phase, whereas PMMA is immiscible with n-hexadecane and separates through polymerization to produce hollow polymer particles filled with n-hexadecane. Different HD:MMA ratios and ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent were considered to optimize the encapsulation process. A new approach by using novel equations from DSC, DLS, and microscopy analyses were developed to estimate shell thickness and the extent of contribution of MMA in the formation of the nanocapsules, pure polymeric particles, and also the void fraction of nanocapsules. It was found that the weight fractions of pure polymeric particles for the prepared samples were 12–17 wt %, and the shell thickness of the nanocapsules was about 12 nm. Also, the void fractions for these samples were 69–77%.

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The reaction of N‐phthaloyl‐L‐leucine acid chloride (1) with isoeugenol (2) was carried out in chloroform, and novel optically active isoeugenol ester derivative 3 as a chiral monomer was obtained in high yield. Compound 3 was characterized by 1H‐NMR, IR, and mass and elemental analysis and then was used for the preparation of model compound 5 and polymerization reactions. 4‐Phenyl‐1,2,4‐triazoline‐3,5‐dione, PhTD (4), was allowed to react with compound 3. The reaction is very fast and gives only one diastereomer of 5 via Diels–Alder and ene pathways in quantitative yield. In order to explain this diastereoselectivity, a nonconcerted two‐step mechanism involving benzylic cation (BC) and aziridinium (AI) have been proposed for the Diels–Alder and ene reactions, respectively. The polymerization reactions of novel monomer 3 with bis(triazolinedione)s [bis(p‐3,5‐dioxo‐1,2,4‐triazolin‐4‐ylphenyl)methane (8) and 1,6‐bis(3,5‐dioxo‐1,2,4‐triazolin‐4‐yl)hexane] (9)] were performed in N,N‐dimethylacetamide (DMAc) at room temperature. The reactions are exothermic, fast, and gave novel optically active polymers 10 and 11 via repetitive Diels–Alder–ene polyaddition reactions. These polymers have inherent viscosities in a range about 0.18–0.22 dL/g. Some physical properties and structural characterizations of these new polymers have been studied and are reported. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1211–1219, 1999

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