*Polymer Properties: Functionalization and Surface Modified Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.84424*

*Role of Novel Drug Delivery Vehicles in Nanobiomedicine*

Hence, polymers are prepared by the abovementioned two versatile polymerization methods, and there are several modified methods and approaches that can be followed for the preparation and synthesis of polymers such as ring-opening polymerization (R-O-P), emulsion polymerization, precipitation polymerization, diffusion polymerization, macroinitiator polymerization, macroinitiator polymerization, and atom transfer radical polymerization (ATRP) methods. As per the literature, first in the 1970s, lactic acid (LA)-based nanoparticles and capsules are

*Some of the polymers with their chemical structure, name, and active functional groups which are involved in* 

**142**

**Figure 1.**

*functionalization and polymerization reactions.*

used for biomedical and other pharmaceutical applications, and later it has been extended for various fields [26]. Polymers when considered for biomedical applications, it needs to refer self-assembly nature and functionality followed by the formation of spherical and sphere-shaped nanocapsules and particles particularly for drug delivery systems. Based on degradability, thermosensitivity, and pHresponsive nature, these are again categorized into various classes and reported in **Figure 2** with some examples. However, biodegradable polymers which show a tendency to degrade in biological systems such as polylactic acid (PLA), polyglycolic acid (PGA) and poly terephthalic acid (PTA), polycaprolactone (PCL), and amino acid (AA)-based polymers are potential materials to engineer nanoparticles and capsules for nanotechnology and nanobiotechnology applications. The polymers which do not degrade in the biological systems are termed as non-biodegradable polymers such as carboxymethyl, ethyl cellulose, and acetates of cellulose. The poly anhydrides like poly sebacic acid (PSA), poly adipic acid (PAA), and other environmental-responsive polymers also enlisted in the non-biodegradable polymers. Thermo-responsive (temperature-sensitive) polymers show a significant change in the size and shape of nanoparticles to tune up based on requirements [27]. The thermosensitive behavior of PNIPAM and pH-responsive nature of L-glutamic acid gamma benzyl ester (L-GluA-5-BE), L-aspartic acid beta benzyl ester (L-AspA-4-BE), polyethylene glycol (PEG), poly L-glycolic acid (PLGA), and PAMAM allow changing the morphology of nanoparticles as well surface profile of the NPs and capsules (**Figure 1**). Apart from these polymers, electrical-responsive polymers show piezoelectric effects which are a characteristic property to mold the nanoparticles based on requirements. The supramolecular interactions between the atoms and molecules lead to compression or elongation and stretching of bonds, and it can play a vital role to change the properties of final compounds. However, polyvinylidene fluoride (PVDF) polymer has been considered as one of the magic polymers which allow structural and morphological modifications through the appropriate synthesis and preparation methodologies [28].

The chemically responsive polymers allow internal changes through the formation of anionic and cationic and amphiphilic nature through the oxidation, reduction, and redox (both oxidation and reduction) reactions and lead to surface modification based on smooth and rough surface. As per the literature, the increase in the size of the particles depends on an increase in monomer units or polymer units. Sometimes branching and hyper-branching nature also lead to the formation of larger nanoparticles and capsules. Polymers prepared with the

**Figure 2.**

*Some of the polymers categorized based on their characteristic properties.*

combination of a large number of high molecular mass polymers give micronsized nanoparticles, and they can be used for bulk phenomenal approaches such as absorption, chemisorption, etc. There is a class of polymers named as block copolymers, and these are again categorized into several such as (a) random block copolymers (BCPs), (b) star block copolymers, (c) grafted block copolymers, and (d) alternating block copolymers, and these are classified based on their synthesis approaches and final structural confirmations, and these are low-density polymers (**Figure 2**) [20, 21, 26–29].
